Micro1009- Ch. 8 Pii Gene Regulation, Transfer, And Mutation

Front 1

Mutation

Back 1

Permanent change in the DNA case sequence

Front 2

General types of mutations

Back 2

1. Base substitution

2. Frame shift mutation

Front 3

Base Substitution

Back 3

One base is replaced with another

Front 4

Types of base substitutions

Back 4

1. Missense mutation

2. Nonsense mutation

3. Silent mutation

Front 5

Missense mutation

Back 5

A different amino acid is called for than the original

Front 6

Nonsense mutation

Back 6

A stop codon is called for too early, leading to an incomplete protein

Front 7

Silent mutation

Back 7

The codon calls for the same amino acid as before, so the mutation has no effect (due to the degenerate nature of genetic code)

Front 8

Frame shift mutations

Back 8

More severe than base substitution mutations

When a base is inserted or deleted from generic code

Front 9

Regulation of gene expression

Back 9

All genes are not always being "expressed" (transcribed and translated)

Front 10

Constitutive genes

Back 10

AKA housekeeping genes

Genes that are turned on all the time

Front 11

What is an example of constitutive genes

Back 11

Respiration

Front 12

Operon

Back 12

Series of structural genes under control of one regulatory gene

Front 13

Parts of an operon

Back 13

1. Control region

2. Regulatory gene

Front 14

Control region

Back 14

Contains promoter and operator

Front 15

Regulatory gene

Back 15

Codes for the repressor protein

Front 16

Promoter

Back 16

The region of DNA where RNA polymerase initiates transcription

Front 17

Operator

Back 17

Allows or prevents the transcription of the structural gene

Front 18

Repressor protein

Back 18

Binds to the operator

Front 19

Types of operons

Back 19

1. Inducible

2. Repressible

Front 20

Inducible operon

Back 20

Usually switched off

Have to be turned on in order for structural genes to be translated

Front 21

Repressible operon

Back 21

Usually on

Transcribed until they are turned off

Front 22

What is an example of a inducible operon?

Back 22

lac operon

Front 23

What is an example of a repressible operon?

Back 23

Tryptophan operon

Front 24

Tryptophan

Back 24

An amino acid

Front 25

Tryptophan operon

Back 25

- Normally turned on to synthesize tryptophan in an anabolic process

- A repressor protein (coded by the regulatory gene) is constantly being made, but is in an inactive form until activated by high levels of tryptophan

- High levels of tryptophan bind to the operator, shutting down transcription of the proteins involved in tryptophan production

Front 26

In the case of tryptophan binding to the operator, what is tryptophan acting as? Why?

Back 26

Corepressor, because it activates the repressor protein

Front 27

What happens when levels of tryptophan rise high enough to bind to the operator, then fall again?

Back 27

The repressor will be inactivated and the operon will be turned on again

Front 28

Lactose

Back 28

Glucose + galactose

Front 29

What causes the lac operon to be turned on?

Back 29

Low levels of glucose and high levels of lactose

Front 30

How does the lac operon work?

Back 30

- a repressor protein gene (coded by the regulatory gene) is constantly being transcribed and translated

- the repressor protein binds to the operator site, preventing RNA polymerase from transcribing the structural genes that code for the enzymes needed for lactose catabolism

- if allolactose is present in the cell, it will bind to, and deactivate, the repressor proteins

- this allows RNA polymerase to transcribe the structural genes and the enzymes that breakdown lactose are made

Front 31

In the case of allolactose binding to repressor proteins, what role is the allolactose playing?

Back 31

The inducer

Front 32

What type of regulation applies to lac operon but not the tryptophan operon?

Back 32

Positive regulation

Front 33

Explain positive regulation in relation to lac operon

Back 33

- when there are low levels of glucose in the cell, high levels of cyclic AMP (cAMP) are formed

- these high levels of cyclic AMP activate CAP protein, making it easier for RNA polymerase to transcribe the genes in the operon

- When glucose is present, cAMP is scarce and CAP proteins remain inactive

Front 34

What is the significance of the CAP protein remaining inactive in the presence of glucose?

Back 34

It makes it difficult for RNA polymerase to bind to the promoter and transcribe the lac operon structural genes

Front 35

Genetic transfer

Back 35

Results in genetic variation

Front 36

Genetic variation

Back 36

Diversity in genes

Needed for evolution

Front 37

In eukaryotes, how is genetic variation achieved?

Back 37

Sexual reproduction

Front 38

In bacteria, how is genetic variation achieved?

Back 38

Mutations and horizontal gene transfer

Front 39

Types of genetic transfer

Back 39

1. Transformation

2. Conjugation

3. Transduction

Hint 39

3

Front 40

Transformation

Back 40

Genes are picked up by bacteria as "naked" pieces of DNA from the surrounding solution

Front 41

Initial identification of transformation

Back 41

First identified by Frederick Griffith in 1928 during what is known as "Griffith's experiment"

Front 42

Griffith's experiment

Back 42

Experiment using Virulent and Avirulent strains of Streptococcus pneumoniae

Front 43

Virulent strain

Back 43

S-strain

Encapsulated

Causes pneumonia

Front 44

Avirulent strain

Back 44

R-strain

Without a capsule

Not pathogenic

Front 45

Conjugation

Back 45

One bacterium passes DNA (often on plasmid) over to another bacterium pilus or pore

Front 46

Pilus

Back 46

Longer connection between cells

Seen in Gram (-) conjugation

Front 47

Pore

Back 47

A close connection between Gram + cells

Front 48

Plasmids

Back 48

Small circular pieces of DNA that contain a few genes and can be spread to other bacteria via conjugation

Front 49

Donor cell

Back 49

An F+ cell

Initiates the conjugation process, spreading the F+ factor to F- cells

Front 50

F+ factor

Back 50

Fertility Factor

Allows for the ability to initiate conjugation

Front 51

Transduction

Back 51

DNA is transferred from one bacterial cell to another by a bacteriophage

Front 52

Bacteriophage

Back 52

A virus that only infects bacteria

Front 53

Describe the process of transduction

Back 53

- bacteriophage injects its DNA into a bacteria cell so that the bacteria will begin to make phage DNA

- bacterial DNA may be broken into pieces and incorporated into new bacteriophages

- these bacteriophages go on to infect other bacteria with the original bacteria's DNA