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Bio 243 Midterm > Theme 2b > Flashcards

Theme 2b Flashcards

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Biology 101 flashcards
1
Q

What does an organisms phenotype depend on

A

Cell number, type and function

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2
Q

What is regenerative medicine

A

Growing a desired tissue type by turning on/off the appropriate genes using molecular techniques

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3
Q

What are the two main structures of a gene

A

Include promoter and transcriptional unit

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4
Q

What is the promoter

A

-DNA sequence (including TATA box) that specified where transcription begins on the chromosome
-located immediately upstream of the transcriptional start point of the nontemplate or coding strand
-recognized and bound by the transcriptional machinery (RNA polymerase and transcription factors) that initiate transcription

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5
Q

What is the transcriptional unit

A

Part of the genome that is copied into RNA

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6
Q

What does the RNA polymerase do

A

Synthesizes RNA transcript in a 5’ to 3’ direction
Unwinds and rewinds DNA helix during RNA synthesis

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7
Q

Does RNA need a primer

A

No just DNA

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8
Q

What are the 3 types of RNA polymerase s

A

1) RNA pol l: transcribes rRNA (noncoding)
2) RNA pol ll: transcribes mRNA (coding)
3) RNA pol lll: transcribes tRNA (noncoding)

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9
Q

What are the 3 steps of transcription

A

1) initiation
2) elongation
3) termination

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10
Q

What are the 2 types of transcriptional initiation

A

1) general transcription factors bind to RNA polymerase and recruit RNA polymerase ll resulting in low transcription levels
2) transcriptional activator proteins bind to enhancer regions resulting I high levels of transcription

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11
Q

What is the rate determining step on transcription

A

Initiation

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12
Q

What happens in transcriptional elongation

A

RNA transcript gets longer by RNA polymerase synthesis (3’ to 5’)

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13
Q

What happens in transcriptional termination

A

5’ sequence in DNA template causes termination after transcribed into RNA

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14
Q

What are the 3 termination factors and which type of cells do they occur

A

1) Rho-independent (prokaryotes)
2) Rho-dependent (prokaryotes)
3) cleavage and polyadenylation specific factor (eukaryotes)

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15
Q

How does Rho-independent termination work

A

-helicase enzyme
-terminator sequence in mRNA base pairs with itself to form G-C hairpin
-causes RNA polymerase to stall and dissociate

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16
Q

How does Rho-dependent termination work

A

-relies on Rho helicase
-terminator sequence in mRNA is recognized and bound by the Rho helicase which unwinds RNA from template DNA and RNA polymerase

17
Q

How does the cleavage and polyadenlation specific factor work

A

-poly(A) sequence in mRNA signals the CPSF to cleave (pentose phosphate backbone) the completed mRNA transcript

18
Q

Are all the termination factors sequence driven

A

Yes

19
Q

What is the advantage of the 5’ and 3’ UTR’s

A

Regulate mRNA stability and translational efficiency

20
Q

What is the open reading frame

A

Region of mRNA that is translated and included the start and stop codons at the borders

21
Q

What is the 5’ cap

A

Modified guanosine triphosphate that is added to the 5’ end of the mRNA and acts as a ribosome binding site and protects mRNA from degradation

22
Q

What is the poly(A) tail

A

Long string of adenine nucleotides added to the 3’ end of the mRNA to protect the mRNA from being degraded and increases translational efficiency

23
Q

What are introns and exons

A

Introns: noncoding segments of DNA
Exons: coding segments of DNA

24
Q

What is the difference between pre-mRNA and mature mRNA

A

Pre-mRNA has introns and exons mature mRNA only has exons that code for amino acids

25
Q

What is the splicosome (snRNA)

A

Recognizes sequence on the introns and forms loops to remove them

26
Q

What is alternative splicing

A

Generating different proteins from one gene

27
Q

What percent of human genes are alternatively spliced

A

75%

28
Q

How does the cell regulate genes

A

Post transcriptional regulation by RNA interference

29
Q

What are microRNAs (miRNAs) and small interfering RNAs (siRNAs)

A

-precursors that are cleaved to 21-23 by double-stranded RNAs by the diver Rnase
-substrates of RISC (RNA induced-silencing complex)

30
Q

What does RISC do

A

-unwinds one of the RNA strands which attract binding of the complementary mRNA
-this interferes with translation initiation or induces mRNA degradation

31
Q

What is transcriptional regulation and what does it depend on

A

-control of mRNA synthesis
-depends on the speed of transcriptional initiation (promoter strength)

32
Q

What is post transcriptional regulation

A

Processing of mRNA which affects wits stability and translational efficiency

Bio 243 Midterm (7 decks)

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