Development L5/6

Question 1

What are homeotic fly mutants?

Answer 1

Flies where one body part –> another

Question 2

What are homeotic genes?

Answer 2

Heritable changes carried in individual genes, act as developmental switches
Encode TFs

Question 3

What is ultrabithorax?

Answer 3

Gene that when mutated gives 2 wings

Question 4

What does mutation in Antennapedia gene result in?

Answer 4

Legs coming out of head: flies make it to adulthood then struggle to eat and die

Question 5

What is a homeodomain protein?

Answer 5

TF with characteristic motif of DNA binding domain,

Question 6

What is the homeobox?

Answer 6

DNA sequence encoding homeodomain (so homeotic genes often abbrevaited to hox)

Question 7

In drosopila where are hox genes located?

Answer 7

In cluster in 3rd chromosome

Sequence of genes along chromosome matches atero-prosterior pattern of expression along the embryo

Question 8

When did plants and animals diverge from common ancestors?

Answer 8

1.6 BYA

Question 9

In plant sciences what is drosophila equivalent?

Answer 9

Arabidopsis, grown in lab in large numbers, 1000s of offspring per plant, one of the smallest plant genomes known, fast life cycle of 6 weeks

Question 10

Draw v basic seedling and flower diagram

Answer 10

(see notes for diagram)

Question 11

Draw basic egg –> mature embryo

Answer 11

(see notes for diagram)

Question 12

How does plant development begin?

Answer 12

1) 2 haploid pollen nuclei reach the ovule
2) one fertilises the egg cell
3) The other fuses with 2 other nuclei in the ovule to form a 3n storage tissue, the endosperm

Question 13

What is a big difference between animal and plant embryos?

Answer 13

Animal embryos are immature versions of adult forms

Plant embryos consist of 2 distinct sets of stem cells (SAM and RAM) and show phenotypic plastcicty after development

Question 14

What are the apical and basal cells?

Answer 14

Apical cell- forms seedling
Basal cell - forms suspensor cells linking the embryo to nutrient tissue (the uppermost suspensor cell contributes to the root meristem)

Question 15

What sets the apico-basal plant embryonic axis?

Answer 15

Little/no maternal contribution to embryo patterning
Axis set by auxin gradients
Auxin actively transported basal to apical cell immediately after first division (is required there for expression of apical characteristics)
At globular stage apical cells start synthesising auxin and flow reverses

Question 16

What are auxin fluxes medicated by?

Answer 16

PIN proteins

Question 17

How is auxin flow polarity switched?

Answer 17

By changing distribution of PIN in embryonic cell plasma membranes

Question 18

Draw flower plant diagram

Answer 18

(see notes for diagram)

Question 19

What happens in agamous gene mutants?

Answer 19

Petals overproduced (pretty :) )

Question 20

How do plant homeotic genes differ from animal ones?

Answer 20

They don’t encode homeodomain containing proteins and the DNA motif is instead called the MADS-box
No clustering or co-linearity, concentric whorl instead of body axis

Question 21

What are key stem cell characteristics?

Answer 21

Stem cells can divide indefinitely under right conditions
Progeny can differentiate into different cell types
Stem cells can self-renew and produce more stem cell progeny on division

Question 22

What happens when tissue sample from any region of an adult plant is cultured?

Answer 22

An undifferentiated callus forms; when cells are separated and individual cells are cultured a whole plant is formed (shows cells are pluripotent)

Question 23

How can you make a transgenic plant?

Answer 23

(see notes for diagram)

Question 24

What is difference with animal differentiation?

Answer 24

Differentiated state highly stable however nuclei remain pluripotent (info for other cell types retained but normally inaccessible)

Question 25

Write out scheme for early mouse embryo-genesis

Answer 25

(see notes for diagram)

Question 26

Draw mouse blastocyst

Answer 26

(see notes for diagram)
Inner cell mass= Embryo tissue, pluripotent
Can be cultured and grown out of embryo allowing us to start doung genetic engineering in higher organisms
Trophectoderm= extra-embryonic tissues, placenta

Question 27

In a mouse how much maternal contribution is there?

Answer 27

Very little, zygotic genes active early

Question 28

How can you make a chimeric mouse?

Answer 28

(see notes for diagram)
Cells injected into the new blastocyst in some cases can contribute to germ line where mutations exist in injected blastocyst progeny

Question 29

What are teratocarcinomas and how can they be induced?

Answer 29

Germ-cell derived cancer, induced by transplanting blastocyst embryos to extra-uterine sites

Question 30

What happens when ES cells are fused with differentiated thymus progenitor cells?

Answer 30

Nuclear reprogramming can be induced turning on stem-cell specific genes eg. oct4

Question 31

What was 2012 nobel prize?

Answer 31

Nuclear factors including oct4 discovered that induce pluripotency of stem cells
opens up exciting possibility of generating stem cells from adult cells instead of embryos
(see notes for diagram)

Question 32

What has stem cell therapy been used in?

Answer 32

2015- age-related macular (pigmented area in retina near eye) degeneration first treated by stem cell therapy
Stem cell therapy used in Zika treatment

Question 33

How much maternal contribution is there to plant axes?

Answer 33

None

Question 34

How have induced pluripotent stem cells been used in NK cells?

Answer 34

Homogeneous NK (natural killer) cells can be generated from iPS (compared to NK cells isolated from peripheral blood)
They effectively kill diverse human tumour cells