Chapter 9.7

Question 1

Two possible outcomes of error in meiosis

Answer 1

1. extra chromosomes

2. missing chromosomes

Question 2

POLYPLOID

Answer 2

“many sets”

one or more complete sets of chromosomes

Question 3

human vs plant polyploid tolerance

Answer 3

human : cease as embryos or fetus

plant : 30% of flowering plants and many crop plants tolerate well ( e.g. durum wheat is tetraploid =4 sets)

Question 4

NONDISJUNCTION

Answer 4

gametes have just ONE extra or missing chromosome

Question 5

why does NONDISJUNCTION occur

Answer 5

When chromosomes fail to separate at either the first or the second meiotic division

the result an egg or sperm cell with 2 copies or non at all, rather than the normal one copy

Question 6

When a gamete with Non disjunction fuses with another in fertilization the result in number of chromosomes

Answer 6

1 too little: 45
1 too many 47
too many is better than too few

Question 7

TRISOMY

Answer 7

An example of 1 extra chromosome resulting from 1 extra

Question 8

3 different types of autosomal trisomy

Answer 8

extra autosomes : 21, 18 13

Question 9

Trisomy 21

Answer 9

the most common cause of Down syndrome that has 3 copies of 21 instead of 2

Question 10

4 possibilities of sex chromosomes abnormalities

Answer 10

Resulting from aa gamete having 2X OR 2Y
XXX TRIPLO-X (FEMALE)
XXY KLINEFELTER (MALE)
XYY JACOBS (MALE)

Resulting from a gamete have no X nor Y
XO TURNER SYNDROME ( FEMALE)

Question 11

Why hasn’t a OY been reported

Answer 11

since a x chromosome carries so much genetic information an embryo would not survive many cell divisions

Question 12

XXX TRIPLO-X (FEMALE)

Answer 12

1.tallness
2. menstrual irregularities
3. normal range IQ
4.

Question 13

XXY KLINEFELTER (MALE)

Answer 13

1. sexually underveloped
2. rudimentary testes
   3 no pubic or facial hair
3. slow to learn
4. large hands long limbs

Question 14

XYY JACOBS (MALE)

Answer 14

1. apparently normal
2. very tall
3. acne
   4, problems with speech and reading

Question 15

XO TURNER SYNDROME ( FEMALE)

Answer 15

1. female with missing x chromosome has only one
2. short
   3 sexually underdeveloped
3. infertile

Question 16

4 smaller scale chromo abnormalities

Answer 16

Normal: ABCDEFG

1. deteltion: ABCD
2. duplication ABCEEFGEFGEFG
3. inversion adcefg
4. translocation

Question 17

DELETION

Answer 17

LOSS OF ONE Of one or more genes

eg cri du chat -gene deletion of some of chromo 5

Question 18

DULPICATION

Answer 18

PRODUCES MULTIPLE COIES OF PART OF A CHROMO

eg Fragile X syndrome= duplication of genes on the X chromosome

Question 19

INVERSION

Answer 19

part of the chromosome flips and reinserts, changing the gene sequence
less harmful than deletion

Question 20

TRANSLOCATION

Answer 20

a non homologous pair exchange parts
It often breaks gens and sometimes result in leukemia
If no genes are broken then they have a normal amount of genes just rearranged

Question 21

What is polyploidy?

Answer 21

Polyploidy means having extra sets of chromosomes, for instance 3n (triploid), 4n (tetraploid), or 6n (hexaploid).

Question 22

How can nondisjunction during meiosis lead to gametes with extra or missing chromosomes?

Answer 22

If the chromosomes don’t separate properly at anaphase I or II, chromatids are unequally portioned into cells during meiosis I or II. Some gametes will have too few chromosomes, whereas others will have too many.

Question 23

How can deletions, duplications, inversions, and translocations cause illness?

Answer 23

Deletions, duplications, inversions, and translocations can delete, duplicate, or damage genes, which may affect the normal production of proteins. Chromosome duplication may be the least harmful, because the spare genes can mutate while the working genes continue their normal functions. Chromosome deletions may mean that an individual cannot make some proteins. Inversion produces symptoms because chromosomes may not align properly, causing fertility problems, miscarriage, or birth defects. In translocation, chromosomes may be missing parts, or genes can be broken. Affected individuals may lack proteins, produce harmful proteins, or have fertility problems

Question 24

How do inversions and translocations cause fertility problems?

Answer 24

Both inversions and translocations result in faulty chromosomes that are missing segments or have segments in which genes are out of order. Because an abnormal chromosome may not successfully match with its homolog during meiosis, an affected person may be infertile. Even if gametes are produced, embryonic development may be abnormal, and the pregnancy often will end in a miscarriage.