Bacterial Morphology And Growth

Question 1

How many bacterial phyla are there?

Answer 1

Thousands

Question 2

How many species of bacteria are there?

Answer 2

100 million ish

Question 3

How many species of bacteria are there in the human gut?

Answer 3

500-1000

Question 4

How many species of bacteria cause human disease?

Answer 4

<100

Question 5

What are the 6 methods for classifying bacteria?

Answer 5

Size
Gross structure
Cell wall
Differential strains
Morphology 
Growth requirements

Question 6

Where is DNA in bacteria?

Answer 6

Free in the cytoplasm

Question 7

What is the bacterial membrane made up of ?

Answer 7

Peptidoglycan

Question 8

Do bacteria have mitochondria

Answer 8

No

Question 9

Do bacteria have membrane bound organelles?

Answer 9

No

Question 10

What does a gram negative cell wall look like?

Answer 10

Extra outer membrane with integral lipopolysaccharides and periplasmic space

Question 11

What does a gram positive cell wall look like?

Answer 11

Thick peptidoglycan layer which is integral with lipo and lipoteichoic acid

Question 12

What does an acid fast cell wall look like?

Answer 12

Thick outer layer of mycolic acids linked by arabino-galactans integral with lipoarabinomannan

Question 13

What is a gram stain?

Answer 13

A differential cell wall stain dividing bacteria into gram positive and gram negative

Question 14

What colour does a gram positive bacteria go when it stains?

Answer 14

Purple/black

Question 15

What colour does a gram negative bacteria go when it stains?

Answer 15

Red/pink

Question 16

Give the steps in doing a gram stain

Answer 16

• Fix the bacteria
• Add crystal violet
• add iodine
• wash with alcohol
• add carbol fuschin or safranin

Question 17

What is the purpose of adding the iodine in a gram stain?

Answer 17

Traps the crystal violet

Question 18

What is the purpose of adding the alcohol in a gram stain?

Answer 18

Dissolves the crystal violet, so if its not strongly attached to the cell wall the colour disappears

Question 19

What are the two types of acid fast stain?

Answer 19

Carbol fuschin and auramine

Question 20

What colour is carbol fuschin?

Answer 20

Red

Question 21

What colour is auramine?

Answer 21

Fluorescent

Question 22

Why may some bacteria not stain?

Answer 22

Some bacteria don’t have a cell wall so can’t stain

Question 23

What is an obligate aerobe?

Answer 23

A bacteria that requires some oxygen to make ATP

Question 24

What are the three types of obligate aerobes? (don’t need names, just general description)

Answer 24

Most tolerate O2
Some only tolerate 5% O2
Some require a higher O2 conc than in air

Question 25

What is a facultative anaerobe?

Answer 25

Use oxygen fermentation or anaerobic respiration

Question 26

What is an aerotolerant anaerobe?

Answer 26

Cannot use oxygen but can tolerate it

Question 27

What is an obligate anaerobe?

Answer 27

Oxygen is toxic to them

Question 28

What can bacteria with the lac gene do?

Answer 28

Ferment lactose

Question 29

What are the 8 factors that affect growth rate of bacteria?

Answer 29

• division rate
• lag phase time
• oxygen availability
• carbon availability
• temperature
• pH
• inhibitors
• growth factors