Developmental Genetics

Question 1

What 3 things does developmental genetics study

Answer 1

Differentiation , growth and morphogenesis of organisms

Question 2

What are the developmental stages in humans

Answer 2

From fertilisation to embryo to a foetus when born

Question 3

What are the 3 approaches to studying development

Answer 3

1- anatomical - why is that organ or tissue in that place

2- physical manipulation - eg transplanting things from one embryo to another to see effect

3- genetics - what genes control development or explain congenital malformations

Question 4

What are the 6 model organisms for development

Answer 4

Mouse 
Chicken 
Drosophila fruit fly 
Frog 
Zebra fish 
C elegans worm

Question 5

What genes for eye development were conserved eg in a mouse, human and drosophila with homologous genes

Answer 5

The pax 6 gene which it 1 allele mutated can cause missing iris

If both alleles mutated there is no eye development

Question 6

What is the cardiac gene conserved in all model organisms

Answer 6

Nkx 2.5

Question 7

What happens in both mice and humans if NKx 2.5 gene is mutated

Answer 7

Heart defects

Question 8

What if 2 copies of the homologous gene to nkx 2.5 is mutated eg in drosophila

Answer 8

No heart is formed

Question 9

What is the term called to describe the homeobox genes of the drosophila fruit fly?

Answer 9

Temporo spacial colinearity

Question 10

What does temporo spacial linearity

Answer 10

Where genes are placed and expressed in order of where they are in body (homeobox genes transcribe the TFs)

Question 11

Why is the fruit fly a model organism

Answer 11

Genome is sequenced
Many mutants available to their homeobox genes
SHORT LIFE CYCLE
Many eggs/offspring

Have homologous genes eg pax 6 for eye development

Question 12

Which 3 model organisms are used for physical manipulation

Answer 12

Zebra fish
Toad
Chicken

Question 13

Why are zebra fish,toad and chicken embryos easily manipulated

Answer 13

Toad and chicken have large eggs

The zebra fish embryo is transparent and they lay many eggs

Question 14

Why can a chicken, mouse and toad be used for the anatomical approach?

Answer 14

Have similar anatomy eg organs are similar

Question 15

Why do we need animals as models?

Answer 15

Due to ethics - can’t manipulate human embryos

Faster life cycles

Can’t use cell culture for drug development, complex disease processes or complex development

Question 16

What are human organoids and what are they formed by

Answer 16

They are 3D cell cultures produced from induced pluripotent stem cells (IPSPs)

Question 17

What can human organoids be used for?

Answer 17

Show early development stages if not full development

Create many organs eg the liver, heart

= less animal research needed

Question 18

Why is the mouse most used to study genetics of development

Answer 18

Can induce for example knockout mice and induce human disease - many homologous genes = recombinant

Question 19

Why can’t mice be used for physical manipulation studies

Answer 19

Because embryos are hard to get a hold of (not external like toads and chicken eggs or zebra fish)

Question 20

How does chemical mutagenesis work

Answer 20

The chemical ENU or X-rays cause mutations (point mutations) which cause loss of function (disease)

Question 21

What are morpholino oligonucleotides and Sirna job in inducing human disease

Answer 21

Knockdown expression of a gene

Eg sirna will bind to a risc complex and stop translation by breaking mrna

Question 22

How does transgenesis cause induction of a disease

Answer 22

Insertion of a foreign piece of dna directly or via a vector can inhibit a gene expression via insertion inactivation

Question 23

What stem cells are used to induce knockouts or knockin mutations in organisms

Answer 23

Embryonic stem cells

Question 24

How do conditional gene modifications differ to knockouts or knockins

Answer 24

It’s a gene knockout but induced in specific tissue or time in development meaning no death of embryo

Question 25

What is the difference between transient and germ line trans genesis

Answer 25

Transient doesn’t acctually go through a gene - it is a short term expression

Germline permanently alters it

Question 26

Explain a way a gene can be knocked out via transgenesis instead of homologous recombination with another gene

Answer 26

Insertion of another gene (transgenesis) into the gene which inactivates it

Can be transient which is short term or germline

Question 27

What does homologous recombination mean

Answer 27

Where the sticky ends bases are complementary enough to be able to cross over

Question 28

What is another term for embryo development

Answer 28

Embryogenesis