Objectives

Every objective will NOT necessarily be covered during class time; you will be independently responsible for some of them.

  1. Model and label the structure of a DNA molecule, including bonding and directionality
  2. Contrast eukaryotic with prokaryotic chromosomes
  3. Model and explain the process of DNA replication, including the actions of enzymes, its semiconservative nature, and how it ensures the conservation of genetic information
  4. Compare and contrast the structure and function of RNA with that of DNA
  5. Model and explain the process of transcription, including the actions of enzymes
  6. Explain the events of post-transcriptional modifications
  7. Model and explain the process of translation, including the events of initiation, elongation, and termination, and the regions of the ribosome
  8. Given information about a DNA sequence, predict the transcribed mRNA sequence, the tRNA sequence, and the amino acid sequence that will result
  9. Compare and contrast protein synthesis in prokaryotes versus eukaryotes
  10. Explain the evolutionary and genetic implications of the universality of the genetic code, and the redundancy of the genetic code
  11. Compare and contrast the structure and function of different kinds of RNA (mRNA, tRNA, rRNA)
  12. Given information about mutations to a DNA sequence, predict any impacts upon RNA, protein structure, and phenotype
  13. Classify mutations based upon the nature and effect of the mutation
  14. List different causes of mutations
  15. Contrast virus structure and function to living cellular structure and function
  16. Compare and contrast the lytic and lysogenic viral cycles
  17. Explain how viral replication results in genetic variation, and viral infection can introduce genetic variation into the hosts
  18. Explain how retroviruses differ from other viruses, why they tend to experience more rapid evolutionary change, and the implications of this for their pathogenicity
  19. Connect Mendelian genetics concepts – allele, homozygous, heterozygous, gene, dominant, recessive – to molecular genetics concepts
  20. Explain how segregation and independent assortment produce genetic diversity and are observable in Mendelian genetics problems
  21. Calculate probable parents and offspring using principles of Mendelian genetics, including Punnett Squares, the rule of multiplication, and the rule of addition
  22. Complete monohybrid cross, dihybrid cross, polyhybrid cross, incomplete dominant, codominance, epistasis, lethal allele, multiallelic, sex-linkage, and pedigree problems
  23. Give examples of how the inheritance patterns of many traits cannot be predicted by simple Mendelian genetics, such as polygenic traits, non-nuclear inheritance, sex-linkage, and environmental influences on phenotype
  24. Explain the contributions of Watson and Crick, Wilson and Franklin, Griffith and Avery and MacLeod and McCarty, Meselson and Stahl, and Hershey and Chase to the modern understanding of genetics*

  • = self-study


Enduring Understandings

Enduring Understandings are the College Board's AP Biology course concepts that you need to know for the AP exam. Below, you'll find those Enduring Understandings relevant to this unit. Numbering and lettering matches the document linked from the main page of this website.
Every Enduring Understanding will NOT necessarily be covered during class time; you will be independently responsible for some of them.


III.
A. Heritable information provides for continuity of life.
1. DNA, and in some cases RNA, is the primary source of heritable information.
  • a. Genetic information is transmitted from one generation to the next through DNA or RNA.
  • b. Genetic information is stored in and passed to subsequent generations through DNA molecules and, in some cases, RNA molecules.
  • c. Noneukaryotic organisms have circular chromosomes, while eukaryotic organisms have multiple linear chromosomes, although in biology there are exceptions to this rule.
  • e. The proof that DNA is the carrier of genetic information involved a number of important historical experiments. These include: contributions of Watson, Crick, Wilkins, and Franklin on the structure of DNA; Avery-MacLeod-McCarty experiments; and the Hershey-Chase experiment.
  • f. DNA replication ensures continuity of hereditary information. Replication is a semiconservative process; that is, one strand serves as the template for a new, complementary strand. Replication requires DNA polymerase plus many other essential cellular enzymes, occurs bidirectionally, and differs in the production of the leading and lagging strands.
  • g. Genetic information in retroviruses is a special case and has an alternate flow of information: from RNA to DNA, made possible by reverse transcriptase, an enzyme that copies the viral RNA genome into DNA. This DNA integrates into the host genome and becomes transcribed and translated for the assembly of new viral progeny.
  • h. DNA and RNA molecules have structural similarities and differences that define function.
  • i. Both DNA and RNA have three components - sugar, phosphate and a nitrogenous base - which form nucleotide units that are connected by covalent bonds to form a linear molecule with 3' and 5' ends, with the nitrogenous bases perpendicular to the sugar-phosphate backbone.
  • j. The basic structural differences include: DNA contains deoxyribose (RNA contains ribose); RNA contains uracil in lieu of thymine in DNA; DNA is usually double stranded and RNA is usually single stranded; the two DNA strands in double stranded DNA are antiparallel in directionality.
  • k. Both DNA and RNA exhibit specific nucleotide base pairing that is conserved through evolution: adenine pairs with thymine or uracil (A-T or A-U) and cytosine pairs with guanine (C-G). Purines (G and A) have a double ring structure, Pyramidines (C, T, and U) have a single ring structure.
  • l. The sequence of the RNA bases, together with the structure of the RNA molecule, determines RNA function. mRNA carries information from the DNA to the ribosome, tRNA molecules bind specific amino acids and allow information in the mRNA to be translated to a linear peptide sequence, rRNA molecules are functional building blocks of ribosomes, and the role of RNAi includes regulation of gene expression at the level of mRNA transcription.
  • m. Genetic information flows from a sequence of nucleotides in a gene to a sequence of amino acids in a protein.
  • n. The enzyme RNA-polymerase reads the DNA molecule in the 3' to 5' direction and synthesizes complementary mRNA molecules that determine the order of amino acids in the polypeptide.
  • o. In eukaryotic cells the mRNA transcript undergoes a series of enzyme-regulated modifications.
  • p. Translation of the mRNA occurs in the cytoplasm on the ribosome.
  • q. In prokaryotic organisms, transcription is coupled to translation of the message. Translation involves energy and many steps, including initiation, elongation and termination.
  • r. The salient features of translation include: the mRNA interacts with the rRNA of the ribosome to initiate translation at the start codon; the sequence of nucleotides on the mRNA is read in triplets called codons; each codon encodes a specific amino acid which can be deduced using a genetic code chart (many amino acids have more than one codon); tRNA brings the correct amino acid to the correct place on the mRNA; the amino acid is transferred to the growing peptide chain; the process continues along the mRNA until a “stop” codon is reached; the process terminates by release of the newly synthesized peptide/protein.
  • s. Phenotypes are determined through protein activities.
3. The chromosomal basis of inheritance provides an understanding of the pattern of passage (transmission) of genes from parent to offspring.
  • a. Rules of probability can be applied to analyze passage of single gene traits from parent to offspring.
  • b. Segregation and independent assortment of chromosomes result in genetic variation.
  • c. Segregation and independent assortment can be applied to genes that are on different chromosomes.
  • e. The pattern of inheritance (monohybrid, dihybrid, sex-linked, and genes linked on the same homologous chromosome) can often be predicted from data that gives the parent genotype/phenotype and/or the offspring phenotypes/genotypes.
  • f. Certain human genetic disorders can be attributed to the inheritance of single gene traits or specific chromosomal changes, such as nondisjunction.
  • g. Many ethical, social and medical issues surround human genetic disorders.
4. The inheritance pattern of many traits cannot be explained by simple Mendelian genetics.
  • a. Many traits are the product of multiple genes and/or physiological processes.
  • b. Patterns of inheritance of many traits do not follow ratios predicted by Mendel's laws and can be identified by quantitative analysis, where observed phenotypic ratios statistically differ from the predicted ratios.
  • c. Some traits are determined by genes on sex chromosomes.
  • d. Some traits result from nonnuclear inheritance.
  • e. Chloroplasts and mitochondria are randomly assorted to gametes and daughter cells; thus, traits determined by chloroplast and mitochondrial DNA do not follow simple Mendelian rules.
  • f. In animals, mitochondrial DNA is transmitted by the egg and not by sperm; as such, mitochondrial-determined traits are maternally inherited.

C. The processing of genetic information is imperfect and is a source of genetic variation.
1. Changes in genotype can result in changes in phenotype.
  • a. Alterations in a DNA sequence can lead to changes in the type or amount of the protein produced and the consequent phenotype.
  • b. DNA mutations can be positive, negative or neutral based on the effect or the lack of effect they have on the resulting nucleic acid or protein and the phenotypes that are conferred by the protein.
  • c. Errors in DNA replication or DNA repair mechanisms, and external factors, including radiation and reactive chemicals, can cause random changes, e.g., mutations in the DNA.
  • d. Whether or not a mutation is detrimental, beneficial or neutral depends on the environmental context. Mutations are the primary source of genetic variation.
  • g. Changes in genotype may affect phenotypes that are subject to natural selection. Genetic changes that enhance survival and reproduction can be selected by environmental conditions.
2. Biological systems have multiple processes that increase genetic variation.
  • a. The imperfect nature of DNA replication and repair increases variation.
3. Viral replication results in genetic variation, and viral infection can introduce genetic variation into the hosts.
  • a. Viral replication differs from other reproductive strategies and generates genetic variation via various mechanisms.
  • b. Viruses have highly efficient replicative capabilities that allow for rapid evolution and acquisition of new phenotypes.
  • c. Viruses replicate via a component assembly model allowing one virus to produce many progeny simultaneously via the lytic cycle.
  • d. Virus replication allows for mutations to occur through usual host pathways.
  • e. RNA viruses lack replication error-checking mechanisms, and thus have higher rates of mutation.
  • f. Related viruses can combine/recombine information if they infect the same host cell.
  • g. HIV is a well-studied system where the rapid evolution of a virus within the host contributes to the pathogenicity of viral infection.
  • h. The reproductive cycles of viruses facilitate transfer of genetic information.
  • i. Viruses transmit DNA or RNA when they infect a host cell.
  • j. Some viruses are able to integrate into the host DNA and establish a latent (lysogenic) infection. These latent viral genomes can result in new properties for the host such as increased pathogenicity in bacteria.


IV.
A. Interactions within biological systems lead to complex properties.
1. The subcomponents of biological molecules and their sequence determine the properties of that molecule.
  • a. Structure and function of polymers are derived from the way their monomers are assembled.
  • b. In nucleic acids, biological information is encoded in sequences of nucleotide monomers. Each nucleotide has structural components: a five-carbon sugar (deoxyribose or ribose), a phosphate and a nitrogen base (adenine, thymine, guanine, cytosine or uracil). DNA and RNA differ in function and differ slightly in structure, and these structural differences account for the differing functions.
  • c. In proteins, the specific order of amino acids in a polypeptide (primary structure) interacts with the environment to determine the overall shape of the protein, which also involves secondary tertiary and quaternary structure and, thus, its function. The R group of an amino acid can be categorized by chemical properties (hydrophobic, hydrophilic and ionic), and the interactions of these R groups determine structure and function of that region of the protein.
  • g. Nucleic acids have ends, defined by the 3' and 5' carbons of the sugar in the nucleotide, that determine the direction in which complementary nucleotides are added during DNA synthesis and the direction in which transcription occurs (from 5' to 3').
  • h. Proteins have an amino (NH2) end and a carboxyl (COOH) end, and consist of a linear sequence of amino acids connected by the formation of peptide bonds by dehydration synthesis between the amino and carboxyl groups of adjacent monomers.
C. Naturally occurring diversity among and between components within biological systems affects interactions with the environment.
1. Variation in molecular units provides cells with a wider range of functions.
  • a. Variations within molecular classes provide cells and organisms with a wider range of functions.
  • b. Multiple copies of alleles or genes (gene duplication) may provide new phenotypes.
  • c. A heterozygote may be a more advantageous genotype than a homozygote under particular conditions, since with two different alleles, the organism has two forms of proteins that may provide functional resilience in response to environmental stresses.
  • d. Gene duplication creates a situation in which one copy of the gene maintains its original function, while the duplicate may evolve a new function.


Textbook Reference

This is the part of your textbook that covers the material for this unit.
Ch. 11-14

Relevant Files

Here, you'll find files for this course. Copies of lecture notes will go here, as will others.
= Molecular Genetics and Viruses, Ch 13-14
= Mendelian Inheritance, Ch 11-12


= Basic Mendelian practice problems + answer key







Links

These connect to materials on other teachers' websites that you may find helpful. Generally speaking, I put links to helpful review materials - like video lectures summarizing the material - towards the top, and links to interesting extensions towards the bottom.
Omics Science Center great animation of the Central Dogma of molecular genetics
Short NOVA movie on RNAi
DNAi History of DNA
The Genetic Science Learning Center
DNA Game
Genetic Code Game
From DNA to Protein
FoldIt Protein Folding Game
Protein Synthesis Flower Children
DNA Interactives
National Center for Biotechnology Information (professional search databases)
Database of Human Genes
Genetics and Ethics
Official Human Genome Project homepage
Glossary of Genetics Terms
Human Health and the Chromosome
Investigating Genetic Disorders
Chromosome Abnormalities Gallery
National Center for Biotechnology Information (professional search databases)
Database of Human Genes
Genetics and Ethics
Gene Map of the Human Chromosome
Genomics and Its Impact on Science and Society
Genomics and Biotechnology Articles
Your Genes, Your Choices
Official Human Genome Project homepage
Heredity and Traits
Mendelian Inheritance in Humans
Mendelian Genetics
Dihybrid Crosses
Genetics Practice Problems
More Genetics Practice Problems