Chapter 4: Sex Determination and Sex Linked Characteristics

Question 1

Are X and Y chromosomes homologous?

Answer 1

No, they pair during meiosis but the genes that are located on each are different

Question 2

What regions of X and Y chromsomes are homologous?

Answer 2

regions at the tips (pseudoautosomal region)

Question 3

What regions are essential for X-Y pairing in meiosis for males?

Answer 3

pseudoautosomal regions

Question 4

What alternates between haploid and diploid states?

Answer 4

sexual reproductions

Question 5

What is the major difference in sexual phenotypes

Answer 5

gamete size

Question 6

Monoecious

Answer 6

both male and female reproductive structures in the same organisim

Question 7

Dioecious

Answer 7

either male or female reproductive structures in one organisim

Question 8

What is the protenor mode mechanisim? What are the genotypes? Where does it occur?

Answer 8

-XX-XO system
-XX: female XO: male
-occurs in grasshoppers

Question 9

What is the Lygaeus mode mechanisim? What are the genotypes? Where does it occur?

Answer 9

-XX-XY System
-XX: female XY: male
-occurs in mammals

Question 10

What is the ZZ-ZW mechanisim? What are the genotypes? Where does it occur?

Answer 10

-ZZ: male
-ZW: female
-Occurs in birds, snakes, butterflies, some amphibians, and fishes

Question 11

What sex has unlike gametes?

Answer 11

heterogenic sex

Question 12

What sex has like gametes?

Answer 12

homogametic sex

Question 13

What is the Genic Sex-Determining System?

Answer 13

no sex chromosomes, only the sex determining gene
-found in some plants, protists, fungi, and fish

Question 14

What is environmental sex determination?

Answer 14

when temperature of embryo affects sex

Question 15

How does temperature affect turtle sex determination?

Answer 15

warm=female
male=cold

Question 16

How does temperature affect alligator sex determination?

Answer 16

warm=male
cold=female

Question 17

Is the X or Y chromosome more important?

Answer 17

X contains other genes than just sex

Question 18

What gene determines maleness?

Answer 18

SRY gene on the Y chromosome

Question 19

What are the odds and symptoms of Turner Syndrome?

Answer 19

XO; 1/3000 female births
-short and sterile

Question 20

What are the odds, genotypes, and symptoms of Klinefelter Syndrome?

Answer 20

XXY, or XXXY, or XXXXY, or XXYY
-1/1000 male births
-often taller with reduced testes size

Question 21

What are the odds, genotypes, and symptoms of Poly-X Syndrome?

Answer 21

-XXX
-1/1000 female births

Question 22

Is it normal for both copies of the X chromsome to be missing?

Answer 22

No

Question 23

How many copies are required of the X Chromosome?

Answer 23

at least 1

Question 24

What is contained in the X chromsome?

Answer 24

contains genetic information that is essential for both sexes

Question 25

What is the male determining gene?

Answer 25

Y chromosome

Question 26

What are the symptoms of androgen-insensitivity syndrome?

Answer 26

-female external features,but are XY -pair of testes inside abdominal cavity -Defective androgen receptor

Question 27

What doesnt allow for male characteristics in androgen-insensitivity syndrome?

Answer 27

defective androgen receptor

Question 28

Where are most of our male and female characteristics in our genes found?

Answer 28

autosomes

Question 29

What is dosage compensation?

Answer 29

the amount of protein produced by X-linked genes and randomly inactived in two sexes

Question 30

What hypothesis found in each female cell, one of the X's are inactivated?

Answer 30

lyon hypothesis

Question 31

What does the inactivated X become?

Answer 31

Barr Body

Question 32

About how many genes on Y chromosome?

Answer 32

75 genes

Question 33

About how many genes on X chromosome

Answer 33

about 1000 genes

Question 34

Males are _____zygous for x-linked traits

Answer 34

hemizygous

Question 35

Females are _____zygous for x linked traits

Answer 35

homozygous

Question 36

Where are barr bodies found?

Answer 36

only in cells with at least XX

Question 37

When does X inactivation stop?

Answer 37

about 6 weeks of development

Question 38

What is a barr body?

Answer 38

an inactivated X chromsome

Question 39

How does X-inactivation occur?

Answer 39

via epigenetics -lncRNA is produced and then coats the inactivated X, recruits chromatin modifying proteins, and make X into heterochromatin