DNA replication

Question 1

Role of Magnesium ions (Mg 2+)

Answer 1

Required for DNA polymerase activity

Question 2

Zidovudine can:

Answer 2

-Prolong life in HIV infected individuals
-Reduce mother to baby transmission by more than 20%

Question 3

Initiator proteins (DNaA protein)

Answer 3

Binds to origin of replication and breaks hydrogen bonds between bases

Question 4

DNA helicase (DNaB)

Answer 4

Opens helix and binds primase to form primosome

Question 5

Helicase inhibitor (DNaC)

Answer 5

Delivers helicase to DNA template

Question 6

DNA primase

Answer 6

An RNA polymerase that synthesizes a RNA primer on the lagging strand to enable DNA polymerase to synthesize DNA strand

Question 7

DNA polymerase I

Answer 7

Remove RNA primer and replace with DNA

Question 8

DNA polymerase III

Answer 8

Synthesis of leading and lagging strands

Question 9

Single stranded binding protein (ssb)

Answer 9

Binds to single stranded DNA in the replication bubble and prevents it from reannealing or forming secondary structure

Question 10

How are the Okazaki fragments joined together

Answer 10

DNA ligase

Question 11

Lagging strand synthesis

Answer 11

Each Okazaki fragment requires a separate primer

Question 12

How is DNA polymerase III loaded and maintained on the single stranded DNA template, and unloaded when it reaches double stranded DNA

Answer 12

Clamp protein

Question 13

Clamp protein

Answer 13

Tightly holds the DNA polymerase onto the template for synthesis of long templates (increases expressivity), and releases DNA pol when it stalls at a region of double stranded DNA

Question 14

For a bacterial replication fork moving at 500 bp per second, the parental DNA helix ahead of the fork must rotate at 50 revolutions per minute. This generates positive supercoils ahead of the replication fork.

Answer 14

Swivel the DNA using Topoisomerase enzymes

Question 15

DNA gyrase (type II topoisomerase)

Answer 15

This enzyme introduces negative supercoils into the DNA. This reduces the positive supercoils introduced by the opening of the DNA. Also aids in the separation of the DNA during replication and transcription.

Question 16

Ciprofloxacin

Answer 16

Is a quinolone drug that inhibits bacterial DNA gyrase. It is used in the treatment of respiratory and UTI and can be used to treat anthrax.

Question 17

Camptothecin

Answer 17

An anticancer drug, binds to and inhibits topoisomerase I activity. The result is DNA breakage

Question 18

Etoposide

Answer 18

Another anticancer drug, inhibits the activity of topoisomerase II

Question 19

SNP

Answer 19

Single Nucleotide Polymorphism: Formally defined as a variant that is found at least in 1% of the population. Single base pair change between individuals.

Question 20

SSR (Simple Sequence Repeat)

Answer 20

These are the most simple type of repetitive sequence; and most polymorphic

Question 21

VNTR

Answer 21

Short tandem repeats. A bit longer than the SSR.

Question 22

LCR

Answer 22

Low copy repeat

Question 23

Pleiotropy

Answer 23

Many different features (phenotypic manifestations, all ascribed to a single genetic cause)

Question 24

Myotonia

Answer 24

Reduced ability to relax after a muscle contraction

Question 25

Myoclonus

Answer 25

Quick, involuntary muscle jerk

Question 26

Haplo-insufficiency

Answer 26

Loss-of-function mutations in which half normal levels (50%) of the gene product result in phenotypic effects. Reduced protein levels (50%) are not sufficient to carry out the normal functions of that protein.

Question 27

Dominant-Negative mutations

Answer 27

A mutant gene product interferes with function of the normal gene product. In some cases, assembly of the multimeric protein is affected (hindered) by the presence of the mutant protein.
-Produce a more severe phenotype than autosomal dominant by haploinsufficiency