bacterial structure I and II - levinson

Question 1

what are the 5 major groups of organisms that cause human diseases?

Answer 1

bacteria
fungi
protozoa
helminths
viruses

Question 2

what organisms are in the prokaryote kingdom?

Answer 2

bacteria

Question 3

what organisms are in the protist kingdom?

Answer 3

fungi (yeasts and molds) and protozoa

Question 4

what organisms are in the animal kingdom?

Answer 4

helminths (worms)

Question 5

how can you distinguish protists from animals and plants?

Answer 5

protists are either unicellular or relatively simple microorganisms

Question 6

which organisms are parasites?

Answer 6

helminths and protozoa

Question 7

biological relationships of pathogenic microorganisms (table)- kingdom- pathogenic microorganisms- type of cells

Answer 7

• animals
  
  • helminths
  • eukaryotic cells
• protists
  
  • protozoa and fungi
  • eukaryotic cells
• prokaryotes
  
  • bacteria
    - prokaryotic
  • viruses
  • noncellular

Question 8

describe the structure of cells.

Answer 8

have a nucleus or nucleoid that contains DNA

nucleus surrounded by cytoplasm where proteins are synthesized and energy generated

Question 9

describe the structure of viruses.

Answer 9

inner core of genetic material but no cytoplasm

depend on host cells to provide the machinery for protein synthesis and energy generation

Question 10

how do eukaryotic cells replicate?

Answer 10

mitosis - one parent cell divides to make two progeny cells while retaining its cellular structure

Question 11

how do prokaryotic cells replicate?

Answer 11

binary fission

Question 12

how do viruses replicate?

Answer 12

disassemble produce many copies of their nucleic acid and protein
reassemble into multiple progeny

Question 13

can bacteria replicate extracellularly?

Answer 13

most can, except rickettsiae and chlamydiae

Question 14

what is the difference in nucleic acid between cells and viruses?

Answer 14

cells have both DNA and RNA viruses have DNA or RNA but not both

Question 15

what are the defining characteristics of eukaryotic cells?

Answer 15

have a true nucleus with multiple chromosomes surrounded by a nuclear membraneuses mitotic apparatus to ensure equal allocation of chromosomes to progenycontain organelles (ie mitochondria and lysosomes) and ribosomes

Question 16

what are the defining characteristics of prokaryotic cells?

Answer 16

nucleoid consists of a single cellular molecule of loosely organized DNA lacks nuclear membrane and mitotic apparatusno organelles and smaller ribosomesrigid external cell wall that contains peptidoglycan

Question 17

what is peptidoglycan and what is it made of?

Answer 17

polymer of AA and sugars that makes up the rigid cell wall of most prokaryotes

Question 18

what is the cell wall of eukaryotes like?

Answer 18

either have a flexible cell membrane or rigid wall of chitin (fungi)

Question 19

what is chitin and what is made of?

Answer 19

makes up rigid cell wall of fungimade of a homopolymer of N-acetylglucosamine

Question 20

what organisms have sterols?

Answer 20

eukaryotic cell membranes contain sterolsno prokaryotes except for mycoplasma do

Question 21

which organisms are motile and which ones aren’t?

Answer 21

protozoa are motile, as are some bacteriafungi and viruses aren’t

Question 22

what do protozoa use to move?

Answer 22

three different organs of locomotion: flagella, cilia and psuedo-pods

Question 23

what do bacteria use to move?

Answer 23

flagella

Question 24

how are microorganisms named?

Answer 24

bacteria, fungi, protozoa, and helminths are named according to binomial Linnean system (uses genus and species)
viruses aren’t

Question 25

what are the different shapes of bacteria?

Answer 25

``` cocci = round bacilli = rods spirochetes = spiral-shaped pleomorphic = variable in shape ```

Question 26

what determines the shape of bacterium?

Answer 26

its rigid cell wall

Question 27

how do cocci bacteria vary in terms of arrangement?

Answer 27

can occur in pairs = diplococci in chains = streptococci grapelike clusters = staphylococci

Question 28

what determines the arrangement of bacteria?

Answer 28

orientation and degree of attachment of the bacteria at the time of cell division

Question 29

how large are bacteria?

Answer 29

range in size from about 0.2 to 5 umsmalles are the same size as the largest viruses

Question 30

what is the outermost component of bacteria?

Answer 30

cell wall most commonlysome have capsule, flagella, and pili as well

Question 31

what is the function of peptidoglycan in the bacterial cell wall?

Answer 31

provides structural support and maintains characteristic shape of cell

Question 32

what factors are different between gram positive and gram negative bacteria? (general)

Answer 32

structure chemical composition thickness of cell wall

Question 33

what are the layers of bacterial cell walls?

Answer 33

``` outer:flagellum, techolic acid, pilus if present capsule outer membrane in gram-negative peptidoglycan cytoplasmic membrane ```

Question 34

how does the peptidoglycan layer vary between gram positive and gram negative bacteria?

Answer 34

much thicker in gram positive bacteria | many gram-positive

Question 35

how does the outer layer of gram positive and gram negative bacteria differ?

Answer 35

gram negative have a complex outer layer of lipopolysaccharide, lipoprotein, and phospholipid

Question 36

what is periplasmic space and which type of bacteria have it? what is found there?

Answer 36

in gram-negative bacteriabetween outer-membrane layer and cytoplasmic membrane where beta-lactamase enzymes are in some species

Question 37

what do beta-lactamase enzymes do? where would they be found?

Answer 37

enzymes that degrade penicillins and other beta-lactam drugs | in periplasmic space in gram-negative bacteria

Question 38

what is endotoxin and where is it found?

Answer 38

in gram-negative bacteria | lipopolysaccharide

Question 39

what are porin proteins and where are they found?

Answer 39

in the cell wall of both gram positive and gram negative bacteria facilitate passage of small hydrophilic molecules into the cell in gram-negative, allow entry of essential substances such as sugars, AA, vitamins, and metals and many antimicrobial drugs

Question 40

what are acid-fast bacteria?

Answer 40

ones that can't be gramstained mycobacteria resist decoloratization with acid-alcohol after being stained with carbolfuchsindue to high concentration of lipids (mycolic acids) in the cell walls

Question 41

what are mycolic acids? where are they found? how do they affect gram staining?

Answer 41

lipids found in high concentration in mycobacteria | prevent gramstaining

Question 42

what are the three components of the bacterial cell wall (that they consider important)?

Answer 42

peptidoglycan lipopolysaccharide teichoic acid

Question 43

what is peptidoglycan and where is it found?

Answer 43

complex, interwoven network that surrounds the entire cell and is composed of a single covalently linked macromolecule found only in bacterial cell walls

Question 44

what is the structural importance of peptidoglycan?

Answer 44

provides rigid support for the cell maintains cell shape allows cell to withstand media of low osmotic pressure (such as water)

Question 45

what is peptidoglycan composed of (ie describe the carbohydrate backbone)?

Answer 45

alternating N-acetylmuramic acid and N-acetylglucosamine moleculestetrapeptide consisting of D- and L-amino acids is attached to each of the muramic acid molecules

Question 46

what aspect of peptidoglycan varies between bacteria?

Answer 46

precise composition of tetrapeptide link attached to muramic acid

Question 47

what is diaminopimelic acid a component of and what organism is it unique to?

Answer 47

unique to bacterial cell walls | component of carbohydrate backbone

Question 48

what is D-alanine a component of and what does it do?

Answer 48

part of bacterial cell walls | involved in cross-links between the tetrapeptide and in the action of penicillin

Question 49

what is different about the AA in the tetrapeptide in bacterial cell walls?

Answer 49

contain the D-isomers of AA | most proteins contain the L-isomers

Question 50

what drugs target bacterial cell walls, and how?

Answer 50

penicillins, cephalosporins and vancomycininhibit the synthesis of peptidoglycan by inhibiting transpeptidase that makes the cross-links between two adjacent tetrapeptides

Question 51

how would gram-negative and gram-positive bacteria appear after being stained?

Answer 51

gram-positive will stain blue | gram-negative will stain red

Question 52

what are the steps in the gram stain procedure?

Answer 52

1: crystal violet dye stains all cells blue/purple 2: iodine solution is added - forms a crystal violet-iodine complex - all cells continue to appear blue 3: organic solvent (acetone or ethanol) extracts the blue dye complex from lipid-rich, thin-walled gram-negative bacteria to a greater degree than from thick-walled gram-positive bacteria 4: red dye safranin stains decolored gram-negative cells red/pink

Question 53

how is the gram stain used clinically?

Answer 53

used to identify bacteria and choose antibacterial treatment

Question 54

how do gram-negative bacteria versus gram-positive bacteria compare in terms of responsiveness to penicillin?

Answer 54

gram-positive are more susceptible

Question 55

what is the sensitivity of the gram stain procedure?

Answer 55

very low because it requires about 100,000 bacteria/mL to see 1 bacterium per microscope field therefore need to incubate patient's blood

Question 56

where is lysozyme found and what does it do to bacteria?

Answer 56

enzyme in human tears, mucus, saliva | cleaves peptidoglycan backbone by breaking glycosyl bonds