Theme 3

Question 1

What conditions must be met for protein growth to occur in prokaroytes?

Answer 1

nutrient rich environment and favourable temperatures

Question 2

housekeeping genes

Answer 2

constantly expressed and are required for normal function (ribosomal, structural)

Question 3

regulated genes

Answer 3

can be turnt on/off on a need basis, controlled by different factors and environment

Question 4

What sources of energy does E. coli bacteria use?

Answer 4

glucose (primary), galactose (secondary)

Question 5

Describe the general process that E. coli bacteria undergoes to switch to an alternative fuel.

Answer 5

When glucose resources are depleted and there is lactose present. There will be a time lag of which beta-galactosidase and lactose permease are produced. When enough of the enzymes are produced, the hydrolysis of lactose begins where galactose and glucose are produced.

Question 6

Describe Jacob and Monod’s experiment.

Answer 6

Discovered that the presence of beta-galactosidase is dependent on lactose levels. When all lactose is depleted, the enzyme production will cease.

Question 7

What are the 3 levels of gene regulation?

Answer 7

transcriptional, translational, post-translational

Question 8

What are the effects of gene regulation?

Answer 8

Transcriptional controls the amount of mRNA produced (on/off), translational controls the stability of the mRNA, and post-translational controls the folding of the protein (active/inactive)

Question 9

What are the relative “speeds” of gene regulation?

Answer 9

Post-translational is the fastest as it quickly activates proteins, transcriptional is the slowest and the most efficient as it requires more steps and often occurs in drastic environments, but it also conserves the most resources

Question 10

What cues initiate the transcription of beta-galactosidase and lactose permease?

Answer 10

1. glucose levels

2. presence of lactose

Question 11

operon

Answer 11

related genes with similar function

Question 12

Describe the lac operon and how gene expression occurs in E. coli cells.

Answer 12

The lac operon consists of a promoter region, operator region (lacO), CRP-cAMP site, and lac Y, Z, and I genes.
Gene expression occurs when the RNA polymerase complex binds to the promoter region, the gene is read and eventually produces beta-galactosidase and lactose permease.

Question 13

Describe negative regulation in E. coli cells.

Answer 13

1. glucose is present
2. repressor and it’s binds to the operator regions of the lac operon
3. DNA is formed into a loop
4. NO transcription occurs

Question 14

Describe how repressor molecules can be inhibited in E coli. cells.

Answer 14

1. lactose is present
2. lactose becomes inducer
3. lactose binds to the repressor and causes a change in confirmation and the repressor is unable to bind to the operator
4. YES transcription occurs

Question 15

Describe positive regulation in E. coli cells.

Answer 15

1. low glucose levels increases the number of active adenyl cyclase
2. high levels of cAMP it to be bound to CRP
3. CRP-cAMP complex binds to the site on the lac operon
4. YES transcription occurs

Question 16

How does inhibition of repressor molecules and positive regulation cause the production of enzymes?

Answer 16

The inhibition of repressor molecules occurs when lactose is present and binds to/inhibits repressor molecules from binding to the operator region. If the glucose levels are also low, there will be an increased activation of adenyl cyclase, which produces more cAMP. As a result, a CRP-cAMP complex is created and binds to the site, allowing for RNA polymerase to bind to the promoter and begin transcription.

Question 17

What are the effects of regulating eukaryotic transcription?

Answer 17

Turning on/off genes ultimately change the cell type and function, and how it works with other proteins.

Question 18

transcription factors

Answer 18

bind to specific DNA sequences and helps to determine the function and type of cell.

Question 19

What are the similarities and differences between eukaryotic and prokaryotic transcriptional regulation?

Answer 19

Both uses RNA polymerase to transcribe genes and use various proteins to regulate transcription.
Prokaryotes have operons that whereas eukaryotes have different promoters/enhancers for every gene and it compacts DNA into chromatins.

Question 20

chromatins

Answer 20

closely wound and packaged DNA around histones to compact it into the nucleus and to be moved during cell division; cannot be expressed unless unwound

Question 21

promoters

Answer 21

section of DNA that initiates transcription

Question 22

enhancers

Answer 22

section of DNA that increases the rate of transcription and changes the shape of the DNA when a protein binds to the site

Question 23

Describe chromatin remodelling.

Answer 23

1. binding of activator/transcription factor to enhancer
2. recruits HAT which attaches acetyl groups to lysine
3. acetylation (decreases positive charge of histone tails)
4. loosening the association of histone octamers from the DNA helix (unwind)
5. transcription

Question 24

Describe other processes that can unwind DNA.

Answer 24

Methylation and phosphorylation changes the charge of the histone tails and generally modifies the amino acids that protrude from histone proteins.

Question 25

What are the 4 DNA binding motifs and how do they activate transcription?

Answer 25

Basic helix loop helix, helix turn helix, zinc finger, and leucine zipper must bind to the grooves of DNA, which causes a confirmation and allows for the control of transcription.

Question 26

How is transcription initiated?

Answer 26

1. regulatory transcription factors bind to enhancer sequences and recruits general transcription factors
2. general transcription factors bind to promoter
3. TATA box is recognized by TBP (subunit of TFIID) and BRE is recognized by TFIIB
4. transcriptional activators bind to enhancer sequences
5. interact with basal machinery
6. can recruit RNA polymerase and initiate transcription

Question 27

How does transcription occur?

Answer 27

1. binding of transcription complex to promoter and enhancer

2.