Intro To Prokaryotes Flashcards
1
Q
Describe a Coccus/Cocci bacterium/bacteria
A
A single round cell
2
Q
Describe a diplocpccus/diplococci bacterium/bacteria
A
A pair of cocci
3
Q
Describe a tetrad (pl. tetrad) bacterium/ bacteria
A
Group of four cocci
4
Q
Describe a Streptococcus(pl. streptococci)
A
A chain of cocci
5
Q
Describe a Staphylococcus (pl. stsohylococci ) bacterium/ bacteria
A
Cluster of cocci
6
Q
Describe a Bacillus(pl. Bacilli)
A
Single-rod shape
7
Q
Describe a Streptobacillus(pl. streptobaccilli)
A
A chain of rods
8
Q
Why is smaller better for prokaryotes?
A
- More surface area relative to volume (higher surface area to volume ratio)
- Substance enter and diffuse quickly(absorb nutrients faster)
- Growth rate is affected by nutrients( small cells can grow faster than big ones)
9
Q
What is the function of the Capsule slime layer of the bacteria?
A
- Prevent bacteriophage attachment
- Evade phagocytosis
- prevent bacteria from getting dried out
10
Q
What is the function of Pili Fimbriae for bacteria?
A
Allows bacteria to :
- Attach to surfaces or tissues
- Attach to each other
11
Q
What is the function of the cell wall of the bacteria?
A
- Keep cell rigid
- Contain all cellular components
12
Q
What is function of the cytoplasmic membrane of bacteria?
A
- Control access in/out site
- Site of metabolism
- Enzyme functions
13
Q
What is the function of endospores inclusion vacuoles in bacteria?
A
To assist bacteria in surviving environmental changes
14
Q
What is the function of flagellae in bacteria?
A
- To allow bacteria to change location in liquid environment
- Move towards something good
- Move away from something bad
15
Q
What are the key layers of a Gram negative bacterial cell?
A
- Cytoplasm ( ribosomes, DNA, lots of enzymes)
- Cytoplasmic/cell membrane
- Peptidoglycan
- Periplasmic space
- Outer membrane
16
Q
What are the key cell layers of a gram positive bacterial cell?
A
- Cytoplasm (ribosomes, DNA, lots of enzymes)
- Cytoplasmic/cell membrane
- Peptidoglycan
- Periplasmic space
17
Q
Describe the cytoplasm of the prokaryotic cell?
A
- Water
- DNA and Ribosomes
- Enzymes
- Proteins
- Inclusion bodies e.g. storage granules
- Endospores
- NO organelles( no mitochondria, ER, Golgi apparatus, nucleus etc.)
- site of many cellular processes(others take place at cytoplasmic membrane)
18
Q
Describe the cytoplasmic membrane in prokaryotes
A
Fluid mosaic model-interface with the external environment (outside of the cell)
- phospholipids- 30%-40%
- proteins- 60%-70%
Phospholipid belayer :
polar heads - hydrophilic
Fatty acyl heads- hydrophobic
19
Q
What are the functions the prokaryotic cell membrane ?
A
- Transport - from the inside to the outside of the cell and vice versa
- Energy production-
a. Proton motive force
b. Oxidative phosphorylation
c. Phosphorylation - Metabolic processes
- Motility- energy for flagella movement.
- Communication- receptors for sensing if environment is favorable or unfavorable (detecting and sending signals)
20
Q
What function does Cell wall have in controlling what enters and leaves a prokaryote?
A
While present in both gram positive and gram negative, cell wall does not control the flow of what goes in or out
21
Q
Differentiate simple diffusion and passive diffusion
A
Simple diffusion: Materials pass through a membrane without the help of proteins
Passive diffusion: materials diffuse across the plasma membrane with the help of membrane proteins
22
Q
Explain what is Bulk Transport
A
Consists of endocytosis and exocytosis
Endocytosis: absorption of larger molecules that are polar in charge and unable to diffuse through hydrophobic cell membrane
Exocytosis: expulsion of larger molecules that are polar in charge and unable to diffuse through hydrophobic cell maybe
23
Q
What is the peptidoglycan cell wall of prokaryotes?
A
“The bacterial exoskeleton”
A multi-layered mesh around the cell
24
Q
What is the function of the peptidoglycan cell wall?
A
Defines cell shape- coccus, bacillus, vibrio etc.
Maintains osmotic integrity inside of the cell
-it is necessary in order to maintain a high intracellular osmotic pressure(prevents lysis of the cell)
25
What is a prokaryotes’ gram staining character defined by?
Thickness, how the layers are cross linking and gram positive bacteria much thicker peptidoglycan layer
26
Between gram positive and gram negative cell walls, which is thicker?
Gram positive bacteria are much thicker
27
What is a peptidoglycan?
A large molecule that is unique only to bacteria
28
Describe the contents of the peptidoglycan Layer
Polysaccharide:
N-acetylglucosamine( NAGj
N-acetylmuramic acid(NAM)
-some amino acids
- Long chains made next to each other that are then cross-linked
- Mesh-like net around the cell
29
Gram negative and gram positive have different....
Cross links
30
What type of linkage occurs between NAM and NAG ?
B 1-4 linkage
31
What are the differences between teichoic acids and lipoteichoic acids?(Gram positive bacteria )
Teichoic acid= acidic polysaccharide
- Polymer of phosphate plus ribitol or glycerol
- If anchored into cell membrane= lipoteichoic acid
32
What are the functions of teichoic acids and lipoteichoic acids?
- Can be a substantial component cell wall
- Anchor other proteins; bind molecules for transport e.g. Mg 2+
- Responsible for overall negative charge of cell surface
- Targets for vaccine and drug development
33
Where are teichoic and lipoteichoic acids?
Gram positive bacteria
34
Bacterial endospores enable resistance to:
- Drying
- Chemicals
- Heat
- Radiation
35
What are the functions of bacterial endospores?
- Survival adaptations from unfavorable environments
- Released when the producing cell dies
- help with long term survival(>100-1000s of years
- Dehydrated, no active protein synthesis or metabolism, unique layers and components
36
What is sporulation?
Formation of endospores
37
What is germination?
Return to vegetative growth when the conditions are favorable
38
Describe the 2-phase life cycle of bacterial endospores
Vegetative cell- bacterial cell is metabolically active and growing
Endospores-in unfavorable environments the cell stores its DNA in the core of the cell and when the timing is right, and conditions are favorable it will become metabolically active again
39
Describe bacterial endospores and their special features
- Unique cellular structure
- Chemical and enzymatic resistance
- Specialized peptidoglycan
- Germ cell wall
- Major permeability barrier
- house’s cell’s DNA
- Dipicolinic acid(10% of spore, dry weight)
40
What is the function of the core layer of the endospores?
Mostly dehydrated and metabolically inactive ; contains dipicolinic acid; chromosomal DNA and ribosomes
41
What is the function of the cortex layer of endospores?
Occupies most of the spore volume;- made up from a unique thick layer of special type of peptidoglycan
42
What is the function of the coat layer of endospores?
Contains keratin; impermeable to most toxins and chemicals(contributes to resistance)
43
What is the function of the exosporium layer of the endospores structure?
Thin outer glycoprotein layer
44
What is the periplasm in gram negative bacteria?
The area between the outer membrane and cytoplasmic membrane
45
What is the periplasm of gram positive bacteria?
Space between the cytoplasmic membrane and peptidoglycan
46
What is the function of periplasmic space?
- Transport(binding proteins)
- Breakdown of food molecules (hydrolysis enzymes)
- Chemoreceptors (chemotaxis: detecting chemical signals)
47
Describe the periplasmic space/ periplasm
Gel-like rather than true space
High concentration of proteins
48
What type of bacteria has an outer membrane?
Gram negative
49
What is the purpose of the outer membrane?
Part of the bacterial defense against the action of antibiotics: some don’t penetrate the cell because their entry is blocked by the outer membrane
50
Describe the porins of the outer membrane of gram negative
Outer membranes contains porins
- proteins that form channels/tunnels through the outer membrane
- Porin size vary, blocking or allowing the entry of certain products
51
Describe the permeability of the outer membrane of gram negative bacteria
Not permeable to proteins or large molecules (traps proteins in periplasmic space -e.g. degradation enzymes, binding proteins, chemoreceptors)
52
What is the outer most layer of gram negative outer membrane?
Lipopolysaccharides
53
What are the layers of the endospores?
Core layer
Cortex layer
Coat layer
Exosporium layer
54
Lipopolysaccharide is also known as ...
“Endotoxin”
55
What are the 3 components of lipopolysaccharides?
1. O-specific polysaccharides
2. Core. Polysaccharide
3. Lipid A
56
Describe the O-specific polysaccharides in lipopolysaccharides
- Very variable between different species
| - “O antigenl
57
Describe the core polysaccharide in lipopolysaccharides
Comprised of 10-15 different sugars
58
Describe Lipid A in lipopolysaccharides
It anchors the lipopolysaccharide in the phospholipid layer. The active “toxic” component
59
Why are lipopolysaccharides medically important?
- Important antigen
- Contributes to some of the symptoms for some gram-negative infections
- Immune system responds to the lipopolysaccharides (good in small amounts, bad in higher)
- Fever and chills
60
What happens when a bacterium is in a harsh environment?
Sporulation (6-8 hours)
61
How is sporulation done?
- bacteria copies it’s genome and pinches the plasma membrane
- spore septum forms
- a double membrane forms around spore septum
- peptidoglycan fills the spore to finalize the spore forming
- endospores is released from the spore with the copier genome and finds a favorable environment to germinate
62
Differentiate slime layer and capsule
Slime layer- less of it, relatively easy to move, loosely organized
Capsule- thick, not easy to remove, highly organized, Capsular Polysaccharides (CPS)/ K Antigen
63
How can bacteria change the color of an algae plate?
-If bacteria are producing a capsule, it changes hows the colonies appear when they are grown on an agar plate
64
What is a function of the capsule in prokaryotes?
-Some capsules can be used to create vaccines to protect against infections e.g. meninges
65
What is the size fimbrae?
- 2-10 nm diameter
| - 1-2 microns long
66
What is the fimbrae known as?
Short attachment, common pili
67
What is the size of the Pillus?
- 2-10 nm in diameter
| - from 10 - over 20 microns long
68
The pillus is involved in_____________
Conjugation
69
A prokaryote has atrichous flagella, what is this?
No flagella
70
A Prokaryote has a polar flagella, what is this?
Single flagella at one or both ends
71
A prokaryote has a lophotrichous flagella, what is that?
Bunch at the end
72
A prokaryote has amphitrichous flagella, what does this mean ?
Bunched flagella at one point
73
A prokaryotic cell has Peritrichous flagella, what is that?
Flagella all around cell
74
Differentiate spirillum and spirochete bacteria
Both are spiral but spirilium is shorter and thicker than spirochete
75
What is a coccobacillus?
Mix of a rod and circular bacteria
76
Describe the difference in staining in gram positive and negative bacteria
Gram positive- thick peptidoglycan and will stain purple
Gram negative- thin peptidoglycan and will stain punk by Safarin counter stain
77
Explain the mesh work of gram positive bacteria
NAG and NAM alternating
Each NAM has a tetrapeptide sticking out connecting to another tetrapeptide via pentagon INR bridge
78
Describe the mesh work of the gram negative cell wall
Alternating chains of NAM and NAG
with a different tetrapeptide than gram positive
Tetrapeptide from NAM connected by a peptide bond
79
Name 2 medically important endospores ?
Clostridia( tetanus) and bacillus (B anthracis)
80
What is a terminal endospores?
Endospore at the end of the cell
81
What is a sub terminal endospore?
Endospore is between the terminal and central
82
What is a central endospore?
Spore in the center of the cell
83
What part of lipopolysaccharides cause symptoms?
The toxic lipid A
84
What 3 structures are external to cell wall?
Capsule, flagella and fimbrae pilli
85
How do bacterial capsules help their bacteria ?
Helps evade the immune system
86
Why is motility important?
- gain access to different areas/body sites
- moves in response to stimulus
- chemotaxis
- move around body in a clockwise or anti clockwise motion
Not all bacteria are motile via flagella
87
A bacteria moves around in a clockwise motion, also known as...
Tumbling motion
88
A Bacteria moves around in an anti clockwise motion, also known as...
Linear. Motion
89
What is the H antigen?
The hair like antigen- flagella antigen
