Test 3 Chapter 14 Microbiology

Front 1

Mutations can be both ______ and ______.

Back 1

spontaneous
induced

Front 2

Name three ways in which spontaneous mutations occur

Back 2

1. Without exposure to external factors
2. Errors in DNA replication
3. Action of mobile genetic elements (transposons)

Front 3

How do induced mutations occur?

Back 3

By agents that directly damage DNA

Front 4

Are induced mutations rare or common?

Back 4

Rare

Front 5

How rare are induced mutations?

Back 5

1 in 10 million
10 to the 7th power
to
10 to 11th power

Front 6

What is a mutagen?

Back 6

A physical or chemical agent (i.e DNA) that changes genetic material and mutates it

Front 7

What is a carcinogen?

Back 7

A substance that is an agent directly involved in causing cancer

Front 8

There is no relationship between a mutagen and a carinogen. T or F?

Back 8

False: there is a relationship: most carcinogens are ALSO mutagens

Front 9

When we test for a mutagenicity, we use this exact same test to screen for ______ ______.

Back 9

carcinogenic potential

Front 10

What is a great example of test that is used to predict mutagenic potential?

Back 10

The Ames Test

Front 11

What does a positive result from an Amest test mean?

Back 11

That the compound being tested is mutagenitic. In this case it MAY act as a carcinogen - but not always!

Front 12

What type of things might we perform an Ames test on?

Back 12

Food aditives, chemical compounds, shampoo

Front 13

What is selective pressure?

Back 13

The alter of behavior and fitness in living things. It is the driving force of evolution and natural selection

Front 14

Mutations are subject to ______ ______.

Back 14

selective pressure

Front 15

Each mutant that survives (and ultimately becomes resistant) to whatever was targeting it, will eventually becomes an ______ form of a ______

Back 15

alternate
gene

Front 16

Why is selective pressure so important?

Back 16

Because it illustrates why antibiotics can become ineffective if ALWAYS used - even when not sick

Front 17

What happens when we continously use antibiotics and other chemicals that kill bacteria (i.e handsoap, cholorine, etc).

Back 17

The bacteria will eventually mutate, survive and then become resistant.

Front 18

Why would we NOT want to be around someone that is on antibiotics?

Back 18

We may pick up bacteria from them that has become RESISTANT due to the antibiotic.

Front 19

How many methods are there in Horizontal Gene Transfer...and what are they?

Back 19

Three
1. Conjugation
2. Transformation
3. Transduction

Front 20

Generally speaking, what is horizontal gene transfer?

Back 20

The moving of gene material from one mature organism to another mature organism

Front 21

What is an exogenote?

Back 21

The DNA donor: the cell transferring its DNA to another cell

Front 22

What is an endogenote?

Back 22

The DNA recipient: the cell receiving the DNA from another cell

Front 23

For this test, we must always assume that horizontal gene transfer is ______.

Back 23

successful

Front 24

What is an F+ plasmid?
What is an F- plasmid?

Back 24

F+: a plasmid that carries a particular function (it is fertile)
F-: a cell that LACKS this particular function

Front 25

The F+ cell will have the "information" in order to form a ______ pilus

Back 25

sex (see figure 14.19) on slide

Front 26

In conjugation, what is TRANSFERRED through the sex pilus?

Back 26

The plasmid: it travels FROM the F+ cell TO the F- cell.
Think of it as a man (F+) impregnating a woman (F-)

Front 27

When conjugation plasmid transfer is complete, what do we end up with?

Back 27

Two F+ cells (they both now contain the plasmid that codes for that specific function)

Front 28

In conjugation, how does the plasmid replicate itself BEFORE it travels thru the sex pilus?

Back 28

Through the rolling circle method (look at slide 20)

Front 29

What is an Hfr cell?

Back 29

This is simply an F+ cell that has INCORPORATED its plasmid INTO is chromosome

Front 30

What happens when an Hfr cell makes contact with an F- cell?

Back 30

Because the Hfr cell's plasmid is INTEGRATED into its chromosome, the ENTIRE chromosme will now be transfered to the F- cell

Front 31

What does Hfr stand for?

Back 31

High frequency recombination

Front 32

May have to diagram the Hfr and F- mating cycle (conjugation)

Back 32

See slide 23

Front 33

What is the final outcome when an Hfr mates with an F-

Back 33

We will now have TWO Hfr cells (the F- cell will INCORPORATE the receiving DNA into its own chromosome)

Front 34

In conjugation, what is an F' (prime) cell?

Back 34

An Hfr cell in which the F factor of the chromosome loops OUT and either:
1. Leave a piece of itself behind OR
2. Takes a peice of the chromosome with it

Front 35

An F' can now mate with an F- through conjugation. What is the result?

Back 35

Two F' cells

Front 36

What is a competent cell?

Back 36

A cell (during the growth phase) that realeases a special protein that allows it to uptake DNA during transformation

Front 37

What is happening during tranformation?

Back 37

Naked DNA is simply taken in by a competent cell (note: competence can be made artificially) See slide 27

Front 38

In simple terms, what is transduction?

Back 38

The transfer of bacterial genes through viruses

Front 39

What is important to understand when describing transduction?

Back 39

The lytic and lysogenic cycles

Front 40

What is generalized transduction?

Back 40

During the lytic cycle, any random piece of the cells genome will ACCIDENTALLY be packaged into the viruses phage-head. The virus will then inject this DNA into a new host

Front 41

What is specialized transduction?

Back 41

During the lysogenic cycle, a temperate virus will begin replicating upon entering the lytic cycle - taking specific pieces of the host's genome with it. (usually an accident)