Exam 1: Ch 3: Prokaryotes Flashcards

1
Q

3 characteristics that help differentiate prokaryotes from eukaryotes:

A

− 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)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Bacterial chromosome

A

has all the DNA that makes the bacteria functional

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Actin cytoskeleton

A

helps w/structure and movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Fimbriae

A

can attack/will make bacteria more pathogenic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Plasmid

A

luxury DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Prokaryotic cell contents

A

− 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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Prokaryotic cell size

A

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)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Prokaryotic cell shape

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Prokaryotic cell arrangement

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Prokaryotic cell organization

A
−	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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Flagella

A

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”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Testing for flagella

A

− 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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Pili

A

allow bacteria to attach to surfaces or to other bacteria

two types: conjugation pili & fimbriae (attachment pili)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Conjugation pili

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Fimbriae

A

(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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Glycocalyces

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Slime layer

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Capsule

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Biofilms

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Cell membrane

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Fluid mosaic model (cell membrane)

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Concentration gradient (cell membrane)

A

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

23
Q

Tonicity (cell membrane)

A

animal always wants an isotonic solution

24
Q

Selective permeability (cell membrane)

A

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

25
Q

Osmosis (cell membrane)

A

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

26
Q

Cell wall

A

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

27
Q

Peptidoglycan

A

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)

28
Q

Gram + cell wall

A

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

29
Q

Gram - cell wall

A

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

30
Q

Lipopolysaccharides

A

(Lipid A + polysaccharide) –

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

31
Q

Acid fast/waxy/myobacteria

A

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)

32
Q

Cytoplasm

A

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

33
Q

Ribosomes

A
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
34
Q

Inclusions

A

store viruses; burst open → viruses enter environment

35
Q

Nuclear region

A

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

36
Q

Endospore

A

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

37
Q

Unique groups of bacteria

A

intracellular parasites

archaea bacteria

38
Q

Intracellular bacteria

A

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

39
Q

Archaea bacteria

A

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

40
Q

Phenotypic methods of classification

A

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

41
Q

Molecular methods of classification

A

DNA sequence, RNA sequence, protein sequence

42
Q

Species in prokaryotes

A

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

43
Q

Subspecies/strain/type of prokaryotes

A

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

44
Q

Serotype of prokaryotes

A

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

45
Q

5 structures found in all bacterial cells

A

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

46
Q

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

A

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

47
Q

Life functions that prokaryotic cells accomplish as a single cell

A

reproduction, metabolism, nutrient processing

48
Q

Encapsulated bacteria

A

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

49
Q

Mycolic acid

A

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)

50
Q

Mycoplasmas

A

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

51
Q

Stimulus that causes bacteria to sporulate and form an endospore

A

− 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

52
Q

Germination of spores

A

(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

53
Q

Importance of classification systems

A

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