BIO206H5 Lecture Notes - Lecture 6: Dna Mismatch Repair, Nucleoside Triphosphate, Dna Replication

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22 Sep 2016

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Occasionally, mutations can make bacteria resistant to antibiotics that are used to kill them. Mutations can also produce smaller variations that underlie many of the differences b/w individuals of the same species. However, mutations can be detrimental: in humans they are responsible for thousands of inherited diseases, and for many types of cancer. Thus, the survival of the cell or organism depends on keeping changes in its dna to a minimum. Dna replication produces two complete double helices from the original dna molecules, each new dna helix identical in nucleotide sequence to the parental dna double helix (unless there was a rare copying error) Each daughter dna double helices ends up with one of the original (old) strands plus one strand that is completely new this style of replication is said to be semiconservative. The dna double helix is normally very stable.

Related Questions

1. In Humans, many types of cancers have been linked to?

A. Duplications
B. Inversions
C. translocations
D. deletions
E all of these

2. 5- bromoouracil is mutagenic because it is a(n)

a. base-modifying agent
b. base analog
c. intercalating agent
d. alkylating agent.

3.Ultraviolet radiation creates __________ in DNA

A. 5-methyl cytosine residues
B. breakages
C point mutations
D. mutational hot spots
E thymine dimers

4. The telomeres of chromosomes is composed of

A. heterochromatin
b. nucleosome
c. histone
d. achromatic

5. In eukaryotes, a replicon is

a. the distance between the origin of replication and thetermination of replication
b. a single chromosome
c. the entire genome
d. one DNA strand of a single chromosome

6. In a nonreciprocal interchomosomal translocation, a segment of achromosome is

a. exchanged with an identical segment on a differentchromosome
b. exchanged with an identical segment on a sister chromatid
c. transferred to a different chromosome without a reciprocalexchange of genetic material
d. transferred to a new location on the same chromosome without areciprocal exchange of genetic material

7. Somatic mutations are always.

a. spontaneous
b. carcinogenic
c. heritable
d. lethal
e. none of these

8. A woman with an XO genotype is

a. aneuploid
b. euploid
c. diploid
d. poluploid

9. Spontaneous mutations may occur as a result of

a. all of these
b. errors in DNA replication
c. transposition
d. none of these
e. normal cell biochemistry

10. In the semi conservative model of DNA replication, progenydouble helices consist of

a. one parental DNA strand and one new strand
b. one parental DNA strand and one new RNA strand
c. two new RNA strands
d. two parental DNA strands
e. two new DNA strands

11. A mutation in a gene may alter a cellâs

a. phenotype
b. genotype and phenotype
c. genotype

12. During replication, the direction of synthesis of new DNA fromthe leading strand is

a. both 5â to 3â and 3â to 5â
b. none of these
c. 3â to 5â
d. from left to right only
e. 5â to 3â only

13. A mutation that results in a switch from a purine-pyramidingbase pair to a pyramiding-purine base pair is a _________mutation.

a. neutral
b. transition
c. missense
d. transversion
e. nonsense

14. A trisomic human cell would contain how many chromosomes?

a. 45
b. 46,
c. 47.
d. 48

15. In a strand of DNA, a _____________ bond connects the phosphategroup of one nucleotide to the sugar of the adjacentnucleotide

a. hydrogen
b. ester
c. phosphodiester
d. phosphate
e. disulfide

16. Cri-du-chat syndrome is caused by which type of chromosomalmutation?

a. deletion
b. duplication
c. translocation
d. transversion
e. inversion

17. During replication, the role of DNA primase is to

a. add nucleotide to the growing DNA chain
b. synthesize a short chain for RNA
c. untwist the double helix at the origin of replication
d. relax the super coiling of the double helix
e. synthesize the primo some

18. A(n) ____________ inversion involves the Centro mere

a. chromocentric
b. paracentric
c. epicentric
d. percentric
e. concentric

19. Which of the following substances mutates DNA by intercalatingbetween adjacent base pairs?

a. methyl methane sulfonate
b. all of these
c. nitrous acid
d. 2-amino urine
e. acridine orange

20. A molecule of RNA is always

a. double stranded
b. helical
c. nonparallel
d. all of these
e. none of these

21. Mutagenesis of cells using radiation or a chemicalintercalating agent could be used to create __________ mutations ina region of DNA.

a. random
b. both random and site-specific
c. site-specific

22. In Griffithsâs tranformation experiments, the mice died whenthey were injected with

a. living, no virulent bacteria
b. living, virulent bacteria
c. heat-killed, no virulent bacteria
d. living, nonvirulent bacteria
e. both B and D

23. A monoploid human cells

a. shows only the excessive phenotype of all these genes
b. would be functionally impaired
c. is normal
d. would not survive

24. Gametes containing an abnormal number of chromosomes may occuras a result of

a. paracentric inversion
b. reciprocal translocation
c. disjunction of chromosomes
d. unequal crossing over

25. DNA may be altered as a result of _____________ events thatoccur normally in cells

a. depurination
b. deamination
c. depyrimidation
d. all of the above
e. none of the above

26. Which enzyme prevents DNA from tangling up as the replicationfork migrates during replication?

a. DNA polymerase I
b. DNA helicase
c. topoisonmerase
d. DNA polymerase III
e. DNA gyrase

27. Which of the following enzymes play an important role in DNAreplication?

a. DNA helicase
b. DNA ligase
c. DNA primase
d. all of them
e. DNA polymerase III

28. A mutation gene sustains a mutation that restores the originalphenotype, This is a

a. frame shift mutation
b. transversion
c. reversion
d. transition
e. forward mutation

29. A dicentric chromosome has two

a. telomeres
b. mutations
c. arms
d. centromeres

30. Which type of chromosomal mutation cannot revert to thewild-type state

a. duplication
b. deletion
c. translocation
d. both A and C
e. all of them

31. Translation of histone mRNAs occurs during which phase of theeukaryotic cell cycle?

a. M
b. G1
c. G2
d. S
e. all of these

32. After removal of the RNA primers, Okazaki fragments are joinedthrough a reaction that involves which enzyme?

a. RNA polymerase
b. DNA helicase
c. DNA polymerase
d. DNA primase
e. DNA ligase

33. Which of the following is required for the synthesis of DNAduring replication?

a. DNA polymerase
b. magnesium ions
c. all of them
d. template DNA
e. dNTPs

34. Most of the genome of an active cell consists of

a. heterochromatin
b. histochromatin
c. poluchromatin
d. euchromatin

35. In eukaryotes, DNA replication begins,

a. a single origin of replication on each chromosome
b. a single origin of replication on each chromosome
c. multiple origins of replication on each chromosome
d. all of the above
e. none of the above

36. A human cell contains 2 sets of 24 chromosomes is

a. euploid
b. haploid
c. polyploid
d. aneuploid

37. Pseudodominance occurs as a result of which type ofmutation?

a. translocation
b. duppolication
c. all of these
d. point mutation
e. deletion

38. The enzymatic activity of a telomerase is best described asa

a. none of these
b. polymerase
c. ligase
d. reverse transcriptase
e. topoisomerase

39. A Barr body is an example of

a. constitutive heterochromatin
b. facultative heterochromatin
c. facultative euchromatin
d. constitutive euchromatin

40. An addition or deletion of one or two base pairs in a genecauses a ____________ mutation

a. Transition
b. frameshift
c. nonsense
d. transversion
e. neutral

41. A heterozygous chromosomal inversion can be detected

a. by cytogenetic observation of loops in chromosomes
b. through genetic studies indicating a decrease in the frequencyof recombination between genes
c. by observing a decrease in the number of viable progenyfollowing genetic crosses
d. all of the above

42. The mutagen 5-bromouracil is an analog of which base?

a. adenine
b. threonine
c. thymine
d. cystosine
e. uracil

43. A mutation that changes a codon from one that represents anamino acid to one that signals a chain termination is a______________ mutation.

a. neutral
b. missense
c. frame shift
d. nonsense

44. A chromosomal mutation that results in an increase in theamount of DNA is a(n)

a. duplication
b. inversion
c. deletion
d. both A and C
e. all of the above

45. Prior to replication, the DNA double helix must be untwisted bywhich type of enzyme?

a. topoisomerase
b. ligase
c. polymerase
d. helicase
e. primase

46. In his transformation experiments, Griffiths used cultures ofwhich bacterium?

a. Sacchromyces cerevisiae
b. Escherichia coli
c. Streptococcus pneumoniae.
d. Bacillus cereus
e. Eneterococcus faecalis

47. A mutation changes a codon from a UCG to a UAG. This is a____________ mutation?

a. point
b. nonsense
c. silent
d. both A and B
e. all of the above

48. In eukaryotes, DNA replication

a. is initiated at several sites on chromosomes
b. occurs bidirectional
c. is semidiscontinuous
d. all of the above
e. none of the above

49. Which of the following bacteria are used in the Amestest?

a. Pseudomonas aeruginosa
b. Escherichia coli
c. Vibrio cholera
d. Salmonella typhimurium
e. Rickettsia rickettsii

50. Which of the following changes represents a missensemutation?

a. UGA (stop) to UAG (stop)
b. AAA (lysine) to AGA (arginine)
c. UUU (phenylalanine) to UAA (stop)
d. AUG (methionine) to UGA (stop)
e. AAA (lysine) to AAG (lysine)

1. Characters that show a continuous range of variation, such as height and eye color, usually are controlled:

a.	by a single gene with two alleles that are codominant.

b.	by many genes with an additive effect.

c.	by epistatic interactions between two genes.

d.	mainly by the environment, with only a small genetic component.

2. In humans, red-green colorblindness is inherited as a sex-linked recessive trait. In order for a woman to be red-green colorblind, which of the following statements must be true.

a.	Her mother must be red-green colorblind.

b.	All of her brothers must be red-green colorblind.

c.	Her father must be red-green colorblind.

d.	All of the above statements must be true if a woman is red-green colorblind.

3. The x-ray crystallography data collected by Rosalind Franklin suggested to Watson and Crick that the:

a.	structure of DNA is a double helix.

b.	two strands of the DNA molecule are joined by hydrogen bonds between the bases.

c.	four bases within DNA pair in a specific way.

d.	two strands of the DNA molecule are joined by covalent bonds between the bases.

4. In the genetic code, _________ one amino acid.

a.	one nucleotide specifies

b.	two nucleotides specify

c.	three nucleotides specify

d.	four nucleotides specify

5. During Meiosis I, a homologous pair of chromosomes may not separate, resulting in daughter cells that have extra chromosomes or are missing chromosomes. This can lead to genetic disorders, including Down Syndrome. This phenomenon is called:

a.	independent assortment.

b.	nondisjunction.

c.	segregation.

d.	crossing over.

6. You are a human geneticist studying the incidence of retinitis pigmentosa in the residents of Tristan de Cunha, a group of small islands in the middle of the southern Atlantic Ocean. The allele for retinitis pigmentosa, which causes a form of blindness, is inherited as an autosomal recessive. You have determined that the frequency of this allele (r) in the population is 0.4 (40%). Using the principles of the Hardy-Weinberg rule, you would estimate the frequency of individuals who are heterozygous for this allele (Rr) in the population to be:

a.	0.16 (16%)

b.	0.24 (24%)

c.	0.36 (36%)

d.	0.48 (48%)

7. Natural selection acts at the level of the:

a.	phenotype.

gene.

c.	population.

d.	nucleotide.

8. You are working with pea plants, trying to recreate the experiments that Mendel performed. You are doing a dihybrid cross with a plant that is heterozygous for both seed shape and seed color, with the genotype RrYy. Which allelic combinations would you expect to find in the gametes produced by this plant?

a.	This plant would produce only RY and ry gametes.

b.	This plant would produce only RrYy gametes.

c.	This plant would produce RY, Ry, rY, and ry gametes.

d.	You cannot determine which gametes this plant can produce without knowing the genotypes of its parents.

9. Biochemist Erwin Chargaff found that in DNA there is a special relationship between the four bases that we now call Chargaff's rule. His observation was that, in an organism's genome the:

a.	percentage of A nucleotides = the percentage of T nucleotides, and the percentage of C nucleotides = the percentage of G nucleotides.

b.	four bases all occur in an equal frequency (25%) within each organism.

c.	percentage of A nucleotides = the percentage of G nucleotides, and the percentage of C nucleotides = the percentage of T nucleotides.

d.	genetic material is composed of proteins, not DNA.

10. During DNA replication:

a.	each strand of the double helix acts as a template for the synthesis of a new strand.

b.	the enzyme DNA polymerase adds nucleotides to the strand being synthesized.

c.	the bases A,C,G and T are required.

d.	All of the above are true of DNA replication.

11. During translation, amino acids are joined by peptide bonds to make polypeptides. The formation of these peptide bonds is catalyzed by:

12. If an allele (R) at a gene with two alleles shows complete dominance, individuals with the genotypes ______ will have the same phenotype.

a.	RR and rr.

RR and Rr

Rr and rr

d.	Each of the three possible genotypes will have a different phenotype.

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BIO206H5 Lecture Notes - Lecture 6: Dna Mismatch Repair, Nucleoside Triphosphate, Dna Replication

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