Block B Part 2: Gradients, Differentiation, Organisation and Sexual Dimorphism

Question 1

What do cells in isolation undergo?

Answer 1

Differentiation
(Lecture 1, Slide 65)

Question 2

What happens in differentiation?

Answer 2

Cells become specialised until they reach their terminally differentiated form.
(Lecture 1, Slide 65)

Question 3

Is differentiation one-way or two-way?

Answer 3

Differentiation is usually a one-way process.
(Lecture 1, Slide 65)

Question 4

What do stem cells do when transplanted?

Answer 4

They adopt the form appropriate for their new home.
(Lecture 1, Slide 68)

Question 5

What 2 processes must be occurring during tissue differentiation?

Answer 5

Local cellular interactions that organise tissues
Long-range “morphogen” signals that determine the orientation of the embryo and its specific regions.
(Lecture 1, Slide 72)

Question 6

What does Long-range “morphogen” signals and local cellular interactions that organise tissues do to a cell?

Answer 6

They cause migration and specific differentiation processes to be irreversibly started.
(Lecture 1, Slide 72)

Question 7

How do cell types organise themselves locally?

Answer 7

They organise themselves into regional embryo-like structures sorting of cells like-with-like
(Lecture 1, Slide 73)

Question 8

What is a morphogen?

Answer 8

A secreted molecule that induces cell fate decisions in recipient cells in a concentration gradient-dependant long-range manner.
(Lecture 1, Slide 75)

Question 9

What 3 things are required for a morphogen to function?

Answer 9

Production from a point source
Long-range distribution
Reception and interpretation by the cell.
(Lecture 1, Slide 75)

Question 10

What can injection of Wnts or Nodal induce?

Answer 10

A secondary axis
(Lecture 1, Slide 83)

Question 11

How do cells interpret and act on Morphogen signals?

Answer 11

Morphogen receptors.
(Lecture 1, Slide 90)

Question 12

What do Homeotic genes regulate?

Answer 12

The development of anatomical structures in various organisms.
(Lecture 1, Slide 91)

Question 13

What can mutations in the Homeotic genes cause?

Answer 13

They can cause transformation of one area of the body in another area of the body.
(Lecture 1, Slide 91)

Question 14

What do Hox genes direct?

Answer 14

The body plan.
(Lecture 1, Slide 93)

Question 15

How are HOX genes arranged on the chromosome?

Answer 15

In a co-linear fashion (having corresponding parts arranged in the same linear order)
(Lecture 1, Slide 93)

Question 16

How many HOX clusters do humans and higher organisms have?

Answer 16

4
(Lecture 1, Slide 94)

Question 17

What 3 things occur in the first trimester of pregnancy?

Answer 17

Early cell divisions, establishment of germ layers, beginning of organogenesis
(Lecture 1, Slide 97)

Question 18

What occurs in the second trimester of pregnancy?

Answer 18

Organogenesis is complete
(Lecture 1, Slide 97)

Question 19

What occurs in the third trimester of pregnancy?

Answer 19

Fetal growth, organ systems become fully functional.
(Lecture 1, Slide 97)

Question 20

How do sperms determine the sex of a fetus?

Answer 20

The sperm (spermatozoa) can contain either an X or a Y chromosome, if the fertilising sperm contains an X chromosome then the fetus becomes female and if the sperm contains a Y chromosome the fetus becomes male.
(Lecture 1, Slide 100)

Question 21

What is the “default” gender in terms of development?

Answer 21

If unspecified the “default” is female
(Lecture 1, Slide 103)

Question 22

Which gene regulates male characteristics and where is it located?

Answer 22

SRY gene on the Y chromosome
(Lecture 1, Slide 103)

Question 23

How does the SRY gene regulate male characteristics?

Answer 23

It promotes development of male reproductive anatomy and supresses development of female reproductive anatomy
(Lecture 1, Slide 103)

Question 24

What drives secondary sexual characteristics?

Answer 24

Hormones.
(Lecture 1, Slide 104)

Question 25

What is Turner’s Syndrome?

Answer 25

Turner’s syndrome is when a female has only 1 X chromosome; XO.
(Lecture 1, Slide 106)

Question 26

What 3 things does Turner’s Syndrome result in?

Answer 26

Female patients do not mature sexually, have a short stature and often have other congenital (from birth) abnormalities.
(Lecture 1, Slide 106)

Question 27

What is Klinefelter’s Syndrome?

Answer 27

Klinefelter’s Syndrome is when a male has 2 X chromosomes and a Y chromosome.
(Lecture 1, Slide 108)

Question 28

What 4 things does Klinefelter’s Syndrome result in?

Answer 28

It results in the male patient being sterile with small testicles, they may have breast growth, they tend to be tall and may have mild mental impairment.
(Lecture 1, Slide 108)