WEEK 6

Question 1

Why are bacteria considered masters of adaptation?

Answer 1

They thrive in extreme environments and have immense genetic diversity. (Slide 3)

Question 2

How do bacteria compare to archaea and eukaryotes in diversity?

Answer 2

Bacterial diversity vastly surpasses that of archaea and eukaryotes. (Slide 4)

Question 3

What are the three most common bacterial shapes?

Answer 3

Spheres (cocci), rods (bacilli), and spirals. (Slide 5)

Question 4

What roles do bacteria play in the environment?

Answer 4

They can be parasites, mutualists, or saprophytes. (Slide 6)

Question 5

Why is gene regulation important in bacteria?

Answer 5

It allows them to adapt to environmental changes by controlling gene expression. (Slide 11)

Question 6

What is an operon?

Answer 6

A unit of genetic function in bacteria consisting of a promoter, operator, and genes with related functions. (Slide 14)

Question 7

What is the role of the promoter in an operon?

Answer 7

It is a DNA sequence recognized by RNA polymerase to initiate transcription. (Slide 13)

Question 8

What is the function of the operator in an operon?

Answer 8

A DNA sequence where regulatory proteins bind to turn gene expression on or off. (Slide 13)

Question 9

How does the Trp operon demonstrate repression?

Answer 9

Tryptophan activates a repressor that binds the operator, blocking transcription. (Slide 15-18)

Question 10

How is gene regulation different in eukaryotes compared to prokaryotes?

Answer 10

Eukaryotic gene regulation occurs at multiple levels, not just transcription. (Slide 20-34)

Question 11

What modifications are associated with active chromatin?

Answer 11

Histone acetylation and some histone methylation. (Slide 21)

Question 12

What is the effect of DNA methylation on gene expression?

Answer 12

It typically silences genes. (Slide 21)

Question 13

What are basal transcription factors?

Answer 13

Proteins like TBP and TFIIA-H that bind the promoter to initiate transcription. (Slide 22)

Question 14

What are enhancers?

Answer 14

Short DNA sequences that bind gene-specific transcription factors to boost expression. (Slide 23)

Question 15

What are Hox genes?

Answer 15

Homeobox genes encoding transcription factors that regulate embryonic development. (Slide 25-27)

Question 16

What is a homeotic mutation?

Answer 16

A developmental mutation where one body part is replaced by another. (Slide 27)

Question 17

What is alternative splicing?

Answer 17

A process where different exons from a gene are spliced to create diverse proteins. (Slide 31)

Question 18

How is translation regulated?

Answer 18

Via factors that control when and how mRNAs are translated into proteins. (Slide 32)

Question 19

What controls ferritin translation?

Answer 19

Iron levels in the blood; low Fe represses, high Fe activates translation. (Slide 32)

Question 20

What are the levels at which eukaryotic gene expression is regulated?

Answer 20

Chromatin remodeling, transcription, RNA processing, stability, translation, post-translation. (Slide 33)

Question 21

What size are most bacterial cells?

Answer 21

Between 0.5–5 µm, smaller than typical eukaryotic cells (10–100 µm). (Slide 5)

Question 22

Why don’t bacteria express all their genes at once?

Answer 22

To conserve energy and resources by only producing needed proteins. (Slide 10)

Question 23

What is polycistronic mRNA?

Answer 23

An mRNA that encodes multiple proteins, typically from genes in the same operon. (Slide 13)

Question 24

What is the function of a co-repressor in a repressible operon?

Answer 24

It binds to a repressor protein to activate it, thus blocking transcription. (Slide 16)

Question 25

In the trp operon, what role does tryptophan play?

Answer 25

Acts as a co-repressor, activating the repressor protein to inhibit gene expression. (Slide 18)

Question 26

What does RNA Polymerase do during transcription?

Answer 26

It binds to the promoter and synthesizes RNA from the DNA template. (Slide 13)

Question 27

What distinguishes basal vs. specific transcription factors?

Answer 27

Basal factors are general; specific factors activate or repress individual genes. (Slide 22)

Question 28

What is the Mediator protein complex?

Answer 28

A multi-protein complex that bridges transcription factors at enhancers and the RNA Pol II machinery. (Slide 24)

Question 29

What are Homeodomains?

Answer 29

Protein domains in Hox proteins that bind DNA in a helix-turn-helix manner. (Slide 27)

Question 30

What are homeotic genes?

Answer 30

Genes that control the identity of body parts during embryonic development. (Slide 27)

Question 31

What is a motif in molecular biology?

Answer 31

A short DNA sequence recognized by a DNA-binding protein. (Slide 27)

Question 32

What are MADS-box genes?

Answer 32

Genes in plants encoding transcription factors essential for flower development. (Slide 30)

Question 33

What is the function of the DSCAM gene?

Answer 33

Involved in neuronal adhesion; through alternative splicing, it can generate ~38,000 different proteins. (Slide 31)

Question 34

How does high-dose vitamin A affect Hox genes?

Answer 34

It disrupts their regulation, potentially causing developmental malformations. (Slide 29)

Question 35

How does gene regulation relate to disease?

Answer 35

Improper methylation and chromatin remodeling can silence tumor suppressor genes in cancer. (Slide 21)

Question 36

Where does transcription and translation occur in bacteria?

Answer 36

In the same space, since they lack a nucleus. (Slide 9)

Question 37

What organism is a model for gene regulation in bacteria?

Answer 37

Escherichia coli (E. coli), commonly found in the human colon. (Slide 11)

Question 38

What are the main components of a bacterial operon?

Answer 38

Promoter, operator, and a cluster of functionally related genes. (Slide 14)

Question 39

How is transcription turned off in the trp operon?

Answer 39

Tryptophan binds to the repressor, activating it to bind the operator. (Slide 18)

Question 40

What happens when tryptophan is absent in the cell?

Answer 40

The repressor is inactive, and the operon is transcribed. (Slide 15)

Question 41

Why is the trp operon called a repressible operon?

Answer 41

Because it is normally on and is turned off when the end-product (tryptophan) is abundant. (Slide 16)

Question 42

Why do all eukaryotic cells contain the same DNA but different expression?

Answer 42

Because not all genes are required at all times in every cell. (Slide 20)

Question 43

What is chromatin remodeling?

Answer 43

A form of gene regulation where chromatin structure is altered to allow or block transcription. (Slide 21)

Question 44

What chemical modifications activate chromatin?

Answer 44

Acetylation of histones is generally associated with active chromatin. (Slide 21)

Question 45

What chemical modifications silence chromatin?

Answer 45

Methylation of histones and cytosines in DNA. (Slide 21)

Question 46

What does the TATA Box Binding Protein (TBP) do?

Answer 46

It helps recruit RNA polymerase by binding to the basal promoter. (Slide 22)

Question 47

What role do enhancer sequences play in gene expression?

Answer 47

They increase transcription by binding activators, even at a distance from the promoter. (Slide 23)

Question 48

What does combinatorial control in transcription involve?

Answer 48

Multiple transcription factors binding together to regulate a single gene. (Slide 24)

Question 49

What are the Ubx and Antp genes?

Answer 49

Homeotic genes in fruit flies involved in segment identity; members of Hox gene family. (Slide 27)

Question 50

What is a domain in protein structure?

Answer 50

A structured part of a protein with a specific function, such as DNA binding. (Slide 27)

Question 51

What is a motif in DNA?

Answer 51

A specific sequence recognized by a DNA-binding protein. (Slide 27)

Question 52

What type of phenotype results from misregulated Hox genes in embryos?

Answer 52

Homeotic transformations, like incorrect body part placement. (Slide 29)

Question 53

What developmental impact can high vitamin A cause?

Answer 53

Disrupts Hox gene expression, leading to birth defects. (Slide 29)

Question 54

What are MADS-box genes involved in?

Answer 54

They regulate flower development in plants. (Slide 30)

Question 55

What is the significance of the AGAMOUS gene?

Answer 55

Its mutation causes stamens and carpels to be replaced by extra petals. (Slide 30)

Question 56

What controls alternative splicing?

Answer 56

Splicing factors, including proteins and some non-coding RNAs. (Slide 31)

Question 57

How does alternative splicing increase protein diversity?

Answer 57

By creating multiple mRNA variants from a single gene. (Slide 31)

Question 58

What happens to ferritin translation when iron is low?

Answer 58

Ferritin mRNA translation is repressed. (Slide 32)

Question 59

What happens to ferritin translation when iron is high?

Answer 59

Ferritin protein is produced to store excess iron. (Slide 32)

Question 60

What are the six levels of eukaryotic gene regulation?

Answer 60

Chromatin remodeling, transcription, RNA processing, mRNA stability, translation, post-translation. (Slide 33)