Eukaryotic Transcriptional Regulation

Question 1

Zygote

Answer 1

all embryonic stem cells were identical, can differentiate into the many different cell types in the body

Question 2

Gene Regulation

Answer 2

-responsible for creating various cell types in multicellular organisms

Question 3

Transcription Factors

Answer 3

determine the pathway that a specific cell type will follow and the final mature differentiated cell type it will form

Question 4

Chromatin Remodelling

Answer 4

DNA is tightly wound in chromatin making it inaccessible

-chromatin must unravel in order for transcription to occur

Question 5

When does chromatin remodelling occur?

Answer 5

when an activator is able to bind to an accessible enhancer site which leads to recruitment of other proteins

• activator proteins can recruit HAT which can attach acetyl groups to the lysine amino acids along the positively charged tails of histones
• the positive charge weakens the association between DNA making it able to bind

Question 6

Core Promoter

Answer 6

binding site required for binding of RNA polymerase and associated transcription factors

Question 7

Silencer Regions

Answer 7

• able to halt transcription

- interfere with general transcription factor assembly which is needed for transcription

Question 8

Hemoglobin Protein in Fetus’s

Answer 8

2 a globins
2 y globins

chromatin is wound tightly around beta globin to prevent transcription

Question 9

Hemoglobin in adults

Answer 9

2 a globins

2 b globins

Question 10

oxygen affinity in fetus

Answer 10

high because gamma globin can bind to oxygen more strongly than beta global

Question 11

oxygen affinity in adults

Answer 11

moderate

Question 12

How can transcription factors regulate transcription?

Answer 12

• able to bind to nucleic acid sequences in DNA and most have alpha helical domains that fit nicely in grooves of DNA
• when a strong enough interaction between the transcription factor and the DNA, control of transcription is allowed
• DNA allows for assembled transcription factors and RNA polymerase to come to close proximity by looping DNA
• adaptor proteins can bind proteins bound to enhancer regions with proteins that are bound to core promoter region
• transcription can occur

Question 13

Regulation by methylation

Answer 13

• when the c’s aren’t methylated, DNA binding proteins and RNA polymerase will recognize and bind
• methylated promoter can further repress transcription
• RNA polymerase cannot bind to methylated sequences preventing transcription