3.4 - Transcription & Protein Processing

Question 1

Purine ribonucleotides

Answer 1

• in RNA
• Have a phosphate, ribose and nitrogenous base
• Adenine & Guanine

Question 2

Pyrimidine ribonucleotides

Answer 2

• in RNA
• Have a phosphate, ribose and nitrogenous base
• Cytosine & Uracil

Question 3

RNA

Answer 3

• ribonucleic acid
• ribose instead of deoxyribose
• uracil instead of thymine
• molecules are single-stranded
• are gene length

Question 4

Transcription

Answer 4

• RNA synthesis using a DNA template

- Has initiation, elongation (of the RNA molecule) and termination

Question 5

Transcription: Initiation

Answer 5

• RNA polymerase (sigma subunit, specifically) binds to promoter
• includes: RNA polymerase, promoter
• no initiator proteins necessary
• no primer necessary
• no helicases

Question 6

Consensus sequences for most E. coli promoters

Answer 6

-35 to -10

15-17 bp between the two

Question 7

Transcription: Elongation

Answer 7

• Addition of RNA nucleotides at 3’ end of growing chain to DNA template strand
• includes: RNA polymerase, NTP precursors

Question 8

Transcription Component: RNA polymerase

Answer 8

• 5’ -> 3’ polymerase activity
• unwinds DNA template DNA strand
• RNA synthesized 3’ to 5’ direction (as polymerase goes 5’ to 3’)

Question 9

Transcription: Termination

Answer 9

-Template DNA contains tts (transcription termination signals) that cause termination

Question 10

2 Types of TTS in E. coli

Answer 10

• intrinsic (requires no other components)

- rho-dependent (requires rho protein)

Question 11

Molecular Genetics Pathway

Answer 11

DNA > RNA > mature RNA > protein > shape > function > phenotype

Question 12

mRNA processing in eukaryotes

Answer 12

-From primary transcript RNA created from transcription to a processsed, mature RNA

1) 5’ cap addition
2) 3’ polyadenylation
3) intron removal (exon splicing)

Question 13

5’ cap addition

Answer 13

• A 7-methylguanosine cap is added to the 5′ end of the pre-mRNA while elongation is still in progress
• 5′ cap protects the nascent mRNA from degradation and assists in ribosome binding during translation

Question 14

3’ polyadenylation

Answer 14

• poly (A) tail is added to the 3′ end of the pre-mRNA once elongation is complete
• protects the mRNA from degradation, aids in the export of the mature mRNA to the cytoplasm, and is involved in binding proteins involved in initiating translation

Question 15

Introns and Exons

Answer 15

• Introns: noncoding regions

- Exons: coding rgions

Question 16

RNA splicing

Answer 16

• Introns are removed and exons joined together
• Spliceosome attach to pre-mRNA by locating 5’ and 3’ splice sites
• Remove the intro sequence alngside SnRNA, that join exons together
• lariat is left-over intron RNA sequence (looks like a loop)

Question 17

Amino acids (protein structure)

Answer 17

• 20 different amino acids, as 20 different R-groups exist w/ different chemical properties
• has amino group, acidic carboxyl group and R-group

Question 18

Chemical properties of R-groups

Answer 18

• nonpolar (hydrophobic)
• polar (hydrophilic)
• uncharged
• charged (basic, acidic)

Question 19

Secondary protein structures

Answer 19

• alpha helix, pleated sheet

- H-bonds between backbone componets

Question 20

Tertiary protein structures

Answer 20

• B-polypeptide
• can contain a heme (metal group)
• interactions between R-groups in the same polypeptide chain

Question 21

Quaternary protein structures

Answer 21

• multiple heme groups

- interactions between R-groups of different polypeptide chains