Chapter 7- Microbial Genetics

Question 1

The genetic code is ______. This basically means that the structure of DNA is similar in all organisms.

Answer 1

The genetic code is universal. This basically means that the structure of DNA is similar in all organisms.

Question 2

The chromosomes in each microbe are found in a ______ ____ in the cell. The chromosomes are not paired but instead are ______ and are usually circular in appearance. Frequently the microbe will have a _______ which is a small DNA molecule that _______ independently of the other chromosomes often carrying information required for replication.

Answer 2

The chromosomes in each microbe are found in a nucleoid region in the cell. The chromosomes are not paired but instead are HAPLOID and are usually circular in appearance. Frequently the microbe will have a PLASMID which is a small DNA molecule that replicates independently of the other chromosomes often carrying information required for replication.

Question 3

Plasmid definition

Answer 3

a small DNA molecule that replicates independently of the other chromosomes often carrying information required for replication

Question 4

4 different types of plasmids

Answer 4

Fertility
Resistance
Bacteriocen
Virulence

Question 5

Fertility

Answer 5

instructions for conjugation

Question 6

Resistance

Answer 6

antibiotic resistance

Question 7

Bacteriocin

Answer 7

kills competitors

Question 8

Virulence

Answer 8

enzymes/toxins that enable pathogenicity

Question 9

Plasmids do not ________________

Answer 9

Plasmids do not control normal metabolism

Question 10

Bacteria has a _____ _____ copy

Answer 10

single chromosome

Question 11

Recall there are 3 steps involved in transcription:

Answer 11

1. Initiation
2. Elongation
3. Termination

Question 12

Difference between eukaryotes and prokaryotes

Answer 12

The ribosome in a eukaryote is 70S, in a prokaryote it’s 80S

Eukaryotes have 46 chromosomes and are diploids while prokaryotes have 23 chromosomes and are haploids. Bacteria has one chromosome.

Question 13

The genes that are transcribed often are found as ________ in bacteria.

Answer 13

The genes that are transcribed often are found as OPERONS in bacteria.

Question 14

Operons are composed of a

Answer 14

a Promoter, a series of genes, and an adjacent regulatory element called an operator.

Question 15

The operator is important in determining when the operon is ______ ______ ______

Answer 15

The operator is important in determining when the operon is actively producing proteins

Question 16

In essence, the bacteria are capable of turning genes off and on in response to changes in the environment. Some of the operons are turned on (_______) while others are turned off (_______). Two examples are the ____ _____ and_____ ______

Answer 16

In essence, the bacteria are capable of turning genes off and on in response to changes in the environment. Some of the operons are turned on (Inducable) while others are turned off (Repressible). Two examples are the lac operon and tryptophan operon

Question 17

To start making any gene, you need a

Answer 17

promoter

Question 18

The repressor gene/protein controls the _____ and needs a _____ to start

Answer 18

operator, promoter

Question 19

The operator controls the _____

Answer 19

operon

Question 20

Tryptophan Operon:
-_______: turns __ when conditions are favorable
-Operon is normally __, allowing bacteria to make its own tryptophan
-Repressor protein is made continuously but is normally _____
-When _______ is in the environment the repressor is ______
-Turns ___ the _____

Answer 20

-Repressible: turns off when conditions are favorable
-Operon is normally on, allowing bacteria to make its own tryptophan
-Repressor protein is made continuously but is normally inactive
-When tryptophan is in the environment the repressor is activated
-Turns off the operon

Question 21

Lac Operon:
-______, turns __ when conditions are right
-Operon is normally ___ at all other times due to the production of a _______ ____
-Repressor protein blocks the _____
-When lactose is present, the bacteria can now ______ it
-Lactose is converted to ______
-________ _______ ___ ______ _____
-_______ of the lac operon can now occur

Answer 21

-Inducable, turns on when conditions are right
-Operon is normally off at all other times due to the production of a repressor protein
-Repressor protein blocks the operator
-When lactose is present, the bacteria can now catabolize it
-Lactose is converted to allolactose
-Allolactose inactivates the repressor protein
-Transcription of the lac operon can now occur

Question 22

Gene Transfer

Answer 22

The genes will be passed to the next generation during binary fission

Question 23

Vertical transmission

Answer 23

passes from one generation to the next as a result of binary fission

Question 24

Horizontal transmission

Answer 24

transmission the bacteria acquire new genes from the same generation which it can then now pass on to the next generation vertically (gives to their ‘friends’)

Question 25

3 methods of horizontal transmission:

Answer 25

Transformation
Transduction
Conjugation

Question 26

Transformation is …
The bacteria capable of this are called _____

Answer 26

Absorption of DNA from the environment
The bacteria capable of this are called competent

Question 27

Transduction

Answer 27

A replicating virus, (called a Bacteriophage), transmits DNA from one cell that is picked up to another

Question 28

Conjugation
-Uses ___ ___
-_____ ___ can be associated with __ ____ OR gene can be _______ ___ ___ ______ (called ___)

Answer 28

-Uses sex pilus
-Fertility gene can be associated with F plasmid OR gene can be integrated into the chromosome (called Hfr)