DNA Structure and Function

Question 1

Electrophoresis

Answer 1

technique used to separate DNA fragments according to size

Question 1

Helicase

Answer 1

during replication, this enzyme helps to open up the DNA helix by breaking the hydrogen bonds

Question 2

Induced mutation

Answer 2

mutation that results from exposure to chemicals or environmental agents

Question 3

Lagging Strand

Answer 3

during replication, the strand that is replicated in short fragments and away from the replication fork

Question 4

Leading Strand

Answer 4

strand that is synthesized continuously in the 5’-3’ direction, which is synthesized in the direction of the replication fork

Question 5

Ligase

Answer 5

enzyme that catalyzes the formation of a phosphodiester linkage between the 3’ OH and 5’ phosphate ends of the DNA

Question 6

Mismatch repair

Answer 6

type of repair mechanism in which mismatched bases are removed after replication

Question 7

Mutation

Answer 7

variation in the nucleotide sequence of a genome

Question 8

Nucleotide excision repair

Answer 8

type of DNA repair mechanism in which the wrong base, along with a few nucleotides upstream or downstream, are removed

Question 9

Okazaki Fragment

Answer 9

DNA fragment that is synthesized in short stretches on the lagging strand

Question 10

Point Mutation

Answer 10

mutation that affects a single base

Question 11

Primase

Answer 11

enzyme that synthesizes the RNA primer; the primer is needed for DNA pol to start synthesis of a new DNA strand

Question 12

Primer

Answer 12

short stretch of nucleotides that is required to initiate replication; in the case of replication, the primer has RNA nucleotides

Question 13

Proofreading

Answer 13

function of DNA pol in which it reads the newly added base before adding the next one

Question 14

Replication Fork

Answer 14

Y-shaped structure formed during initiation of replication

Question 15

Silent Mutation

Answer 15

mutation that is not expressed

Question 16

Single Strand binding protein

Answer 16

during replication, protein that binds to the single-stranded DNA; this helps in keeping the two strands of DNA apart so that they may serve as templates

Question 17

Sliding Clamp

Answer 17

ring-shaped protein that holds the DNA pol on the DNA strand

Question 18

Spontaneous mutation

Answer 18

mutation that takes place in the cells as a result of chemical reactions taking place naturally without exposure to any external agent

Question 19

Telomerase

Answer 19

enzyme that contains a catalytic part and an inbuilt RNA template; it functions to maintain telomeres at chromosome ends

Question 20

Telomere

Answer 20

DNA at the end of linear chromosomes

Question 21

Topoisomerase

Answer 21

enzyme that prevents overwinding of DNA when DNA replication is taking place

Question 22

Transformation

Answer 22

process in which external DNA is taken up by a cell

Question 23

Transition Substitution

Answer 23

when a purine is replaced with a purine or a pyrimidine is replaced with another pyrimidine

Question 24

Transversion Substitution

Answer 24

when a purine is replaced by a pyrimidine or a pyrimidine is replaced by a purine