Exam 3

Question 1

What is one of the functions of spliceosomes?

Answer 1

Remove introns

Question 2

Which of the following features is common to both DNA replication and transcription?

Answer 2

A sugar phosphate bond is formed between the 3’ hydroxyl and the 5’ phosphate

Question 3

Which histone protein is not part of the nucleosome structure?

Answer 3

H1

Question 4

What would you expect to find bound to the stop codon at the ribosomal A site?

Answer 4

A release factor

Question 5

Why are abnormalities in the number of sex-chromosomes in mammals usually less severe in their phenotypic effects than abnormalities in the number of autosomes?

Answer 5

There are relatively few functional genes on the Y chromosome
Random X chromosome activation

Question 6

A chromosome contains the following gene-order: ABCD-EFGH, which of the following rearrangements represents a pericentric inversion?

Answer 6

AFE-DCBGH

Question 7

What is one difference between DNA replication in bacteria versus eukaryotes?

Answer 7

Eukaryotic chromosomes have many origins of replication, while bacteria have only one origin of replication

Question 8

If you heat a solution containing DNA molecules?

Answer 8

The hydrogen bonds will be disrupted and the two strands will separate

Question 9

Ribozymes are enzymes that

Answer 9

are composed of RNA

Question 10

Which of the following enzymes neither makes nor breaks phosphodiester bonds?

Answer 10

Helicase

Question 11

Consider synapsis in prophase I of meiosis for two plant species that each carry 36 chromosomes: Species A is diploid and species B is triploid. What characteristics of homologous chromosome synapsis can be used to distinguish these two species?

Answer 11

The diploid will have 18 bivalents whereas the triploid will have a combination of trivalents, bivalents, and univalents.

Question 12

Which of the following statements about ddNTPs is true?

Answer 12

They have a hydrogen at the 3’ carbon of the ribose sugar

Question 13

Which of the following is most likely attributable to a base substitution at a 5’ splice junction?

Answer 13

A longer than usual final transcript

Question 14

You wish to create a mutation in which you prevent access of RNA polymerase to the gene. Which region of a gene would you target?

Answer 14

Promoter sequence

Question 15

Which of the following is a common consequence of unequal crossover between homologs in repetitive DNA regions of the chromosome?

Answer 15

Partial duplication and deletion

Question 16

Which type of chromosome rearrangement results in the fusion of the long arms of two nonhomologous chromosomes to produce a larger chromosome and a net reduction in chromosome number?

Answer 16

Robertsonian translocation

Question 17

If an organism is an inversion heterozygote

Answer 17

Homologous chromosomes align during meiosis through formation of an inversion loop at synapsis

Question 18

An organism with the genome size of n=23 experienced a Robertsonian translocation. How many chromosomes would you expect to see in the karyotype of a somatic cell in an affected individual?

Answer 18

44

Question 19

Which of the following features is common to both DNA replication and transcription?

Answer 19

A sugar-phosphate bond is formed between the 3’ hydroxyl and 5’ phosphate.

Question 20

If you heat a solution containing DNA molecules

Answer 20

The hydrogen bonds iwll be disrupted and the two strands will separate

Question 21

Ribozymes are enzymes that

Answer 21

are composed of RNA

Question 22

Which chemical group is at the 5’ end of a single polynucleotide strand?

Answer 22

Phosphate group

Question 23

Which one of the following enzymes neither makes nor breaks phosphodiester bonds?

Answer 23

helicase

Question 24

Which of the following is a common consequence of unequal crossover between homologs in repetitive DNA regions of the chromosome?

Answer 24

Partial duplication or deletion

Question 25

Which type of chromosome rearrangement results in the fusion of the long arms of two nonhoomologous chromosomes to produce a larger chromosome and a net reduction in chromosome number?

Answer 25

Robertsonian translocation

Question 26

If an organism is an inversion heterozygote

Answer 26

Homologous chromosomes align during meiosis through formation of a Holliday junction at synapsis

Question 27

Humans with the condition of familial Down syndrome exhibit which type of chromosomal aberration?

Answer 27

Chromosome 14/21 Robertsonian translocation

Question 28

What is one difference between DNA replication in bacteria versus eukaryotes?

Answer 28

Eukaryotic chromosomes have many origins of replication, while bacteria have only one origin of replication

Question 29

Which of the following statements about ddNTPs is true?

Answer 29

They have a hydrogen at the 3' carbon of the ribose sugar

Question 30

Which of the following is most likely attributable to a base substitution at a 5' splice junction?

Answer 30

A longer than usual final transcript

Question 31

You wish to create a mutation in which you prevent access of RNA polymerase to the gene. Which region of a gene would you target?

Answer 31

Promoter sequence

Question 32

Which regions of a gene are not found within the mRNA transcript?

Answer 32

promoter region

Question 33

Which of the following feature is common to both DNA replication and transcription?

Answer 33

A sugar phosphate bond is formed between the 3' hydroxyl and the 5' phosphate

Question 34

What are syntenic genes?

Answer 34

Genes that are located on the same chromosome

Question 35

Syntenic genes can assort independently when

Answer 35

They are far apart on a chromosome and crossing over occurs frequently between the genes

Question 36

The two loci A/a and D/d are linked. The following test cross is made: AD/ad x ad/ad. The progeny consisted of: AD/ad (50%) and ad/ad (50%). What can you deduce about the distance between A/a and D/d?

Answer 36

A/a and D/d are linked so closely that no crossovers ever occur

Question 37

The loci A/a and B/b are linked 22 cM apart. From an individual Ab/aB, what proportion of gametes will be AB?

Answer 37

11%

Question 38

In drosphila, the eye-color mutation scarlet (st) and the bristle mutation spineless (ss) are located in chromosome 3 at a distance of 14 map units. What phenotypes and in what proportions would you expect in the progeny from the mating of st+ ss+/ st ss females x st ss/st ss males?

Answer 38

43% wild type; 43% scarlet spineless; 7% scarlet; 7% spineless

Question 39

For a given cross, the expected number of double recombinants is 20 and the observed number of double recombinants is 15. What is the interference in this region?

Answer 39

0.25

Question 40

In a temperature-sensitive mutant strain of E. Coli, Okazaki fragments accumulate, and DNA synthesis is never completed. What is the enzyme or function likely affected in this strain?

Answer 40

DNA ligase

Question 41

What is one of the functions of spliceosomes?

Answer 41

Remove introns

Question 42

If you heat a solution containing DNA molecules

Answer 42

The hydrogen bonds will be disrupted and the two strands will separate

Question 43

Which one of the following enzymes neither makes nor breaks phosphodiester bonds?

Answer 43

Helicase