This is a chronological look at the weekly learning objectives for the old AP Biology curriculum. Please visit jcibapbiology.wordpress.com for my take on the redesigned curriculum. There you will find “The Daily Grind“, a blow-by-blow look at my class, and “Essential Readings and Essential Figures”, here I am directing my students to the basic stuff they should already know or can learn on their own. I’m saving the more difficult and interesting content for class.
The schedule below, and the more the detailed account found on my AP Biology Weekly Schedule page of this blog will remain here for posterity(?), a historical perspective, and serve as contrast between the “old” course and the “new” course.
If you are hitting all of the learning objectives described below before mid April, then you are on pace and your students will be successful on their AP Biology exam. If you have questions, comments and concerns, just leave a reply. I will respond to your comments and adjust this page as needed.
AP Biology Overview:
I don’t want to bog down with too much educational philosophy early in the post. You can get a decent understanding for the way I approach AP Science from the page “11 things every AP Science teacher should know”. However, I do want emphasize three major points that should guide your AP Biology class.
First, although this pacing guide begins with Ecology, it is not a complete reversal of the way you have taught AP Biology in the past. Robert Summers and I are constructing a pacing guide for the entire year, but we have only completed the first unit. We envision your AP Biology class to progress as follows:
Unit I: Themes in Biology; Ecology
Unit 2: The Chemistry of Life,
Unit 3: The Cell
Unit 4: Bioenergetics
Unit 5: Molecular Biology
Unit 6 Genetics
Unit 7: Evolution
Unit 8: Biodiversity of microorganisms and animals
Unit 9: Animal Structure and Function I (Neurophysiology, Endocrine Physiology, Cardiovascular Physiology, Immunology)
Unit 10: Animal Structure and Function II: Digestive Physiology; Excretory Physiology; Reproductive Physiology and Development
Unit 11: Plant Biodiversity and Botany
Unit 12: If time permits: review of major concepts like Bioenergetics, Homeostasis and regulation
Our goal is to guide you and your students through the 80% of the curriculum that comprises roughly 100% of the AP Biology exam. We want to focus on the most important parts of the curriculum.
Second, AP Biology is a marathon, not a sprint. We are progressing through a long race that begins easy, that allows you to get into a groove once you’re warmed up, that gets harder as your endurance flags, that pushes you to “the wall.” Whether you hit the wall or not, you will get to the finish line, you will proud of your accomplishments, you will be worthy of praise for doing something most people will never attempt and your students will be successful on the AP Biology exam on Monday, May 9, 2011 .
The third point is also philosophical. You have to set the tone for the entire year during the first week of class. You have to establish your classroom culture; you should set your expectations high. You should be very upfront with your students about the effort involved in an AP science class, but you should also let them know they will be rewarded for their efforts. Most importantly, establish a culture of collaboration.
AP Biology has to be a group effort. It’s too big a load for one person to carry. This isn’t about teacher versus students. It’s about teacher working with students, and students working with other students. You can’t establish that culture if you’re lecturing all the time. You need to enter into a dialogue with your students. You need to know what your students know, and you need to know what your students don’t know. You need to start relatively slow. You need to engage them in relevant activities this week and you need to provide them feedback as to how the week has progressed. There will be time to increase the volume of content and the difficulty of the activities. But this is not that time.
AP Biology Week 1, Learning Objectives
1) Assess students’ basic understanding of cell biology through writing.
How: give students an opportunity to write an answer to the Question One (Q1) of the 2006 AP Biology Free Response Questions (FRQ).
2) Review the major themes of biology, emphasizing the biological hierarchy (a systems approach), as a model for identifying the major themes in biology.
How: Discuss the major themes in chapter 1 and asking students to fill in a matrix that links each level of biological organization with the major themes in biology. These themes in biology are the characteristics all biological systems possess. Examples of these characteristics, however, are dependent on the system under investigation. For instance, a cell within a tissue has a different mode of maintaining dynamic balance than an organism does.
3) Review the basics of Ecology including the scale of ecology (populations – biosphere), the importance of incoming solar radiation and the tilt of the Earth in determining the distribution of major terrestrial biomes, and the basics of characteristics of aquatic biomes.
How: Discuss the basic elements of chapter 50 and use one of two potential activities to describe biome distribution. Present students with a climograph and have them label each major biome and research the average precipitation and temperature regime for each biome. Or, give them the maximum and minimum temperature and precipitation data for each biome and have them graph the biomes on a horizontal axis (for temperature) and a vertical axis for precipitation.
4) Introduce the major concepts related to population ecology including: i) distribution of populations, ii) survivorship curves and iii) r- vs. k- selection.
How: i) present students with three common distribution patterns of populations, have them describe the pattern, come up with a population that would exhibit the pattern and explain why the pattern exists. ii) have students graph three typical survivorship curves based on data from condensed Life Tables, then have students predict what type of population would exhibit each type of curve. iii) relate the survivorship to life history strategies (r- vs. k-) and ask students to describe the characteristics of both r-selected and k-selected organisms.
There is a theme here, get your students to do the work. You could tell your students all of this, and they may or may not “get it”. You don’t have any real way of knowing until the exam comes up in late August. On the other hand, if you are engaging your students and getting to graph the data you present them and interpret those graphs with their peers and with you, then you will get a good idea of whether or not your students understand the concepts you are trying to teach.
AP Biology Week 2, Learning Objectives.
1) Continue working with major concepts in population ecology. Link survivorship curves and r- and k- selection with the Logistic Growth Model and emphasize the importance of “carrying capacity” (K). Teach the components of the Logistic Growth curve and describe what is happening to a population at each phase of the logistic curve (lag phase, log phase, and as it approaches and hovers near K).
How: Provide your students with data sets that show population size vs. time, have them graph the data and describe what is happening at each point in the curve.
2) Discuss the basic concepts of community ecology: focus on species interactions as a win/win or win/lose situation (See Campbell). Also focus on concepts like niche, generalist and specialist
How: Lead a discussion of community interactions and use an interaction matrix to guide the discussion.
3) Discuss the more dynamic, and difficult, aspects of community ecology including Disturbance, Succession and Island Biogeography.
How: Lead a discussion on these concepts. It might be a good idea to use the 2010 AP Biology FRQ 4 to lead this discussion. Allow students to write to the prompts, but not for a grade. I would avoid the graphs on island biogeography, and approach about this concept as a geography lesson (a mainland and large and small and near and far islands. (I can design a power point slide if necessary).
4) Discuss the trophic aspects of community ecology: food webs, food chains and trophic structure.
How: Students can draw typical food chains for different biomes. If time permits, take your students outside and let them find a community and draw a food web within that community. Be sure to discuss why food chains are rarely more than 4 “links” long.
5) Introduce the Ecosystem model featured early in Chapter 54. Students should be able to recognize the different trophic levels in this model and see that Energy flows through ecosystems and materials are recycled within ecosystems. Be sure to emphasize the role of detritus and remineralizers within the ecosystem.
How: Have students fill in a blanked out ecosystem model on Figure 54.2 and describe organisms within each trophic level. Explain the “Rule of 10” within trophic pyramids.
This was a whirlwind week, but you hit about 7 to 8% of all the ecology on the AP Biology Exam by the end of it. Next week you will wrap up Ecosystems, perform your first of the twelve required labs and have your first exam. Notice the emerging theme: you are not teaching everything. You’re teaching the content that shows up on the AP Biology exam in a deeper, more meaningful way. Notice also that you are only working out of 4 of the 6 chapters in Ecology. There are a few chapters in Campbell and Reese (Ed. 7) that can easily be skipped, this unit contains two of those chapters. Chapter 55, Conservation Ecology, rarely shows up on the AP Exam, and the chapter on Animal Behavior is so “readable” your students will pick it up on their own.
AP Biology Week 3, Learning Objectives.
1) Continue teaching the ecosystem concept. Make sure you emphasize two things: the synergy between decomposers and remineralizers and how they maintain ecosystem function. This is what really keeps sustains ecosystems. The energy for an ecosystem is ultimately derived from the sun, but the remineralizers return the raw materials back to primary producers so they can sustain the trophic pyramids.
How? Continue working with the ecosystem model in Chapter 54.
2) Discuss the fundamental zones of aquatic ecosystems (photic and aphotic zones, littoral zone, benthic zone). Relate these zones to the trophic levels. Who lives in each zone? Producers? Consumers? Remineralizers? All of the above?
How? Lead a discussion on aquatic biomes and relate it back to the ecosystem model in Chapter 54.
3) Ensure that students understand community productivity and community respiration and the difference between Gross Primary Productivity, Respiration and Net Primary Productivity.
How? Perform AP Lab 12, Part B, The Light and Dark Bottle Experiment. This lab allows students to measure the difference between community productivity, community respiration and the effects of abiotic factors (light) on ecosystem function.
Relax. Breathe deep. You just completed your first AP Bio unit of the year. At this point the students should know your expectations. They should know they are expected to show up to class ready to work, they should be comfortable graphing data, explaining what the graphs represent and they should be gaining confidence in their ability to articulate the reasons for the trends they describe.
Pat yourself on the back and give your students the credit they deserve. You all just uncovered 10% of the content of the AP Biology exam and it’s not even Labor Day. None of those schools in the Northeast, the mid-Atlantic, the Midwest and the West Coast have even started school yet!
Get ready to dive deep into the stuff these ecosystems are made of. The next unit is on the Chemistry of Life. Following that, you and your students will take a close look at the basic unit of structure and function of all biological systems…The Cell. Ohhh, this is going to be so much fun.
AP Biology Week 4: The Chemistry of Life I, Learning Objectives
1) Review basic chemistry and emphasize the importance of water in biological systems.
How? Assign Chapter 2 as homework. Discuss Chapter 3.
2) Discuss the importance of carbon, the “big 6” functional groups, monomers vs. polymers and dehydration synthesis vs. hydrolysis (notice the importance of water here)
How? Discuss Chapter 4, have student groups research one of the six functional groups and report back to the class.
3) Teach the structure and function of the four major classes of macromolecules:
a. Carbohydrates: structure and energy
b. Lipids: energy, structure and chemical signals
c. Nucleic Acids: information storage
d. Proteins: communication, structure, movement and enzymes
How? Integrate building models of important macromolecules with a discussion of their structure and function. If you have modeling kits available. If you need advice on inexpensive model ideas, please let me know.
AP Biology Week 5: The Chemistry of Life II, Learning Objectives
1) Teach the structure of proteins from primary to quaternary structure. Be sure to emphasize the role of hydrophobic and hydrophilic interactions in protein folding and the role of interactions between r-groups that hold proteins in a stable conformation.
How? Have students to use models like plastic “tangles”, pipe cleaners, or the like to build the various structures of a protein
2) Teach the importance protein function within a cell. Emphasize their role in cell structure, cell communication and as enzymes.
How? Lead a discussion on the various roles proteins play. End with enzymes. Use your best activity to engage students in how enzymes work. Ask me for ideas if you’re tired of your activities.
3) Teach the essential role of enzymes as biological catalysts.
How? Perform AP Lab 2: Enzyme Catalysis. Options include: the College Board’s published AP Lab 2, using probe ware and Oxygen or pressure sensors, or using Hudson Alpha’s cholinesterase lab. If you need assistance with any of these options, please ask.
4) Assess Chemistry of Life Unit
How? Give students Question 1, Part A from the 2008 FRQ Exam. The multiple choice exam should follow on Monday.
AP Biology Week 6: The Chemistry of Life Assessment/Cells, an introduction. Learning Objectives
1) Conduct a formative assessment of your Chemistry of Life Unit.
How? Unit 2 Exam. I suggest no more than 45 MCQ. Use released AP questions, AP-level questions from LTF Diagnostics, AP-Level Questions from your test bank. I have old tests I am happy to share.
2) Compare and contrast eukaryotic and prokaryotic cells. Pay particular interest to what a cell is NOT. It is not a 2-D thing on a microscope slide. Cells are 3-D objects with internal structures, deep connections with the extracellular environment. They exhibit all the properties of biological systems.
How? Lead a discussion of cell structure and function and embed a quick microscope lab looking at a “typical” plant and animal cell. I prefer Elodea and human cheek cells. If your anatomy teacher has good animal tissues; kidney, lung or intestinal cells work well.
3) Emphasize the essential concept of surface area to volume relationships (SA:Vol), and how that relationship drives the evolution of cell shape and the evolution of membrane-bound organelles. Surface area to volume also governs transport across membranes. I believe SA:Vol is one of the most important concepts in all of AP Biology. If the students grasp this concept here, they will be well on their way to understanding both bioenergetics and plant and animal structure and function.
How? This concept is best addressed through a laboratory activity. Several good labs exist: LTF’s “Larger is not always better”, the bullion cube lab, or PASCO or Vernier’s Cool Fruit lab. The last two can be conducted with our without probeware.
4) Teach structure and function of cell membranes and all the various ways cells exchange materials with their environment: passive transport (diffusion, osmosis, facilitated diffusion); active transport; co-transport. These are also essential concepts, and will be applied during bioenergetics and plant and animal structure and function units.
How? Lead a discussion and perform AP Lab 1, Part A as a demo or have students conduct this in small groups.
Notice the recurring theme. Minimize the lecturing and emphasize the laboratory work and the activities. Students should be held responsible for their reading and the conceptual underpinning of the laboratories. You can assess this on your unit exams and on your laboratory write ups. I think you should spend the majority of your time in class working with your students, doing science. This will increase their understanding of the content and help them be successful on their AP Biology exam.
AP Biology Week 7: Cells, intercellular interactions. Learning Objectives
1) Students should have a good working knowledge of diffusion, osmosis, water potential and tonicity.
How? Perform AP Lab 1, Parts B, C, and E. Part D can be done for homework.
2) Students should understand the following structures and functions: the cytoskeleton, plant cell walls, the animal Extra cellular Matrix (ECM) and intercellular junctions (plasmodesmata, tight junctions and gap junctions).
How? Lead a discussion of these components. If time permits conduct more microscope work. This time stain elodea with Safrannin and stain potato slices with saffranin and iodine. Students should be able to see cell walls and amyloplasts clearly.
3) Students should have a basic understanding of Cell-to-cell Communication. I think they only need to know the components of a Signal Transduction Pathway and what types of cellular responses occur. These concepts will be reapplied during student activities with the endocrine system, the nervous system and plant hormones.
4) Introduce the concept of the Cell Cycle. Your focus should be on why cells divide anyway, what is being replicated and divided (DNA) and Figure 12.5 (both 7th and 8th Edition). Notice the emphasis on mitotic (nuclear) division in the context of the entire Cell Cycle.
AP Biology Week 8: Cells, The Cell Cycle. Learning Objectives
1) Students should have a good understanding of the phases of mitosis and their relationship to the Cell Cycle.
How: Students should perform AP Lab 3A, Parts 1 & 2. I recommend Onion Root tips. Carolina and Wards have excellent prepared slides. I would skip Whitefish blastula and definitely skip AP Lab 3B (Meiosis).
I have a good kinesthetic model for describing the cell cycle. I will share it with anyone interested.
2) Students should understand the internal controls of the cell cycle. Special emphasis should be placed on Checkpoints (see Figure 12.14) and the importance of cyclins and kinases in pushing the cell through these checkpoints.
How: I hate to say it, but lecture on this material. If anyone has a good model for this, please share it.
3) Students should have a basic understanding of external influences on cell division like density dependence and anchorage dependence. This will lead to a brief discussion of cancer, characteristics of cancerous cells and metastasis.
How: Lead a discussion on these concepts.
AP Biology Weeks 9-11, Bioenergetics: Learning Objectives. (Chapters 8, 9, 10)
The Key to the bioenergetics unit, typically the most challenging unit in AP Biology, is to focus on the big picture ideas and avoid bogging down in the details. For each phase of cellular respiration and photosynthesis, students should know the inputs and the outputs. Only rarely are the details of each phase important (exceptions being oxidative phosphorylation of ATP in mitochondria and photophosphorylation of ATP in chloroplasts). Even when the details matter, look for ways to link these complex processes to prior student knowledge.
There are four major learning objectives in this unit:
Objective 1) Understand laws of thermodynamics and how
they relate to biological systems and the biological processes of metabolism, glycolysis, oxidative phosphorylation and photosynthesis.
Objective 2) Understand that organisms are interdependent, open systems that respond to their environment by converting energy from one form to another form of energy. (Energy is conserved, it’s merely transformed. Students already know that these energy transformations aren’t 100% efficient because they have learned about trophic pyramids.)
Objective 3) Understand how mitochondria work within the cell to harvest chemical energy, and how chloroplasts work to convert solar energy to chemical energy.
Objective 4) Understand the fundamental cellular process of chemiosmosis and its central role in ATP production.
Hint: I don’t spend a lot of time on fermentation, and I save photorespiration for my botany unit at the end of the year. Students struggle mightily with fermentation, so I let it go. I bring photorespiration in at the end of the year allowing me to focus on plant evolution and review bioenergetics.
Veteran teachers may find this approach overly simplistic, but trust me; breaking down these complex processes into simple steps works.
Allow me to give you an example of this strategy. Look at Figure 9.15 (Campbell, Edition 7). This is one of the most complicated figures in the entire text. I see it as three simple processes with one big pay off. First, I highlight Protein Complex 1 as “Active transport” a membrane-bound protein is shuttling an ion against its concentration gradient using energy. In this case the energy is the flow of electrons across the inner membrane of the mitochondria). Second, I focus on the “protons” in the orange part. This is a high concentration of hydrodronium ions (a low pH). They’re positive ions, and they’re Hydrogen, therefore it’s an electro-chemical gradient. Particles in high concentration “want” to move to low concentration. How do these protons move? This brings us to point number three. The ions can only move through the ATPase protein complex…this is facilitated diffusion. In this case, facilitated diffusion of H+ ions is coupled with ATP synthesis (the big payoff). We call this process oxidative phosphorylation because oxygen was “pulling” the electrons down the ETC, supplying energy for the electro-chemical gradient, which was tapped to make ATP. See, it’s easy!
Unit 5: Molecular Genetics. Yes, I want you start with molecular genetics and then come back and teach “classic genetics” and meiosis. I realize this is a micro-to-macro approach, but there are several reasons for this approach. First, students are naturally interested in DNA and modern aspects of biology. The simple elegance of DNA replication and DNA translation are fascinating to students. They “get it.” Students intuitively understand that their genes help direct their growth and development. It is important to explicitly state that gene products interact with each other and these genes and their products are under the influence of the environment. Second, knowing what DNA is, and knowing what genes are, helps students better understand the abstract ideas of alleles, diploid, homozygous and heterozygous, and all the other terms that go with Mendelian Genetics. Finally, the concept of genetic mutation gets applied in the next unit (Unit 5) when students study polygenic inheritance and human genetic diseases. This approach allows students to develop an appreciation for the importance of DNA and the gene products that stem from DNA.
I hope you’ve learned this by now, but you need to emphasize the big picture and not get bogged down in the details. These chapters are thick with details. Please follow my lead and focus on the big picture and essential details that support the big ideas.
During the next four weeks you will uncover 11% of the entire AP Biology Curriculum (according to the Course Outline available at AP Central). This includes Molecular Genetics (9%) and Eukaryotic Genomes (2%). At the end of Unit 5, you will have uncovered 46% of the AP Biology curriculum.
Week 12: DNA Structure and Function (Chapter 16, Campbell Ed. 7),
Objective 1) Students should understand the “Road to the Double Helix”. They might groan at the history lesson, but history is important. Uncovering the experiments of Grifith (the “dead mouse guy’), Avery (the “naked DNA guy”), and Hershey and Chase (the blender experiment), and then applying these results to the descriptive science of Chargoff, and (Franklin), Watson and Crick. This allows students to appreciate the step-wise nature of science and how evidence can be compiled to come up with understanding.
Objective 2) Students need to understand the basic structure of DNA. Look at Figure 16.7 (it’s essential). They should be able to confidently describe the over all structure, the bonding patterns between nucleotides, and the concept of “anti parallel”. This last point helps students understand why the orientation of the molecule (5’ to 3’ vs. 3’ to 5’) is important, and it sets them up to understand how DNA can be an excellent information storage molecule.
Objective 3) DNA replication is “semi-conservative” Half of the old strand is saved every time a DNA strand is replicated.
Objective 4) DNA replication (NOT DNA EXPRESSION) is necessary for chromosome replication (mitosis and meiosis) and this replication is facilitated by a host of enzymes (Table 16.1 and Figure 16.6). The biggest hang up is the “leading strand vs. the lagging strand). Email me if you need help with that.
Week 13: From Gene To Protein (Chapter 17, Campbell, Ed. 7).
Like Chapter 9, this is one of the most important chapters in the book. It’s got lots of details, but we need to focus on the big picture. I avoid the more difficult concepts like Beadle and Tatum’s experiment and Sanger’s experiments where he cracked the Genetic Code.
Objective 1) Jump right in on Page 311, Basic principles of transcription and translation. This is very straightforward. Students should know the basic components of the “Central Dogma of Molecular Biology” the concept of a Codon and how Codons are translated by t-RNA, and how ribosomes bring mRNA, tRNA and their associated Amino Acids together.
Objective 2) Transcription: DNA directed, and Protein mediated, synthesis of mRNA. Focus on the three main steps: Initiation, Elongation and Termination. Figure 17.7 is the essential figure here. Students need to know that RNA polymerase does bind to a promoter and that it works in a 5’ to 3’ direction…therefore the template strand of DNA is the 3’ to 5’ strand.
Objective 2a) mRNA splicing. Prokaryotes don’t splice mRNA, eukaryotes do splice mRNA. Students need to know the difference between introns and exons (exons exit the nucleus and are expressed!). They need to know about the cap and tail on mRNA, and they need to know that Spliceosomes do the splicing (Check out figure 17.10 and 17.11)
Objective 2b) Translation: RNA directed synthesis of a polypeptide. You’ll need a good animation to teach this, I like: http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter15/animations.html it’s simple, but get all the points across. Your students need to know all the players (mRNA, tRNA and rRNA). They need to know the BASIC structures of these molecules and they need to know that ribosome “move along” mRNA in a 5’ to 3’ direction. Why does this matter? This orientation determines the primary structure of the resulting polypeptide.
Objective 2c) Post-translation:
i) Discuss the role of polyribsomes…a little bit of mRNA can go a long way.
ii) All protein synthesis starts in the cytosol, however “free ribsomes” usually synthesize proteins that stay in the cell. Ribosomes that are translocated to the Rough ER synthesize proteins that are secreted by the cell (check out figure 17.21)
Objective 3) The molecular basis of mutation. Students need to be able to differentiate between silent mutations, mis-sense mutations and non-sense mutations. They should know that substitutions are usually less harmful than insertions and deletions because the latter can lead to “frame shifts” (all the “downstream” codons are mis-read).
Check out http://learn.genetics.utah.edu/ for interactive computer simulations on Transcription and Translation. I rely heavily on my “pop beads” to teach synthesis of DNA, RNA and Protein. It’s likely you have good interactive models from your pre-AP biology class. These interactives are great, you provide more detail with your discussion and then reinforce these ideas with AP Biology Lab 6a and 6b.
Week 14: Application of Gene to Protein and microbial genetics.
(Ch. 18 Campbell’s Biology, Ed. 7)
Reinforce the concepts from Chapter 17 (From gene to protein) and teach Chapter 18 (The genetics of viruses and bacteria) simultaneously by performing a bacterial transformation. Bio-Rad’s pGLO kit is the best one I know of. I teach the bacterial genetics (Section 18.3) first; Operons and control of gene expression (Section 18.4) second, and then come back and brush up on viral genomics (Sections 18.1 &18.2). I go light on genetics of viruses because bacterial genetics (and AP Bio Lab 6a) are emphasized on the exam.
Objective 1) Bacteria have one chromosome, and speed of replication is of the essence. The majority of genetic mutations in bacteria rely on the speed or replication and the fact that genes mutate to cause the genetic changes that natural selection works on.
Objective 2) In addition to spontaneous mutation, genetic diversity of bacteria is caused by transformation, conjugation, transduction and transposition.
Objective 3) Although bacteria don’t have introns, they can control gene expression. The most basic way bacterial cells control gene expression is through operons. Students need to understand both inducible and repressible operons.
Objective 4) Students should be familiar with different types of viruses. Focus on phages and retroviruses. These are the two types that AP Biology test development will focus on. Students should understand both the lytic and lysogenic cycles of phage development. They should also understand the lifecycle of a retrovirus. Focus on HIV. You can also save this concept for your Immunology Unit.
WEEK 15: Brief Overviews of EUKARYOTIC GENOMES (Ch. 19) and BIOTECHNOLOGY (Ch. 20). Molecular Genetics Exam.
Objective 1) There are really only four essential concepts to eukaryotic control of gene expression.
1a) Most control is PRE-TRANSCRIPTIONAL! I tell my students, if it’s transcribed, it’s likely to be translated…that wastes energy if the protein isn’t needed (Fig 19.3)
1b) Genomic control happens on the chromatin level thanks to histone proteins. If the histones are wrapped tightly (methylated), the genes are likely to be “locked down”. If the histones are loose (acetylated), then genes are likely to be open for transcription (Figs 19.2 and 19.4)
1c) Intron and exon splicing adds to control of gene expression (Fig 19.5).
1d) Distal control elements and transcription factors interact with promoter regions to control gene expression. Bottom line, eukaryotic genomes are bigger, more complicated and have more complex promoter regions. (See Figure 19.6) This is a 200-level genetics topic. If students get the basics, they’re in great shape.
Objective 2) Understand the principle of electrophoresis and the role of restriction enzymes in cutting DNA and cloning genes. Students should also be familiar with PCR, Southern Blotting (using radioactive DNA probes) Western Blotting (using Antibodies to look for proteins) and they should have heard of bioinformatics. (Bioinformatics and PCR will become more important in the coming years, but don’t worry too much about it now.)
Weeks 19-20: Classic Genetics (Ch. 13, Ch 14, Ch 15)
This is a fast and furious look at one of the most important aspects of biology, Genetics. I intend for you to teach the concepts students need to know to be successful on the AP Biology Exam. Much of the content in Biology by Campbell and Reece belongs in a college-level genetics course. We are trying to give our students a fundamental understanding of genetics. We are not trying to teach them the more complex aspects of genetics. They can chose to study more genetics later in their careers.
I have looked at this pacing guide several times, and I see nine essential concepts that should be taught. Below is an outline of these concepts and the supporting ideas that go with each concept.
1. Mendel’s Laws
2. Chromosome Behavior during Meiosis
3. Evolutionary advantages of genetic recombination and sex
4. Penetrance/Spectrum of Dominance: Simple Dominance (autosomal recessive/autosomal dominant), Codominance (e.g. blood type), Incomplete Dominance (e.g. snap dragons)
5. Genetic basis for human disease
6. Genetics of complex traits: sex-linked traits, epistasis, pleitropy, multiple alleles, polygenic inheritance
7. Pedigree Analysis
8. Gene Linkage
9. Abnormal chromosome behavior: Non disjunction and aneuploidy, Alterations of chromosome structure
WEEK 19: CLASSIC GENETICS 1
Objective 1) Students need to understand the chromosomal basis of inheritance and that genes are “particulate” entities found on chromosomes.
Objective 2) Students they need to know what a gene is and how gene products interact in the cell to produce a phenotype.
Objective 3) Student need to be familiar with Mendel and Mendel’s laws. The Mendelian laws help explain how chromosomes (and therefore, non-linked genes) separate during meiosis.
Why Mendel? Mendel’s observations of monogenic traits in peas help explain the particulate nature of inheritance and his observations provide insight into how more interesting traits (e.g. Sickle Cell Anemia) found in humans. Finally, his use of 100% penetrant (“simple dominant” traits) helps explain other Patterns of Inheritance like codominance, incomplete dominance, and polygenic inheritance.
Author’s Note: AP Biology teachers use many different labs to reinforce Mendelian genetics. Given the complexity and time necessary to work with live Drosphila, this may not be an option for first year teachers.
There are three viable alternatives. You can use the virtual Drosophila Robert Dennison guided teachers on at the Auburn APSI. The link is http://www.sciencecourseware.org/vcise You need to register as a teacher and set up a class. Another virtual alternative is the “Biology Place, AP Lab 7”. The link is http://www.phschool.com/science/biology_place/labbench/lab7/intro.html with lab bench, there is no need to set up a class, but the visuals are not very dynamic. The assessments are pretty basic. The LTF lesson “Amazing Maize” is excellent, but you need to order the corn from Ward’s or Carolina. Robert and I each have class set we can make available to you. You will need to use your LTF username and password to access the protocol.
Regardless of the strategy you choose, College Board wants students to be able to quantify the results of an F1 and F2 cross, and compare the observed results to the expected results. This is the Chi-squared (X-2) analysis. Learning Chi Square should happen prior to the end of the curriculum. If you are comfortable with teaching this analysis, then do it now. If you’re not, Robert or I can come and work with your students prior to the end of the year. Don’t bog down on Chi-square now because the snow days have pulled everyone off pace.
Week 20: The Genetics of Complex Traits and the Chromosomal Basis of Inheritance (Ch. 14 and 15)
Objective 1) The genetics of complex traits
Objective 2) How errors during meiosis lead to chromosomal abnormalities.
See AP Biology Weekly Schedule for suggested daily schedule. The expectation is you will help your students discover this material over the course of two weeks and have an exam (summative assessment) at the end of the second week. Don’t feel locked in to the daily pace. If you’re ahead, press on. If you’re behind, don’t get bogged down and move on to the essential material.
I’d like to offer one final note on genetics. My spell check was going crazy when I spell checked the genetics portion of this pacing guide. It didn’t recognize any of the genetics terms. In fact, genetics can feel like a second language. As my colleauge Robert Summers will tell you, Biology is a descriptive science. The words matter. When new terms arise challenge students to use the words in context and have them explain the words to you and to their peers. This is much more effective than memorizing terms.
Weeks 21-23: Evolution
Evolution is the central, the overarching, and the underlying concept in biology, evolution. Students we serve will likely have misconceptions about what evolution is. They won’t appreciate the genetic underpinnings of evolution; and they probably won’t have a concept of THE AMOUNT OF TIME over which evolution on this planet has occurred. That’s okay. We will teach our students the most current (and best) science we can. Hopefully we will inspire them to think scientifically about the world around them.
The best approach to evolution is by starting with evidence. Let the evidence lead to the ideas. Forgive me for sounding high handed, but it is unlikely that your students will completely understand the concepts presented in this unit. I have been struggling with the complexity of these ideas, and subtlety of these processes, for over twenty years. Working to better understand evolution, and to understand the processes that have lead to the geological and biological diversity on this planet, has been one of the great joys of my life.
Given that we can’t teach our students everything, I think it’s best to concentrate on Five major Learning Objectives in this unit.
1) Students should understand Darwin’s two main ideas/his two great insights, and they should have an appreciation for the evidence that supports his ideas.
2) Students should have an understanding of the mechanism of evolution, natural selection…and it’s ultimate results: a) Differential Reproductive Success and b) change in the populations’ phenotype to suit its environment (microevolution).
3) Students should understand the genetic underpinning of natural selection as well as population genetics and Hardy-Weinberg Equilibrium
4) Students should be able to extrapolate the concept of microevolution to macroevolution. Emphasis should be placed on reproductive isolation and modern concepts in macroevolution. They should also be able to articulate macroevolution through a variety of diagrams (character tables, phylogenetic trees and cladograms).
5) Students should be familiar with age of the earth, origins of life, evolution of eukaryotic cells (endosymbiosis), and the major adaptive radiations that have occurred since the evolution of eukaryotes.
As with most units in AP Biology, you are just scratching the surface. Hopefully your students will walk away from this unit understanding more about how this planet works and how life has, and continues to, evolve.