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Chapter 16
The Molecular basis of inheritance
Objectives
3. List the three components of, a nucleotide.
Figure 15.3 pg 285
4. Distinguish between deoxyribose and ribose.
Deoxyribose- sugar component of DNA
Ribose- sugar component of RNA, has one more hidroxyl group than deoxyribose.
5. List the nitrogen bases found in DNA, and disgtinguish between pyrimidine and purine.
Adenine- A Purine- two organic rings
and
Thymine- T Pyrimidine- single ring
Guanine- G Purine- two organic rings
and
Cytosine- C Pyrimidine- single ring
7. Explain the “base-pairing rule” and describe its significance.
Dictates the combinations of nitrogenous bases that form the rungs of the double heilex. This means that
the linear sequence of the four bases can be varied in countless ways, and each gene has a unique order,or
base sequence.
8. Describe the structure of DNA, and explain what kind of chenical bond connects the nucleotides to each
strand and together.
Figure 15.5 pg 286
Hydrogen bonds.
9. Explain, in their own words, semiconcentrative replication, and describe the meselson-Stahl experiment.
Figure 15.7 pg 288
Figure 15.8 pg 289
10. Describe the process of DNA replication, and explain the role of helicase, single strandbinding protein,
DNA polymerase ligase and primase.
Figure 15.14 pg 293
helicase- enzyme that untwists the double heilex
single-strand binding protein- attach in chains along the unpaired DNA strands, holding these templates
straight entil the new complementary strand can be synthesized.
DNA polymerase- elongates new DNA
DNA ligase- joins the okazaki fragments into a single DNA strand
primase- Joins the RNA nocleotides to make the primer
12. Define antiparallel, and explain why continuous synthesis of both DNA strands is imposible.
Antiparallel- in the double heilex, the two sugar-phosphate backbones are upside-down, relative to
eachother
Nucleotides can only be added to the free 3’ end of a growing DNA strand.
13. Distinguish between the leading and laging strands.
Figure 15.12 pg 291
14. Explain how the lagging strand is synthesized when DNA polymerase can add nucleotides only to the
3’ end.
As a replication buddle opens, polymerase can work its way from the replication fork.
15. Explain the role of DNA polymerase, ligase, and repair enzymes in DNA profreading and repair.
DNA polymerase- functions as a missmatch repair
DNA ligase- Fills gaps that are cur out.
repair enzymes- cuts out damaged strand segments.
CHAPTER17
FROM GENE TO PROTEIN
OBJECTIVES
4. Explain how RNA differs from DNA.
The differences between DNA and RNA is that while DNA has deoxyribose as its sugar, RNA has ribose,
and instead of the nitrogen base thimin (T), RNA uses Urasil (U).
5. In your own words, briefly explain how information flows from gene to protein.
Figure 16.3 pg. 301
6. Distinguish between transcription and translation.
Figure 16.3 pg. 301
7. Describe where transcription and translation occur in prokaryotes and eucariotes; explain why it is
significant that in eucariotes, transcription and translation are separated in space and time.
Figure 16.3 pg. 301
8. Define codon, and explain what relationship exists between the linear sequence of codons on mRNA and
the linear sequence of amino acids on a polipeptide.
Figure 16.4 pg. 302
9. List the three stop codons and the one start codon.
Figure 16.5 pg. 303
10. Explain in what way the genetic code is redundant and unmistakable.
The genetic code is redundant and unmistakable because it is not random, the information is placed in a
determined order.
11. Explain the evolutionary significance of a nearly universal genetic code.
This universal code shows that all organisms evolved form a single one, making all of them related.
12. Explain the process of transcription including the three major steps of initiation, elongation, and
termination.
Figure 16.7 pg. 305
16. Distinguish among mRNA, tRNA, and rRNA.
mRNA- Transcript of the gene’s protein building instructions
tRNA- Transfers amino acids from the cytoplasm’s amino acid pool to a ribosome.
rRNA- together with proteins, forms ribosomes that coordinates the coupling of tRNA
17. Describe the structure of tRNA and explain how the structure is related to function.
Figure 16.10 pg 307
26. Describe the difference between procariotic and eucariotic mRNA.
The difference between prokaryotic and eukaryotic mRNA is that eukaryotic RNA is transcribed and
translated separately, while prokaryotic RNA is translated during transcription.
28. Describe some biological functions of introns and gene spicing.
Enables different kinds of cells in the same organism to make different proteins from a common gene.
29. Explain why base-pair insertions or deletions usually have a greater effect than base pair substitutions.
mRNA is read in a series of nucleotide triplets during translation, the insertion or deletion of nucleotides
may alter the reading frame (triplet grouping) of the genetic message.
30. Describe how mutagenesis can occur.
Errors during DNA replication, repair, or recombination.
Chapter 18
Microbial models: the genetics of viruses and bacteria
Objectives
2. List and describe structural components of viruses.
Figure 17.2 pg. 326
3. Explain why viruses are obligate parasites
They can only reproduce within a host cell
Can’t replicate when isolated
Can’t make their own proteins
5. Explain the role of reverse transcriptase in retroviruses
Can transcribe DNA from an RNA template (RNA--> DNA)
6. Describe how viruses recognize host cells
Figure 17.6 pg. 331
7. Distinguish between lytic and lysogenic reproductive cycles using phage T4 and phage 1 as examples.
Figure 17.4 pg. 329
Figure 17.5 pg. 329
11. Explain how viruses may cause disease symptoms, and describe some medical weapons used to fight
viral infections.
Some viruses produce or cause the cells to release toxins that cause the disease symptoms.
Fever, aches, and inflammation are most likely to come from the body’s own defenses.
Vaccines are the main weapon to prevent viral infection.
12. List some viruses that have been implicated in human cancers, and explain how tumor viruses
transform cells.
Retroviruses
Papovaviruses
Adenovirus
Herpesvirus
14. List some characteristics that viruses share with living organisms, and explain why viruses do not fit
our usual definition of life.
Same as objective 3
16. describe the structure of a bacterial chromosome.
The chromosomes of prokaryotes are one thousands the size of eukaryotic cells’. Which is still a lot for
such limited space.
18. List and describe the three natural processes of genetic recombination in bacteria.
Transformation- Is the alteration of a bacterial cell’s genotype by the uptake of naked, foreign DNA from
the surrounding environment.
Transduction- phages (the viruses that infect bacteria) transfer bacterial genes from one host cell to another.
Conjugation- is the direct transfer of genetic material between two bacterial cell that are temporarily joined.
20. Explain how the F plasmid controls conjugation in bacteria.
Figure 17.12 pg. 341
27. Briefly describe two main strategies cells use to control metabolism.
Figure 17.16 pg. 344
30. distinguish between structural and regulatory genes.
Structural genes- code for polypeptides
Regulatory genes- produces receptors
Chapter 19
The organization and control of organic genomes
Objectives
1. Compare the organization of prokaryotic and eukaryotic genomes
Cell division is more elaborate in eukaryotes than prokaryotes
2. Describe the current model for progressive levels of DNA packing.
Figure 18.1 pg. 353
4. Distinguish between heterochromatin and euchromatin.
heterochromatin- portion of certain chromosomes that exist in the highly condensed state during interphase
euchromatin- the less compact, unraveled form of chromatin
Chapter 20
DNA technology
1. Explain how advances in recombinant DNA technology have helped scientists study the eukaryotic
genome.
Now they can create more copies of the gene itself, so that it can be studied further.
2. Describe the natural function of restriction enzymes.
Restriction enzymes protect bacteria against intruding DNA from other bacteria.
3. Describe how restriction enzymes and gel electrophoresis are used to isolate DNA fragments.
First, restriction enzymes digest DNA. Then using gel electrophoresis, the macromolecules are separated
depending on size, electrical charge and other physical properties.
7. List and describe two major sources of genes for cloning.
9. Describe how “genes of interest” can be identified with the use of a probe.
10. Explain the importance of DNA synthesis and sequencing to modern studies of eukariotic genomes.