2. prokaryotic cell structure

Question 1

are prokaryotes bigger or smaller than eukaryotes?

Answer 1

smaller

Question 2

how many chromosomes do prokaryotes have and what shape are most of the chromosomes?

Answer 2

one; circular

Question 3

since prokaryotes do not have a nucleus, where are the chromosomes found?

Answer 3

nucleoid region

Question 4

T/F: prokaryotes have membrane0bound organelles

Answer 4

false

Question 5

T/F: prokaryotes have a more complex cell envelope than eukaryotes

Answer 5

true - made of membrane, cell wall and bacterial capsule

Question 6

what process do prokaryotes use in order to reproduce?

Answer 6

binary fission

Question 7

what was the first macro bacteria that was seen by the naked eye back in 1999?

Answer 7

thiomargarita namibiensis

Question 8

this is where the DNA of bacteria is packaged without being surrounded by a membrane

Answer 8

nucleoid

Question 9

how is DNA stabilized in the nuceloid region?

Answer 9

By the neutralization of the negative charge of the DNA by small polyamines (have +ve charge) and Mg2+ ions.
- histone like proteins (maintain DNA architecture and regulation DNA transactions such as replication, recombination/repair and transcription)

Question 10

what are the TWO main functions of the prokaryotic cell envelope?

Answer 10

1. protection - from hostile environments such as osmolarity, and harsh chemicals and antibiotics)
2. pathogenicity - contribute to the invasiveness of pathogenic bacteria

Question 11

list the three layers that make up the cell envelope

Answer 11

1. cell membrane (all bacteria have cell membranes)
2. cell wall (all bacteria except 1 species has a cell wall)
3. the capsule (not all bacteria have capsules)

Question 12

this is composed of a phospholipid bilayer and proteins including integral proteins which float in the bilayer and peripheral proteins that are associated on the inner membrane surface

Answer 12

cell membrane

Question 13

these are lipid molecules that play a role in the fluidity of the membrane

Answer 13

hopanoids

Question 14

when the temperature increases, the fluidity of the cell membrane also increases. therefore, more things can enter the bacteria. a result of this will be _____ (more/less) hopanoids produced to stabilize temperature

Answer 14

more

Question 15

what are the functions of the cell membrane

Answer 15

• permeability and transport
• electron transport and oxidative phosphorylation
• excretion of hydrolytic exoenzymes and pathogenicity proteins
• biosynthetic functions
• chemotactic systems

Question 16

this type of transport across the cell membrane relies on diffusion from high concentration to low concentration

Answer 16

passive transport

Question 17

this type of passive transport requires NO energy or proteins

Answer 17

simple diffusion

Question 18

this type of passive transport requires the use of channel proteins in order to transport molecules such as O2, CO2, H2O, and glycerol

Answer 18

facilitated diffusion

Question 19

this type of transport across the cell membrane requires energy and transport proteins to travel from low concentration to high concentration

Answer 19

active transport

Question 20

this type of transport across the cell membrane requires energy (ATP) to phosphorylate the molecule during the transport process and then use it in metabolism; use to uptake sugars by bacteria where the source of energy is from phosphoenolpyruvate (e.g. glucose and mannose)

Answer 20

group translocation

Question 21

using specialized molecules such as siderophores to transport iron which is locked up in nature as Fe(OH)3, and insoluble and unavailable for transport

Answer 21

special transport processes

Question 22

these are small molecular iron chelators that are produced by microbes and whose function is to sequester iron from the host and provide this essential metal nutrient to the microbe

Answer 22

siderophore

Question 23

this function of the cell membrane is an analog function to the mitochondria function in eukaryotes

Answer 23

electron transport and oxidative phosphorylation

Question 24

this function of the cell membrane contains six pathways of protein secretion, names type I - the VI secretion systems; used to secrete hydrolytic enzymes and pathogenicity toxins and other proteins

Answer 24

excretion of hydrolytic exoenzymes and pathgenicity proteins

Question 25

this function of the cell membrane explains that the cell membrane is the site of the enzymes of phospholipids and cell wall biosynthesis

Answer 25

biosynthetic functions

Question 26

this function of the cell membrane relates to the cell membrane having specific receptors that can bind to different kinds of attractants and repellants

Answer 26

chemotactic systems

Question 27

this is a structural support that surrounds the cell in order to protect it. it - gives shape to the cell and protects it from cell lysis - protects the cell from toxic substances - has components that contribute to the bacteria pathinogenicity - is the site of action of several antibiotics

Answer 27

cell wall

Question 28

what are the two different groups of bacteria based on their cell walls

Answer 28

gram-negative bacteria and gram-positive bacteria

Question 29

do gram-negative or gram-postive bacteria have a thicker peptidoglycan sheet?

Answer 29

gram-positive

Question 30

do gram-negative or gram-positive bacteria contain an outer membrane and a cell membrane

Answer 30

gram-negative

Question 31

do gram-negative or gram-positive bacteria contain lipoteichoic acid and teicehoic acid

Answer 31

gram-positive

Question 32

this portion of the cell wall is responsible for its strength

Answer 32

peptidoglycan layer

Question 33

what are the three parts of the peptidoglycan layer?

Answer 33

1. the backbone - consisting of alternating sugar derivatives NAG and NAM 2. a set of identical tetra peptide side chains attached to NAM 3. peptide cross-links or inter bridges

Question 34

what are the two special components of gram-positive cell walls

Answer 34

1. teichoic acids 2. polysaccharides

Question 35

these are partially responsible for the negative charge of the cell surface of gram-positive cell wall. they constitute major surface antigens of gram-positive bacteria

Answer 35

teichoic acids

Question 36

what are the two different types of teichoic acids in gram-positive bacteria cell walls?

Answer 36

wall teichoic acids (WTA) and lipoteichoic acid (LTA)

Question 37

in streptococcus pyogens (gram positive bacteria), what facilitates the attachment to host cells

Answer 37

LTA and M proteins

Question 38

in some species, like those with gram-positive cell walls, sugars such as mannose, arabinose and glucuronic acid exist as subunits of _______ in the cell wall

Answer 38

polysaccharides

Question 39

what are the special components of gram-negative cell walls

Answer 39

1. outer membrane 2. lipopolysaccharide 3. porin channels 4. lipoprotein 5. the periplasmic space

Question 40

this component of gram-negative cell walls is a bilayer structure. the outer edge contains lipopolysaccharides and channel proteins

Answer 40

outer membrane

Question 41

this component of gram-negative cell walls consists of glycolipids (lipid A) and polysaccharides and it prevents the diffusion of hydrophobic materials (toxic compounds) through the outer membrane

Answer 41

lipopolysaccharide

Question 42

this is a lipid component of an endotoxin held responsible for the toxicity of gram-negative bacteria

Answer 42

lipid A

Question 43

this is attached to the core polysaccharide and extends from the core out into the environment. it consists of repeating oligosaccharide subunits made up of three to five sugars; it renders additional protection from the antimicrobial action of certain antibiotics

Answer 43

o antigen

Question 44

this portion of the cell wall permits the passive diffusion of low molecular weight hydrophilic compounds, such as sugars, amino acids and certain ions

Answer 44

porin channels

Question 45

large antibiotic molecules (such as beta lactams) have very ____ permeability therefore gram-negative bacteria have resistance to some antibiotics

Answer 45

low

Question 46

this portion of the cell wall cross links the outer membrane and peptidoglycan layers to stabilize and anchor the outer membrane layer; it is the most abundant protein of gram-negative cells

Answer 46

lipoprotein

Question 47

this is the space between the inner and outer membranes and the peptidoglycan layers

Answer 47

periplasmic space

Question 48

if a gram-stained cell is stained purple what kind of bacteria is it?

Answer 48

gram positive

Question 49

what are some examples of gram positive bacteria

Answer 49

bacillus, staphylococcus, streptococcus

Question 50

if a gram-stained cell is stained red what type of bacteria is it

Answer 50

gram-negative

Question 51

some bacteria such as mycobacteria tuberculosis have cell walls that contain large amounts of waxes called ____________. these cannot be stained with gram stains

Answer 51

mycolic acids

Question 52

T/F; bacteria that contain cell walls with mycolic acids are resistant to antibiotics and many harsh chemicals including detergents and strong acids

Answer 52

true

Question 53

this type of bacteria have no cell wall and contain no peptidoglycan. they are genetically closer to gram-positive bacteria; they are resistant to cell-wall inhibiting antibiotics (e.g. penicillins and cephlosporins)

Answer 53

mycoplasmas

Question 54

this is an enzyme that attacks cell walls - found in human secretions (tears, saliva and nasal secretions) - break down the peptidoglycan backbone

Answer 54

lysozymes

Question 55

T/F: the outer membrane of gram-negative cell walls prevents access to lysozyme therefore gram negative more resistant

Answer 55

true

Question 56

this is an enzyme that attacks cell walls - secreted by the bacteria itself to catalyze the degradation and turnover of peptidoglycan, to participate in cell wall growth and cell separation - responsible for the dissolution of dead cells (autolysis)

Answer 56

autolysins hydrolytic enzymes

Question 57

this is an enzyme that attacks cell walls - these degrade bacterial cell walls and digest whole bacteria ( such as protozoa and the phagocytic cells of animals )

Answer 57

hydrolytic enzymes of higher organisms

Question 58

this is an extracellular layer lying outside the cell, composed mainly of polymer of polusaccharides

Answer 58

capsule

Question 59

how does the capsule contribute to the invasiveness of pathogenic bacteria?

Answer 59

- encapsulated bacteria are protected from phagocytosis - the glycocalyx plays a role in the adherence of bacteria to the host cells (e.g. streptococcus mustans adhere tightly to the tooth surface by its glycocalyx trapping other bacterial cells of the same or different species which from the plaque on the tooth and then acid products are excreted by these bacteria causing dental caries)

Question 59

how does the capsule contribute to the invasiveness of pathogenic bacteria?

Answer 59

- encapsulated bacteria are protected from phagocytosis - the glycocalyx plays a role in the adherence of bacteria to the host cells (e.g. streptococcus mustans adhere tightly to the tooth surface by its glycocalyx trapping other bacterial cells of the same or different species which from the plaque on the tooth and then acid products are excreted by these bacteria causing dental caries)