DNA transcription - lecture 3

Question 1

What do introns do?

Answer 1

Get spliced out - non coding part of the DNA

Question 2

What are histones? What is their structure?

Answer 2

Histones wrap up the DNA. They are made up of 8 molecule. Made positive via amino acids such as lysine. Aceytlation allows the histones to open or close.

Question 3

what are prokaryotic operons?

Answer 3

operon- group of genes transcribed together

Question 4

Do bacteria have introns and exons?

Answer 4

No . Don’t have a nucleus , therefore no processing

Question 5

making mature mRNA. Capping?

Answer 5

Addition of 7- methyl - guanosine at 5’ .

Question 6

what enzymes mediates capping?

Answer 6

Mediated by guanylytransferase.

Question 7

What does capping do?

Answer 7

acts against degradation , serves as recognition site for ribosomes, transports hnRNA from nucleus to cytoplasm

Question 8

What is tailing?

Answer 8

addition of poly(A) residues at 3’ end

Question 9

How is tailing achieved?

Answer 9

poly(A)polymerase and cleavage & polyadenylation specificity factor (CPSF)

Question 10

What is splicing?

Answer 10

precise removal of intron sequences

Question 11

How are introns removed?

Answer 11

Made into a lariat ( loop of DNA) and removed

Question 12

What is alternative splicing?

Answer 12

removal different exons/ introns to produced different transcripts

Question 13

How is gene expression controlled?

Answer 13

promoters , activators, repressors, enhancers, suppressors

Question 14

snRNA

Answer 14

small nuclear RNA, function in a variety of nuclear processes, including the splicing of pre-mRNA

Question 15

snoRNA

Answer 15

small nucleolar RNA , functions in nuclear processes, including the splicing of pre-mRNA

Question 16

miRNA

Answer 16

regulates gene expression by blocking mRNA and causes their degradation

Question 17

siRNA

Answer 17

small interfering RNA, turns off gene expression by degradation of mRNA

Question 18

piRNA

Answer 18

Piwi - interacting RNAs, binds to pewit proteins

Question 19

IncRNA

Answer 19

Long non coding RNA, many of which severe as scaffolds

Question 20

What is the basic structure of a eukaryotic gene ?

Answer 20

contains a regulatory region , coding region and a flanking region

Question 21

What are activators and silencers/repressors

Answer 21

Proteins associated with a promoter which enhance/repress gene expression.