Bacteria

Question 1

two types of cells

Answer 1

eukaryotic cell and prokaryotic cell

Question 2

three domains of life

Answer 2

eukarya, archaea, bacteria

Question 3

prokaryotes

Answer 3

• are microscopic organisms that contain no nucleus
• they include the bacteria and archaea
• prokaryotes are the most abundant and diverse organisms on earth

Question 3

archaea

Answer 3

• no known pathogens
• some archaea live in extreme environments and are called extremophiles
• extreme halophiles = high saline environments
• extreme thermophiles = hot environments

Question 4

general features of a bacterial cell

Answer 4

• lack nucleus but have nucleoid region
  prokaryotes - have small genomes
  - one big ring in nucleoid region = chromosome
  - smaller rings = plasmids
• ribosomes are smaller and have a different makeup than the ribosomes of eukaryotes
  - different protein and RNA content
• the genes for these rRNAs are often used for classification

Question 5

bacterial genomes

Answer 5

• the prokaryotic genome has less DNA than the eukaryotic genome
• the typical prokaryotic genome is a ring of DNA (a circular chromosome) that is not surrounded by a membrane and that is located in a nucleoid region
• some species of bacteria also have smaller rings of DNA called plasmids

Question 6

smaller rings of DNA in bacterial genomes- plasmids

Answer 6

• plasmids can replicate independently of the chromosome
• often have genes useful for the survival of the bacteria (e.g. for resistance to antibiotics, or for the ability to metabolize a particular nutrient like lactose)

Question 7

prokaryotes divide by

Answer 7

binary fission

Question 8

eukaryotes dived by

Answer 8

mitosis/meiosis

Question 9

bacterial classification - historically

Answer 9

• microscopic observations (e.g. shape, response to stains)
• biochemical characteristics (& growth conditions)

Question 10

bacterial classification - more recent

Answer 10

• serological characterization (using antibodies/immune response)
• compare DNA sequences (% similarity of rRNA genes)
  - for clinical analysis, we can identify bacteria using PCR (a method to amplify DNA)

Question 11

bacterial morphologies - coccus

Answer 11

circle/sphere

Question 12

bacterial morphologies - bacillus

Answer 12

rod shaped

Question 13

bacterial morphologies - vibrio

Answer 13

curved rod shape/comma

Question 14

bacterial morphologies - spirillum

Answer 14

squiggly/ spiral

Question 15

bacterial morphologies - staphylo

Answer 15

cluster

Question 15

bacterial morphologies - diplo

Answer 15

pairs of spheres

Question 16

bacterial morphologies - strepto

Answer 16

line

Question 17

peptidoglycan

Answer 17

is used for support in bacterial cell walls

Question 18

gram stain - red/pink

Answer 18

gram-negative

Question 19

gram stain - purple

Answer 19

gram-positive

Question 20

gram-negative bacteria have

Answer 20

less peptidoglycan and an outer membrane that can be toxic, and they are more likely to be antibiotic-resistant

Question 21

gram-positive stain

Answer 21

• thick wall
  - peptidoglycan
• e.g. bacillus anthracis

Question 22

gram-negative stain

Answer 22

• thin wall between 2 membranes
• e.g. e.coli

Question 23

gram-negative - periplasm

Answer 23

- the region between the membranes - contains enzymes which can degrade toxins & antibiotics

Question 24

gram-negative - lipopolysaccharides (LPS)

Answer 24

- a unique lipid/carbohydrate found on the outer layer of the outer membrane - LPS is an endotoxin (may cause a severe immune reaction

Question 25

toxins

Answer 25

are substances (such as proteins) produced by some microorganisms that can cause pathologic effects associated with infectious diseases - non-infectious (they cannot be transmitted from person to person) - non-replicating - can cause acute toxic disease, as well as long-term effects - classified as either endotoxins or exotoxins