L4 Chromosome Structure Flashcards Preview

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Flashcards in L4 Chromosome Structure Deck (50)
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1

What do diploid eukaryotic cells contain

two copies of each chromosome

2

What can individual chromosomes be easily distinguished

metaphase of mitosis

3

Karotype

organised representation of all chromosomes at metaphase

4

Describe the organisation of individual chromosomes in interphase

occupy distinct subnuclear terriotories

5

Chromosome

highly coiled fibre of chromatin

6

Types of chromatin

euchromatin, heterochromatin

7

Nucleosome

building material of chromosomes

8

Types of histone

4 distinct types

9

Core histones

protein subunit of nucleosome

10

Function of histone tails

interact with proteins, facilitate regulation of chromatin

11

H1

linker histone

12

Function of H1

straps DNA onto histone octamers - limits DNA movement

13

What does H1 facilitate

establishment of transcriptionally silent heterochromatin

14

Interphase chromatin

set of dynamic fractal globules

15

Nuclear periphery in interphase cells composition

transcriptionally inactive DNA

16

Heterochromatin

transcriptionally silent

17

Inner part of the nucleus in interphase cells

RNA transcripts, transcriptionally active genes

18

Telomere

DNA sequences at ends of linear chromosome

19

Telomere function

maintain chromosomal integrity

20

Replication origin

DNA sequence, initiation of DNA replication

21

Centromere

DNA sequences, kinetochore assembly

22

Centromere function

Mediate chromosome segregation

23

Kinetochore

protein complex

24

Kinetochore function

binds microtubules in mitotic spindle

25

Telomerase

DNA polymerase that replicates telomeres

26

True or False - telomeres are double stranded

false

27

Two forms of kinetochore

inner and outer plate

28

Inner kinetochore plate function

binds to chromatin containing alpha satellite DNA

29

Kinetochore outer plate function

binds to protein components of mitotic spindle

30

What do centromeres contain

alpha satellite DNA repeats

31

Alpha satellite DNA repeats function

form condensed heterochromatin with histone octamers

32

CENP-A

specialised histone in centromeric chromatin

33

CENP-A function

connects inner kinetochore plate to methylated histones

34

H3-K4me

methylated histone

35

H3-K4me function

hold sister chromatids together

36

Kinetochore in yeast

Hollow cylinder / basket

37

Kinetochore in yeast function

links single nucleosome of centromeric chromatin to single microtubule

38

Relationship between complex organisms and protein coding genes

More complex organisms, more protein coding genes, more non protein coding DNA

39

Transposons

mobile repeated DNA sequences

40

Types of transposons

DNA transposons, Retroviral retrotransposons, Non-retroviral polyA retrotransposons

41

DNA transposon movement

cut and paste mechanism, without self duplication

42

Requirements of DNA transposon movement

transposase

43

DNA transposon discovery

Maize by Barbara McClintock

44

Retroviral transposons function

replicate via RNA intermediates, produce new DNA copies - integrate at new genomic locations

45

Retroviral transposon requirement

self encoded reverse transcriptase

46

non-retroviral retrotransposons

replicate via RNA intermediate, copy and paste

47

non-retroviral retrotransposon requirement

retrotransposon encoded reverse transcriptase

48

TRUE or FALSE - most transposons are defective

true

49

Large numbers of transposable elements are found in...

genomes of more complex organisms

50

How much of the human genome is made up of transposons

around 50%