Transcription Factors

Question 1

eukaryotic regulation

Answer 1

• begins with transcription initiation with transcription factors
• presence of certain factors at specific times in specific cells helps to determine when and where a gene is expressed

Question 2

coordinated expression (prokaryotes)

Answer 2

• occurs when an organism expresses many genes at the same time in the same tissue
• when genes are needed for a certain process or pathway
• mediated by operons or by the action of sigma figures

Question 3

coordinated expression (eukaryotes)

Answer 3

coordinated expression of distant genes or genes on different chromosomes are mediated by transcription factors

Question 4

eukaryotic promoters

Answer 4

• contain regulatory elements recognized by transcription factors
• sequences near the 5’ end that RNA polymerase binds to begin transcription
• contain a sequence called the TATA

Question 5

transcription factors

Answer 5

• mediate transcription initiation in eukaryotic cells
• general transcription factors bind to the promoter region and RNA polymerase
• helps RNA polymerase find the promoter -> increase the chances it will bind and begin transcribing

Question 6

structural motifs

Answer 6

• transcription factors have common structural motifs that bind to DNA
• the interior facing recognition helix interacts with the bases inside the DNA
• the exterior facing helix sits on the sugar phosphate backbone, ensuring that the interior helix is presented to bases in the correct configuration

Question 7

general transcription factors

Answer 7

• involved in the transcription of multiple genes
• involved in coordinated expression: when a certain TF is present, then those genes will be transcribed

Question 8

cell differentiation

Answer 8

• mediated by transcription factors
• (in)activation of transcription factors governs differential gene expression during development
• all differentiated cells contain the entire genome; specific characteristics arise from differential gene expression
• general transcription factors are responsible for coordinating expression of multiple genes

Question 9

specific transcription factors

Answer 9

• only bind to regulatory sequences associated with a few genes
• present in certain cells or certain points in the cell cycle or respond to environmetal change
• may bind proximal or distal to the promoter to affect rate of transcription

Question 10

distal control regions

Answer 10

a specific transcription factor may bind far away and bend the DNA to bind to the RNA polymerase complex

Question 11

enhancers

Answer 11

up-regulation
transcription factors (called activators) bind to enhancers to increase rate of transcription

Question 12

silencers

Answer 12

down regulation
transcription factors (repressors) binding to silencers decrease the rate of transcription

Question 13

transcription efficiency

Answer 13

• depends on promoters and transcription factors
• more promoters increase the chance for RNA polymerase and factors to bind
• increase rate of transcription