IMMS DNA AND GENETICS Flashcards Preview

PHASE 1 REVISION GUIDE > IMMS DNA AND GENETICS > Flashcards

Flashcards in IMMS DNA AND GENETICS Deck (94)
Loading flashcards...
1

where is DNA found?

in the nucleus and mitochondria

2

what is the structure of DNA?

arranged in double alpha helix with complimentary base pairings
DNA coils around histones and form nucleosomes -> supercoils -> chromosomes

3

how many chromosomes are there?

46 chromosomes
22 pairs and 2 sex chromosomes

4

what are autosomes?

chromosomes that don't determine sex

5

what is the karyotype?

the number and appearance of chromosomes in a cell
the spreads are arranged in size order

6

what is DNA like in prokaryotes?

no nuclear membrane
DNA in single chromosomes
DNA can be circular

7

what is DNA like in eukaryotes?

DNA is in a nucleus
DNA is bound to proteins

8

what is the structure of a chromosome?

made of 2 identical strands of chromatids joined in the centre by a centromere

9

what are the functions of DNA?

- storing and transferring genetic information
- template and regulator for transcription and protein synthesis
- DNA is the genetic material and the structural basis of hereditary and genetic diseases

10

what are nucleotides?

they are the building blocks of DNA

11

what are nucleotides made of?

pentose sugar
nitrogenous base
phosphate

12

which nitrogenous bases are found in DNA?

adenine
cytosine
guanine
thymine

A = T
C = G

13

which nitrogenous bases are found in RNA?

adenine
cytosine
guanine
uracil

A = U
C = G

14

what are duplication mutations?

sections repeat themselves
incorrect protein is generated

15

what are the different types of deletion mutations?

out of frame
in frame

16

what are out of frame deletion mutations?

the sequence shifts meaning the reading frame of the sequence is changed

17

what are in frame deletion mutations?

one codon is removed thus only one amino acid is lost
reading frame is not changed

18

what are mutations of regulatory sequence?

the coding sequence is still intact, but the gene itself is switched on or off

19

what can cause DNA damage?

chemicals
UV
radiation

20

what are DNA repair issues?

base or nucleotide excision
mismatch repair or transcription-couples repair

21

what are non-sense mutations?

a mutation that produces a stop codon
this results in an incomplete, usually non-functional protein
eg duchenne muscular dystrophy

22

give an example of a condition caused by a non-sense mutation

duchenne muscular dystrophy

23

what is a mis-sense mutation?

a point mutation in which a single nucleotide change results in a codon that codes for a different amino acid (substitution)
can have varied effect and can be silent non-functional protein

24

give an example of a condition caused by a mis-sense mutation

sickle cell disease
CAG is replaced with CTG

25

what is a splice site mutation?

it affects the accurate removal of an intron

26

what is the expansion of a tri-nucleotide repeat mutation?

a triple repeat is repeated several times in the first part of the coding sequence

27

give an example of a condition caused by a tri-nucleotide repeat?

huntigntons disease
if CAG is repeated >36 times the patient will develop huntingtons

28

what is anticipation?

in diseases such as Huntington's, repeats get bigger when they are transmitted to the next generation
this results in earlier symptoms of greater severity

29

what is the effect of an insertion mutation?

causes a frame shift
non-functional protein

30

what is the role of DNA helicase in DNA replication?

separates the DNA strands by breaking hydrogen bonds between base pairings