Exam 1: Lecture 4

Question 1

Anaerobic Respiration (Fermentation)

Answer 1

1. Partial breakdown of organics that occurs without O2

2. Yields 2 ATP

Question 2

Aerobic Respiration

Answer 2

1. Complete breakdown of organics with O2

2. Yields 36 - 38 ATP

Question 3

Comparison of Aerobic Respiration & Fermentation

Answer 3

Both use Glycolysis (Glucose -> pyruvate)

Have different final e- acceptors (O2 vs pyruvate/acetaldehyde)

36/38 ATP vs 2 ATP

Question 4

Obligate aerobes

Answer 4

Require an ample oxygen source to perform respiration

Question 5

Microaerophilic/microaerobic

Answer 5

Requires small amounts of oxygen

Question 6

Capnophilic

Answer 6

Microbes require low oxygen and high carbon dioxide conc

Question 7

Facultative Anaerobes

Answer 7

Organisms that perform anaerobic glycolysis in the absence of oxygen but can perform aerobic respiration in the presence of oxygen

Question 8

Obligate anaerobes

Answer 8

Die in presence of oxygen because they lack chemistry to produce organic compounds via reduction of oxygen

Question 9

3 Main mechanisms bacteria use to adapt to changing environments

Answer 9

Mutation
Gene Transfer
Regulation of gene expression

Question 10

Types of Mutations in bacteria

Answer 10

Base substitutions
Removal or addition of nucleotides
Transposable elements

Question 11

Types of Gene Transfer in bacteria

Answer 11

Transformation
Transduction
Conjugation

Question 12

Base substitutions

Answer 12

Most common

occurs when one base pair is changed (point mutations)

Question 13

Silent mutation

Answer 13

single base sub in 3rd base nucleotide of codon.

results in NO change in amino acid, 1st 2 letters of genetic code are most critical

Question 14

Missense mutation

Answer 14

single base sub in 1st/2nd base position

results in changed amino acid

Question 15

Nonsense mutation

Answer 15

single base sub that yield stop codon

3 nonsense codons in genetic code

Question 16

Frameshift mutation

Answer 16

genetic mutation caused by insertions or deletions of a number of nucleotides in DNA sequence that is not divisible by 3

Question 17

Transposable Elements

Answer 17

Special segments of DNA that move spontaneously from 1 gene to a different gene

Transposons may disrupt the integrity of the gene and render its protein product nonfunctional

Question 18

Gene Transfer

Answer 18

Widespread among bacterial cells

intercellular transfer = genetic material passes from donor cell to recipient cell

Leads to genetic diversity

Question 19

Transformation

Answer 19

Recipient cell directly takes up naked DNA released from the donor cell altering its genotype

It can occur in the medium

Natural transformation can also occur

Frederick Griffith (Griffiths Experiment) showed 1st demonstration of transformation

Question 20

Transduction

Answer 20

process by which DNA is transferred from one bacterium to another by a virus

Question 21

Conjugation

Answer 21

suitable donor cell (male) comes near a recipient cell (female), established direct cell to cell contact and transfers genetic material

Plasmids most frequently transferred by conjugation

Sex pilus responsible or attachment of donor (F*) to recipient (F)

Transfer of antibiotic resistance can occur by conjugation

Question 22

Operon info

Answer 22

Group of genes that are transcribed at the same time

usually control important biochemical process

Only found in prokaryotes

Genes are turned on/off via operons

Question 23

Operon Structure

Answer 23

Promoter + operator + structural genes

Repressor binds to operation = transcription prevented

Question 24

Lac operon

Answer 24

consists of 3 genes each involved in processing the sugar = lactose

One of them is the gene for enzyme B-galactosidase (lactase)

This enzyme hydrolyses lactose into glucose and galactose

Question 25

Symptoms of Lactose intolerance

Answer 25

Bloating
Pain or cramps in lower belly
Gurgling sounds
Gas
Loose stools
Diarrhea

Possible nappy rash

Question 26

When Lactose Gene is turned off….

Answer 26

there s no lactose to inhibit the repressor, so repressor binds to the operator, which obstructs the RNA polymerase from binding to the promoter and making lactose

Question 27

When Lactose Gene is turned on….

Answer 27

Lactose is inhibiting the repressor, allowing RNA polymerase to bind with the promoter, and express the genes, which synthesize lactose.

Eventually, lactase will digest all of the lactose, until there is none to bind to the repressor.

The repressor will then bind to the operator, stopping the manufacture of lactose

Question 28

Gram + color of stain

Answer 28

Purple

Question 29

Gram - color of stain

Answer 29

pink

Question 30

Structure of Gram +

Answer 30

Peptidoglycan (thicker than Gram -) - outer

Membrane - inner

Question 31

Structure of Gram -

Answer 31

Outer membrane - outer
Peptidoglycan - middle
Membrane - inner

Question 32

Phases of Microbial Growth

Answer 32

Lag
Log
Stationary
Death

Question 33

Lag phase

Answer 33

1. occurs after microbes have been added and represents the period of time the organisms need to adapt to new environment

pop growth at this time is slight, very close to 0

Question 34

Log phase

Answer 34

1. represents period of optimal population growth

microbes approach carrying capacity (K), if pass it then run out of nutrients/space and can crash

Question 35

Stationary phase

Answer 35

1. populations levels and growth nears 0

2. can last for a long time

Question 36

Death phase

Answer 36

1. waste and dead cells begin to accumulate

2. pop declines, but doesn’t crash

Question 37

Infection

Answer 37

invasion of an organisms body tissues by disease-causing agents, there multiplication and the reaction of host tissues to these organisms and the toxins they produce

Question 38

Infectious disease

Answer 38

known as transmissible disease or communicable disease

illness resulting from an infection