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Micro > Chapter 3 > Flashcards

Chapter 3 Flashcards

1
Q

Why is it important that cells have high surface area to volume ratio

A

It increases nutrient uptake and diffusion of molecules across the cell
The bigger the cell the more energy expended to move things across the cell

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2
Q

What is the cell envelope and what is it made of

A

Layers that surround the cell
Made of plasma membrane and cell wall and sometimes another additional layer such as capsule or slime layer

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3
Q

What molecules move across the cell easiest

A

Small, non polar

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4
Q

What are some plasma membrane functions

A

Innermost membrane that encompasses the cytoplasm
Selectively permeable that takes nutrients and eliminates waste
Interacts with external environment
Required for all living organisms

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5
Q

What are hydrophilic lipids

A

Contain polar ends that interact with water

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6
Q

What are hydrophobic lipids

A

Non polar rails that are insoluble in water and interact with each other

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7
Q

What are peripheral membrane proteins

A

Loosely connected to membrane and can be easily removed

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8
Q

What are integral membrane proteins

A

Amphipathic proteins that are embedded within the membrane and not easily removed
Hydrophobic part is buried in the membrane and hydrophilic interacts on the outside

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9
Q

What are hopanoids

A

Hydrophobic molecules similar to cholesterol that give structure and intengrity to the plasma membrane
They increase structural rigidity for bacteria

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10
Q

What are functional membrane micro domains

A

Platforms used for protein complex assembly

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11
Q

What are macronutrients

A

Required in large amounts
Found in organic molecules
Contain cations that contribute to activity and stability of molecules and cell structures

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12
Q

What are micronutrients

A

Required in small amounts
Can support microbial growth and works to assist enzyme catalysis and maintain protein structure

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13
Q

What are growth factors

A

Organic compounds required for survival

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14
Q

What are siderophores

A

Secreted by bacteria, work with ferric iron for transport into cell
They hold onto iron until needed

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15
Q

Why is iron so crucial for bacteria

A

It is usually a limiting nutrient for many bacteria
No iron means no enzyme functionality

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16
Q

Why is the cell wall essential to bacteria in regards to osmosis

A

Water goes in and will explode to the bacteria without the cell wall
The cell wall pushes back on osmotic stress

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17
Q

What is peptidoglycan

A

Mesh like polymer that has two alternating sugars, NAM and NAG
they have helical shape and their chains are cross linked by peptides for strength

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18
Q

What is direct cross link

A

Connecting carboxyl group and amino groups between amino acids

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19
Q

What are indirect cross link

A

Peptide inter bridge may form

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20
Q

What is gram positive

A

Stains purple, thick peptidoglycan
Can be monoderm which is having a singular membrane

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21
Q

What is gram negative

A

Stains pink or red
Thin peptidoglycan and outer membrane
Has diderm which has plasma membrane and outer membrane

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22
Q

Why does penicillin work against gram positive

A

Because it has a larger peptidoglycan layer than gram negative

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23
Q

What does the peptidoglycan structure look like

A

Mesh like polymer that forms long strands from its polymers
NAG and NAM alternate
Strands have helical shape and are cross linked with peptides for strength

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24
Q

What is direct cross linking

A

Connecting carboxyl group and amino groups between amino acids

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25
Q

What is indirect cross linking

A

Peptide inter bridge may form

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26
Q

What are gram positive cell walls mostly made of

A

Peptidoglycan and teichoic acid

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27
Q

What is teichoic acid

A

Polymers of glycerol that help maintain cell envelope
Protects against environmental substances and binds to host cells to initiate infection
Is negatively charged

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28
Q

What are gram negative cell walls composed of

A

Thin layer of peptidoglycan surrounded by outer membrane
The outer membrane has lipopolysaccharides (LPS)
No teichoic acid in gram negative

29
Q

What does LPS consist of

A

Lipid A which is buried in the membrane
Core polysaccharide which is a 10 sugar structure joined to lipid A
O side chain which is a polysaccharide that extends outward from the core

30
Q

What are some importances of LPS

A

Contributes to negative charge on cell surface
Helps stabilize outer membrane structure
Creates permeability barrier
Hosts defense protection and acts as endotoxin
Elicits strong immune response

31
Q

What happens in hypotonic environments

A

Solute concentration outside cell less than inside cell so water moves in and cell swells
Cell lysis occurs

32
Q

What happens in hypertonic environments

A

Solute concentration outside cell greater than inside so water leaves and cell shrivels
Plasmolysis occurs which is shrinking of cytoplasm

33
Q

What are lysozymes

A

Part of immune system that breaks bonds between NAG and NAM

34
Q

What are two ways that would cause a cell to lyse in hypotonic solution

A

Penicillin inhibits peptidoglycan synthesis
Lysozymes break NAM and NAG bonds

35
Q

What is the difference between cidal and static

A

Cidal is when a cell explodes and static is when a cell dies of old age

36
Q

What is the glycocalyx

A

Polysaccharide extension that aids in attachment to solid surfaces
Examples include the capsule and slime layers

37
Q

What are capsules

A

Well organized layers made of polysaccharides that are bonded covalently and difficult to wash away
They are visible in light microscope and can resist phagocytosis
Can also protect from desiccation

38
Q

What are slime layers

A

Polysaccharide layers that are unorganized and easy to wash away
Slime may facilitate motility

39
Q

What are s layers

A

Geometric patterns made of protein that aid in protecting from ion and ph fluctuations, osmotic stress, enzymes, and predation
Maintain shape and rigidity of cell and promote adhesion to surface
Protect from host defenses

40
Q

What is a cytoskeleton

A

Protein filaments that polymerize to form functional filaments that extend to dimension of cell
Participate in cell division, localize proteins, and maintain cell shape

41
Q

What are some examples of bacterial cytoskeleton molecules

A

FtsZ which are many bacteria and from rings at center of dividing cell that constrict as daughter separates (very good at binary fission)
MreB which are many rods and maintain shape by positioning peptidoglycan synthesis machinery
CreS which maintains curve shape

42
Q

What are intracytoplasmic membranes

A

Plasma membrane foldings
Can be observed in photosynthetic bacteria or bacteria with high respiratory activity

43
Q

Ask Annabelle about slide 38

A

Idk

44
Q

What are carboxysomes

A

CO2 fixing bacteria
Contain carbonic anhydrase that releases co2 into shell and accumulates in high concentration then rubisco makes sugar

45
Q

What are micro compartments

A

Compartments for specific functions not bound to membranes

46
Q

What are gas vacuoles

A

Involved in bacterial movement and provide buoyancy to aquatic bacteria

47
Q

What are magnetosomes

A

Found in aquatic bacteria that magnetite particles for orientation in earths magnetic field

48
Q

What are ribosomes

A

Site of protein synthesis
70s because 30s for small unit and 50 s for large unit

49
Q

What is the nucleoid

A

Usually not membrane bound
Chromosome and associated proteins found here
Usually a closed, circular, double stranded dna molecule
Supercoiling and associated proteins aid in folding and structure

50
Q

What are plasmids

A

Extra chromosomal dna, usually small and circular
Exist and replicate independently of chromosome

51
Q

What are episomes

A

Plasmids that can integrate into a chromosome

52
Q

What is the difference between pili/fimbriae and flagella

A

Pili and fimbriae are used for attachment
Flagella aids in movement

53
Q

Why are sex pili important

A

They are genetically encoded on plasmids and are required for conjugation
They are specialized genes are allow for gene transfer

54
Q

What is monotrochous

A

One flagellum

55
Q

What is a polar flagellum

A

Flagellum at the end of a cell

56
Q

What is amphitrichous

A

One flagellum at each end of a cell

57
Q

What is lophotrichous

A

Cluster of flagella at one or both ends

58
Q

What is peritrichous

A

Spread over entire surface of cell

59
Q

What are the three components of a bacterial flagella

A

Filament which extends from cell surface to the tip
Basal body which is embedded in the cell envelope
Hook which is a short curved segment

60
Q

How is flagella synthesized

A

Flagellin molecules transported through hollow filament
Filament subunits self assemble with help of filament cap at the tip not the base

61
Q

How do flagella move and what is the importance or directionality in regards to them

A

They rotate like a propeller
If moving counterclockwise they run in forward direction
If clockwise they tumble instead

62
Q

What are spirochete and how do they move

A

Contain multiple internal flagella
Move by corkscrew movement since multiple flagella form axial fibril which winds around cell and exhibits spinning and flexing movements

63
Q

True or false: twitching and gliding is true motility

A

False, it’s Brownian movement which isn’t true motility

64
Q

What is involved with twitching motility

A

Pili at the end of cell
Short jerky motions
Cells are in contact with each other and surfaces

65
Q

What does gliding consist of

A

Smooth movements that don’t require appendages

66
Q

What is chemotaxis

A

Movement toward a chemical attractant or away from chemical repellent
In presence of attractant or repellant the tumbling frequency is reduced

67
Q

What are chemoreceptors

A

Chemical attractants and repellants bind to them and transmit signals throughout chemo sensing system

68
Q

What are bacterial endospores

A

Complex, dormant structures that are formed by some bacteria in response to nutrient depletion
Can resist uv radiation, gamma radiation, chemical disinfectants

69
Q

What is sporulation

A

Process of endospores formation
Usually starts when growth slows due to lack of nutrients
Produces dormant cell that can persist until nutrients are available and growth resumes

Micro (8 decks)

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