Chapter 10 Nucliec Acids

Question 1

Nucleotides

Answer 1

The building blocks of DNA

Question 2

Genome

Answer 2

The complete complement of an organisms genetic material

Question 3

Three components of nucleotides

Answer 3

Phosphate group
Pentose group
Nitrogenous base

Question 4

What is the complement of 5’ - TTAGCCAT- 3’ in 5,-3,?

Answer 4

ATGGCTAA

Question 5

In the DNA double helix, complementary base pairs are held together by

Answer 5

Hydrogen bonds

Question 6

Replication models

Answer 6

Semi conservative
Conservative
Dispersive

Question 7

Semi conservative

Answer 7

During replication two parental strands separate and serve as template strands
New nucleotides must obey the AT/GC rule
End result two new double helices with same base sequences as original

Question 8

Replication forks

Answer 8

A replication bubble is formed when the DNA helix opens at an origin of replication
Two forks are formed
Leading and lagging strand

Question 9

Leading strand Synthesis

Answer 9

A single RNA primer is made at the origin made by primase
The primer is extended with DNA, DNA polymerase attaches nucleotides in a 5’ to 3’ direction as it slides forward
Makes one long molecule

Question 10

Lagging Strand

Answer 10

Multiple RNA primers are made, not at origin
Direction is opposite to fork movement
Synthesis of DNA is in pieces , Okazaki fragments

Question 11

Used in DNA synthesis

DNA helicase

Answer 11

Binds to DNA and travels 5’ to 3’ using ATP to separate strand and move fork forward

Wraps around DNA and separates the strands

Question 12

Used in DNA synthesis

Topoisomerase

Answer 12

Relieves additional coiling ahead of replication fork

Comes and cuts DNA, then put them together again

Question 13

Used in DNA synthesis

Single strand binding proteins

Answer 13

Keep parental strands open to act as templates

Question 14

DNA polymerase

Answer 14

Covalently links nucleotides
Breaks a covalent bond to release pyrophisphate (2P)
Provides energy fir polymerization

Question 15

What statement best describes DNA polymerase?

Answer 15

It is an enzyme required to glue DNA fragments together

Question 16

Important features of DNA polymerase

Answer 16

1. DNA cannot begin DNA synthesis on a bare template strand alone
2. DNA polymerase can work only 5’ to 3’

Question 17

Primase

Answer 17

Makes RNA primer at the origin

A second primer is made at the fork for the lagging strand

Question 18

Primer removal

Answer 18

RNA primer must be removed and replaced

Both tasked are performed by a special DNA polymerase, DNA polymerase I (in bacteria)

Question 19

DNA ligase

Answer 19

Used after removal of RNA and its replacement with DNA
Works once on leading strand and over again on lagging strand

Catalyzes the phosphodiester bond between the DNA fragments of the lagging strand

Question 20

Which is most likely consequence of a deficiency of DNA ligase

Answer 20

Failure of DNA fragments to link into a single continuous strand

Question 21

Three important issues for DNA polymerase

Answer 21

Speed, fidelity, completeness

Question 22

Telomeres

Answer 22

Series of short nucleotide sequences repeated at the ends of eukaryotic chromosomes
Enzyme attaches many copies of DNA repeat sequence to the ends of chromosomes
3’ hangover
Cause aging