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Cell Bio > Week 6B > Flashcards

Week 6B Flashcards

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Biology 101 flashcards
1
Q

What is the central dogma of molecular biology

A

Flow of genetic information within a biological system DNA makes RNA which makes protiens

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2
Q

Do all genes encode for protiens

A

NO some encode for small RNAs miRNA

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3
Q

What do miRNA control

A

How many protiens are made by other protien-coding genes

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4
Q

What do the effects of miRNA depend on

A

Presence of mRNA

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5
Q

How do miRNA work

A

Bind to the complemanry sequence in protiein coding mRNA at the 3’ unstranslated region that either block protien translation or induce mRNA degradation

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6
Q

What is the process of miRNA

A

Transcribed by RNA pol II as pri-miRNA
THen folds into a hairpin it is usually long in length
endonuclease enzyme Dorsha makes inital cleave and makes pre-mirna
Exportin5 exports premiRNA out of the nucleus into the cytoplasm through difussion
RNAase Dicer processes pre-RNA into a double stranded miRNA
One of the two strands binds to Argonature which is a core protein of the RNA-induced silencing complex RISC
They then associate with the traget MRNA at 3’UTR and either block or degrade

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7
Q

What were miRNA first foun in

A

neamtode C.elegans encoded by non protien coding genes lin-4 and let-7

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8
Q

What do lin-4 and let-7 regulate

A

embryogenesis and larval development

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9
Q

Which gene was conserved

A

let-7

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10
Q

What are characterstics of miRNA

A

Similar structure of hairpins with imperfect base paring which suggest they can produce different mature miRNA from the same pre-miRNA

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11
Q

What is the miRBase database

A

Serachable database of publishe miRNA sequence each enetery represent a predicted hairpin portion of the miRNA mir and the information on the location and sequence of the mature miRNA miR

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12
Q

what does the first part represent of hsa-mir-123-5p

A

Homo sapiens numbering is when they were disocvered extension are either from the 3’ or the 5’ arm

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13
Q

Can a single miRNA recogninze mutiple targe genes

A

YES

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14
Q

What is the most critcal for target mRNA

A

Seed sequence region which is the first 2-8 nucleotides starting at the 5’end and counting to the 3’end

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15
Q

What is a 6mer

A

A perefect WC match between miRNA see and mRNA for six nucleotides

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16
Q

What is 7mer-m8

A

a perfect WC match from nucleotides2-8 of the miRNA seed

17
Q

What is 7mer-A1

A

A perfect WC match from nucelotides 2-7 in addition to an A across from the miRNA nucleotide 1

18
Q

What is a 8mer

A

a perfect WC match from nucleotides 2-8 of the miRNA with an addition to an A across from the miRNA nucleotide 1

19
Q

What is the difference between perfect complemntarity and imperfect

A

Imperfect leads to inhibition of protien syntheis and perfect is degradation of the mRNA

20
Q

What do miRNA exhibit in stress conditions

A

Phenotypic crisis

21
Q

In response to stress what do cells do

A

Choose to restore or reporgram their gene expression patterns change in the expression of miRNA can affect the presence of different protiens

22
Q

How do cells modulate miRNA upon stress

A

Change in the level of miRNA
Change in mRNA targets
Change in the mode of action of miRNA protien complex
Change in the activity of miRNA protien complex

23
Q

What does the heat map show

A

Tha hypoxia changes the expression on many miRNA in HT29 cells in a time depende maner

23
Q

What happens under normal conditions

A

It is repressed by miRNA A and B and has basal level of expression

24
Q

What happens upon stress

A

Expression of mRNA target decrease in the level of miRNA C increase

25
Q

What could also happen under stress conditions

A

mRNA increases if the level of miRNA B decrease

26
Q

What is there a realtionship between

A

miRNA load and target mRNA expression

27
Q

What is target mimicry

A

Individual miRNA can interact with different target mRNAs which are called mimics of mRNA of your intrest. mRNA increases if the expression of mRNA targets increase upon stress because the targets compete for the same binding of miRNA causing relief in the repression of mRNA targets

28
Q

What is creation/deletion of miRNA binding sites

A

Upon stress cells could express different isoforms of the mRNA target where miRNA binding sitres could be created or delted

29
Q

What happens if miRNA sites are created

A

Expresion of the isoform will be decrease

30
Q

What if the miRNA sites are deleted

A

The expression of the isoform will be stabilized

Cell Bio (13 decks)

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