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Developmental Biology > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

What is are the functions of the 5’ cap?

A

protect mRNA from degradation

assists ribosome binding in translation

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2
Q

Describe the translation initiation complex.

A

Poly A tail binds poly A binding protein (PABP) which interacts with translation initiation factor eIF4G. eIF4G interacts with 5’ cap binding protein eIF4E which forms a loop by bringing the 5’ and 3’ ends together.

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3
Q

What enzyme cleaves decapped mRNA? And in what direction?

A

XRN1 in 5’ to 3’ direction

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4
Q

Where does XRN1 come from? Where does it bind (5/3)?

A

The removal of a polyA tail and subsequential interaction with decapping proteins, binds 5’ side.

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5
Q

What is CPE?

A

Cytoplasmic Polyadenylation Element

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6
Q

Poly A tail in absence of sperm

A

Not able to bind PABP as Poly A tail is shorter (not elongated)

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7
Q

Describe the translation complex before fertilization.

A

CPEB bind CPE contained in maternal mRNA. CPEB interacts with maskin which interacts with the cap binding protein eIF4E. Maskin inhibits interaction eIF4e with eIF4G and 40s recruitment does not occur.

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8
Q

What is the cap binding protein?

A

eIF4E

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9
Q

What links PABP and eIF4E

A

eIF4G

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10
Q

Describe what happens to the initiation complex following fertilization.

A

Signals from fertilization stimulate phosphorylation of CPEB allowing for elongation of the poly A tail and the PABP is allowed to interact eIF4G and 5’ initiation factor eIF4E which displaces maskin, initiating translation

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11
Q

In what region of DNA initiates translation in oocyte?

A

3’ UTR

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12
Q

What is ribosomal heterogeneity?

A

ribosomes have some structural differences that allow for specialization of their function. These differences essentially mean that ribosomes are able to select what mRNA is translated

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13
Q

What is epigenetics?

A

Molecular mechanisms that allow the environment to alter how genes behave without changing the information they contain

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14
Q

What are some major non-coding mRNAs?

A

miRNA, siRNA, piRNA, lncRNA

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15
Q

What is the function of non-coding RNA?

A

To protect from mutation

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16
Q

What is the RNA induced silencing complex (RISC), and name at least three components?

A

The RISC targets mRNA with complementary sequences to the guide RNA. It binds si and mi RNA which mediate repression of RNA. Three components: si and mi RNA along with argonaute protein

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17
Q

What happens when imperfect base pairing occurs between small RNA and target gene?

A

repression of translation or deadenylation and degradation in P-body

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18
Q

What happens when perfect base pairing occurs between small RNA and target gene?

A

Ago is endonucleolytic to target mRNA

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19
Q

Describe the synthesis of siRNA

A

anti-sense mRNA (ds) (anti sense to target gene) which is cleaved and shortened by dicer to produce short nt sequence for RISC

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20
Q

Describe synthesis of miRNA

A

miRNA gene forms pri-miRNA which has multiple hairpins, drosha cleaves one hairpin at end and exits nucleus to be cleaved into short dsRNA by dicer that will bind to RISC

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21
Q

Which strand of miRNA/siRNA recognizes DNA to be silenced

A

guide strand, passenger strand is discarded

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22
Q

What effect does the RISC have on translation?

A

-mRNA target cleavage
-Translational repression
mRNA deadenylation

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23
Q

What is the use of shRNA

A

Since introduction of RNA-RNA duplexes to cytoplasm results in protein synthesis inhibition, shRNA has a hairpin loop effective for cleavage by dicer to effectively silence genes

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24
Q

What is the role of miRNA430 in transition from mother to zygote

A

Rids zygote of mRNA no longer needed

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25
Q

Name three possible locations of mRNA

A

diffusion and local anchoring
localized protection with deadenylation in cytoplasm
active transport along cytoskeleton via microtubule mol.

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26
Q

Describe a gene regulatory network

A

controlled by signaling ligands (hormones used in cell to cell communication) and are able to control cell differentiation

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27
Q

Do (housekeeping genes/transcription factors) have a longer half-time?

A

House-keeping genes bc produce enzymes used for creation of energy or other essential processes.

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28
Q

What is the fn of the poly-A tail?

A

prevent mRNA degradation
aids in the export of mature mRNA to the cytoplasm
binds proteins involved in initiating translation

29
Q

What is the function of shRNA

A

provide a single stranded 3’ end to anchor the PAZ domain of dicer which brings about silencing

30
Q

What conveys a message from outside the cell to influence cell differentiation?

A

Extrinsic factors

31
Q

Give an example of an extrinsic factor

A

Constitutive production of ecdysone. However, cells only respond once receptor begins to be produced

32
Q

What is local cell signaling called?

A

juxtacrine signaling

33
Q

If local cell signaling is between two of the same recepotrs, what is it called?

A

homophillic binding

34
Q

If local cell signaling is between two different proteins it is called…

A

heterophilic binding

35
Q

Signaling between distant cells is called

A

paracrine signaling

36
Q

Proteins that are secreted from a cell and designed to communicate a response in another cell

A

ligands

37
Q

Which type of signaling is transmembrane

A

juxtacrine

38
Q

Which type of signaling is ligand-receptor

A

paracrine

39
Q

Cells found centrally have

A

greater surface cohesion (attachments to one another)

40
Q

Which cells will have the greatest surface tension

A

The ones found inside the gastrula

41
Q

What are the glue-like proteins responsible for creating the adhesion gradient?

A

Cadherins

42
Q

Where can P cadherin be found?

A

placenta for adhesions to uterus

43
Q

Where is E cadherin found

A

Early embryo for migration and epiboly of the epiblast in zebrafish

44
Q

Where is N-cadherin found

A

throughout developing cells of the nervous system

45
Q

Where is R-cadherin found?

A

retina formation

46
Q

What is the function of protocadherins and what makes them structurally different? What is its function?

A

lacks the attachment to the actin cytoskeleton through catenin, keeping migrating epithelial cells together, and expressing dissimilar protocadherins is an important way of separating tissues

47
Q

What causes epiboly in the early embryo zebrafish?

A

E cadherin is expressed at higher levels in more superficial layers

48
Q

E/M: regular columnar morphology

A

Epithelial cells

49
Q

E/M: loss of apico-basal polarity

A

Mesenchymal

50
Q

E/M: high degree of cell adhesion

A

epithelial

51
Q

E/M: irregular rounded or elongate morphology

A

E

52
Q

E/M: cell-cell junctions

A

E

53
Q

E/M: highly motile

A

M

54
Q

E/M: underlying basement membrane composed of basal lamina and reticular lamina

A

epithelial

55
Q

E/M: front back polarity

A

M

56
Q

E/M specialized apical membrane

A

E

57
Q

E/M: static

A

E

58
Q

E/M: dynamic adhesions

A

M

59
Q

E/M: lamellipodia and filopodia

A

M

60
Q

The ability to control cell differentiation and are controlled by cell signaling

A

Gene regulatory networks

61
Q

These genes have a longer half-life, enzymes used for creation of energy or other essential processes that need to be conducted by the cell

A

House-keeping genes

62
Q

These have a shorter mRNA half-life

A

transcription factors

63
Q

This post-transcriptional modification prevents mRNA degradation and assists in ribosome binding during translation

A

5’ guanosine cap

64
Q

This post-transcriptional modification helps to prevent mRNA degradation, aids in export of mature mRNA into cytoplasm and is involved in binding protein involved in translation.

A

3’ poly A tail

65
Q

Part of the mRNA that are removed in the nucleus prior to cytoplasmic export

A

introns

66
Q

Longer poly A tail confers

A

longer mRNA half life

67
Q

Controlling mRNA controls…

A

the amount of protein produced by a cell

68
Q

Initiation of translation is controlled by

A

interactions between the 5’ cap and 3’ poly A tail

69
Q

What are transpsons?

A

known as “jumping genes” since they can insert into other parts of the genome. An important source of mutation that helps with adaptation to environmental stressors

Developmental Biology (1 decks)

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