Characteristic of Bacteria

Question 1

Prokaryotes

Answer 1

contain a single chromosome of double-standed DNA in a circle called a nucleoid that is not surrounded by a membrane; plasmids may be present; cell wall is present and rigid

Question 2

Eurkaryotes

Answer 2

nucleus contains double-stranded DNA in one or more chromosomes surrounded by a nuclear membrane; mitochondria are sites of energy; most do not have cell walls

Question 3

What is one example of a prokaryote?

Answer 3

bacteria

Question 4

What are some examples of eukaryotes

Answer 4

fungi, algae, protozoa, plant cells, animals cells (human)

Question 5

What is the scientific nomenclature for organisms?

Answer 5

the genus is the first name and always capitalized, and the species follows and is not capitalized. Both are either underlined OR italicized

Question 6

Strain

Answer 6

genetically identical or clonal representatives of a species; a species is composed of related strains

Question 7

Isolate

Answer 7

representative bacterial colony recovered from a particular source (e.g., patient)

Question 8

What makes a cell wall gram-positive?

Answer 8

a thick protective peptidoglycan layer; teichoic and lipoteichoic acid are unique to GP cell walls

Question 9

What makes a cell wall gram-negative?

Answer 9

2 layers, a thin inner peptidoglycan layer and outer membrane containing lipopolysaccharide (LPS); responsible for fever and shock in patients with GN bacteria and provides attachment site

Question 10

What is an acid-fast cell wall?

Answer 10

a gram-positive cell wall structure that also have a waxy layer of glycolipids and mycolic (fatty) acids bound to the exterior of cell wall
ex. Mycobacterium and Nocardia

Question 11

What happens to bacteria that have no cell wall?

Answer 11

they contain sterols in cell membranes
ex. Mycoplasma

Question 12

Gram-stain

Answer 12

basis for initial grouping of medically important bacteria; placed into two groups based on stain results (purple-positive, or pink/red-negative)

Question 13

What are the steps to gram-staining?

Answer 13

1) fixing bacteria to a slide with heat
2) saturate with crystal violet
3) pour iodine on it
4) saturate with alcohol, this removes the dye from gram- cells
5) rinse with safranin, this gives decolorized gram- cells their pink/red color

Question 14

What is the difference in gram-positive and gram-negative bacteria?

Answer 14

gram positive bacteria contain multiple layers of peptidoglycan while gram negative bacteria contain a single peptidoglycan layer

Question 15

Cocci

Answer 15

spherical shape; can be diplococci, streptococci, or staphylococci

Question 16

Bacilli

Answer 16

rod shaped; can be coccobacilli, pleomorphic, branching, palisading, or spirochetes (helical)

Question 17

Flagella

Answer 17

exterior protein filaments that provide locomotion and propel the bacteria towards food sources or away from detrimental chemicals; several kinds of attchments

Question 18

Pili or fimbriae

Answer 18

hair like structures/protein fibers that do not provide motility but allow attachment to the host

Question 19

Endospores

Answer 19

highly durable dehydrated cells with thick walls resistant to heat/drying/chemicals; forms from vegetative cell when environment triggers process; can survive/stay dormant for decades in environment; only some gram positive bacteria form these!

Question 20

Capsules

Answer 20

covers the cell wall and shields the bacteria from immune and phagocytic responses; one of the most important virulence factors

Question 21

Toxin

Answer 21

virulence factor, multiple kinds (exotoxin, endotoxin, entreotoxin)

Question 22

Exotoxin

Answer 22

produced in the cell and excreted

Question 23

Endotoxin

Answer 23

toxin derived from cell wall or gram-negative rods

Question 24

Enterotoxin

Answer 24

toxins that give rise to gastrointestinal symptoms when ingested or formed in the gut

Question 25

Psychrophiles

Answer 25

organisms that can survive colder temperatures (like refrigeration)

Question 26

Mesophiles

Answer 26

organisms that survive at room/body temperature and cause disease in humans

Question 27

Thermophiles

Answer 27

survive in hot temperatures like hot springs

Question 28

What pH do most medically important bacteria prefer?

Answer 28

pH of 6.0-8.0

Question 29

Obligate aerobes

Answer 29

require oxygen

Question 30

Obligate anaerobes

Answer 30

will not grow in presence of oxygen

Question 31

Facultative anaerobes

Answer 31

grows with or without oxygen

Question 32

Capnophilic

Answer 32

grows better when atmosphere is enriched with extra CO2

Question 33

How do microbes grow?

Answer 33

replication by binary fission; the time required for one cell to divide into two cells is generation/doubling time

Question 34

Phases of bacterial growth

Answer 34

lag phase, log/exponential phase, stationary phase, death/decline phase

Question 35

Lag phase

Answer 35

growth is undetected

Question 36

Log/exponential phase

Answer 36

constant, maximal growth rate (most active)

Question 37

Stationary phase

Answer 37

balanced number of cells dying and dividing

Question 38

Death/decline phase

Answer 38

most cells are dying