DNA form and function

Question 1

What do proteins act as

4 points

Answer 1

1. enzymes
2. structural
3. receptors
4. messengers - hormones and cytokines

Question 2

Most genes encode a

Answer 2

single protein

Question 3

DNA (deoxyribonucleic acid) structure of DNA nucleotide
6 points

Answer 3

1. Phosphate
2. Sugar = deoxyribose

3. Base:
adenine
guanine
cytosine 
thymine 

4. Carbons in sugar are named 1’, 2’, 3’, 4’ and 5’
5. Base linked to the 1’ carbon
6. Phosphate linked to the 5’ carbon

Question 4

Pyrimidine nucleotides

3 points

Answer 4

1. 6 membered rings
2. dTMP (thymine)
3. dCMP (cytosine)

Question 5

Purine nucleotides

3 points

Answer 5

1. 9 membered rings
2. dAMP (adenine)
3. dGMP (guanine)

Question 6

DNA structure

bonds between

Answer 6

5’ and 3’ ends of nucleotides

Question 7

The nucleotides in DNA are linked by

2 points

Answer 7

1. phosphate bonds (phosphodiester bonds) between the sugars
2. The 3’ carbon of one sugar linked to the 5’ carbon of the next nucleotide

Question 8

Ends of DNA strand are called the

Answer 8

1. 5’ and 3’ ends
2. 5’ end: The 5’ carbon of the terminal nucleotide is free
3. 3’ end: The 3’ carbon of the terminal nucleotide is free

Question 9

who discovered structure f DNA in 1953

Answer 9

watson and crick

Question 10

Franklin and wilkins

Answer 10

X-ray diffraction pattern indicating a helical structure

Question 11

Base pairing

Hydrogen bonds

Answer 11

A to T 2
2 apples in tree

G to C 3
3 cars in garage

Question 12

antiparallel strands

Answer 12

one in direction 5’ to 3’

other in direction 3’ to 5’

Question 13

Base-pairing is specific:

Answer 13

Adenine  Thymine (2 hydrogen bonds)
Guanine Cytosine (3 hydrogen bonds)

Always Purine paired to Pyrimidine

Question 14

Genotypic function

2 points

Answer 14

1. information storage and replication.
2. Genetic material must store genetic information and accurately transmit that information from parents to offspring, generation after generation.

Question 15

Phenotypic function

2 points

Answer 15

1. gene expression.
2. Genetic material must control the development of the phenotype of the organism. i.e. the genetic material must dictate the growth and differentiation of the organism from the zygote to the mature adult.

Question 16

Evolutionary function

2 points

Answer 16

1. mutation.
2. Genetic material must undergo changes so that organisms can adapt to modifications in the environment. Without such changes, evolution could not occur.

Question 17

unity and diversity of life

Answer 17

DNA in all species shows

1. molecular consistency (similar structure)
2. variation (unique base sequences)

Question 18

genomes

Bacteria

Answer 18

10 6 nucleotides; one circular chromosome

Question 19

genomes

Yeast/fungi

Answer 19

10 7-10 8; linear chromosomes

Question 20

genomes

Plants

Answer 20

10 8-10 11; linear chromosomes

Question 21

genomes

mammals

Answer 21

3.4 x 10 9 nucleotides; 23 pairs of chromosomes

Question 22

Each chromosome is made of

Answer 22

1. Chromatin - a very long linear DNA molecule

2. proteins that maintain structure and regulate activity of the genes

Question 23

Packaging DNA

3 points

Answer 23

1. DNA double helix wrapped around a complex of histone proteins = forms a nucleosome
2. Nucleosomes on the strand of DNA coil or fold to form a chromatin fibre
3. The chromatin fibre forms looped domains which further fold to form the chromosome

Question 24

packaging DNA

5 steps

Answer 24

DNA helix
Nucleosomes
Chromatin
Looped chromatin
Chromosome