Ch. 11 The Control of Gene Expression

Question 1

Gene Expression

Answer 1

When certain regions of the chromosome are transcribed and translated into proteins

• the flow of genetic info from genes to proteins
• to produce proteins when and where needed
• genotype -> phenotype
• regulated by turning on/off transcription

Question 2

Promoter

Answer 2

Nucleotide sequence at the start of a gene

• start of genes designed to produce certain enzymes
• binding site for active repressor

Question 3

Operator

Answer 3

The sequence of nucleotides b/w the promotor and gene

• binding site for the active repressor
• shuts transcription down, off switch

Question 4

Operon

Answer 4

The unit of genetic regulation in prokaryotes

- cluster of genes designed to produce certain enzymes

Question 5

Repressor

Answer 5

A protein that clocks the transcription of a gene/operon

- proteins that block the transcription of a gene

Question 6

Regulatory gene

Answer 6

A gene that codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes
- codes for active repressor, located outside the person

Question 7

Activators

Answer 7

Protein that turns the operon on by binding to the DNA

- switch on gene

Question 8

Cellular Differentiation

Answer 8

The specialization in the structure and function of cells that occurs during the development of an organism; results from selective activation/deactivation of the cell’s genes

Question 9

Clone

Answer 9

To produce genetically identical copies of cell, organism, or DNA molecule

Question 10

Histones

Answer 10

A small basic protein molecule associated w/ DNA and important in DNA packing in the eukaryotic chromosomes

• framework for DNA
• provide structure/organization for DNA strand

Question 11

Nucleosome

Answer 11

The beadlike unit of DNA packaging in a eukaryotic cell; consists of DNA wound around a protein core made up of 8 histone molecules

Question 12

What can prevent gene expression?

Answer 12

DNA Packing

Question 13

X Chromosome Inactivation

Answer 13

Inherited by cell’s descendants

Question 14

What is the most important stage for regulating gene expression?

Answer 14

Initiation

Question 15

What differs in eukaryotic genes?

Answer 15

Own promoter and control sequences.
Activator proteins > Repressors
“default state” = “off”

Question 16

Transcription Factors

Answer 16

In the eukaryotic cell, a protein that functions in initiating or regulating transcription; bind to DNA or to other proteins that bind to DNA

Question 17

Enhancer

Answer 17

A eukaryotic DNA sequence that helps stimulate the transcription of a gene at some distance from it; functions by means of an activator which binds to it and then to rest of transcription apparatus
- stimulates the transcription of a gene

Question 18

Silencers

Answer 18

A eukaryotic DNA sequence that functions to inhibit the start of gene transcription; may act analogously to an enhancer by binding a repressor
- inhibits the state of gene transcription

Question 19

Introns

Answer 19

In eukaryotes, a non expressed (noncoding) portion of a gene; it is excised from the RNA transcript

Question 20

Exons

Answer 20

In eukaryotes, a coding potion of a gene

Question 21

RNA splicing

Answer 21

The removal of introns and joining of exons in eukaryotic RNA, forming an mRNA molecule with a continuous coding sequences
- occurs before mRNA leaves nucleus

Question 22

Alternative splicing

Answer 22

Generating different mRNA from the same RNA transcript

Question 23

Homeotic gene

Answer 23

A master control gene that determines the identity of a body structure of a developing organism, presumably by controlling the developmental fate of groups of cells

Question 24

Signal-Transduction Pathway

Answer 24

A series of molecular changes that converts a signal on a target cell’s surface into a specific response inside the cell

Question 25

What are the steps of Signal-Transduction Pathway?

Answer 25

1) Signaling cell first secrets the signal molecule 2) Signal molecule binds to a specific receptor protein embedded in target cell's plasma membrane 3) Binding activates the first in a series of relay proteins w/in the target cell 4) Last relay molecule in series activates a transcription factor 5) Factor triggers transcription of specific gene 6) Translation of mRNA produces a protein

Question 26

Homeoboxes

Answer 26

A 180 nucleotide sequence w/in a homeotic gene encoding the part of the protein that binds to the DNA of the genes regulated by the protein

Question 27

Why do cells escape from control?

Answer 27

Changes in cell's gene or how they are expressed

Question 28

Oncogene

Answer 28

A cancer-causing gene; usually contributes to malignancy by abnormally enhancing the amount/activity of a growth factor made by cell

Question 29

Proto-oncogene

Answer 29

A normal gene that can be converted to a cancer causing gene

Question 30

Tumor Suppressor genes

Answer 30

A gene whose product inhibits cell division, thereby preventing uncontrolled cell growth

Question 31

Carcinogens

Answer 31

A cancer-causing agent, either high energy radiation or a chemical

Question 32

What is the difference b/w gene expression in prokaryotes and eukaryotes?

Answer 32

Prokaryotes...simple b/c have no cell specialization | Eukaryotes...have different proteins for each cell b/c specialization

Question 33

What does E. coli do?

Answer 33

Constantly turning genes on/off when the cell is surrounded by sugar or carb or protein etc.

Question 34

How can the operon be turned on if the repressor is always present?

Answer 34

Lactose binds to the repressor, changing its shape, preventing the repressor from attaching

Question 35

How does cloning work?

Answer 35

Take an egg cell, expose it to radiation to destroy nucleus - insert nucleus of a different cell into that cell - implant into an animal's womb

Question 36

What is gene expression based on and what is transcription based on?

Answer 36

Gene expression is based on the regulation of transcription | Transcription is based on the regulation of transcription factors

Question 37

What is more important for eukaryotes? Activation or repression?

Answer 37

Activation

Question 38

RNA transcript

Answer 38

The copying of DNA's code onto mRNA | - result of transcription

Question 39

What are the 3 modifications added to RNA before leaving nucleus?

Answer 39

1) Capped - single guanine nucleotide is placed at one end 2) Tailed - long chain of adenine nucleotides are attached to other end 3) Edited - Introns are edited out, externs are spliced together

Question 40

What does capped and tailed modifications do?

Answer 40

Prevents attack from cellular enzymes and identifies mRNA.

Question 41

What is cancer a disease of?

Answer 41

A disease of gene expression b/w cell escapes control