Transcription and post Transcription 2B part 1

Question 1

Differential expression of genome (4)

Answer 1

Gives rise to different cell types and tissues

1. Every cell nucleus contains the complete genome established in the fertilized egg. In molecular terms, the DNAs of all differentiated cells are identical.

2.
The unused genes in differentiated cells are not destroyed or mutated, and they retain the potential for being expressed.

3.
Only a small percentage of the genome is expressed in each cell, and a portion of the RNA synthesized in the cell is specific for that cell type.

Question 2

every cell in an organism has an (3)

Answer 2

identical genome, DNA sequence/ same set of ACTG sequence, Chromosomes

Question 3

Regenerative Medicine

Answer 3

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

Question 4

A gene includes

Answer 4

promotor and transcriptional unit

Question 5

Promotor

Answer 5

DNA sequence that specifies where transcription begins on the chromosome

Question 6

The promotor is located

Answer 6

upstream or 5’ end of the transcriptional start point of the coding DNA strand

Question 7

Transcriptional machinaery

Answer 7

RNA polymerase and transcription factors that initiate transcription

Question 8

Transcriptional unit

Answer 8

Part of the gene that is copied into RNA

Question 9

RNA polymerase (3)

Answer 9

Synthesizes RNA transcript 5’-3’ while reading 3’-5’

Does not need a primer for initation of RNA synthesis

Unwinds and rewinds DNA helix during RNA synthesis (RNA has helices active in the enzyme to break H bond). Reannealed behind in the transcription bubble.

Question 10

RNA Pol 1

Answer 10

makes ribosomal RNA

Question 11

RNA pol 2

Answer 11

makes mRNA

Question 12

RNA pol 3

Answer 12

makes tRNA

Question 13

two types of transcriptional imitation processes: (2)

Answer 13

General transcription factors bind to promotor and recruit RNA polymerase resulting in low basal level of transcritopn or not many RNA made per time or highly expressed (1/2 mRNA made per hour)

Transcriptional activator proteins bind to enhancer regions distant from the promotor to cause DNA looping bring mediator and RNA polymerase to the promotor resulting in high level of transcription. (Highly expressed genes)

Question 14

Tata box

Answer 14

only in eukaryotic cells, stabilizes RNA polymerase

Question 15

Transcription factors are

Answer 15

proteins that help turn specific genes “on” or “off” by binding to nearby DNA.

Question 16

general transcription factors

Answer 16

part of the cell’s core transcription toolkit, needed for the transcription of any gene.

Question 17

activators proteins in transcription….(what they do)

Answer 17

They increase DNA transcription by making the assembly time of the transcription factors faster

Question 18

Reannealing of DNA

Answer 18

Growing RNA is displaced from the DNA template strand (it use to be double helixes to the template strand) and RNA pol butt reannelas DNA

Question 19

Rho independent Termination/Intrinsic termination (3)

Answer 19

only in prokaryotes

Terminator sequence in mRNA base pairs, coded from DNA strand pairs with itself to form a G-C hairpin as the mRNA base pairs are inverted (CCCCG-…….-GGGGC). This hairpin causes RNA polymerase to stall and dissociate

No ATP is used

Question 20

Rho Dependant Termination (5)

only in+steps (4)

Answer 20

• only in prokaryotes
• Rho binds to RNA on the recognition sequence
• Move along the RNA via ATP
• RNA polymerase pauses at terminator and Rho catch up
• Terminator sequence in mRNA is recognized and bound by the Rho helicase which unwinds the RNA from the template DNA and RNA polymerase by breaking H bonds.

Question 21

Cleavage and polyadenylation specific factor

Answer 21

only in eukaryotes

Poly A sequence in mRNA signals the CPSF to cleave the completed mRNA transcript thereby separating it from RNA polymerase