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Flashcards in Genetics Deck (37)
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1

Each human has how many pairs of chromosomes?

23 pairs in total
22 autosomal pairs, 1 sex-linked pair

2

G0 phase of the cell cycle

Most cells are resting, carrying out their normal function

3

G1 phase of the cell cycle

1st growth phase as chromosomes become ready to be replicated

4

S phase of the cell cycle

DNA replication occurs

5

G2 phase of the cell cycle

2nd growth phase involving proteins etc.

6

M phase of the cell cycle

Mitosis - mechanical separation of cell into two daughter cells
Two daughter cells are identical, diploid cells

7

Variation occurs during meiosis by two main methods, which are?

Crossing over
Independent segregation of homologous chromosomes

8

In meiosis, one diploid cell becomes...

Four haploid daughter cells

9

Examples of sequence variations between genes?

Single nucleotide polymorphisms (SNPs)
Deletions/duplications

10

A polymorphism is...

A change in the genome that does not cause disease in its own right, but can predispose to a common disease

11

Chromosome 22 looks like a...

Teddy bear

12

A chromosome consists of...

Telomeres at each end
Short arm (p)
Centromere
Long arm (q)

13

A chromosome is metacentric if...

Both arms are roughly the same length

14

A chromosome is acrocentric if...

The p (short) arm is so short it is hard to observe

15

A chromosome is telocentric if...

The centromere is located at the terminal end of the chromosome

16

An aneuploidy is...

An abnormal number of chromosomes
Monosomy - missing chromosome from one pair
Trisomy - extra chromosome in a pair

17

Reciprocal translocations are when...

Segments from two different chromosomes have been exchanged

18

Robertsonian translocations are when...

A chromosome attaches to another chromosome at the centromere
Only occurs with 13, 14, 15, 21, 22

19

Monosomy of the sex chromosomes causes...

Turner's syndrome

20

Trisomy of chromosome 21 causes...

Down's syndrome

21

What is FISH?

DNA probes specifically bind to areas of individual chromosomes and apply a fluorescein stain to make the chromosome visible
Useful for detecting aneuploidies

22

Penetrance is defined as...

The likelihood of having the disease given you have the genetic mutation

23

Mendelian inheritance encompasses which disorders?

Autosomal dominant
Autosomal recessive
X-linked
Mitochondrial

24

Autosomal dominant disease occurs when...

There is one faulty copy of the gene
Seen in all generations
50% risk of affected child if parent affected

25

Autosomal recessive disease occurs when...

There are 2 faulty copies of the gene
Often only one generation affected
25% risk of affected child if parents are carriers
Increased likelihood if parents are related

26

X-linked disease occurs when...

The disease is carried on the X-chromosome only
50% of male children of a female carrier affected
50% of female children of a female carrier affected
All male children of a male carrier normal
All female children of a male carrier will be carriers

27

Mitochondrial disease occurs when...

Diseased mitochondria passed from mother to child

28

What is mosaicism?

Occurs when cells within the same person have a different genetic makeup

29

Epigenetic variation describes...

Functional modifications to the genome that do not involve a change in the nucleotide sequence

30

Methylation inhibits which process?

DNA transcription