Exam 1: Ch 3: Prokaryotes

Question 1

3 characteristics that help differentiate prokaryotes from eukaryotes:

Answer 1

− The way their DNA is packaged (lack of nucleus and histones) (have way less DNA b/c histones help eukaryotes pack DNA tightly)
− The makeup of their cell wall (peptidoglycan and other unique chemicals)
− Their internal structure (lack of membrane bound organelles)

Question 2

Bacterial chromosome

Answer 2

has all the DNA that makes the bacteria functional

Question 3

Actin cytoskeleton

Answer 3

helps w/structure and movement

Question 4

Fimbriae

Answer 4

can attack/will make bacteria more pathogenic

Question 5

Plasmid

Answer 5

luxury DNA

Question 6

Prokaryotic cell contents

Answer 6

− All bacteria have: membrane, bacterial chromosome, ribosomes, actin cytoskeleton, cytoplasm
− Some bacteria have: fimbriae, outer membrane, cell wall, pilus, capsule, inclusion, plasmid, flagellum, endospore, intracellular membranes ← all of these things (except inclusions) have the ability to make bacteria more pathogenic

Question 7

Prokaryotic cell size

Answer 7

most are very small (0.5-2.0 um in diameter); large surface to volume ratio for nutrients to enter cell quickly → can release things much faster (use diffusion)

Question 8

Prokaryotic cell shape

Answer 8

coccus (sphere), bacillus (rod), spirillum, spirochete, vibrio (spiral)

Question 9

Prokaryotic cell arrangement

Answer 9

diplo- (pairs), strepto- ( strip), staphylo- (cluster like ppl at a staff meeting)

Question 10

Prokaryotic cell organization

Answer 10

−	External 
o	Appendages: flagella, pili, fimbriae
o	Glycocalyx: capsule, slime layer
−	Cell envelope
o	Cell wall
o	Membranes
−	Internal 
o	Cytoplasm
o	Ribosome
o	Inclusions
o	Nucleoid/chromosome
o	Endospore
o	Plasmid

Question 11

Flagella

Answer 11

bacterial locomotion; comprised mainly of proteins; 360 degrees rotation
− ~50% of bacteria have it
− Function: motility, chemotaxis – can chemotax toward or away from substances or cells (like WBCs) using “run and tumble motions”

Question 12

Testing for flagella

Answer 12

− Testing for flagella: semi solid media, staining the flagella, hanging drop
o Hanging drop method – drop of liquid w/specimen hanging upside down from undersurface of coverslip
• Bacteria are alive so we can see motility; difficult to visualize since microbes are not stained
• Motile bacteria will flit and dart around in the drop
• Non-motile bacteria will wobble back and forth but make no progress away from a stop

Question 13

Pili

Answer 13

allow bacteria to attach to surfaces or to other bacteria

two types: conjugation pili & fimbriae (attachment pili)

Question 14

Conjugation pili

Answer 14

bacteria attach to each other w/conjugation pili and transfer plasmids (mini chromosomes) down the pilus

Question 15

Fimbriae

Answer 15

(attachment pili) – facilitates attachment to other bacteria, surfaces and other types of cells (such as RBCs)
o Can be involved w/formation of a biofilm

Question 16

Glycocalyces

Answer 16

“sugar coat” comprised of polysaccharides and protein; varies in thickness
− Used to: avoid phagocytosis and for adhesion (biofilms)
− Two varieties:
slime layer & capsule

Question 17

Slime layer

Answer 17

unorganized loose thin glycocalyx; promote adherence to surfaces; protects cells from drying out, traps nutrients & binds cells together; important in biofilm production

Question 18

Capsule

Answer 18

organized, tightly packed, thick glycocalyx; prevents phagocytosis of bacteria by WBCs; cloaking device – hides the bacteria from the immune system → more likely to infect
• Capsid: bound more tightly to the cell, denser and thicker than slime layer; visible by negative staining; produces a sticky (mucoid) character to colonies
o Encapsulated bacterial cells generally have higher pathogenicity b/c they can hide from the host’s immune system

Question 19

Biofilms

Answer 19

glycocalyces (slime) and fimbriae (attachment)
− Formation: First colonists stick to surface → as cells divide, they form a dense mat bound together by sticky extracellular deposits and sometimes fimbriae
− Fimbriae also act to attach bacteria together in a biofilm
− Once they attach → start making genes to make slime → create their own environment → building apartment complex → make it livable for other bacteria → layers of different environments form

Question 20

Cell membrane

Answer 20

forms a boundary btwn inside and outside of cell
− Highly selectively permeable – regulates chemicals that enter and exit the cell
− Contains respiratory enzymes which enable the membrane to capture or harness cellular energy in the form of ATP
− Structure: similar to eukaryotic cells; fluid mosaic model w/phospholipids in a “fluid” dynamic bilayer and proteins arranged in “mosaic” model

Question 21

Fluid mosaic model (cell membrane)

Answer 21

described as fluid b/c molecules are able to move; described as mosaic b/c it is made up of many different kinds of components

Question 22

Concentration gradient (cell membrane)

Answer 22

difference in concentration of molecules in one area compared to another; Brownian motion: all the molecules in your body/everywhere are constantly vibrating

Question 23

Tonicity (cell membrane)

Answer 23

animal always wants an isotonic solution

Question 24

Selective permeability (cell membrane)

Answer 24

selective about what crosses based on: size, electrical charge, other properties

Question 25

Osmosis (cell membrane)

Answer 25

type of passive diffusion that moves water across a selectively permeable membrane from an area of lower solute concentration to an area of higher (Brownian motion); does NOT involve movement of solutes
o Maintaining a proper water balance is vital for every cell

Question 26

Cell wall

Answer 26

supports the shape of the cell and prevents osmotic lysis; external to cell membrane
3 types: gram +, gram -, acid fast/waxy/myobacteria

Question 27

Peptidoglycan

Answer 27

repeating framework of long glycan (sugar) chains cross-linked by short peptide (protein) fragments; provides cell wall strength to resist rupturing due to osmotic pressure; very strong structure; synthesis inhibited by penicillin (lyses cell)

Question 28

Gram + cell wall

Answer 28

components: peptidoglycan, membrane proteins, cell membrane, envelope, lipoteichoic acid, wall techoic acid

many layers of peptidoglycan; thick layer of it; one plasma membrane
• Techoic acid – function is unclear; binds w/crystal violet and iodine to form insoluble complex in gram stain (positive = purple)
• Envelope of gram positive bacteria has one cell membrane
• The thick layer of peptidoglycan is what protects the cell from the high level salt in MSA
• The 4 P’s:
1. Positive – gram pos cells
2. Peptidoglycan – have many layers
3. Purple – stain purple in gram stain
4. Penicillin – susceptible to penicillin b/c it targets the many peptide crosslinks in peptidoglycan

Question 29

Gram - cell wall

Answer 29

components: peptidoglycan, membrane proteins, cell membrane, outer membrane layer, porin proteins, LPS, phospholipids, lipoproteins, periplasmic space

few layers of peptidoglycan; thin layer of it; outer membrane has LPS
• Has 2 membranes: cell membrane (same as gram pos) + an outer membrane → much more resistant to antibiotics and some other chemicals than gram pos b/c of the outer membrane
• Lipopolysaccharides

Question 30

Lipopolysaccharides

Answer 30

(Lipid A + polysaccharide) –

• Endotoxins - cause fever and shock: O-antigen is recognized by host and initiates immune response

Question 31

Acid fast/waxy/myobacteria

Answer 31

have cell walls composed of mycolic acid (a waxy lipid); very protective cell walls
• Use the acid fast stain to characterize mycobacteria – the stain requires heating the stain to penetrate thru the cell wall
• Difficult to disinfect and treat due to cell wall composition (Myobacteria tuberculosis, Myobacteriia leprosae)

Question 32

Cytoplasm

Answer 32

cytosol and all the structures in the cell; site of metabolism (the buildup and breakdown of molecules)
− Cytosol – gel like, water based fluid in cell; ~80% water

Question 33

Ribosomes

Answer 33

protein synthesis (little protein production factories); composed of rRNA and protein
−	Bacterial ribosomes similar to eukaryotic except bacteria have 70S ribosomes and eukarya have 80S ribosomes (units for size, eukarya are larger)
−	Fungus (eukarya) attacl bacteria by going after their ribosomes – inhibit protein synthesis

Question 34

Inclusions

Answer 34

store viruses; burst open → viruses enter environment

Question 35

Nuclear region

Answer 35

(b/c there is no nucleus)
− Nucleoid – mostly DNA; contains one circular chromosome
− Plasmid – mini chromosome that contains non essential “luxury” DNA

Question 36

Endospore

Answer 36

not a cell structure but a cell state…
− Some bacteria have ability to produce endospores, resting stages
− Structure: DNA + spore coat (extremely tough) + small amt of cytoplasm
− Function: allow bacteria to survive adverse conditions (heath, lack of water, disinfectants for thousands of years); difficult to sterilize and present huge problem in hospitals
− Life cycle: vegetative cell (infects the host) → can live in an unlivable environment for awhile in vegetative state → transform into endospore → hangout until it becomes livable enough to infect
o Dormancy period = can be around for a long time

Question 37

Unique groups of bacteria

Answer 37

intracellular parasites

archaea bacteria

Question 38

Intracellular bacteria

Answer 38

intracellular bacteria must live IN host cells in order to undergo metabolism and repdroduction (they have their own reproductive ability but need to be inside host cells)
− Chlamydia
− Hard to kill off inside of cell but is still possible

Question 39

Archaea bacteria

Answer 39

in every habitat on earth, growing in soil, acidic hot springs, radioactive waste, water, deep in the earth’s crust, in organic matter, in live bodies of plants and animals
− Don’t have peptidoglycan in cell walls
− No examples of pathogenic archaea bacteria
− Get nutrients from environmental things

Question 40

Phenotypic methods of classification

Answer 40

− Microscopic phenotypes (ex. Staphylococcus)
− Cultural phenotypes (yellow, round, convex, mucoid colonies, etc)
− Biochemical tests

Question 41

Molecular methods of classification

Answer 41

DNA sequence, RNA sequence, protein sequence

Question 42

Species in prokaryotes

Answer 42

A collection of bacterial cells, all of which share an overall similar pattern of traits and 70-80% of their genes
Members of given species can show variations

Question 43

Subspecies/strain/type of prokaryotes

Answer 43

terms used to designate bacteria of the same species that have differing characteristics

Question 44

Serotype of prokaryotes

Answer 44

refers to representatives of a species that stimulate a distinct pattern of antibody (serum) responses in their hosts; distinct immunological pattern; what antibody is being made in the body

Question 45

5 structures found in all bacterial cells

Answer 45

cell (cytoplasmic) membrane, bacterial chromosome (nucleoid), ribosomes, actin cytoskeleton, cytoplasm — majority have: cell wall and glycocalyx

Question 46

8 specific structures found in some (not all) bacterial cells

Answer 46

fimbriae, outer membrane, cell wall, pilus, capsule, plasmid, inclusion, flagellum

Question 47

Life functions that prokaryotic cells accomplish as a single cell

Answer 47

reproduction, metabolism, nutrient processing

Question 48

Encapsulated bacteria

Answer 48

has greater pathogenicity b/c the capsule protect the bacteria against phagocytes (WBCs); phagocytes would attack and destroy thru phagocytosis, but the coating blocks the mechanisms that phagocytes use → they are free to multiply and infect body tissues

Question 49

Mycolic acid

Answer 49

found in non typical cell wall (Myobacterium); virulent: thick waxy nature imparted to cell wall makes for a high degree of resistance to certain chemicals and dyes; the resistance is the basis for the acid fast stain used to diagnose TB (Myobacterium tuberculosis)

Question 50

Mycoplasmas

Answer 50

bacteria that naturally lacks a cell wall; the membrane is stabilized by sterols and resistant to lysis (Mycoplasm pneumonia – walking pneumonia)

Question 51

Stimulus that causes bacteria to sporulate and form an endospore

Answer 51

− The depletion of nutrients, especially an adequate carbon or nitrogen source
− Once the stimulus is received by the vegetative cell → undergoes conversion into sporangium → endospore

Question 52

Germination of spores

Answer 52

(return to vegetative state) – in the presence of water and a specific chemical or environmental stimulus (germination agent) ← often an amino acid or inorganic salt

Question 53

Importance of classification systems

Answer 53

aid in differentiating and identifying unknown species; organized prokaryotes and studying their relationships and origins