Post embryonic development and cancer

Question 1

Growth is a key factor to determine what?

Answer 1

Shape

Question 2

How does most growth occur?

Answer 2

Proliferation = hyperplasia
Cell enlargement = hypertrophy
Accretion

Question 3

What is accretion?

Answer 3

Gradual accumulation of layers/matter

Question 4

Which cyclins control which cdks?

Answer 4

A/B = Cdk1
D = Cdk 4/6
E = Cdk 2 
A = Cdk 2

Question 5

Describe the cell cycle of nuclei in the syncitium

Answer 5

Very rapid cylces of S and M phases only, no G phases

Question 6

At which cycle is G2 introduced?

Answer 6

14

Question 7

What happens to nuclei when they migrate to the periphary?

Answer 7

Cellularisation occurs as a result of the membrane involuting

Question 8

The AP and DV axis can affect division in what way?

Answer 8

Position can affect the cells division rate

Cells form mitotic domains

Question 9

What is the role of string?

Answer 9

It is a phospatase that activates the Cdks

Question 10

Describe the distribution of string in divisions 1 to 13, and then afterwards

Answer 10

In 1 - 13 it is evenly ditributed = rapid and synchronous division
After it is under control of the patterning genes which set up the AP or DV axis

Question 11

Name the only exception where string does not have the expected effect and why this is

Answer 11

The mesoderm - one of the first to express string but it is the 10th to divide
This is due to trubble which inhibits string
It is inhibited as mesoderm needs to invaginate - cell division would inhibit this

Question 12

Describe what happens if a limb bud is taken from a large animal and transplanted to a smaller one

Answer 12

The limb would grow to the size of the original limb bud from the bigger animal

Question 13

What happens if additional thymus glands are transplanted?

Answer 13

They all maintain their size and multiple amounts of tissue is made

Question 14

Describe the inactivation of the Hippo pathway

Answer 14

Inactive = transcription factor Yki/Yap/Taz in the nucleus is stimulating growth

Question 15

What happens when the Hippo pathway is active?

Answer 15

The transcription factors are excluded from the nucleus stopping further growth

Question 16

What may active the hippo pathway?

Answer 16

Cell to cell contact eg overcrowding

Question 17

What happens if hippo is mutated?

Answer 17

The pathway is inactivated = innapropriate growth

eg mice overall size is the same but the liver is not

Question 18

Why do pygmies have a short stature?

Answer 18

They do not undergo a second growth rate in puberty

Question 19

In drosophila, what determines the size of the adult fly?

Answer 19

The size of the larva

Question 20

What determines the size of the larva?

Answer 20

By insulin signalling - this affects both the duration and rate of larval growth

Question 21

What induces metamorphis?

Answer 21

Ecdyson

Question 22

Which pathways may be responsible for determing the size of different dog breeds?

Answer 22

IGF and GH

Question 23

Where is growth hormone produced?

Answer 23

In the pituitary

Question 24

What stimulates growth hormone release and what inhibits it?

Answer 24

Stimulate = growth hormone releasing hormone
Inhibit = somatostatin
Both come from the hypothalamus

Question 25

How can a mother influence growth?

Answer 25

The enviroment of the wound

Question 26

How can maternal conditions affect life postembryonically?

Answer 26

Inadequate growth in uterus due to a diet can lead to life long consequences
The embryo may catch up in growth but effects still seen eg obesity, diabetes and CHD later on in life

Question 27

Where are cancers most commonly found?

Answer 27

In tissues that continously divide through life eg epithelia and blood

Question 28

What is a teratoma?

Answer 28

Cells similar to embryonic cells which can give rise to all three germ layers
They form a tumour made up of many different cell types

Question 29

What are protooncogenes called if their activated?

Answer 29

oncogenes

Question 30

List examples of protooncogenes

Answer 30

Ras
Raf
Epidermal growth factor receptor
Myc

Question 31

List examples of tumour suppressor genes

Answer 31

Retinoblastoma
p53
Patched
Adenomatous polyposis coli
Von Hippel Lindou

Question 32

How is molting and metamorphis coordinated?

Answer 32

Influences from the enviroment that act on the CNS

Question 33

Why do Arthropods have to molt?

Answer 33

To grow - their cuticle is rigid so they have to molt

This is called ecdysis

Question 34

Molting is initiated by what?

Answer 34

The activation of stretch receptors in the cuticle

This releases protothoracicotrophic hormone

Question 35

Where does protothoracicotopic hormone come from?

Answer 35

The corpus alatum

Question 36

Which hormone causes molting?

Answer 36

Ecdyson

Question 37

How does a new cuticle form?

Answer 37

The free epidermal cells proliferate and secrete a fluid to form a barrier
They then start secreting a new cuticle
Then the old cuticle will shed

Question 38

Metamorphis occurs under the influence of what in insects?

Answer 38

Nutrition, temp and light

Question 39

Which hormones prevent metamorphis?

Answer 39

Juvenile hormones

Question 40

What is the effect of thyroxin on the limbs and tail in frogs?

Answer 40

Growth of limbs and degeneration of tail