Meiosis

Question 1

How many version of each chromosome do diploid organisms have?

Answer 1

2

Question 2

What 2 locations does meiosis occur?

Answer 2

• ovary
• testes

Question 3

What 2 processes occur during meiosis 1?

Answer 3

Crossing-over & segregation (genetic diversity is generated by recombination between homologous chromosomes)

Question 4

What is the main difference between meiosis 2 and mitosis?

Answer 4

the cells on meiosis 2 are haploid, whereas the cells in mitosis are diploid

Question 5

What must occur for homologous recombination to take place?

Answer 5

everything must be very close together

Question 6

What proteins (complexes) facilitate pairing of homologous pairs?

Answer 6

synaptonemal complex proteins

Question 7

What are the 2 purpose of meiotic prophase?

Answer 7

1. aligns the chromosomes up ready for anaphase
2. allows for genetic recombination between paternal & maternal DNA on the same chromosome

Question 8

How close are chromosomes homologs bought together?

Answer 8

40nm

Question 8

What is the purpose of the axial core?

Answer 8

Proteins that bind the chromatin via cohesion

Question 8

What is the fundamental difference between mitosis & meiosis?

Answer 8

Mitosis - sister chromatids separate
Meiosis - homologs separated

Question 8

What is the role of the synaptonemal complex?

Answer 8

• aligns the two chromosomes
• helps in homologous recombination

Question 8

What allows for crossing over?

Answer 8

physical linkage between homologs

Question 9

How many crossings are there per bilavent?

Answer 9

at least 1, no more than 4 (ensures at least 1 crossover forms)

Question 9

What is the result of crossover interference?

Answer 9

once one crossover forms, it inhibits others close by.

Question 9

What are 2 categories of chromosomes abnormalities?

Answer 9

1. abnormalities in chromosome number.
2. chromosome structural rearrangements

Question 9

What is aneuploidy?

Answer 9

when there is is a non-typical number of chromosomes in a cell

Question 9

What is the name given when there is a whole extra set of chromosome?

Answer 9

polyploidy

Question 10

What are the 2 types of aneuploidy?

Answer 10

1. Monosomy - 1 copy of a chromosome
2. Trisomy - 3 copies of chromosome

Question 11

What is aneuploidy caused by?

Answer 11

non-disjunction

Question 12

Can polyploidy be embryonically lethal?

Answer 12

Yes

Question 13

What is the result of aneuploidy in sex chromosomes?

Answer 13

Additional sex chromosomes - minor problems relatively normal lifespan

Lacking sex chromosomes - turner’s syndrome (lacking X), rest normal but infertile

Question 14

What are the consequences of autosomal trisomy 22?

Answer 14

• congenital heart disease
• malformed ears
• underdeveloped mid face

Question 15

What are the consequences of autosomal trisomy 18?

Answer 15

Edwards syndrome:
- severe intellectual disability
- low birth weight
- small jaw/mouth

Question 16

What is an example of a disease resulting from monosomy?

Answer 16

Turner’s syndrome

Question 17

What % of trimester abnormalities are caused by structural arrangements?

Answer 17

4.7%

Question 18

What does pairing of homologues before segregation allow for?

Answer 18

crossing over