M1: Sex Determination

Question 1

Basis of Sex Determination in an Organism

Answer 1

Genes and Sex Autosomes

Question 2

Females have two X chromosome and Males have one X chromosome. Unequal chromosome number, female have more sex chromosome

Answer 2

Protenor System (XX/XO)

Question 3

Basis for Protenor System

Answer 3

Protenor Butterfly

Question 4

Equal chromosome number and most famous sex determination

Answer 4

Lygaeus System (XX/XY)

Question 5

Characteristics of Male in Lygaeus System

Answer 5

• Heterogametic
• Unlike Gametes
• Heteromorphic Chromosomes
• Determines sex of progeny

Question 6

Characteristics of Female in Lygaeus System

Answer 6

• Homogametic
• Like Gametes
• Homomorphic Chromosomes

Question 7

Opposite of Lygaeus System and females dictate the sex of pyrogeny

Answer 7

ZW system (ZZ/ZW)

Question 8

Females are diploid and Males are haploid

Answer 8

Haplo-Diplo System

Question 9

Neither male nor female intervenes and need to find haploid alleles

Answer 9

X Chromosomes: Haploid Number

Question 10

A threshold for maleness is reached when the X:A ratio is 1:2

Answer 10

Genic Balance Theory

Question 11

Ratio of X chromosomes: 1.0 - 1.5

Answer 11

Female

Question 12

Ratio of X chromosomes: 0.67 - 0.75

Answer 12

Intersex

Question 13

Ratio of X chromosomes: 0.33 - 0.50

Answer 13

Male

Question 14

Incubation temperature of eggs during a critical period of embryonic development

Answer 14

Temperature Variation

Question 15

Houses the genetic information necessary for maleness and trigger gonodal ridge development into ovaries or testes

Answer 15

Y chromosome in Humans

Question 16

Only region that synapses and recombine with X-Chromosome during meiosis

Answer 16

Pseudo Autosomal Region (PAR)

Question 17

Non-recombining region of Y and share homology with genes on X chromosome

Answer 17

Male-Specific Region of Y (MSY)

Question 18

Region that contains functional genes

Answer 18

Euchromatic regions

Question 19

Region that lacks genes

Answer 19

Heterochromatic regions

Question 20

Originally derived from the X chromosome

Answer 20

X-transposed Region

Question 21

Contains DNA sequences that are even more distantly related to those present on the X chromosome

Answer 21

X-degenerative Region

Question 22

Critical gene that controls male sexual development

Answer 22

Sex-determining Region of Y (SRY)

Question 23

Causes the undifferentiated gonadal tissue of the embryo to form the testes

Answer 23

Testis-determining Factor (TDF)

Question 24

Lack of counterparts on X chromosome and expression is limited to Testes

Answer 24

Amplionic Region

Question 25

Associated with an increased risk of congenital disorders of the offspring

Answer 25

Y Chromosome and Paternal Age Effects (PAE)

Question 26

Genetic mechanism that balances the due of X chromosome gene expression in males and females

Answer 26

Dosage Compensation

Question 27

3 Dosage Compensation Mechanisms

Answer 27

1. Downregulation of X-linked genes in females 2. Hyperactivation of X-linked genes in males 3. Inactivation of one copy of X-linked genes in females

Question 28

Process of inactivation of an X chromosome

Answer 28

Lyonization

Question 29

They developed the Lyon Hypothesis

Answer 29

Mary Lyon and Liane Russel

Question 30

Inactivation of X chromosome at early embryonic development and all descendant cells have the same X chromosome inactivated their initial progenitor cell

Answer 30

Lyon Hypothesis

Question 31

Physical Evidence of Lyonization

Answer 31

1. Barr Body 2. Mosaicism

Question 32

Sex chromatin body and lies against the nuclear envelope

Answer 32

Barr Body

Question 33

They developed the Barr Body

Answer 33

Murray L. Barr and Evart G. Bertuan

Question 34

Barr body arises from one of two X chromosome

Answer 34

Ohno's Hypothesis

Question 35

Formula for number of Barr Bodies

Answer 35

N - 1

Question 36

Does not normally occur in the very early stages of development

Answer 36

Barr Body Formation

Question 37

Formation of mosaic patterns in heterozygous females

Answer 37

Mosaicism