Microbiology Cell Structure

Question 1

What are the three domains of classification?

Answer 1

eukaryota - eukaryotic

bacteria - prokaryotic
archaea - prokaryotic

Question 2

What are bacteria and archaea?

Answer 2

prokaryotic cells

• unicellular organista that lack organelles or internal membranes bound structures
• do not have a membrane bound nucleus

Question 3

What are examples of bacteria and archaea?

Answer 3

bacteria
- cyanobacteria, gram +/- bacteria

archaea - extreme organisms
- extreme halophiles, methanogens, hyperthermophiles

Question 4

What are eukaryotes?

Answer 4

eukaryotic cells

• has membrane bound structures and organelles
• have a membrane bound nucleus

Question 5

What are the five kingdoms of classification?

Answer 5

animalia - vertebrates or invertebrates, multicellular, mobile, aerobic, sexual heterotrophic eukaryotes

plantae - immobile, sexual/asexual, multicellular, eukaryotic nature

fungi - multicellular, aerobic, heterotrophic eukaryotes

protista - unicellular, move by cilia/flagella/amoeboid

monera - bacteria and archaea (prokaryotes), unicellular

Question 6

What are the structures that eukaryotes have but bacteria do not?

Answer 6

nucleus - membrane bound
nucleosomes/histones - associated with DNA
introns - non-coding sections of genes
TATA box binding protein
organelles - membrane bound

Question 7

What are the structures that bacteria have but eukaryotes do not?

Answer 7

operons/ polycistronic mRNA

cell wall - peptidoglycan

Question 8

What are the structures that both bacteria and eukaryotes have?

Answer 8

chromosomes
bacteria - one, circular
eukaryotes - more than one

RNA polymerase
bacteria - one, simple
eukaryotes - more than one, complex

protein initiator amino acid
bacteria - N-formly methionine
eukaryotes - methionine

Question 9

What are the structures that animal cells, plant cells and prokaryotic cells all share?

Answer 9

cell membrane

cytoplasm

Question 10

What are the properties that animal and plant cells share?

Answer 10

membrane bound nucleus

Question 11

What are the properties that plant and prokaryotic cells share?

Answer 11

cell wall
plant - cellulose
prokaryotic - peptidoglycan

Question 12

What are the properties that only plant cells have?

Answer 12

permanent vacoule

chloroplasts

Question 13

What are the properties that prokaryotic cells have?

Answer 13

plasmids

DNA free in the cytoplasm

Question 14

What is are plasmids?

Answer 14

extra chromosomal DNA
multiple copy number

codes for pathogenesis (development of disease) and antibiotic resistance factors

bacterial replication

Question 15

What are the properties and structure of gram negative bacteria?

Answer 15

• thin peptidoglycan cell wall
  = cannot retain crystal violet stain
• stains red-pink by retaining counter stain safranin
• has an outer membrane made of lipopolysaccharide
• produces exotoxins and endotoxins
• has periplasmic space
  = region between inner and outer membrane containing enzymes, proteins, etc

Question 16

What are the properties and structure of gram positive bacteria?

Answer 16

• has a thick peptidoglycan cell wall
  = can retain crystal violet stain and stain purple-blue
• no outer lipid membrane
• produce exotoxins
• does not have periplasmic space

Question 17

What are flagella?

Answer 17

locomotory organelles
- enable movement

can also function as a sensory organelle

• taste environment
• respond to food/poison

move by a propeller-like action

Question 18

What are pili?

Answer 18

hair-like projections

function is to attach the cells to surfaces = adhesion to host epithelium

involved in sexual conjugation in bacteria

• sexual mode of genetic transfer
• via cell to cell contact or a bridge-like connection

Question 19

What causes wall-less forms of bacteria?

Answer 19

have no cell wall

• enzymes lytic for cell wall
• antibiotics inhibiting peptidoglycan synthesis

usually non-viable - unable to survive

Question 20

What examples of wall-less bacteria that do and do not replicate?

Answer 20

do not

• spheroplasts (with an outer membrane)
• protoplasts (no outer membrane)

do
- L forms

Question 21

What are capsules and slime layers?

Answer 21

outside the cell envelope

glycocalyx is not defined

• capsule and slime layer are two types glycocalyx
• coating or layer external to the cell wall

capsule is well defined
slime layer is not defined

Question 22

What is an endospore?

Answer 22

dormant, tough and non-reproductive structure produced by some bacteria
- usually gram positive bacteria

resistant to adverse conditions - protects the bacteria

produced when the bacteria is starved - lack of nutrients, extreme conditions

contain calcium dipicolinate

Question 23

How is an endospore formed?

Answer 23

1 - vegetative state is deprived of nutrients

2 - DNA is replicated
membrane wall called the spore septum forms asymmetrically between the DNA and the rest of the cell - core
3 - the plasma membrane surrounds the wall and pinches off to form a double membrane around the forespore
4 - calcium dipicolinate is incorporated into the forespore
5 - peptidoglycan cell wall forms between the two layers of membrane = acts as a cell wall after germination
6 - bacterium adds a spore coat to the outside of the forespore
7 - the endospore is dehydrated and allowed to mature before being released from the mother cell when the surrounding vegetative cell is degraded