Bacteria - Concepts

Question 1

What is beneficial (for prokaryotes) about prokaryotes small size?

Answer 1

The small size means a faster growth rate. Allowing them to establish large populations in short time periods.

Question 2

Gram-positive bacteria

Answer 2

Bacteria that have a thick mesh-like cell wall made of peptidoglycan. Will stain purple by crystal violet.

Question 3

Gram-negative bacteria

Answer 3

Bacteria that have thin cell walls (thin peptidoglycan layers). Will not stain purple. Instead they are stained pink by safranin.

Question 4

The two major categories of antibiotics

Answer 4

Beta lactam antibiotics (penicillin family) and Glycoeptide antibiotics.

Question 5

How do the two main categories of antibiotics work?

Answer 5

They act by inhibiting peptidoglycan, making the cell more vulnerable.

Question 6

What physically happens to a bacteria before it lyses?

Answer 6

It elongates and then the cell wall bulges.

Question 7

What compound do we naturally produce that breaks down peptidoglycan?

Answer 7

Lysozyme

Question 8

What is the difference between a prokaryote’s and a eukaryote’s cell membrane?

Answer 8

Prokaryotes lack steroids in their membranes.

Question 9

How many layers of membrane does a prokaryote have?

Answer 9

2

Question 10

What is the outer membrane of a prokaryote made of?

Answer 10

Lipopolysaccharides

Question 11

LPS layer

Answer 11

The outer membrane of a prokaryote

Question 12

Instead of internal membranes, what do prokaryotes use instead?

Answer 12

Infoldings of their cellular membrane. This creates more surface area.

Question 13

Is prokaryote DNA double stranded or single-stranded?

Answer 13

Double stranded.

Question 14

How many times more DNA do humans have than E. coli?

Answer 14

1000 times more

Question 15

How many more genes do humans have than E. coli?

Answer 15

Seven times as many genes.

Question 16

Plasmids

Answer 16

Small ring shaped DNA, don’t carry vital information.

Question 17

Benefits conferred by plasmids…

Answer 17

Production of antimicrobial compounds, the facility to metabolize unusual molecules, resistance to antibiotics, pathogenicity, and the ability to transfer DNA between cells.

Question 18

The three main ways that bacteria increase genetic variability.

Answer 18

Transformation, transduction, and conjugation.

Question 19

Transformation

Answer 19

A way that bacteria can increase genetic variability. It occurs when a bacterium takes up free DNA from its immediate environment, and incorporates the new DNA into its genome, resulting in a change/transformation it’s typical characteristics. Not all prokaryotes can do this.

Question 20

Transduction

Answer 20

Gene change/transfer facilitated by viral vectors.

Question 21

Conjugation

Answer 21

Gene transfer from one bacterium to another. This is a one-way transfer. It requires the presence of conjugation plasmid.

Question 22

Why is the current state of taxonomy of prokaryotes in a state of flux?

Answer 22

Major ongoing shifts in our understanding due to advances in molecular biology.

Question 23

The four types of -trophs.

Answer 23

Photoautotrophs, chemoautotrophs, photoheterotrophs, chemoheterotrophs.

Question 24

What is the metabolic behaviour of chemoautotrophs?

Answer 24

They use chemical compounds as a source of energy with which they then make organic carbon.

Question 25

Who are some of the most important chemoautotrophs?

Answer 25

The nitrifiers.

Question 26

The most common way that bacteria causes disease.

Answer 26

The most common mechanism is by the production of toxins.

Question 27

How do exotoxins cause problems?

Answer 27

By interfering with normal self functioning, or by damaging the host cell, and they are usually very tissue specific.

Question 28

How can someone get food poisoning without having an active bacterial infection?

Answer 28

Because exotoxins produce disease symptoms separately from the prokaryote that produced them.