Gene Regulation (Promoters/ Operators)

Question 2

What is a gene?

Answer 2

A specific sequence of nucleotides in DNA or RNA that codes for a product that provides a function for the organism.

Question 3

What marks the beginning of a gene in DNA?

Answer 3

Promoter.

Question 4

What are the two short sequences contained in a promoter?

Answer 4

• -10: TATAAT
• -35: TTGACA

Question 5

What binds to the promoter to start transcription of the gene?

Answer 5

RNA Polymerase.

Question 6

What is the operator in gene regulation?

Answer 6

Region of DNA between promoter and gene where a repressor protein can bind.

Question 7

True or False: The binding of a repressor to the operator always occurs.

Answer 7

False.

Question 8

What is quorum sensing?

Answer 8

Cell–cell communication in bacteria achieved through the accumulation of signaling molecules.

Question 9

What is an operon?

Answer 9

A group of genes that participate in the same metabolic activity.

Question 10

What is the primary metabolic activity controlled by the lac operon?

Answer 10

Lactose catabolism.

Question 11

What are the three genes in the lac operon?

Answer 11

• lacZ
• lacY
• lacA

Question 12

What prevents RNA polymerase from binding to the promoter in the lac operon?

Answer 12

Lac repressor protein.

Question 13

What promotes transcription in the lac operon?

Answer 13

Catabolite activator protein (CAP).

Question 14

What derivative of lactose inhibits the lac repressor?

Answer 14

Allolactose.

Question 15

What type of regulation does the lac operon experience?

Answer 15

Both positive and negative signals.

Question 16

Fill in the blank: Lactose positively regulates the lac operon, while _______ negatively regulates it.

Answer 16

Glucose.

Question 17

What complex binds to the lac promoter region and stimulates transcription?

Answer 17

cAMP–CRP complex.

Question 18

What molecule binds to the promoter site of the lac operon for effective transcription?

Answer 18

Catabolite activator protein.

Question 19

How does glucose indirectly affect the transcription of the lac operon?

Answer 19

Low levels of glucose upregulate the transcription of this operon.

Question 20

What is a promoter in gene regulation?

Answer 20

A promoter is a DNA sequence that initiates transcription of a gene.

Question 21

True or False: Operators are found downstream of promoters.

Answer 21

False: Operators are typically found downstream of the promoter but can also be located within the promoter region.

Question 22

Fill in the blank: The __________ is a region of DNA where RNA polymerase binds to initiate transcription.

Answer 22

promoter

Question 23

What role do operators play in gene regulation?

Answer 23

Operators serve as binding sites for repressor proteins that inhibit transcription.

Question 24

Which of the following is NOT a component of gene regulation? A) Promoter B) Operator C) Ribosome

Answer 24

C) Ribosome

Question 25

What is the function of a repressor protein?

Answer 25

A repressor protein binds to the operator to prevent transcription.

Question 26

True or False: Enhancers are the same as promoters.

Answer 26

False: Enhancers are regulatory sequences that can enhance the transcription of a gene but are not the same as promoters.

Question 27

What is the basic function of RNA polymerase in relation to promoters?

Answer 27

RNA polymerase binds to the promoter to initiate the transcription of DNA into RNA.

Question 28

What is an example of a prokaryotic operon?

Answer 28

The lac operon is an example of a prokaryotic operon.

Question 29

Fill in the blank: In the lac operon, the presence of __________ causes the repressor to release from the operator.

Answer 29

lactose

Question 30

What is the purpose of a transcription factor?

Answer 30

Transcription factors help regulate the transcription process by binding to specific DNA sequences.

Question 31

True or False: Promoters are always located at the start of a gene.

Answer 31

True

Question 32

What type of RNA is produced during transcription?

Answer 32

Messenger RNA (mRNA)

Question 33

What are cis-regulatory elements?

Answer 33

Cis-regulatory elements are regions of non-coding DNA that regulate the transcription of nearby genes.

Question 34

Fill in the blank: The __________ is a DNA sequence that can enhance transcription from a distance.

Answer 34

enhancer

Question 35

What does the term 'operon' refer to?

Answer 35

An operon is a cluster of genes under the control of a single promoter and regulated together.

Question 36

True or False: All genes have both a promoter and an operator.

Answer 36

False: Not all genes have an operator; it is characteristic of operons.

Question 37

What is the role of an activator in gene regulation?

Answer 37

An activator enhances the binding of RNA polymerase to the promoter, increasing transcription.

Question 38

What is the significance of the TATA box?

Answer 38

The TATA box is a conserved DNA sequence found in many promoters that helps initiate transcription.

Question 39

Fill in the blank: In eukaryotic cells, promoters often contain __________ elements that help regulate transcription.

Answer 39

core

Question 40

What is a common characteristic of prokaryotic promoters?

Answer 40

Prokaryotic promoters typically have a conserved sequence known as the -10 and -35 regions.

Question 41

True or False: Operators can be found in eukaryotic gene regulation.

Answer 41

True: Eukaryotic genes can have operator-like sequences, though they are generally less characterized.

Question 42

What does it mean for a promoter to be 'constitutive'?

Answer 42

A constitutive promoter is always active and drives constant expression of the gene.

Question 43

Multiple Choice: What is the primary function of the sigma factor in prokaryotic transcription? A) To bind to the promoter B) To initiate translation C) To splice mRNA

Answer 43

A) To bind to the promoter

Question 44

What is the difference between a strong and weak promoter?

Answer 44

A strong promoter has a high affinity for RNA polymerase, leading to high levels of transcription, while a weak promoter has a lower affinity.

Question 45

True or False: The lac operon is an example of negative control in gene regulation.

Answer 45

True

Question 46

What is the function of the CAP protein in the lac operon?

Answer 46

CAP (catabolite activator protein) enhances the transcription of the lac operon in the presence of cAMP.

Question 47

Fill in the blank: The __________ is a sequence that can bind transcription factors to regulate gene expression.

Answer 47

promoter

Question 48

What does 'transcriptional activation' refer to?

Answer 48

Transcriptional activation refers to the process of increasing gene expression through various regulatory mechanisms.

Question 49

True or False: All genes are regulated by both promoters and operators.

Answer 49

False

Question 50

What is the role of histone modification in gene regulation?

Answer 50

Histone modification can alter the accessibility of DNA for transcription and thus regulate gene expression.

Question 51

Fill in the blank: __________ are sequences that can repress gene expression by binding to operators.

Answer 51

Repressors

Question 52

What is the role of chromatin remodeling in gene regulation?

Answer 52

Chromatin remodeling alters the structure of chromatin to allow or restrict access to DNA for transcription.

Question 53

Multiple Choice: Which of the following is a feature of eukaryotic promoters? A) Operons B) TATA box C) Sigma factor

Answer 53

B) TATA box

Question 54

What does the term 'negative feedback' mean in the context of gene regulation?

Answer 54

Negative feedback refers to a mechanism where the product of a gene inhibits its own expression.

Question 55

True or False: Inducible operons are usually off and can be turned on in response to specific signals.

Answer 55

True

Question 56

What is the main difference between a repressible operon and an inducible operon?

Answer 56

A repressible operon is usually on and can be turned off, while an inducible operon is usually off and can be turned on.

Question 57

Fill in the blank: The __________ is a protein that binds to the operator to block transcription.

Answer 57

repressor

Question 58

What is the significance of the -10 and -35 regions in prokaryotic promoters?

Answer 58

They are conserved sequences that help RNA polymerase identify the correct initiation site for transcription.

Question 59

True or False: Gene regulation only occurs at the transcriptional level.

Answer 59

False: Gene regulation can occur at multiple levels, including transcriptional, post-transcriptional, and translational.

Question 60

What is the purpose of alternative splicing in gene regulation?

Answer 60

Alternative splicing allows for the production of multiple protein isoforms from a single gene, influencing gene expression.

Question 61

Fill in the blank: __________ are sequences that can enhance transcription by binding to activators.

Answer 61

Enhancers

Question 62

What is the role of the promoter-proximal region?

Answer 62

The promoter-proximal region contains regulatory elements that influence the efficiency of transcription initiation.

Question 63

What is the function of transcriptional coactivators?

Answer 63

Coactivators assist transcription factors in increasing the rate of transcription without directly binding to DNA.