Development Embryopathy

Question 1

Why is it essential that only one sperm nucleus fuses with the egg nucleus during fertilization?

Answer 1

Extra chromosomes could cause severe developmental issues

Question 2

One of the first organisms that was studied for developmental biology was the…

Answer 2

frog/xenopus

Question 3

Cell-cell signalling is triggered by what?

Answer 3

Chemicals that are laid down in a track
Chemicals that are diffused to nearby cells
Chemicals that induce other cells
Mechanical signalling

Question 4

In development biology, the gradient of ________ can trigger differentiation in cells

Answer 4

proteins/morphogens

Question 5

Most developmental defects that occur ______ tend to be fatal

Answer 5

early

Question 6

What sort of harmful substances does the placenta allow to pass?

Answer 6

Alcohol
Drugs
Nicotine
Hormones
German measles
Lead mercury

Question 7

What are 4 processes of embryogenesis?

Answer 7

• Cell migration
• Cell signalling
• Cell determination and differentiation
• Cell induction

Question 8

Fusion of the sperm with the egg induces a wave of ________ ________ release. Where does this wave originate from?

Answer 8

intracellular calcium

Originates from the site of sperm-egg fusion

Question 9

What is the general strategy that most organisms have to prevent more than one sperm fertilising an egg?

Answer 9

Block to polyspermy

Question 10

__________ during gastrulation changes the embryo’s shape and cell arrangements

Answer 10

Morphogenesis

Question 11

What are morphogenetic movements?

Answer 11

Cells changing shape during gastrulation

Question 12

What are morphogenetic movements caused by?

Answer 12

Localised contractions of cells as well as cell movements. It involves rearrangement of the cytoskeleton and requires adhesion molecules

Question 13

What is involution?

Answer 13

When cells at the site of the future blastopore change their shape

Question 14

What are 3 things cell-cell signalling is responsible for?

Answer 14

• Regulating cell fate of nearby cells through induction
• Triggering cell contractions and elongations
• Controlling and directing cell migrations

Question 15

What is embryopathy?

Answer 15

Developmental defects in an embryo or fetus

Question 16

What are 2 examples of substances that can cause embryopathy?

Answer 16

Thalidomide

Alcohol

Question 17

What is Thalidomide?

Answer 17

A drug developed in the 1950’s in Germany used to treat cancer, and some skin conditions

Question 18

Why did scientists not realise Thalidomide caused embryopathy?

Answer 18

It was not tested in humans, and not even in pregnant animals

Question 19

Why did pregnant women use Thalidomide?

Answer 19

Marketed to alleviate morning sickness

Question 20

What were some defects of Thalidomide babies?

Answer 20

• Brain damage
• Deformed facial features
• Blind and deafness
• Short, twisted arms and legs

Question 21

What is a teratogen? Is Thalidomide a teratogen?

Answer 21

Substances that cause defects in the embryo or fetus after the mother is exposed to it
Yes

Question 22

How do most teratogen affect the embryo?

Answer 22

Crosses the mothers’ placenta and enters it

Question 23

What is the placenta mainly used for?

Answer 23

Nutrient, gas, and waste exchange between mother and fetus

Question 24

How does Thalidomide disrupt limb formation?

Answer 24

It inhibits signalling molecules essential for limb formation. Specifically, FGF10

Question 25

Why did it take so long to discover that Thalidomide caused birth defects?

Answer 25

• Over 50 different names in 46 countries
• Contradicting drug information
• Symptoms similar to other diseases
• Pharma companies want to sell, sell, sell

Question 26

What was an after effect of the Thalidomide crisis?

Answer 26

Tougher testing and licensing rules for drugs.

Question 27

Why did the US avoid Thalidomide babies?

Answer 27

Frances Kelsey was sceptical of the drug and did not approve it. The drug was also known to have neural side effects

Question 28

Drinking ________ in the first 2 weeks following fertilisation does not affect the zygote

Answer 28

alcohol

Question 29

Why are fetuses affected by alcohol?

Answer 29

• No liver, meaning it cannot eliminate ethanol
• Re absorption through the amniotic fluid

Both lead to prolonged alcohol exposure, disrupting cell signalling

Question 30

What are symptoms of FAS?

Answer 30

• Facial deformities
• Vision and hearing defects
• Deformed limbs and fingers
• Poor coordination
• Intellectual disability