L3 Meiosis Flashcards Preview

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Flashcards in L3 Meiosis Deck (30)
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1

What cells are haploid

sperm and eggs

2

What does meiosis produce

sperm and egg cells

3

Diploid definition

organisms with two versions of each chromosome

4

What happens during the S phase of meiosis

DNA is replicated

5

How is genetic diversity created

recombination between homologous chromosomes

6

What does recombination depend on

proximity of chromosomes

7

When are sister chromatids separated in meiosis

anaphase II

8

What is the difference between mitosis and meiosis

meiosis produces haploid gametes, mitosis produces diploid cells

9

What is the function of the synaptoneal complex

facilitates DNA base pairing between homologues

10

What does the synaptoneal complex recognise

double stranded DNA breaks

11

How are homologues bound during recombination

cross linking by transverse filaments, axial cores and cohesin

12

How many crossing over sites occur per bivalent

1-4

13

What are the two types of chromosome abnormality

chromosome number and chromosome structural rearrangements

14

What is aneuploidy

Abnormal number of chromosome material in cells

15

Monosomy

one copy of a chromosome

16

trisomy

3 copies of a chromosome

17

Polyploidy

extra sets of chromosomes

18

Where does polyploidy apper

cell lines

19

Causes of aneuploidy

non-disjunction of chromosomes or sister chromatids

20

Non-disjunction

failure to separate

21

Non-disjunction in which phase of meiosis has more serious consequences

meiosis I

22

Are normal gametes produced if non-disjunction occurs in meiosis I

no

23

Nullsomy

missing pair of chromosomes

24

Embryonic lethal aneuploidy

monosomy, trisomy usually embryonic lethal

25

How lethal is nullsomy

pre-implantation lethal

26

Are embryos with one Y chromosome viable

NO

27

What is a common symptom of chromosomal abnormalities

congenital heart defects

28

Turner's syndrome

complete or partial absence of second X chromosome in phenotypic females

29

Why is lethality exhibited when one X chromosome is lacking

haplo-insufficiency

30

Why can it be difficult for foetus to survive post-implantation

defective placental development