Biochemistry: Nucleic Acid Structure and Function

Question 1

The phosphate group on a nucleic acid strand is usually found at what end: the 5’ end or the 3’ end?

Answer 1

5’ end of the nuclei acid strand on the pentose sugar

Question 2

The hydroxyl group on the pentose sugar of the nucleic acid strand found at what end: the 5’ end of the 3’ end?

Answer 2

the 3’ end of the nuclei acid strand on the pentose sugar

Question 3

Nucleotides are linked by what specific type of bonds?(include the numbers for the bonds)

Answer 3

3’-5’ phosphodiester bonds

Question 4

What is significant about the 3’ and the 5’ end of a nuclei acid strand or a DNA molecule?

Answer 4

The fact that they’re distinct

Question 5

The sequence of a nucleic acid strange are always conveyed in what direction?

Answer 5

5’ end tot he 3’ end

Question 6

What type of nucleotides are found in the genome in eukaryotes? What is the exception?

Answer 6

dsDNA and ssRNA. Some viruses have dsRNA and ssDNA.

Question 7

What is the structural formula of a DNA molecule and where do you find all of the significant bonds?(hydrogen bonds and phophodiester bonds)

Answer 7

Question 8

What is Chargaff’s rule?

Answer 8

%G = % C and %T = %A and %purine = % pyrimidine

Question 9

How many base pairs per complete turn of the DNA helix?

Answer 9

10 bases

Question 10

Z-DNA is right handed or left handed?

Answer 10

left handed

Question 11

Z-DNA is rich in what type of nucleic acid base pairs?

Answer 11

G-C

Question 12

These drugs exert their effects by intercalating between the bases of DNA, thereby interfering with the activity of topoisomerase II and preventing proper replication of the DNA

Answer 12

doxorubin or danourubicin

Question 13

What is the mechanism of danourubicin and doxorubicin?

Answer 13

intercalates between bases of DNA and interfere with the action of topoisomerase II

Question 14

What drug binds tightly to the DNA, cauasing structural distortion and malfunction

Answer 14

cisplatin

Question 15

Where is the major groove and the minor groove on a DNA molecule?

Answer 15

Question 16

Denaturation of DNA takes place via what processes?(3 points)

Answer 16

heat, alkaline pH and chemicals

Question 17

What are examples of chemicals that may denature DNA?(2 points)

Answer 17

urea and foramide

Question 18

What is the general shape of mitochondrial DNA and DNA of most prokaryotes?

Answer 18

closed circular structures

Question 19

What type of supercoiled DNA is used in most biologic reactions?

Answer 19

(-)

Question 20

What is the difference betwen positive supercoiled and negative supercoiled?

Answer 20

Negative supercoiled is wound less tightly then Watson-Crick model and positive supercoil is wound more tightly than the Watsin-Crick model of the DNA

Question 21

What is the basic packaging unit of chromatin?

Answer 21

nucleosome

Question 22

A series of chromosome can be described structurally and numberically as what?

Answer 22

10 nm of chromatin fiber

Question 23

The histone octamer is formed by what?

Answer 23

two copies of H2A, H2B, H3 and H4 histone proteins

Question 24

What is the purpose of the H1 histone protein?

Answer 24

Histone H1 is associated with the linker DNA found between nucleosomes to help package them into a solenoid-like structure, which is a thick 30 nm fiber

Question 25

How is DNA packaged in the chromatin structure?

Answer 25

The DNA is wound aroun the outside octamer, forming the nuclesome

Question 26

How is DNA associated with the histone octamer?

Answer 26

it is wound around the outside of the histone octamer

Question 27

Histones are rich in what type of amino acid?

Answer 27

Lysine and Arginine

Question 28

What type of charge is on the histone protein

Answer 28

positive charge

Question 29

Each eukaryotic chromosome in Go or G1 contains what specific type of DNA?

Answer 29

one linear molecule of dsDNA

Question 30

What form of chromatin is more open and available for gene expression?

Answer 30

euchromatin

Question 31

The special ribosome assembly occurs in what organelle/suborganelle in a eukaryotic cell?

Answer 31

nucleolus

Question 32

A base compositional analysis that deviates from Chargaff's rule is indicate of what?

Answer 32

single stranded nucleic acid molecule, not double stranded

Question 33

The addition of a phosphate to a nucleoside converts it to what?

Answer 33

a nucleotide

Question 34

Why is it important for the histone protein in the octamer molecules to have a positive charge?

Answer 34

the DNA has a negative charge, it facilitates better interaction

Question 35

Answer 35

D

Question 36

Answer 36

C

Question 37

Answer 37

A

Question 38

Answer 38

E