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CHAPTER 16
THE MOLECULAR BASIS
OF INHERITANCE
OUTLINE
II. DNA Replication and Repair
A. During DNA replication, base-pairing enables existing DNA strands to serve as templates for new
complementary strands
B. .A large team of enzymes and other proteins carries out DNA replication
C. Enzymes proofread DNA during its replication and repair damage to existing DNA
3. List the three components of a nucleotide.
Five-carbon sugar, a phosphate, and a nitrogenous base.
4. Distinguish between deoxyribose and ribose.
A deoxyribose is the sugar component of DNA, having one less hydroxyl group
than ribose, the sugar component of RNA, which ribose is the sugar component
of RNA.
5. List the nitrogen bases found in DNA, and distinguish between pyrimidine and purine.
-Adanine
-Thymine
-Guanine
-Cytosine
pyrimidine T-C one ring
purine X-G two large rings
7. Explain the "base-pairing rule" and describe its significance.
Only A-T and C-G can form th mRNA
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.
Double helix
Covalent bond
Hydrogen bond
9. Explain, in their own words, semiconservative replication, and describe the Meselson-Stahl experiment.
Semiconservatives replication is when the two strands of the parental
molecule sepeprate, and each functions as a template for synthesis of a new
complementary strand.
10. Describe the process of DNA replication, and explain the role of helicase, single strand binding protein, DNA
polymerase, ligase, and primase.
A short segment of DNA has been untwisted to convert
the double helix to a two-dimensional version of the molecule that resembles
a ladder. The first step in replication is separation of the two DNA
strands. Each “old” strand now serves as a template that directs synthesis
of “new” complememntary strands. Nucleotides plug into specific sites along
the templates surface according to the base-pairing rules. The nucleotides
are connected to form the sugar-phosphate backbones of the new strands.
Each DNA molecule now consists of one “old” strand and one “new” strand,
resulting in two copies identical to the one DNA molecule with which we
started. Helicase is an enzyme that works at the crotch of the replication
fork, untwisting the double helix and separating the two “old” strands.
Single-strand binding proteins then attach in chains along the unpaired DNA
strands, holding these templates straight until new complementary can be
synthesized. DNA ligase, an enzyme, joins RNA nucleotides to make the
primer. Only one primer is required to polumerase to begin synthesizing the
leading strand of new DNA.
12. Define antiparallel
Antiparalle is when the 5’to3’ direction of one strand runs counter to the
other strand.
13. Distinguish between the leading strand and the lagging strand.
(See figure 15.12)
14. Explain how the lagging strand is synthesized when DNA polymerase can add nucleotides only to the 3’ end.
(see figure 15.12)
15. Explain the role of DNA polymerase, ligase, and repair enzymes in DNA proofreading and repair.
One DNA repair mechanism, called mismatch repair, fixes mistakes, when DNA
is copied. The polumerase proofreads each nucleotide against its template
as soon as it is added to the strand. One function of the DNA repair
enzymes in our skin cells is to repair genetic damage caused by the
ultraviolet rays of sunlight.
CHAPTER 17
FROM GENE TO PROTEIN
OUTLINE
I. The Connection between Genes and Proteins
B. Transcription and translation are the two main processes linking gene to protein:
an overview
C. In the genetic code, nucleotide triplets specify amino acids
II. The Synthesis and Processing of RNA
A. Transcription is the DNA-directed synthesis of RNA: a closer look
B. Eukaryotic cells modify RNA after transcription
III. The Synthesis of Protein
A. Translation is the RNA-directed synthesis of a polypeptide: a closer look
B. Signal peptides target some eukaryotic polypeptides to specific locations in the cell
C. RNA plays multiple roles in the cell: a review
D. Comparing protein synthesis in prokaryotes and eukaryotes: a review
E. Point mutations can affect protein structure and function
4. Explain how RNA differs from DNA.
RNA
- one single strnd
- contains urasil
- there are three types:
mRNA
tRNA
rRNA
DNA
- double helix
- one type
5. In your own words, briefly explain how information flows from gene to protein.
Information flows from gene to protein by transcription to RNA processing to translation, in Eukaryotic cells and it
flows from transcription to translation in prokaryotic cells.
6. Distinguish between transcription and translation.
Transcription - the transfer of information from a DNA molecule to an RNA
molecule
Translation - is the transfer of information of an RNA molecule
into a polypeptide, involving a change of language from nucleic acids to
amino acids.
7. Describe where transcription and translation occur in prokaryotes and in eukaryotes;
(See figure 16.3)
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.
A codon is a mRNA base triplet.
(See figure 16.4)
12. Explain the process of transcription including the three major steps of initiation, elongation, and termination.
As an RNA polymerase molecule moves along a gene from the initiation site to
the termination site., it synthesizes an RNA molecule that consists of the
nucleotide sequence determined by the template strand of the gene. The
entire stretch of DNA that is transcribed is called a transcription unit.
Transcription begins at the initiation site when the polymerase separates
the two strands for base pairing with nucleotides. The RNA polymerase works
its way “downstream” from the initiation site, prying apart the two strands
and elongating the mRNA in the 5’to3’ direction. In the wake of
transcription, the two DNA strands re-form the double helix. The RNA
polymerase continues to elongate the RNA molecule until it reaches the
termination site, a specific sequence of nucleotides along the DNA that
signals the end of the transcription unit. The mRNA, a transcripts of the
gene, is released, and the polymerase subsequently dissociates from the DNA.
13. Describe the general role of RNA polymerase in transcription.
(See figure 16.7)
16. Distinguish among mRNA, tRNA, and rRNA.
mRNA messenger
tRNA tranfer
rRNA ribosomal
17. Describe the structure of tRNA and explain how the structure is related to function.
The structure of tRNA contains the four base paired regions and three loops
characteristics of all tRNAs. At one ens of the molecule is the amino acids
attachment site, which has the same base sequence for all tRNA, within the
middle loop is the anticodon triplet, which is unique to each tRNA type.
The structure of a tRNA molecule fits its function as a shuttle for a
specific amino acid.
(See figure16.11)
18. Given a sequence of bases in DNA, predict the corresponding codons transcribed on mRNA and the
corresponding anticodons of tRNA.
21. Describe the structure of a ribosome, and explain how this structure relates to function.
(See figure 16.12)
22. Describe the process of translation including initiation, elongation, and termination.
(See figures 16.13 for initiation of translation, 16.14 for elongation of translation, and 16.15 for termination of
translation)
26. Describe the difference between prokaryotic and eukaryotic mRNA.
27. Explain how eukaryotic mRNA is processed before it leaves the nucleus.
First, it helps protect themRNA from hydrolytic enzymes. Second, after the mRNA reaches the cytoplasm, the 5’
capfunctions as an “attach here” sign for small ribosomal subnits. The other end of an mRNA molecule, the 3’end, is
also modified before the message exits the nucleus.
29. Explain why base-pair insertions or deletions usually have a greater effect than base-pair substitutions.
CHAPTER 18
MICROBIAL MODELS: THE GENETICS OF
VIRUSES AND BACTERIA
2. List and describe structural components of viruses.
Nucleic Acid (DNA or RNA) and Protein Coat; both make the Capsid
3. Explain why viruses are obligate parasites.
Parasites destroy the host cell and so do viruses
5. Explain the role of reverse transcriptase in retroviruses.
Transcribing DNA from an RNA template.
6. Describe how viruses recognize host cells.
A lock and key fit between proteins on the outside of
the virus and specific receptor molecules on the
surface of the cell.
7. Distinguish between lytic and lysogenic reproductive cycles using phage T4 and phage l as examples.
(See Figure 17.4 and 17.5)
11. Explain how viruses may cause disease symptoms, and describe some medical weapons used to fight viral
infections.
They cause cells to be destroyed having the body
compensate for destroyed cells lowers the bodies’
potential to operate. The best way to combat a virus
is by getting a bacterial injection and having it is
lysogenic.
12. List some viruses that have been implicated in human cancers, and explain how tumor viruses transform cells.
Cancer for Hepatitis, the Epstein-Barr virus and
Burkit’s lymphoma. When a tumor virus lacks oncogenes
and transforms the cell simply by turning on or
increasing the expression of one or more of the cells
own oncogenes.
14. List some characteristics that viruses share with living organisms, and explain why viruses do not fit our usual
definition of life.
They can replicate and use also host cell’s nutrients
to stay alive. It doesn’t meet because it cannot
replicate its own genes and produce ATP.
16. Describe the structure of a bacterial chromosome.
Double stranded and is in a circular shape containing
3000 genes.
16. Describe the structure of a bacterial chromosome.
18. List and describe the three natural processes of genetic recombination in bacteria.
Transformation-alteration of a bacterial cell’s
genotype by the uptake of naked, foreign DNA from the
surrounding environment, Transduction-Figure 17.10,
Conjugation and Plasmids-direct transfer of genetic
material between two bacterial cells that are
temporarily joined.
20. Explain how the F plasmid controls conjugation in bacteria.
(See fugure17.12)
27. Briefly describe two main strategies cells use to control metabolism.
30. Distinguish between structural and regulatory genes.
CHAPTER 1 9
THE ORGANIZATION AND CONTROL OF
EUKARYOTIC GENOMES
OUTLINE
I. The Structure of Chromatin
A. Chromatin structure is based on successive levels of DNA packing
II. Genome Organization at the DNA Level
A. Repetitive DNA and other noncoding sequences account for much of a eukaryotic genome
B. Gene families have evolved by duplication of ancestral genes
C. Gene amplification, loss, or rearrangement can alter a cell’s genome
1. Compare the organization of prokaryotic and eukaryotic genomes.
Prokaryotic DNA circular, and the nucleoid is so small that it can be seen only with electron microscope.
Eukaryotic chromosomes contain an enormous amount of DNA relative to their strength.
2. Describe the current model for progressive levels of DNA packing.
(See Figure 18.1)
3. Distinguish between heterochromatin and euchromatin.
Heterochromatin is denser than euchromatin (true chromatin)
CHAPTER 20
DNA TECHNOLOGY
OUTLINE
I. DNA Cloning
A. DNA technology makes it possible to clone genes for basic research and commercial applications: an overview
B. Restriction enzymes are used to make recombinant DNA
C. Genes can be cloned in recombinant DNA vectors: a closer look
D. Cloned genes are stored in DNA libraries
E. The polymerase chain reaction (PCR) clones DNA entirely in vitro
1. Explain how advances in recombinant DNA technology have helped scientists study the eukaryotic genome.
Scientists can now make gene copies of the gene they want to study. They can also be good in that they produce
new protein product, and also a plasminogen activator and giving powers to cells that do not have a certain power.
2. Describe the natural function of restriction enzymes.
Enzymes protect bacteria against intruding DNA from other organisms, such as viruses or other organisms.
3. Describe how restriction enzymes and gel electrophoresis are used to isolate DNA fragments.
Restriction enzymes can cut out a specific segment of the DNA to Isolate. Gel electrophoresis separates them from
big to small.
7. List and describe the two major sources of genes for cloning.
DNA isolated directly from an organism and complementary DNA made in the laboratory from mRNA templates.
9. Describe how "genes of interest" can be identified with the use of a probe.
With having knowledge of what the complementary sequence is you can probe to find the gene. With that you get
to find the gene and its location in the DNA and thus getting copies of the gene and using it for further study.
10. Explain the importance of DNA synthesis and sequencing to modern studies of eukaryotic genomes.
With having knowledge of what the complementary sequence is you can probe to find the gene. With that you get
to find the gene and its location in the DNA and thus getting copies of the gene and using it for further study.