DNA and chromosome basics

Question 1

diameter of DNA

Answer 1

2nm

Question 2

whats on the outside of dna structure

Answer 2

phosphate- -ve charge which attracts polar water

Question 3

double helix is supported by..

Answer 3

a sugar phosphate back bone which increases the stability of the molecule

Question 4

the two strands run..

Answer 4

parallel but opposite to each other–> due to 5 prime and 3 prime strand

Question 5

why do strands run opposite to each other

Answer 5

due to 5 prime and 3 prime strands

Question 6

intermolecular forces between strands

Answer 6

H bonds- individually weak but together very strong

Question 7

DNA is a ….. handed double helix

Answer 7

DNA is a RIGHT handed double helix

Question 8

A + T

Answer 8

2 bonds

Question 9

C+G

Answer 9

3 bonds

Question 10

the DNA right handed double helix is made up of..

Answer 10

minor and major grooves

Question 11

how is DNA faithfully replicated

Answer 11

Semi-conservative replication- otherwise mutations would be very common and this would lead to many disorders and cancers

Question 12

total DNA in the nucleus

Answer 12

the GENOME - organelles like mitochondria and chloroplasts have their own genomes (circular- majority still found in nucleus

Question 13

which organelles have their own genomes

Answer 13

mitochondria and chloroplasts - circular

Question 14

nucleotides are mad cup of..

Answer 14

sugar (deoxyribose); base; phosphate

Question 15

nucleoside=

Answer 15

sugar and base

Question 16

what gives rise to minor and major grooves

Answer 16

the fact that A+T and C+G have diff number of hydrogen bonds

Question 17

Deoxyribose and adenine

Answer 17

deoxy adenosine

Question 18

Deoxyribose and guanine

Answer 18

deoxy guanosine

Question 19

deoxyribose and cytosine

Answer 19

deoxy cytidine

Question 20

deoxyribose and thymine

Answer 20

deoxy thymidine

Question 21

what does right handed double helix mean

Answer 21

the strand that appear on the top of the molecule will run from right to left

Question 22

how is 5 prime strand different to the 3 prime strand

Answer 22

5 prime is able to connect with a further phosphate group whereas 3 prime is unable to do so

Question 23

enzyme work along DNA from the..

Answer 23

5’ to 3’

Question 24

new strand of DNA is formed from the

Answer 24

3’ to 5’

Question 25

minor groove

Answer 25

oxygen in deoxyribose points downwards

Question 26

major groove

Answer 26

oxgen in deoxyribose points upwards

Question 27

every human has around

Answer 27

2m worth of DNA- each nucleus has around 10 micrometers diameter

Question 28

what is DNA wrapped around and how many times

Answer 28

DNA wraps twice around 8 core histone proteins to form nucleosomes

Question 29

why will DNA wrap twice around 8 core histones

Answer 29

DNA is negatively charged due to phosphate group and the histones are positively charged

Question 30

nucleosome

Answer 30

a structural unit of a eukaryotic chromosome, consisting of a length of DNA coiled around a core of histones.

Question 31

what does histone H1 do?

Answer 31

brings the nucleosomes together to form chromatin fibres

Question 32

what forms a chromatin fibre

Answer 32

when histone H1 brings nucleosomes together

Question 33

what further condenses chromatin

Answer 33

scaffold proteins

Question 34

net result of DNA folding

Answer 34

each DNA molecule has been packaged into a mitotic chromosome that is 10,000 fold shorter than its fully extended length

Question 35

interphase chromosomes are organised in the..

Answer 35

nucleus

Question 36

chromosome territories

Answer 36

chromosomes organise themselves into discrete patches- located near the chromosomes territory boundary