DNA

Question 1

Structure of DNA?

Answer 1

DNA coils round histones
Nucleosomes
Supercoils
Chromosomes

Question 2

Where is DNA found? Structure?

Answer 2

Nucleus, mitochondria (maternal)
Double helix with comp bp

Question 3

How many chromosomes are there (sex)

Answer 3

46
22 pairs- autosomes (not sex)
XY- Male
XX- Female

Question 4

Define karyotype

Answer 4

Number and appearance of chromosomes in cell

Question 5

What is a spread?

Answer 5

Arranged in size order

Question 6

Difference between prokaryotes and eukaryotes?

Answer 6

Prokaryotes- less compartmentalisation
- no nuclear membrane
- DNA single chromosomes
Eukaryotes- more compartmentalisation
- DNA in nucleus
- bound to proteins

Question 7

What joins chromatids together to from chromosome?

Answer 7

Centromere

Question 8

Functions of DNA? (3)

Answer 8

Store and transfer genetic information
Template and regulator for transcription and protein synthesis
Structural basis of hereditary and genetic diseases

Question 9

What are the building blocks of DNA
What provides energy for reaction to occur?

Answer 9

Nucleotides
Free phosphate groups

Question 10

What bp are there?

Answer 10

Adenine and thymine
Cytosine and guanine

Adenine and uracil (RNA)

Question 11

Folding

Answer 11

Question 12

State mutations that can occur?

Answer 12

Duplications- section repeating
Deletions
Substitution
DNA damage- chemicals, UV, radiation
Mutations regulatory seq- gene on/off
DNA repair issues- base excision

Question 13

What is difference between out of frame and in frame deletion?

Answer 13

Out frame- seq shift- reading frame of gene
changed- big impact
In frame- one codon removed- one aa lost-
reading frame NOT changed

Question 14

Define non-sense mutation?
Example

Answer 14

Point mutation produces stop codon
Result incomplete, non functional protein
E.g. Duchenne’s muscular dystrophy

Question 15

Define mis-sense mutation?
Example

Answer 15

Point mutation- single nucleotide change results in codon that codes for diff aa (sub)
Can result in silent mutation and non-functional protein
E.g. Sickle cell- CAG replaced CTG

Question 16

What mutation effect during creating mature messenger RNA?
Define intron?
Define exon?

Answer 16

Splice site mutation
Intron- non-coding
Exon- coding

Question 17

Define expansion of tri-nucleotide repeat?
Example?

Answer 17

Triple repeat is repeated multiple times
E.g. Huntingtons (CAG)
>36 patient develop Huntingtons

Question 18

Define anticipation?

Answer 18

Repeats get bigger as transmitted to next generation
Results earlier symptoms of greater severity
E.g. Huntingtons

Question 19

Answer 19