Cell Biology - Chapter 8

Front 1

All diploid cells of an organism have the exact same DNA: T/F

Back 1

T

Front 2

If all cells of an organism have the same DNA, explain why there are different cell types.

Back 2

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Front 3

Briefly describe the experiment with frogs (which was later done with sheep and many other animals) that answered the question if all diploid cells in an organism have the same DNA

Back 3

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Front 4

Explain how gene expression can be regulated at levels OTHER THAN transcription. List other modes of regulation.

Back 4

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Front 5

Summarize the structural features of the 3 common DNA-binding domains from Chapter 8.

Back 5

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Front 6

What are transcriptional repressors and activator? Where do they bind? How do they work?

Back 6

T. repressors repress transcription
T. activators facilitate transcription

Transcription is controlled by regulatory proteins binding to regulatory DNA sequences in the promoters of genes.

Front 7

What is an operon? What is an operator? In what type of organisms are both found?

Back 7

Operon - a functioning unit of key nucleotide sequences including an operator, a common promoter, and one or more structural genes, which is controlled as a unit to produce messenger RNA (mRNA), in the process of transcription.

Operator - 15bp region in promoter which acts as a binding site for the repressor protein

Prokaryotes

Front 8

What are similarities and differences between prokaryotic and eukaryotic gene regulation?

Back 8

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Front 9

Give the functions of the RNA polymerases used for transcription by eukaryotes.

Back 9

RNA pol I - most rRNA genes
RNA pol II - all protein-coding genes, some genes for small RNAs (those in spliceosomes)
RNA pol III - tRNA genes, 5S rRNA gene, genes for some small structural RNAs

Front 10

Eukaryotic transcription cannot be initiated without the general transcription factors, which participate in the formation of a transcription initiation complex. What is the primary role of the GTFs? What are the specific functions of the 2 GTFs discussed in lecture?

Back 10

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Front 11

What ways can chromatin be relaxed?

Back 11

1) Reg Factors can recruit CHROMATIN REMODELING FACTORS.

These insert in the DNA and relax the structure.

2) Reg Factors can be/recruit
HISTONE ACETYLTRANSFERASES

Front 12

Describe Histone Acetyltransferases (HATs)

Back 12

Enzymes that add an acetyl group to positively charged histone proteins, removing the charge. This disrupts their association with DNA!

Front 13

Describe Histone Deacetylases (HDACs)

Back 13

remove the acetyl groups that were added by the HISTONE ACETYLTRANSFERASES (HATs) and cause 'condensation' of the DNA

Front 14

The same enhancer sequence can exist in many genes: T/F

Back 14

T

Front 15

The same enhancer sequence can exist in many genes. This means:

Back 15

the cell can control many genes with a SINGLE PROTEIN

Front 16

Describe the lac operon regulators and how they act:

Back 16

One that is an ACTIVATOR (CAP) - binds when there is no glucose
One that is a REPRESSOR - binds when there is no lactose

Front 17

Describe enhancers

Back 17

Small DNA sequences (6-10 bp) that are bound by regulatory proteins, and can affect transcription in a POSITIVE or NEGATIVE manner.

Analogous to the OPERATOR in the operon!

Unlike the operator (located within the polymerase binding site), enhancers can function 1000s of bps upstream or downstream from the start site.

“Action at a Distance”

Front 18

Describe regulatory transcription factors

Back 18

Proteins that associate with the DNA to ACTIVATE or REPRESS transcription.

Front 19

All genes have a SERIES of enhancer sequences. T/F

Back 19

T

Front 20

Each gene has a specific enhancer sequence, it exists in no other genes. T/F

Back 20

F