M5 L1

Question 1

Why cant RNA polymerases just bind to DNA and start transcription in terms of CHROMATIN?

Answer 1

Because DNA is tightly packed into CHROMATIN

Question 2

Which part of the chromatin can be transcribed Euchromatin or Heterochromatin?

Answer 2

EUCHROMATIN

Question 3

Can you explain the DNAse hypersensitivity experiment?

Answer 3

• So DNAse = breaks down DNA
  Experiment=
  Reticulocyte used, in experiment A , in which reticulocytes was NOT expressing gene for GLONIB formation
  EXP B = reticulocyte was EXPRESSING gene for GLOBIN formation

Question 4

Can you describe the interaction between DNA and HISTONES?

Answer 4

• DNA has negative backbone which interacts with positive snakey arms of HISTONE
• during gene expression, negative molecules = CH3-, CH3CO-, PO4- interact with HISTONE instead of DNA so DNA becomes free for transcription

Question 5

What are the three POST-TRANSLATIONAL modification that can occur in DNA?

Answer 5

• Methyolation
• Acetylation
• Phophorylation

Question 6

Can you explain how METHYLATION as post-translational modification affects DNA and what it can do?

Answer 6

-CH3 group added to lys and his in histone
- involved for gene ACTIVATION, REPRESSION, DNA REPLICATION

Question 7

CAN you explain what acetylation does to DNA?

Answer 7

(-CH3CO2- added to lys in histones,
Lead to = nucleosome assembly, gene activation

Question 8

Phosphorylation in DNA

Answer 8

adds Po4- to lysines in H1
- = cell division/transcription/chromatin structure