Chapter 6

Question 1

What is chromosome morphology based on the centromere location? (chromosomes are classified into four types- what are they?)

Answer 1

1. Metacentric
2. Submetacentric
3. Acrocentric
4. Telocentric

Question 2

What is a Karyotype?

Answer 2

A complete set of chromosomes possessed by an organism.

Question 3

How are karyotypes made?

Answer 3

Through cytogenetics, which uses a blood sample, separates the cells from serum by centrifuge, removing the white cells, culturing, stimulating the cells to divide, disable mitotic spindle, add hypotonic solution to swell cells, squash cells on a slide, fix, and stain, and then examine the chromosomes.

Question 4

What do karyotypes tell us?

Answer 4

Karyotyping is a test to examine chromosomes. It can help identify abnormalities and rearrangements.

Question 5

How do you determine if a karyotype is abnormal?

Answer 5

A karyotype is abnormal if you don’t have the right amount of chromosomes (either too many or too few). To determine if a karyotype is abnormal, check to see if it has the normal full set of 46 chromosomes.

Question 6

What are the four types of chromosome mutations/rearrangements?

Answer 6

1. Duplication
2. Deletion- (pseudodominance and haploinsufficient)
3. Inversion- (pericentric and paracentric)
4. Translocation- (reciprocal and robertsonian)

Question 7

What is duplication?

Answer 7

A segment of the chromosome is duplicated. Can cause problems in pairing of homologous chromosomes in meiosis, gene dosage- extra genes, possibly extra gene products, allow genes to mutate for evolution. Types of staining are G bands and Q bands

Question 8

What is deletion (two types)?

Answer 8

A segment of the chromosome is deleted.

Question 9

What are psuedodominance and haploinsufficient in a deletion?

Answer 9

Pseudodominance can uncover a recessive mutation (recessive allele expressed and it looks dominant).
Haploinsufficient means one copy isn’t enough to provide the phenotype that we would expect; it’s insufficient to give the phenotype we’re looking at.

Question 10

What is an inversion (two types)?

Answer 10

A segment of the chromosome is turned 180 degrees. Alter gene expression based on location in chromosome. (pericentric and paracentric)

Question 11

What are pericentric and paracentric inversions?

Answer 11

Pericentric inversions occur right next to the centromere. Paracentric inversions occur further away from centromere, no change directly next to centromere.

Question 12

What is translocation (two types)?

Answer 12

A segment of a chromosome moves from one chromosome to a nonhomologous chromosome or to another place on the same chromosome. (Reciprocal and Robertsonian)

Question 13

What is Reciprocal and Robertsonian translocation?

Answer 13

Reciprocal- two different chromosomes have exchanged segments with each other.
Robertsonian- An entire chromosome attaches to another centromere.

Question 14

Where do mutations happen? (Two types of alterations)

Answer 14

Somatic alterations- something happens to one of your somatic cells (non-sex cells)
Germ-line alterations- something happens to germ cells and/or gametes.

Question 15

What is the difference between germ-line and somatic alterations?

Answer 15

Somatic means changing genes in some of the cells of an existing person in a way that does not impact their reproductive cells, and germ-line means changing the genes in someone’s offspring and, ultimately and in a small way, the human species

Question 16

What are the outcomes of chromosome mutation? Both for gene dosage and evolution.

Answer 16

Duplications:
gene dosage- extra genes, possibly extra gene product.
evolution- allows genes to mutate.
Deletion:
gene dosage- not enough genes, resulting in too little gene product.
evolution- allows genes to mutate.
*Duplication, deletion, inversion, and translocation have all played a huge role in evolution, allowing for alterations in genetic change. Mutations that allow organisms to change and outcompete- which has to do with how chromosomes are arranged.

Question 17

What is polyploidy?

Answer 17

The presence of more than two sets of chromosomes.

Question 18

What is aneuploidy?

Answer 18

An increase or decrease in the number of individual chromosomes.

Question 19

What causes aneuploidy? (3 things)

Answer 19

1. Deletion of centromere. during mitosis or meiosis.
2. Robertsonian translocation
3. Nondisjunction during meiosis or mitosis.

Question 20

What causes polyploidy?

Answer 20

Total nondisjunction of chromosomes during mitosis or meiosis.

Question 21

What are the four types of aneuploidy?

Answer 21

Nullisomy: 2n-2 (loss of both members of homologous pair)
Monosomy: 2n-1 (loss of a single chromosome)
Trisomy: 2n+1 (gain of a single chromosome)
Tetrasomy: 2n+2 (gain of 2 homologous chromosomes, so 4 of 1 type)

Question 22

What are the effects of aneuploidy in plants?

Answer 22

Mutants could be trisomics (having a single extra chromosome)

Question 23

What are the effects of aneuploidy in humans and what are some examples? (two types of aneuploids)

Answer 23

Sex chromosome aneuploidy
- Turners syndrome (XO) and Klinefelter syndrome (XXY).

Autosomal aneuploidy
- Trisomy 21: Down syndrome, Primary down syndrome (random nondisjunction in egg formation- 95% of cases), familial down syndrome (Robertsonian translocation between chromosomes 14 and 21), Edward syndrome (trisomy 18), Patau syndrome (trisomy 13), Trisomy 8.

Question 24

What is autopolyploidy?

Answer 24

Developing extra sets of chromosomes from a single species.

Question 25

What is allopolyploidy?

Answer 25

Developing extra sets of chromosomes from two species.

Question 26

What will polyploidy cause?

Answer 26

-Increase in cell size
-Larger plant attributes
-Evolution: may give rise to new species