Chapter 15

Question 1

Where are genes located on

Answer 1

chromosomes

Question 2

Mendel’s hereditary factors were purely what

Answer 2

abstract when first proposed

Question 3

Who worked with the process of mitosis in 1875 using improved techniques of microscopy

Answer 3

ctyologists

Question 4

When did scientists note the parallels and when did the chromosome theory of inheritance begin to form

Answer 4

1900

Question 5

locus means what in Latin

Answer 5

location

Question 6

Who is the founder of the Drosophila genetics

Answer 6

T.H Morgan

Question 7

Why would be flies be used for genetics

Answer 7

1. Small
2. Cheap to keep
3. Prolific
4. Short generation time
5. only four chromosomes
6. small genome

Question 8

Morgan crossed a mutant male to a red eyed female. All the offspring were red eyed. Then set up sib matings of F1 generation. F2 had a 3:1 ratio of red to white eyes. But all the females were red eyed and half the males were whited eyed. Explain this.

Answer 8

Sex linked

Question 9

name some disorders caused by recessive alleles on the X chromosome in humans

Answer 9

1. Color Blindness
2. Duchenne muscular dystrophy
3. Hemophilia

Question 10

X linked genes follow what

Answer 10

specific patterns of inheritance

Question 11

What needs to happen in order for a recessive X linked trait to be expressed

Answer 11

1. a female needs two copies of the allele

2. a male needs only one copy of the allele

Question 12

In mammals the Y chromosome acts as what

Answer 12

a dominant male determinant

Question 13

The early human gonad is bipotential until when

Answer 13

the sixth week of development

Question 14

the gonad sex determination will determine what

Answer 14

the sexual phenotype

Question 15

What is the SRY gene

Answer 15

Sex determining region on Y

Question 16

What happens if the SRY gene is activated

Answer 16

the genetic gonad follows the male pathway and becomes a testis

Question 17

What are some genotypes of sex reversed individuals

Answer 17

XX males

XY females

Question 18

XX males have what portion that includes SRY

Answer 18

portion on the Y chromosome

Question 19

XY females lack what portion that includes SRY

Answer 19

portion of the Y chromosome

Question 20

If the SRY gene was deleted the animal would develop as

Answer 20

Without SRY animal develops as a female

Question 21

In females 1 of these is inactivated in order to ensure that there are only one set of proteins

Answer 21

1 X chromosome

Question 22

What is the inactive X called

Answer 22

Barr body

Question 23

is the process of barr body random and what does it produce

Answer 23

Yes the process is random and it produces a mosaic

Question 24

Where do cats carry their coat color

Answer 24

on the X chromosome

Question 25

Where do tortoishell cats get their color from

Answer 25

X- inactivation

Question 26

Calico cats are similar to toroishell cats but have an additional what

Answer 26

spotting gene

Question 27

Each chromosome has hundreds or thousands of genes except which chromosome

Answer 27

Y

Question 28

What are linked genes

Answer 28

genes located on the same chromosome that tend to be inherited together

Question 29

Do linked genes assort independtly

Answer 29

No because they are on the same chromosome

Question 30

What is genetic recombination

Answer 30

the production of offspring with combinations of traits differing from either parent

Question 31

Who's genetic findings relate to the chromosomal basis of recombination

Answer 31

Mendel's and Morgan's

Question 32

What are parental types

Answer 32

Offspring with a phenotype matching of the parental phenotypes

Question 33

what are the recombinant types

Answer 33

offspring with nonparental phenotypes

Question 34

what is the frequency of recombination observed for any two genes on different chromsomes

Answer 34

50%

Question 35

Morgan discovered that genes can be linked but the linkage was incomplete. Explain why

Answer 35

Some recombinant phenotypes were observed

Question 36

What did Morgan propose to explain why the linkage was incomplete

Answer 36

Some process must be occasionally break the physical connection between genes on the same chromosome

Question 37

The process must be occasionally break the physical connection between genes on the same chromosome what is this mechanism known as today

Answer 37

the crossing over of homologous chromosomes

Question 38

Morgan also discovered that the rate of crossing over between genes could be used to determine what

Answer 38

the genetic distance between them

Question 39

What is a genetic map

Answer 39

an ordered list of the genetic loci along a particular chromosome

Question 40

Who first constructed a genetic map

Answer 40

Alfred Sturtevant

Question 41

Sturtevant predicted what

Answer 41

the farther apart two genes are, the higher the probability that a crossover will occur between them and therefore the higher the recombination frequency

Question 42

What is a linkage map

Answer 42

a genetic map of a chromosome based on recombination frequencies

Question 43

What is a map unit

Answer 43

distances between genes

Question 44

One map unit is equal to what

Answer 44

1% recombination frequency

Question 45

Map units indicate what

Answer 45

relative distance and order, not precise locations of genes.