Lecture 12 - Control of Gene Expression (Eukaryotes)

Question 1

Acetylation of DNA

Answer 1

reduces histone binding to DNA and leads to transcription

Question 2

Cis-acting regulatory sequences (DNA)

Answer 2

regulatory sequences that are on the same strand of DNA that they are regulating (cys = same). They are bound by Trans-acting factors (proteins).

Examples:

• Promoter
• Enhancers
• Hormone response elements

Question 3

Properties of Enhancers:

Answer 3

• Work when located long distances from the promoter
• Work when upstream or downstream from the promoter
• Work when oriented in either direction
• Work by binding one or more proteins (can bind repressors or activators)
• Work by facilitating binding of the basal transcription complex to the promoter

Question 4

DNA binding motifs commonly found in transcription factors:

Answer 4

• Helix-turn-helix (HTH)
• Helix-loop-helix (HLH)
• Zn finger
• Leucine zipper

Question 5

Tissue-specific trans-acting factors

Answer 5

allow certain genes to only be expressed in certain cell types

Question 6

Signal-specific trans-acting factors

Answer 6

gene expression can be triggered by external signals. Hormone response elements bound by steroid-type hormone receptors. Hormone receptors are in cytoplasm, not in membrane.

Question 7

Types of post-transcriptional regulation of gene expression:

Answer 7

• Alternative RNA processing
• mRNA editing
• mRNA stability
• mRNA translation - with translation repressors