Bacteria Structure and Function

Question 1

What is microbiology

Answer 1

The study of organisms too small to be seen by the naked eye

Question 2

what are the 2 types of microorganisms?

Answer 2

Eukaryote and Prokaryotes

Question 3

What are the 3 domaines of life?

Answer 3

Archaea, bacteria, Eukarya

Question 4

What are characteristics of Archaea?

Answer 4

• prokaryotic
• contain no peptidoglycan
• often extremophiles
• not human pathogens

Question 5

What are characteristics of bacteria?

Answer 5

• prokaryotic
• cell walls contain peptidoglycan
• sensitive to traditional bacteria
• they include the majority of pathogenic microorganisms

Question 6

What are characteristics of Eukarya?

Answer 6

• Eukaryotic
• if they have cell walls they do have peptidoglycan
• not sensitive to traditional antibiotics
• include fungi/plants/animals/protists

Question 7

differences between Prokaryotes and Eukaryotes

Answer 7

1. prokaryote is not compartmentalised - don’t have certain structures
2. prokaryote only have a single circular chromosome - nucleoid - no membrane bound nucleus
3. Eukaryotes are larger
4. bacterial membranes generally do not have sterols like cholesterol

Question 8

Bacteria cell structure

Answer 8

• cytoplasmic membrane and a peptidoglycan cell wall
• fluid syptoyplasm contains a nuclear region and ribosomes
• external structures like capsule/flagella/pilli

Question 9

Fungal cell structure

Answer 9

• cell wall
• cytoplasmic membrane
• mitocondria
• nucleus
• endoplasmic reticulum
• Golgi apparatus
• lysosomes
• vacuoles

Question 10

Why are cell wall important

Answer 10

• confers structure rigidity and shape
• protects bacteria from osmotic lysis

Question 11

Why can we use cell walls to tell the difference between prokaryotes and animal cells?

Answer 11

cause the structure and synthesis is unique to prokaryotes so some antibiotics target cells wall as mammal cells are immune to them - this is called selective toxicity

Question 12

What does Penicillin do?

Answer 12

Inhibit cell wall synthesis

Question 13

What is the structure of Peptidoglycan?

Answer 13

A thick layer between gram + and gram - cells - made of overlapping lattice od 2 sugars that are cross linked by amino acid bridges

Question 14

How is the degree of rigidly of peptidoglycan determined?

Answer 14

by the amount of peptide cross-links

Question 15

What are the 2 types of sugar in peptidoglycan?

Answer 15

1. N-acetyl glucosamine (NAG)
2. N-acetyl muramic acid (NAM)

Question 16

Which sugar are the cross-link of 4 amino acid attached to?

Answer 16

NAM

Question 17

What is a gram stain useful for?

Answer 17

showing the difference between gram positive and gram negative structures - this helps to classify different types of bacteria

Question 18

What do gram negative structures have that gram positive structures don’t

Answer 18

a Periplasmic space and outer membrane

Question 19

What some bacteria have?

Answer 19

peptide interbridge

Question 20

What does a gram stain measure?

Answer 20

the ability of iodine-dye completes to leak out of the cell following decolorisation

Question 21

what colours do bacteria turn after the gram stain?

Answer 21

gram positive turn purple / gram negative turn pink

Question 22

Difference shapes of bacteria?

Answer 22

Bacilli - oval
Cocci - lots of little balls
Spiral - wavy line

Question 23

Obligate aerobes

Answer 23

require oxygen

Question 24

obligate anaerobes

Answer 24

require no oxygen

Question 25

what species are spore present?

Answer 25

Clostridium and bacillus

Question 26

What are the ways to differential types of bacteria?

Answer 26

shape, gram stain, atmosphere, spores, different types of tests

Question 27

Nucleoid DNA

Answer 27

• one chromosome
• DNA in giant circular molecule
• its supercoiled by DNA gyrase
• can be uncoiled by enzyme topoisomerase I

Question 28

Steps of bacterial chromosomes replications

Answer 28

1) are the origin of replication helices unwinds - single stranded DNA
2) primase synthesis primers and them DNA-dependant DNA polymerase synthesis new DNA semi-conservatively
3)2 identical daughter chromosomes are formed

Question 29

aspects of Binary Fission

Answer 29

• asexual reproduction
• causes population to double every time

Question 30

Limitation of binary fission

Answer 30

no genetic recombination - so it cannot survive in the rapid environmental change - no genetic diversity
- good as stops overpopulation of bacteria - means antibiotics usually work

Question 31

Steps of binary fission

Answer 31

1)chromosome replication indication at the membrane
2)DNA replication starts at the origin
3)there is extension of the cell wall and membrane
4)there is septum formation
5)membrane attachment of the chromosome pull each daughter chromosomes into a new cell
6)cell operation: cytokinesis

Question 32

what type of bacteria are spores found in

Answer 32

gram postive

Question 33

what are endospores resistant too

Answer 33

high temperature, disinfectants, low energy radiation, drying

Question 34

ways to kill spores

Answer 34

autoclaving and canning

Question 35

What are capsules made of?

Answer 35

polysaccharides or polypeptide slime

Question 35

why are capsules important?

Answer 35

encapsulate pathogens and determine virulence
- protects bacteria from drying and traps nutrients
- resists phagocytic engulfment by white blood cells
- adhere to surfaces and resist flushing

Question 36

What is a Pili

Answer 36

protein tubes in the cytoplasmic membrane - all gram negative bacteria
- composed of protein piling
- has a adhesive tip - lectin - binds to specific sugars on glycoprotein or gllycolidip receptor at the host cell surface

Question 37

What is a Flagella?

Answer 37

organ of locomotion
- enables organism to fine source of nutrients
- enables orgainsmto penetrate host mucus