Transcription and RNA processing

Question 1

normal process of information flow (3)

Answer 1

• DNA (replication)
• RNA (transcription)
• protein (translation)

Question 2

central dogma of biology

Answer 2

• Normal process of producing proteins from DNA–> copy certain block of sequence of DNA and into RNA version
• Do protein synthesis (ribosomes do this) - must have RNA copy of particular genes
• Goes through ribosomes to make particular protein
• *information flow from DNA–>RNA–>protein

Question 3

Mechanism of information flow

Answer 3

• Start sequence and stop sequence for transcription to know where to start/stop
• That will be made into RNA copy
• Additional signals that tell you within RNA where to begin protein synthesis (initiation (amino terminus) and termination (carboxy terminus))

Question 4

mRNA

Answer 4

• when you have a gene and it goes through transcription, the code for this gene- RNA copy that carried gene from RNA

Question 5

rRNA

Answer 5

• Ribosomes composed of mix of proteins and rRNA
• Ribosome is in 2 chunks (top bigger than bottom)
• Prokaryotes- large RNA (23S) goes with top piece, small RNA (16S) goes with bottom piece
• In Eukaryotes- sizes are different (28S and 18S)
• *difference between protein synthesis in bacteria vs. eukaryotes (ribosomes size)

Question 6

tRNA

Answer 6

• Transfer- carry amino acids to ribosome for protein synthesis procedure
• Ribosome makes proteins and need amino acids- pick off of tRNA that bring them in

Question 7

transcription

Answer 7

• Copying information from one nucleic acid to another
• One strand used as template strand, never use the other strand as a template for transcription
• Other strand is the coding strand (carried exact code that RNA will have)- 5’–>3’
  Replication bubble opens–> then RNA sequence will have U instead of T (but otherwise identical to coding strand)
• An RNA transcript has same sequence as the DNA coding strand (except U for T), and the complementary sequence to the template strand

Question 8

Transcription by RNA polymerase

Answer 8

• use polymerase to transcribe
• transcription bubble has been created by this enzyme
• Enzyme can open strand and creates single stranded region
• RNA polymerase can start de novo (does NOT require a primer)
• NO editing function

Question 9

Transcription in bacteria

Answer 9

• Transcription begins at the Promotor region- a sequence of DNA that tells the RNA polymerase where to sit down to begin transcription
• Sigma factor (σ)- a subunit of the polymerase that is able to recognize the promotor region
• position of -10, see TATATT sequence, and the complementary sequence
• TATA is critical for RNA polymerase to know where to sit and start

Question 10

Transcription in Prokaryotes can be terminated in two ways:

Answer 10

1. Rho protein termination
   - Secondary structure- particular protein sees secondary structure and yanks whole thing off so everything stops (requires some ATP)
   - Basically RNA forms special shape and Rho jumps on and stops
2. Hairpin or Rho-independent termination
   - Transcription goes along and comes to sequence that is complementary, so when you make RNA, both sections are complementary
   - Can form a hair pin in the single stranded RNA–> causes transcription mechanism to fall off