Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Genetics > Early vertebrate development & developmental genetics (lectures 22&23) > Flashcards

Early vertebrate development & developmental genetics (lectures 22&23) Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

when does patterning occur in early development?

A

in the first 3 weeks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is morphogenesis?

A

the emergence of form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is axis formation?

A

occurs in a number of parts of the developing embryo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is body plan?

A

the map of an organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are the 3 crucial axis that embryos must develop?

A

anterior-posterior - runs from head to tail

dorso-ventral - runs from back to belly

left-right - between 2 lateral sides of the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

dorsal

A

back

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

ventral

A

body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

anterior

A

front
head
rostral
cranial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

posterior

A

back
tail
caudral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

components of cell signalling

A

release of signal by source cell
reception of signal by target cell
transaction of signal
cellular response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what are morphogens?

A

substance that controls positions of specialised cell types during morphogenesis

pattern the embryo

form gradients which activate different genes at different concentrations

influence cell fate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

how do morphogens achieve long range signalling?

A 
growth factors are often morphogens 
different mechanisms 
diffusion over long distances 
relay from cell to cell 
cellular extensions 
not mutually exclusive
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the first step in establishing A-P polarity in flies?

A

a gradient of bicoid
fly egg us a single cell so free diffusion possible

low affinity binding sites at high concentrations of bicoid activate orthodenticle and hunchback mRNA

high affinity binding sites at low concentrations of bicoid repress caudal protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

signalling centres in early mammalian embryos

A

anterior visceral endoderm (AVE)

node (‘organiser’)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the anterior visceral endoderm (AVE)?

A

appears first and patterns only the anterior part of the embryo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is the node (‘organiser’)?

A

patterns the whole embryo, working cooperatively with the AVE at the anterior end of the embryo

loss of the organiser genes expression affects the body plan of the embryo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

left-right axis formation

A

vertebrate body is not bilaterally symmetrical

left is different from the right - especially organs
• heart, stomach and spleen on left
• liver on right
• lungs have different number of nodes on the left and the right

breaking of symmetry first takes place at the node
morphogens resustin the activation of a specific signalling pathway only on the left side

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

left-right signalling pathway

A

1) initiated at the node
2) nodal (a TGF-beta family morphogen) signalling activated on the left side of the embryo
3) nodal activates Pitx2 (a homeobox containing gene) which regulates downstream gene expression
4) an organ specific process, dependent on dosage of Pitx2, governs asymmetric organ development

right side is the default
if pathway isn’t activated, left side would be the same as the right side

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

experimental technique that taught as abut left-right pattering

A

invert and transplant node

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

genetic technique that taught as abut left-right pattering

A

knockout lefty-1 gene

right-left determination factor 1

21
Q

the A-P axis is determined by a number of morphogens

A

Wnt signals specify the anterior region

RA patterns the midbrain, hindbrain and trunk

FGF gradient pattens the caudal region

hox genes

22
Q

hox genes in mammals and flies

A

hox genes are homologous to homeotic selector genes in flies

4 hox clusters in mammals, 1 in flies

specific identity of AP patterned structures is defined by homeobox containing genes

23
Q

how is the limb patterned?

A

in several axis
patterns in the proximal-distal axis
if you disrupt the pattern you disrupt the limb

24
Q

D-V patterning

A

neural tube is patterned
• BMP from dorsal region
• Shh from ventral region

opposing gradients of the BMP and Shh specify neuronal subtypes
activates expression of homeobox genes

essential for normal development of the nervous system

25
Q

what are congenital malformations?

A

those already present at birth

usually occur during embryogenesis
congenital anomalies result from disruption of normal development

can have genetic or environmental causes

26
Q

what is embryogenesis?

A

first trimester in humans

27
Q

genetic causes of congenital malformations

A

chromosomal defects
syndromes
single genes
multi-gene interactions

28
Q

environmental causes of congenital malformations

A 
maternal diabetes 
fever 
prescription drugs 
recreational drugs 
pollutants 
dietary deficiencies/excesses
29
Q

what are we trying to achieve by studying congenital malformations?

A

identify cause of malformation

predict whether it is likely to happen again

understand why specific factors lead to malformations

devise strategies for preventing malformations

30
Q

anatomical approach to studying development

A

study of naturally occurring mutations in human and animal models

utilised histological techniques to study how the defective structures formed and how they ended up

31
Q

key methodologies for anatomical approach to studying development

A

gross morphology - dissection
histology

embryos/tissues dehydrated
embedded in paraffin wax
thin slices cut
different tissues/cell types visualised

32
Q

physical manipulation approach to studying development

A

understanding development tells us about normal development

manipulation of developing embryos are used to ask specific questions and test hypotheses

33
Q

key methodologies for physical manipulation approach to studying development

A

removal of part of the embryo and looking at the consequences

replacing one part of an embryo with another

using a drug to interfere with a developmental process

followed by anatomical analysis

34
Q

genetic approach to studying development

A

congenital abnormalities are frequently caused by defects in genes

have a lot of genetic information from studying families with congenital malformations
basic science research has revealed many new genes that act in pathways

35
Q

key methodologies for genetic approach to studying development

A

visualisation of gene/protein expression

measurement of levels of gene/protein expression

disruption of gene function
• total knockout - in every cell of the embryo
• conditional knockout - in cell types of choice

ectopic or ‘extra’ gene expression - knockins and transgenes

36
Q

genetic expression analysis

A

powerful tool for showing where genes are active
closely linked to anatomical approach

gives spacial and temporal information

crucial for linking genes to specific cell types

mRNA and protein localisation is not always the same

37
Q

methods for analysing gene expression

A

in situ hybridisation - mRNA

immunohistochemistry - protein

linkage of gene regulatory elements to a reporter gene - transgenesis

38
Q

what are knockout mice?

A

creating a mouse with an inactive copy of the gene of interest

1) manipulate the DNA
2) transfer mutated DNA into mouse embryonic stem cells by transgenesis
3) incorporate transgenic ES cells into normal embryo
4) breed mice to obtain ‘knockout’ offspring

39
Q

creating a traditional knockout mouse

A

modified ES cell and host embryo have different coat colours

1) clone gene and put in bacteria
2) manipulate gene so its malfunctional
3) transfer into embryonic stem cells
4) transfer into an early embryo to be incorporated into the inner cell mass
5) transfer new embryo into a new mother which has a different coat colour to the original
6) allow offspring to be born
7) select embryos that have mixed coat colour
8) breed until you get offspring that are only the coat colour of the ES cells - these are the knockout mice

takes 1-2 years

40
Q

what is CRISPR/Cas9?

A
  • uses synthetic RNA to guide enzyme (Cas9) to correct place in the genome
  • inject RNA and nucleases into fertilised embryos
  • cuts both DNA strands at the same time
  • can target multiple sites in the genome

can generate transgenic/mutant twice in < 1 month

cheap and efficient

41
Q

what is the effect of knocking out a gene?

A

can knockout gene of choice

see what effects it has on the embryo

complemented by anatomical analysis

42
Q

what is gastrulation?

A

the process where 3 germ layers are formed

occurs in early development
key process is formation of the embryo

43
Q

why do lp mice get neural tube defects?

A

lp mouse first described in 1948

gross morphology shows us that embryos are short and that neural tube closure is initiated

histology revealed a broadened floor plane

anatomical approach tells us what the main abnormalities are

1/1000 live births generally

44
Q

hypothesis - broad floor plane prevents neural folds coming together

A

will tying together the neural tube will lead to closure?

ties threat around neural tube and Brough neural folds together
followed by histological analysis

did not result in neural tube closure

45
Q

lp gene in Vangl2

A

shown to be a component of a signalling pathway - Wnt dependent pathway

regulates convergence-extension movements at gastrulation in vertebrates

46
Q

PCP signalling regulates convergent extension movements

A
  • take place at gastrulation
  • occur by a process of cell intercalation
  • result in the narrowing and lengthening of the embryo
  • disruption leads to short fat embryos
  • disruption of PCP signalling in mice also causes neural tube defects
47
Q

human patients with neural tube defects

A

1/1000 babies have neural tube defects

now have identified mutations in PCP genes in human families with neural tube defects 
• Vangl1 
• Scrib 
• Celsr1 
• Prickle

allows genetic counselling

48
Q

new therapies fro NTDs?

A 
folic acid (B vitamin) can prevent some NTD 
• NTD seen in lp are not prevented by folic acid

inositol (another B vitamin) can prevent NTD in mice
inositol is now in clinical trial for prevention of NTD in humans

Genetics (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions