Lecture 25. Regulation of Gene Expression

Question 1

What is the function of gene expression ?

Answer 1

Required to convert the information that resides within our DNA into gene products

Question 2

What do gene products of gene expression influence ?

Answer 2

The phenotype of the cell

Question 3

What are the gene products of gene expression ?

Answer 3

RNA and protein

Question 4

How do cells differentially express their genes ?

Answer 4

They turn on or off specific subsets of genes at different times and places

Question 5

What is the function of differential expression ?

Answer 5

To achieve huge diversity of cell types or cellular activation states

Question 6

What are some cellular activation state ?

Answer 6

Dividing, non-dividing, differentiating, activated, secreting

Question 7

What does the ability to regulate gene expression occur through ?

Answer 7

Molecules that bind to the regions that flank the coding sequences of genes

Question 8

What is the ability to regulate gene expression critical to achieving ?

Answer 8

Different outputs/phenotypes from the same genome

Question 9

What is the classical definition of a gene ?

Answer 9

A genetic variant affecting a trait where a genetic mutation has an effect on some phenotype

Question 10

What are the two locations of mutations ?

Answer 10

1. Protein coding part

2. Regulatory part

Question 11

What is the molecular definition of a gene ?

Answer 11

A transcriptional unit encoding an RNA or protein, where the gene product has some biochemical or cellular function

Question 12

What does the gene encompass ?

Answer 12

1. The coding sequence

2. DNA regulatory elements

Question 13

What is the coding sequence ?

Answer 13

The sequence that is transcribed into RNA

Question 14

What is another name for DNA regulatory element ?

Answer 14

Promoter

Question 15

What is the function of DNA regulatory elements ?

Answer 15

Regulate the expression of the gene in a positive or negative manner

Question 16

What can variants of a gene be caused by ?

Answer 16

1. Mutation

2. Natural sequence variation

Question 17

What areas do variants of a gene effect ?

Answer 17

Either:

1. The coding sequence
2. Regulatory sequence

Question 18

What do changes to gene expression effect ?

Answer 18

When, where and how much of a gene is expressed which in turn effects phenotypes

Question 19

What do changes to the coding sequence of the gene effect ?

Answer 19

They subtly or radically change the protein or RNA product encoded by the gene and also impacts the cellular phenotype

Question 20

What do all genes encode ?

Answer 20

RNA molecules

Question 21

Which RNA molecules are translated into proteins ?

Answer 21

mRNA

Question 22

What makes cells different from each other and responsible for the different activity states?

Answer 22

The protein coding fraction of the genome

Question 23

Do all genes that encode RNAs become translated into proteins ?

Answer 23

No

Question 24

What do RNAs which do not become translated into proteins possess ?

Answer 24

Enzymatic or regulatory functions

Question 25

What are the key non-translated RNAs ?

Answer 25

1. Ribosomal RNA 2. Transfer RNA 3. Regulatory RNA

Question 26

What are some types of regulatory RNAs ?

Answer 26

1. snRNA (Small nuclear RNA) 2. microRNA (miRNA) 3. Long non-coding RNA (lncRNA)

Question 27

What are the major gene expression products ?

Answer 27

1. Proteins 2. Structural RNAs 3. Regulatory RNA

Question 28

What are the structural RNAs ?

Answer 28

1. rRNA | 2. tRNA

Question 29

How much do ribosomal and transfer RNAs comprise of the total RNA within cells ?

Answer 29

80-90%

Question 30

How much of the total RNA within the cell does mRNA comprise of ?

Answer 30

2-3%

Question 31

What are some characteristics of prokaryotic genomes ?

Answer 31

1. Relatively compact | 2. Gene dense

Question 32

What do genomes of higher organisms contain ?

Answer 32

A huge proportion of non-coding sequences

Question 33

What does the non-coding sequence have ?

Answer 33

Gene regulatory function

Question 34

How many protein coding genes is there in the human genome ?

Answer 34

25000

Question 35

What does non-coding sequences do ?

Answer 35

Regulate the expression of the coding fraction of the genome

Question 36

How do higher eukaryotes get more from their genes ?

Answer 36

Alternative splicing of their protein coding mRNAs

Question 37

What does alternative splicing of the protein coding genes of mRNAs achieve ?

Answer 37

Make different variations of the same protein or proteins with very distinct functions

Question 38

What are fully differentiated cells capable of ?

Answer 38

Expressing all of the genes required to build an organism

Question 39

Where do all cells differentiate from ?

Answer 39

A fertilized embryo

Question 40

What happens as cells differentiate ?

Answer 40

They lose expression of some genes and acquire expression of others

Question 41

In general, most cells are capable of reconstituting the whole organism upon reaching the fully differentiated state. What are the exceptions to the rule ?

Answer 41

1. Where cells lose their nuclei as they differentiate eg. erythrocytes 2. Where their genome is irreversibly altered in some way eg. senescent cells that have lost their chromosome ends called telomeres (skin cells or neurons)

Question 42

What switches on or off the expression of specific genes that distinguish one cell type from another?

Answer 42

Environmental and developmental cues through activating transcription factors

Question 43

Are all genes expressed in every cell ?

Answer 43

No

Question 44

What is differential gene expression controlled through ?

Answer 44

Activating signaling pathways that activate transcription factors

Question 45

How are transcription factors switched on ?

Answer 45

Achieved through external signals from the environment or other cells

Question 46

What are spatial signals ?

Answer 46

Instruct cells within the embryo to express genes involved in making the different parts of the fly along the anterior to posterior axis and instructing what is the dorsal or ventral surface

Question 47

What is bicoid ?

Answer 47

1. A transcription factor that forms a gradient running from head to tail of the developing embryo 2. The gradient then induces the expression of a variety of transcription factors depending on the bicoid concentration

Question 48

What are some transcription factors ?

Answer 48

1. Hunchback 2. Kruppel 3. Knirps 4. Giant

Question 49

What does the different combination of transcription factors do ?

Answer 49

Switched on a battery of additional developmental genes that tell the cell where they are and what what fly parts they should specify

Question 50

What specifies where the cells are and what fly part they should specify ?

Answer 50

Hox genes

Question 51

What do hox genes do ?

Answer 51

Switch on the correct genes to make a leg, a wing, an antenna, a sex bristle etc

Question 52

What are pathogen associated molecular patterns ?

Answer 52

Receptors for conserved components of infectious agents

Question 53

What is the function of pathogen associated molecular patterns receptors ?

Answer 53

Enable cells of the immune system to detect the presence of pathogens

Question 54

What is a class of pathogen associated molecular patterns receptors ?

Answer 54

Toll-like receptors

Question 55

What is the function of a toll-like receptor ?

Answer 55

Detects foreign substances

Question 56

What does the binding of a PAMP receptor to a toll-like receptor activate ?

Answer 56

A transcription factor called NFkappaB

Question 57

What does NFkappaB do ?

Answer 57

Involved in coordinating the process of inflammation, which helps the body fight infection