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Chapter 16 Objectives
3. List the three components of a nucleotide.
Nitrogen base, sugar and phosphate.
4. Distinguish between deoxyribose and ribose.
The difference is in the nitrogen base thymine, which in ribose is replaced by
uracil.
5. List the nitrogen bases found in DNA, and distinguish between pyrimidine and purine.
The nitrogen bases found in DNA are adenine, thymine, guanine and cytosine.
Pyrimidines are thymine and cytosine and purine are adenine and guanine.
7. Explain the "base-pairing rule" and describe its significance.
The base-pairing rule says that each base has to bond with its complementary one
like A-T and G-C.
8. Describe the structure of DNA, and explain what kind of chemical bond connects the
nucleotides of each strand and what type of bond holds the two strands together.
DNA had a double helix structure. Hydrogen bonds connects the nucleotides of
each strand and holds the two strand together.
10. Describe the process of DNA replication, and explain the role of helicase, single
strand binding protein, DNA polymerase, ligase, and primase.
Know from AP Cliffs Notes
.
12. Define antiparallel
Is when the continuous syntheses of both DNA strand and replication fork are not
possible.
13. Distinguish between the leading strand and the lagging strand.
Leading strand is the complementary strand and lagging strand is the required one
to assemble the leading strand.
15. Explain the role of DNA polymerase, ligase, and repair enzymes in DNA
proofreading and repair.
Polymerase proofreads each newly added nucleotide against its template. If polymerase
detects an incorrectly paired nucleotide, the enzyme removes and replaces it before continuing
with synthesis.
Chapter 17 Objectives
4. Explain how RNA differs from DNA.
Know from AP Cliffs Notes
5. In your own words, briefly explain how information flows from gene to protein.
6. Distinguish between transcription and translation.
Transcription = The synthesis of RNA using DNA as a template
Translation = Synthesis of a polypeptide, which occurs under the direction of
messenger RNA (mRNA)
7. Describe where transcription and translation occur in prokaryotes and in eukaryotes.
Know from AP Cliff Notes
8. Define codon, and explain what relationship exists between the linear sequence of
codons on mRNA and the linear sequence of amino acids in a polypeptide.
Codon = A three-nucleotide sequence in mRNA that specifies which amino acid will be
added to a growing polypeptide or that signals termination; the basic unit of the genetic code.
12. Explain the process of transcription including the three major steps of initiation,
elongation, and termination.
Know from AP Cliff Notes
13. Describe the general role of RNA polymerase in transcription.
Know from AP Cliff Notes
16. Distinguish among mRNA, tRNA, and rRNA.
mRNA is messenger RNA which is a single strand of RNA that provides the template use
for sequencing amino acids into a polypeptide.
tRNA is transfer RNA which is a short RNA molecule that is used for transporting amino
acids to their proper place in mRNA template.
rRNA is ribosomal RNA which molecules build blocks of ribosome.
17. Describe the structure of tRNA and explain how the structure is related to function.
Know from AP Cliffs Note
21. Describe the structure of a ribosome, and explain how this structure relates to
function.
Ribosome is a cell organelle constructed in the nucleolus, consisting of two
subunits and functioning as the site of protein synthesis in the cytoplasm.
22. Describe the process of translation including initiation, elongation, and termination
Know from AP Cliff Notes
27. Explain how eukaryotic mRNA is processed before it leaves the nucleus.
RNA transcripts in eukaryotes are modified, or processed, before leaving the nucleus to
yield functional mRNA.
Chapter 18 Objectives
2. List and describe structural components of viruses.
The virus particle, consists of nucleic acid enclosed by a protein coat and sometimes a
membranous envelope.
3. Explain why viruses are obligate parasites.
Because they can express their genes and reproduce only within a living cell.
5. Explain the role of reverse transcriptase in retroviruses.
Retrovirus = (Retro = backward) RNA virus that uses reverse transcriptase to transcribe DNA
from the viral RNA genome.
6. Describe how viruses recognize host cells.
Viruses recognize host cells by a complementary fit between external viral proteins and
specific cell surface receptor sites.
7. Distinguish between lytic and lysogenic reproductive cycles using phage T4 and phage
l as examples.
Know from AP Cliffs Book
11. Explain how viruses may cause disease symptoms, and describe some medical
weapons used to fight viral infections.
Damage or kill cells. In response to a viral infection, lysosomes may release hydrolytic enzymes.
Be toxic themselves or cause infected cells to produce toxins. Cause varying degrees of cell
damage depending upon regenerative ability of the infected cell. We recover from colds because
infected cells of the upper respiratory tract can regenerate by cell division. Poliovirus, however,
causes permanent cell damage because the virus attacks nerve cells which cannot divide. Be
indirectly responsible for disease symptoms. Fever, aches and inflammation may result from
activities of the immune system. Medical weapons used to fight viral infections include vaccines
and antiviral drugs. Vaccines = Harmless variants or derivatives of pathogenic microbes that
mobilize a host's immune mechanism against the pathogen
12. List some viruses that have been implicated in human cancers, and explain how tumor
viruses transform cells.
Viral Group
Retrovirus
Herpesvirus
Papovavirus
Hepatitis B virus
Examples/Diseases
HTLV-1/adult leukemia
Epstein-Barr/infectious mononucleosis
Papilloma/human warts
Chronic hepatitis
Cancer Type
Leukemia
Burkitt's lymphoma
Cervical cancer
Liver cancer
Tumor viruses transform cells by inserting viral nucleic aids into host cell DNA.
16. Describe the structure of a bacterial chromosome.
Composed of one double-stranded, circular molecule of DNA. Structurally simpler and
has fewer associated proteins than a eukaryotic chromosome. Found in the nucleoid region; since
this region is not separated from the rest of the cell (by a membrane), transcription and translation
can occur simultaneously.
18. List and describe the three natural processes of genetic recombination in bacteria.
Know from AP Cliffs Book.
20. Explain how the F plasmid controls conjugation in bacteria.
It contains genes that enable a bacterium to produce pili.
27. Briefly describe two main strategies cells use to control metabolism.
1. Regulation of enzyme activity. The catalytic activity of many enzymes increases on
decreases in response to chemical cues.


2.
For example, the end product of an anabolic pathway may turn off its own
production by inhibiting activity of an enzyme at the beginning of the pathway
(feedback inhibition).
Useful for immediate short-term response.
Regulation of gene expression. Enzyme concentrations may rise and fall in response to
cellular metabolic changes that switch genes on or off.
 For example, accumulation of product may trigger a mechanism that inhibits
transcription of mRNA production by genes that code for an enzyme at the
beginning of the pathway (gene repression).
 Slower to take effect than feedback inhibition, but is more economical for the
cell. It prevents unneeded protein synthesis for enzymes, as well as, unneeded
pathway product.
30. Distinguish between structural and regulatory genes.
Structural gene = Gene that codes for a polypeptide
Regulatory genes = Genes that code for repressor or regulators of other genes
Chapter 19 Objectives
1. Compare the organization of prokaryotic and eukaryotic genomes.
Prokaryotic DNA is:
• Usually circular
• Much smaller than eukaryotic DNA; it makes up a small nucleoid region only visible with an
electron microscope
• Associated with only a few protein molecules
• Less elaborately structured and folded than eukaryotic DNA; bacterial chromosomes have some
additional structure as the DNA-protein fiber forms loops that are anchored to the plasma
membrane
Eukaryotic DNA is:
• Complexed with a large amount of protein to form chromatin
• Highly extended and tangled during interphase
• Condensed into short, thick, discrete chromosomes during mitosis; when stained, chromosomes
are clearly visible with a light microscope
4. Distinguish between heterochromatin and euchromatin.
Euchromatin describes regions where DNS is loosely bound to nucleosomes.
DNA is these regions is actively transcribes.
Heterochomatin represents areas where the nucleosomes are more tightly
compacted, and where DNA is inactive
Chapter 20 Objectives
1. Explain how advances in recombinant DNA technology have helped scientists study
the eukaryotic genome.
2. Describe the natural function of restriction enzymes.
The natural function of restriction enzymes is to combat invading viruses.
3. Describe how restriction enzymes and gel electrophoresis are used to isolate DNA
fragments.
Sticky ends of restriction fragments are used in the laboratory to join DNA pieces from
different sources (cells or even different organisms).
• These unions are temporary since they are only held by a few hydrogen bonds.
• These unions can be made permanent by adding the enzyme DNA ligase, which catalyzes
formation of covalent phosphodiester bonds.
7. List and describe the two major sources of genes for cloning.
There are two major sources of DNA which can be inserted into vectors and clones:
1. DNA isolated directly from an organism
2. Complementary DNA made in the laboratory from mRNA templates
DNA isolated directly from an organism contains all genes including the gene of interest.
9. Describe how "genes of interest" can be identified with the use of a probe.
DNA fragments containing genes of interest can be isolated, purified, and then recovered
from the gel with full biological activity.