Chromosomes

Question 1

autosomes:

Answer 1

22 pairs of normal chromosomes

Question 2

features: mitochondrial DNA

Answer 2

• high copy number
• from mum
• 13 genes, 22 tRNA
• high mutation rate

Question 3

endosymbiont theory:

Answer 3

• precursor to eukaryotic cells
• host cell engulf prokaryote which becomes mitochondria
• another photosynthetic= chloroplast

Question 4

how many bases make up kilobase

Answer 4

1 000 bases

Question 5

how many make up megabase?

Answer 5

1 000 000 bases

Question 6

how many bases in human genome:

Answer 6

3000 Mb

Question 7

chromosome: definition

Answer 7

DNA and proteins

Question 8

chromatid:

Answer 8

2 sister chromatids join to form chromosome

Question 9

centromere:

Answer 9

where two chromatids join

Question 10

how many chromosomes in humans:

Answer 10

23 pairs of chromosomes

Question 11

features: ploidy

Answer 11

humans have 2n chromosomes (diploid)

• n= haploid
• 3n= triploid
• polyploid more than 2 sets of chromosomes

Question 12

chromosome structure:

Answer 12

• short (p) and long (q) arm due to uneven centromere

- TP53 gene 17p 13.1

Question 13

karyotype:

Answer 13

number and appearance of chromosomes of eukaryotic cell

Question 14

chromatin:

Answer 14

makes up chromosomes: DNA and proteins

Question 15

euchromatin:

Answer 15

loosely packaged chromatin, actively expressed genes

Question 16

heterochromatin:

Answer 16

unexpressed (inhibited or silenced) genes

Question 17

how are they found: euchromatin and heterochromatin

Answer 17

• they could be condensed into heterochromatin and vice versa
• condensed genes are less likely expressed

Question 18

how is DNA packaged: histones

Answer 18

eukaryotes:

• DNA is wound around histone proteins
• DNA + histones = nucleosome
• 2x of 4 histone proteins = histone core

Question 19

what are the histone proteins:

Answer 19

H2A
H2B
H3
H4

Question 20

nucleosome consists of:

Answer 20

• octamer of protein

- 146 bp of DNA

Question 21

thickness of condensed chromatin fibre:

Answer 21

30 nm thick

Question 22

chromosome architecture: flow

Answer 22

DNA double helix - (beads on a string) nucleosome - 30 nm fibre - 1 loop - 1 rosette (6 loops) 300 nm fibre - 1 coil (30 rosettes) chromatid 700 nm (10 coils each)

Question 23

list 4 chromosome mutations:

Answer 23

deletion
duplication
inversion
translocation

Question 24

deletion:

Answer 24

removes a chromosomal segment

Question 25

duplication:

Answer 25

repeats a segment

Question 26

inversion:

Answer 26

reverses a segment in chromosome

Question 27

translocation:

Answer 27

moves segment from one chromosome to nonhomologous chromosome

Question 28

list eg of linear and circular DNA

Answer 28

linear:
nuclear DNA

circular:
mitochondria, chloroplast

Question 29

different eg of sex determination:

Answer 29

humans: XY
XY

chickens: ZW
ZW (females) or ZZ (males)

grasshopper: X0
XX (female) or X (male)

bees: haplo-diploid
- diploid (32) females or haploid (16) for males