Fundamental Processes And Gametogensis

Question 1

What is the most sensitive time for induction of a birth defect?

Answer 1

Embryonic period (3-8 weeks)

Question 2

What weeks are the embryonic period?

Answer 2

Weeks 3-8

Question 3

At which levels is gene expression regulated?

Answer 3

Regulation of gene transcription
Regulation of selective mRNA translation
Differential Protein Modification

Question 4

Describe the epithelial-mesenchymal interaction

Answer 4

Differentiation of undifferentiated tissue into specialized organ

-initial signal from first tissue induces second tissue to differentiate

Question 5

What is the term for the first tissue in an epithelial - mesenchymal interaction?

Answer 5

Inducer

Question 6

What is the term for the second tissue in an epithelial - mesenchymal interaction?

Answer 6

Responder

Question 7

True or false: once the induction process is initiated, signals are transmitted in both directions to complete the differentiation process

Answer 7

True

Question 8

Which pathway does the paracrine signaling use?

Answer 8

Signal Transduction pathway

Question 9

What is another term for paracrine factors?

Answer 9

Growth and differentiation factors (GDFs)

Question 10

Describe the standard signal transduction pathway

Answer 10

Ligand binds to its receptor
Activation of an enzyme
Phosphorylation cascade of several proteins
Activation of transcription factor that initiates gene expression

Question 11

What are the four different families of paracrine factors?

Answer 11

FGF
SHH
WNT
TGF-B

Question 12

What is the FGF paracrine factor?

Answer 12

Fibroblast growth factor

Question 13

What does the FGF paracrine factor do?

Answer 13

Produce hundreds of protein isoforms by alternative splicing

Question 14

What is the SHH paracrine factor?

Answer 14

Sonic HedgeHog

Question 15

What does the SHH paracrine factor do?

Answer 15

Sonic HedgeHog involved in developmental events - master gene for embryogenesis

Question 16

What does the WNT paracrine factor do?

Answer 16

Regulating limb patterning, midbrain development, somite and urogenital differentiation

Question 17

What is the TGF-B paracrine factor?

Answer 17

Transforming Growth Factor - beta

A superfamily

Question 18

What does the TGF-B paracrine factor do?

Answer 18

A super family
Important for extra cellular matrix formation,
Epithelial branching in kidney
Salivary gland development

Question 19

Describe juxtacrine signaling

Answer 19

A protein on one cell surface binds to receptor on adjacent cell
- does not involve diffusible factors -

Question 20

True or False: juxtacrine signaling is best described as direct transmission of signals through gap junctions

Answer 20

True

Question 21

Describe autocrine signaling

Answer 21

Cells secrete signaling molecule that binds to one of its own receptors leading to cellular change/response

Question 22

Define gametogenesis

Answer 22

Production of gametes through meiosis

Question 23

What is the term for production of female gametes?

Answer 23

Oogenesis

Question 24

What is the term for production of male gametes?

Answer 24

Spermatogenesis

Question 25

How many chromosomes are inside a primary oocyte or primary spermatocyte?

Answer 25

46 double-structured chromosomes

Question 26

How many chromosomes are in a secondary oocyte or spermatocyte?

Answer 26

23 double-structured chromosomes

Question 27

How many chromosomes are in an ovum or spermatid?

Answer 27

23 single chromosomes

Question 28

Describe generally the result of meiosis I

Answer 28

A primary oocyte spermatocyte splits from 46 double structured chromosomes to 23 double-structured chromosomes

Question 29

Describe generally the result of Meosis II

Answer 29

A secondary oocyte/spermatocyte split from 23 double-structured chromosomes to 23 single chromosomes

Question 30

What are polar bodies?

Answer 30

A result of oogensis as meiosis I and meiosis II remove half of chromosomes and are discarded

Question 31

True or false: Polar bodies are a result of oogenesis only and are not created in spermatogenesis

Answer 31

True

Question 32

What are the types of abnormal meitotic division?

Answer 32

Nondisjunction in meiosis I | Nondisjunction in meiosis II

Question 33

In what phases is oogenesis arrested?

Answer 33

Prophase in Meiosis I

Question 34

At what point in life does oogenesis continue?

Answer 34

Puberty - one primary oocyte at a time

Question 35

Describe the continuation of oogenesis once it is unpaused

Answer 35

At puberty, a primary oocyte per ovarian cycle will complete meiosis I and enter Meiosis II and arrest in metaphase

Question 36

At what point does meiosis II continue for a secondary oocyte?

Answer 36

Fertilization by sperm

Question 37

In what stage is a secondary oocyte paused?

Answer 37

Metaphase of Meiosis II

Question 38

Define spermatogenesis

Answer 38

Events by which spermatogonia transform into spermatozoa

Question 39

How many days for spermatogonium to develop into mature spermatozoon?

Answer 39

Approx 74 days

Question 40

What are examples of abnormal oocytes?

Answer 40

Primordial follicle with two ooctyes- sometimes results in twins Trinucleated oocyte - never survives

Question 41

What are examples of abnormal spermatozoa?

Answer 41

``` Double head Double tail Short tail Rounded head **all naturally selected against and will not fertilize an egg ```