chapter 8 lecture 10

Question 1

Metacentric

Answer 1

Centromere located approx. in the middle

- Arms of equal length

Question 2

submetacentric

Answer 2

○ Centromere displaced toward one end
○ Creating along arm and a short arm
○ In humans long arm = q
○ Short arm - p

Question 3

Acrocentric

Answer 3

○ Centromere is near one end, producing a long arm and a knob, or satellite at the other end

Question 4

telocentric

Answer 4

centromere is at or very near the end of the chromosome

Question 5

karyotyping

Answer 5

• complete set of chromosomes possessed by an organism
• chromosomes prepared from actively dividing cells
  e. g. WBCs or bone marrow
• halted in metaphase (with Colchicine)
• chromosomes arranged according to size

Question 6

G bands

Answer 6

Giemsa stain

distinguishes areas of DNA rich in A-T base pairs

Question 7

Q bands

Answer 7

quinacrine stain
- viewed under UV
variation of brightness from differences in relative amounts of C-G and A-T base pairs

Question 8

C bands

Answer 8

reveals centromeric heterochromatin

Question 9

R bands

Answer 9

regions rich in C-G base pairs

reverse Giemsa stain

Question 10

T- banding

Answer 10

telomeric banding after heat denaturation

Question 11

Aneuploidy

Answer 11

the loss or gain of (individual) chromosomes

Question 12

polyploidy

Answer 12

contain more than two complete paired (homologous) sets of chromosomes

Question 13

4 types of chromosome rearrangements

Answer 13

duplication
inversion
deletion
translocation

Question 14

chromosomes duplication

Answer 14

a segments of the chromosome is duplicated

- have an extra copy

Question 15

chromosome inversion

Answer 15

a segments of the chromosome is turned 180 degrees

Question 16

chromosome deletions

Answer 16

a segment of the chromosome is deleted

• loss of a segment
• large ones detected because during pairing normal chromosome loops out

Question 17

translocation

Answer 17

a segments of a chromosome moves from one chromosome to a nonhomologous chromosome or to another place on the same chromosome

Question 18

what are 3 effects of deletions

Answer 18

• imbalances of gene products
• pseudodominance
• haploinsifficiency

Question 19

pseudodominance

Answer 19

expression of a normally recessive gene

Question 20

haploinsufficiency

Answer 20

gene not sufficient to produce a wild-type phenotype

Question 21

paracentric inversion

Answer 21

inversion in which the breakpoints are confined to one arm of a chromosome
- the inverted segment does not span the centromere

Question 22

pericentric inversion

Answer 22

inversion in which the breakpoints occur on both arms of a chromosome. the inverted segment spans the centromere

Question 23

dicentric chromatid

Answer 23

has two centromeres

Question 24

acentric chromatid

Answer 24

lacks a centromere

Question 25

``` a dicentric chromosome is produced when crossing over takes place in an individual heterozygous for which type of chromosome rearrangement? a. duplication b. deletion c. paracentric inversion pericentric inversion ```

Answer 25

a. paracentric inversion

Question 26

nonreciprocal translocation

Answer 26

segment moves from the first chromosome to the second without any transfer from the second to the first - results in a chromosome will less material than it is supposed to have

Question 27

reciprocal translocation

Answer 27

a 2-way exchange of segments between the chromosomes | -

Question 28

Robertsonian translocation

Answer 28

the short arm of one acrocentric chromosome is exchanged with the long arm of another - creates a large metacentric chromosome and a fragment that often fails to segregate and is lost.

Question 29

What is the outcome of a Robertsonian translocation? a. two acrocentric chromosomes b. one metacentric chromosome and one chromosome with 2 very sort arms c. one metacentric chromosome and one acrocentric chromosome d. two metacentric chromosomes

Answer 29

b. one metacentric chromosome and one chromosome with 2 very sort arms

Question 30

causes of aneuploidy

Answer 30

- deletion of centromere during mitosis and meiosis - robertsonian translocation - nondisjunction during meiosis and mitosis

Question 31

Nullisomy

Answer 31

type of aneuploidy - loss of both members of a homologous pair of chromosomes 2n-2

Question 32

monosomy

Answer 32

type of aneuploidy - loss of a single chromosome 2n-1

Question 33

trisomy

Answer 33

type of aneuploidy gain of a single chromosome 2n+1

Question 34

tetrasomy

Answer 34

gain of two homologous chromosomes | 2n+2

Question 35

a diploid organism has 2n=36 chromosomes, How many chromosomes will be found in a trisomic member of this species?

Answer 35

2n+1 36+1 = 37

Question 36

Turner syndrome is ? Klinefleter syndrome is ? what's another common example of a trisomy?

Answer 36

Turner XO Klinefelter XXY Down syndrome or trisomy 21

Question 37

Briefly explain why in humans and mammals, sex chromosome aneuploids are more common than autosomal aneuploids

Answer 37

No mechanism of dosage compensation for autosomal chromatids. Autosomes carry more genes. Most autosomal aneuploids are spontaneously aborted

Question 38

uniparental disomy

Answer 38

both chromosomes are inherited from the same parent | - mosaicism and nondisjunction in mitotic division

Question 39

What factors in humans increase aneuploidy?

Answer 39

increases with maternal age

Question 40

Autopolyploidy

Answer 40

all chromosome sets are from a single species | - can arise through nondisjunction in mitosis or meiosis

Question 41

allopolyploidy

Answer 41

Chromosome sets are from two or more species | - arises from hybridization between two species

Question 42

What is the link between polyploidy and cancer?

Answer 42

nondisjunction can happen and mitosis occurs so we get a tetraploid. it's unstable and has a dosage problem;; if survives get cells with extra copies and when overcome checkpoints become overstable. If the cell survives it is stronger and grows more/faster than the rest to yield cancer

Question 43

species A has 2n= 16 chromosomes and species B has 2n=14. How many chromosomes would be found in an allotriploid of these two species? a. 21 or 24 b. 42 or 48 c. 22 or 23 d. 45

Answer 43

c 22 or 23 2A+B = 16+7=23 A+2B = 8+14=22