Chapter 15: chromosomes inheritance

Question 1

chromosome theory of inheritance

Answer 1

Mendelian genes have specific loci and chromosomes undergo segregation and independent assortment

Question 2

wild type

Answer 2

phenotype most common in the wild

Question 3

sex linked gene

Answer 3

gene located on either sex chromosome

Question 4

duchenne muscular dystrophy

Answer 4

x-linked disorder; progressive weakening of muscles and loss of coordination (dystrophin)

Question 5

hemophilia

Answer 5

x-linked recessive disorder; absence of 1+ proteins for blood clotting

Question 6

Barr body

Answer 6

inactive x chromosome in each female cell; forms randomly and independently in each embryonic cell at time of X inactivation

Question 7

mosaicism

Answer 7

half of cells in heterozygous female express one X allele and half express another

Question 8

X inactivation

Answer 8

modification of DNA and histone proteins, and attachment of methyl groups.
1. region of each x chromosome with specific inactivation genes interact
2. XIST becomes active on chromosome that will form Barr body
3. multiple copies of RNA product of XIST attach to chromosome and initiate inactivation

Question 9

linked genes

Answer 9

genes located near each other on chromosomes that tend to be inherited together

Question 10

genetic recombination

Answer 10

reproduction of offspring with different combinations of traits than parents

Question 11

parental types

Answer 11

offspring with phenotype of parents

Question 12

recombinants

Answer 12

nonparental phenotypes
- 50% offspring genotypes means 50% frequency of recombination

Question 13

crossing over

Answer 13

exchange parental/maternal chromosomes

Question 14

genetic map

Answer 14

ordered list of genetic loci along a particular chromosome

Question 15

linkage map

Answer 15

genetic map based on recombination frequencies
- distance separating loci proportional to probability of crossover between two genetic loci
- maximum frequency = 50%

Question 16

map units

Answer 16

distances between genes
- 1% recombination frequency

Question 17

nondisjunction

Answer 17

homolog pairs do not move apart in meiosis 1 or sister chromatids don’t separate in meiosis 2

Question 18

aneuploidy

Answer 18

abnormal number of chromosomes

Question 19

monosomic

Answer 19

2n-1 (missing chromosome)

Question 20

trisomic

Answer 20

2n+1; 3 copies of one chromosome

Question 21

Polyploidy

Answer 21

2+ complete chromosome sets in all somatic cells

Question 22

deletion

Answer 22

chromosomal fragment is lost

Question 23

duplication

Answer 23

repeats a segment in chromosome

Question 24

inversion

Answer 24

reverses segment within chromosome

Question 25

translocation

Answer 25

moves segment from one chromosome to nonhomologous chromosome

Question 26

syndrome

Answer 26

set of traits characteristic of the type of aneuploidy

Question 27

Down syndrome

Answer 27

trisomic for chromosome 21

Question 28

Klinefelter syndrome

Answer 28

extra X chromosome in males. abnormally small testes and sterile. XXY

Question 29

trisomy X

Answer 29

females with 3 X chromosomes XXX. fertile

Question 30

Turner syndrome

Answer 30

females with one X chromosome. sterile because sex organs do not mature

Question 31

chronic myelogenous leukemia (CML)

Answer 31

cancer when reciprocal translocation happens during mitosis of white blood cells. (22 exchanges w 9)

Question 32

Philadelphia chromosome

Answer 32

shortened chromosome 22 caused by reciprocal translocation with chromosome 9. Causes CML

Question 33

genomic imprinting

Answer 33

only one copy of allele is expressed (From mother or father)
- other copy suppressed by methyl groups, or sometimes activated

Question 34

extranuclear genes

Answer 34

genes located in organelles

Question 35

variegation

Answer 35

coloration patterns in plants