DAT bio chapter 7. Heredity P2

Question 1

nondisjunction

Answer 1

improper segregation of
chromosome pairs during anaphase; it produces
daughter cells with an incorrect number of
chromosomes.

Question 2

Single nondisjunction of homologous

chromosomes during meiosis I

Answer 2

46 chromosomes in diploid parent cell
→
24, 24, 22, 22 chromosomes in haploid daughter
cells

Question 3

Single nondisjunction of sister chromatids

during meiosis II

Answer 3

46 chromosomes in diploid parent cell
→
24, 22, 23, 23 chromosomes in haploid daughter
cells

Question 4

Single nondisjunction of sister chromatids

during mitosis

Answer 4

46 chromosomes in diploid parent cell
→
47, 45 chromosomes in diploid daughter cells

Question 5

Aneuploidy

Answer 5

abnormal number of

chromosomes in the daughter cells.

Question 6

examples of aneuploidy

Answer 6

trisomy (3 chromosomes copies) or

monosomy (1 chromosome copies) can occur.

Question 7

Down syndrome

Answer 7

a trisomy of chromosome #21

each diploid cell has 47 chromosomes total

Question 8

Turner syndrome is

Answer 8

a monosomy of the X
chromosome in females (each diploid cell has 45
chromosomes total). Affected individuals have
physical abnormalities and sterility

Question 9

Klinefelter’s syndrome i

Answer 9

is a trisomy of the sex
chromosomes in males, giving them XXY (each
diploid cell has 47 chromosomes total). Individuals
usually have disorders in intellectual, physical, and
reproductive developmen

Question 10

test-cross pairs what and what

Answer 10

pairs unknown genotype with a homozygous recessive

Question 11

How do we determine unknown genotype?

Answer 11

looking at the offspring from a test cross

Question 12

True-breeding organisms are

Answer 12

homozygous for all the traits of interest

Question 13

What is the F1 generation>

Answer 13

first
generation cross between true-breeding parents
with different alleles. The offspring are all
heterozygous.

Question 14

What is the F2 generation?

Answer 14

second generation cross between the
heterozygous offspring from the F1 generation.
This is where Mendel’s three laws can be studied

Question 15

What is a monohybrid cross?

Answer 15

single gene is examined from 2 generations. In the F2 generation, the genotype ratio
(AA:Aa:aa) should be (1:2:1) and the phenotype
ratio (dominant:recessive) should be (3:1).

Question 16

Dihybrid cross

Answer 16

two genes on separate chromosomes are examined. The phenotype ratio is (9:3:3:1).

Question 17

single allele

crosses you should memorize

Answer 17

Homozygous x homozygous = 1/1 AA or
1/1 Aa or 1/1 aa
2. Homozygous x heterozygous = ½ AA (or
aa) and ½ Aa
3. Heterozygous x heterozygous = ¼ AA, ½
Aa, ¼ aa

Question 18

What does pedigree charts do?

Answer 18

track inherited traits
over many generations to see inheritance
patterns.

Question 19

Females are represented by what in pedigree charts

Answer 19

circles

Question 20

males are represented by what in pedigree charts?

Answer 20

squares

Question 21

Individuals

affected and unaffected by the trait in question are represented how?

Answer 21

shaded for affected individuals and unaffected individuals are not shaded/

Question 22

Individuals

affected and unaffected by the trait in question are represented how?

Answer 22

shaded for affected individuals and unaffected individuals are not shaded/

Question 23

recombinant gametes s

Answer 23

gametes (sex cells) that receive the genetically unique chromatids (new combination of alleles)

Question 24

non-recombinant

gametes

Answer 24

gametes that receive
parental chromatids (alleles match parent’s
alleles)

Question 25

Linked genes location

Answer 25

are found close together on the same

chromosome

Question 26

How do we calculate the distance of linked genes

Answer 26

by looking at recombination
frequencies, we can deduce the relative distance
between these genes.

Question 27

what is one map unit

Answer 27

chromosomal
distance that would allow 0.01 crossover events
per generation.

Question 28

Example of map unit

Answer 28

20 map units would mean 0.2
crossover events occur between the two genes per
generation, or that there is a 20% chance of
recombination.

Question 29

Recombination frequencies of less than 50%

mean what?

Answer 29

two genes are linked

Question 30

. A random

assortment of unlinked genes have what

Answer 30

50%

recombinant progeny.

Question 31

what can be drawn out using map units to infer the distance between genes on a chromosome?

Answer 31

linkage maps

Question 32

a group of genes that are usually
inherited together because they are located in
close proximity to each other

Answer 32

haplotype

Question 33

haplotype

Answer 33

a group of genes that are usually
inherited together because they are located in
close proximity to each other

Question 34

Sex-linked traits

Answer 34

come from genes located on the

sex chromosomes

Question 35

Most sex-linked disorders have

X-chromosome linkage. how many types of sex linked traits are there

Answer 35

three types

Question 36

X-linked dominant -

Answer 36

• dominant inheritance on
  the X chromosome. Any offspring (male or
  female) that receive the affected allele will end
  up with the disorder

Question 37

X-linked recessive

Answer 37

recessive inheritance on
the X chromosome. For males, only one
affected allele is needed to cause the disorder.
For females, two affected alleles are needed to
cause the disorder because females have two
X chromosome

Question 38

Y-linked

Answer 38

inheritance on the Y chromosome.
Can only be passed from father to son. Will
always be expressed whether it is dominant or
recessive because males only have one Y
chromosome.

Question 39

Genomic imprinting

Answer 39

genes that are
expressed depending on parental origin and are
influenced by epigenetic factors. (different from sex-linked traits because they can
come from autosomal chromosomes (non-sex
chromosomes) as well.)

Question 40

X-inactivation

Answer 40

process by which one of a
female’s X chromosomes is inactivated, forming a
Barr body and preventing excess transcription.

Question 41

When can female carrier become an affected individual for a disease?

Answer 41

if her unaffected
X chromosome with a normal wild-type allele is
inactivated, leaving behind a recessive allele that is
not covered up.

Question 42

What does epigenetics do?

Answer 42

does not involve modifying the
genetic code, but instead the REGULATION of when
genes are expressed. Epigenetic changes are
heritable.

Question 43

examples of epigenetic changes

Answer 43

DNA methylation -
histone acetylation
histone de acetylation
heterochromatin
histone methylation