Introduction to DNA

Question 1

What is the structure of DNA?

Answer 1

right handed double helix

antiparallel strands

Question 2

What is the smallest unit of packaged DNA?

Answer 2

nucleosome

Question 3

How many chromosomes in the human genome?

Answer 3

24

Question 4

What is in a nucleoside?

Answer 4

sugar and base

Question 5

What is in a nucleoetide?

Answer 5

sugar, base and phosphate group

Question 6

What are the two pentose sugars? What is the difference between the two? In which molecules are they found?

Answer 6

ribose (RNA) or 2-deoxyribose (DNA)
ribose 2C OH group
2-deoxyribose 2C H only

Question 7

Name the two purine bases

Answer 7

adenine

guanine

Question 8

Name the pyrimidine bases

Answer 8

cytosine
thymine
uracil

Question 9

What type of bonds are nucleotides joined by?

Answer 9

phosphodiester bond

Question 10

How many H bonds between G and C

Answer 10

3

Question 11

How many H bonds between A and T and A and U

Answer 11

2

Question 12

What occurs in G1?

Answer 12

cell content replication

Question 13

What occurs in S-phase?

Answer 13

DNA replication

Question 14

What occurs in G2?

Answer 14

double check and repair

Question 15

What occurs in M phase?

Answer 15

cell division

Question 16

What enzyme separates the DNA strands?

Answer 16

DNA helicase

Question 17

What enzyme creates the new DNA strand?

Answer 17

DNA polymerase

Question 18

What enzyme joins the DNA fragments?

Answer 18

DNA ligase

Question 19

Why is a kickstart by primase required?

Answer 19

DNA polymerase can only extend from 3’ end

Question 20

What are the fragments in the lagging strand called?

Answer 20

OZKAZAKI

Question 21

What does primase do and why?

Answer 21

produce short sequence of RNA that acts as a primer to kickstart transcription by DNA polymerase
They are later removed

Question 22

What does the exonuclease domain of DNA polymerase do?

Answer 22

part of proofreading function

cleaves phosphodiester bonds from end

Question 23

What does the endonuclease domain of DNA polymerase do?

Answer 23

part of proof reading function

cleave phosphodiester bonds from middle