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Morphology and Physiology of Bacteria Flashcards

1
Q

What is the unit of measurement for bacteria size?

A

micron (micrometer)

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2
Q

What is the typical size range of bacteria?

A

0.02-1.5 micrometer in diameter and 3-5 micrometer in Length

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3
Q

what is the limit of resolution of the naked eye?

A

200 microns

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4
Q

What are the different shapes of bacteria?

A

Cocci
Bacillus
Vibrio (comma shaped)
Spirilla (Rigid spiral)
Spirochaetes (flexible spiral)
Actinomycetes (Branching filamentous)
Mycoplasmas

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5
Q

Which bacterial shape is rod like?

A

Bacillus

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6
Q

Which bacterial shape is comma ?

A

Vibrio

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7
Q

Which bacterial shape is Rigid spiral ?

A

Spirilla

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8
Q

Which bacterial shape is Branching filamentous

A

Actinomycetes

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9
Q

Which bacterial shape is flexible spiral?

A

Spirochaetes

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10
Q

What is unique about Mycoplasmas compared to other bacteria?

A

They lack a cell wall and have no stable morphology that is no specific shape (Pleomorphic)

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11
Q

What are the major components of a typical bacterial cell?

A

Cell envelope
cytoplasm
nucleoid
pili
flagella
plasmids
ribosomes

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12
Q

Functions of bacterial cell membrane?

A

encloses cytoplasm
site of oxidative phosphorylation
control movement of substances in and out of the cell

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13
Q

Role of bacterial cell wall

A

Provides rigidity, protects from osmotic lysis and give shape to the cells

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14
Q

What is the primary component of bacterial cell walls?

A

Peptidoglycan (murein)

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15
Q

Which bacterial structure allows adhesion to host surfaces?

A

Pilli (fimbriae)

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16
Q

what are plasmids and their functions

A

Extra-chromosomal DNA that carries genes for antibiotic resistance and virulence factors

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17
Q

What is the glycocalyx and what forms can it take?

A

A secretory layer external to the cell wall which can be a capsule (rigid) or slime layer (loose)

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18
Q

What is the functions of bacterial capsule?

A

Protects against phagocytosis and helps in immune evasion

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19
Q

which bacterial species has a capsule made of polypeptides instead of polysaccharides?

A

Bacillus anthracis

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20
Q

function of bacterial flagella

A

Locomotion via a propeller- like motion

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21
Q

Structure of flagella

A

—> number of proteins including flagellin that are well embedded
—> consist of various rings ( C, MS, P ,L Ring) which help filament to move

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22
Q

What is the main difference in the cell wall of the Gram Positive bacteria compared to the Gram-Negative bacteria?

A

Gram +ve have thicker peptidoglycan layer

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23
Q

Do Gram-Positive bacteria have an outer membrane?

A

No

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24
Q

What is the role of teichoic acids in Gram Positive bacteria?

A

They provide structural support and regulate ion transport endotoxin activity antigenic adhesion to host cells

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25
Why are Gram- Positive bacteria more susceptible to lysosome?
Their thick peptidoglycan layer is directly exposed to the environment and can be broken down by lysozyme
26
Do Gram-Positive have periplasmic space?
No
27
What additional structure do Gram -ve have that Gram +ve bacteria lack?
An outer membrane
28
What is the function of the outer membrane in Gram -ve bacteria?
Acts as a major permeability barrier, protecting against antibiotics and toxins
29
what is the periplasmic space and what is stored there?
The space between the inner and outer membranes, which degrative enzymes are stored
30
why are the Gram -ve bacteria more resistant to antibiotics?
Their outer membrane prevents large molecules form easily passing through
31
What component of Gram-ve acts as an endotoxin?
Lipopolysaccharides (LPS) in the outer membrane
32
Which type of bacteria has thinner peptidoglycan layer?
Gram -ve bacteria
33
Which bacteria lack peptidoglycan in their cell walls?
Mycoplasmas (they lack a cell wall entirely)
34
Which type of bacteria is more susceptible to penicillin?
Gram Positive since they lack outer membrane that would block the antibiotic entry
35
What process do bacteria use to reproduce?
Binary fission
36
how does binary fission progress?
Exponentially (1--->2--->4--->8--->16)
37
Generation Time
Time taken to complete each cycle
38
What factors control bacterial generation time?
Environmental conditions (water, nutrient, carbon, nitrogen, phosphorus) and bacterial species
39
Which bacteria have the fastest and slowest generation times?
Clostridium perfringes (approx 10 mins fast) Escherichia coli (approx 20 mins) Mycobacterium tuberculosis (12-16 hrs slow)
40
why growth curve is used for the study of bacteria?
To count the number of bacteria in a particular condition
41
What are the different phases of bacterial growth in a culture?
Lag phase Log (exponential) phase Stationary phase Death Phase
42
What happens during the lag phase of bacterial growth?
Bacteria acclimate to the environment, produce required proteins and prepare for cell division but do not multiply significantly
43
Why do bacteria enter the stationary phase?
Growth slows due to depletion of nutrients, accumulation of toxins and changes in pH
44
What causes cell death in the death phase of bacterial growth?
Accumulation of toxic waste, depletion of essential nutrients and unfavorable environmental changes
45
Why do some cells remain viable even in the death phase?
Some bacteria can form spores or enter a dormant state to survive unfavorable conditions
46
What are some ABIOTIC factors affecting microbial growth?
Oxygen, temperature, osmotic pressure, salinity, sunlight
47
What are BIOTIC factors influencing microbial diversity?
Presence of predators, symbiotic relationships, competition
48
What are some organic compounds affecting microbial diversity?
Carbohydrates, polysaccharides, proteins and amino acids
48
How do heavy metals influence bacterial diversity?
Metals like Lead (Pb), Iron (Fe) and Copper (Cu) can be toxic or essential for bacterial metabolism
49
What are the two main sources of energy for bacteria?
Chemical compounds (Chemotrophs) and Light (Phtototrophs)
50
What is the difference between phototrophs and chemotrophs?
Phototrophs use light for energy while chemotrophs use chemical compounds
51
What are the two main types of chemotrophs?
chemoautotrophs and chemoheterotrophs
52
How do photoautotrophs obtain carbon?
From carbon dioxide (CO2)
53
What is an example of a photoautotrophic bacterium?
Cyanobacteria
54
What is the final electron acceptor in aerobic respiration?
Oxygen (O2)
55
What happens if an organism uses an inorganic compounds instead of O2 as the final electron acceptor
It undergoes anaerobic respiration
56
What are the two types of bacteria based on their electron sources?
Lithotrophs (inorganic compounds) and Organotrophs (organic compounds)
57
What is the carbon source for autotrophs bacteria?
Carbon Dioxide
58
What is the carbon source for heterotrophic bacteria?
Organic compounds
59
Which bacteria use ammonia as an electron source?
Nitrosomonas (chemolithotroph)
60
Which bacteria require hemin (X factor) and NAD (V factor) for growth?
Haemophilus influenzae
61
What are the environmental factors affecting bacterial growth?
Temperature gas(oxygen) pH osmotic pressure
62
What are some essential metal ions for bacterial growth?
Potassium Calcium Magnesium Iron
63
Name two vitamins required by some bacteria and their producers
Riboflavin (Clostridium tetani) Thiamine B1 (Bacillus anthracis)
64
What is the role of Zinc in Bacterial metabolism?
Zinc is involved in metabolic activities DNA and RNA biosynthesis and DNA binding proteins
65
Why is copper important for bacteria?
It is essential for cellular respiration and is a component of cytochromes in ATP synthesis
66
What is the function of boron in bacterial cells?
It is a component of cytochromes in ATP synthesis and is involved in genetic biosynthesis and energy production
67
How do oxygen requirements differ among bacteria?
Some are strict aerobes, some are facultative anaerobes and others are strict anaerobes
68
Name an example of a strict aerobe
Pseudomonas species
69
What is a facultative anaerobe?
A bacterium that can grow with or without oxygen
70
Name two examples of strict anaerobes
Clostridium species Lactobacillus species
71
What are fastidious organisms?
Bacteria that require specific nutrients like vitamins and growth factors
72
What type of environment does Helicobacter pylori require?
Microaerophilic enviroment
73
Why does Haemophilus influenzae require chocolate blood agar?
It needs X and V factors (hemin and NAD) from blood to grow
74
Where do obligate anaerobes grow in a test tube?
They grow at the bottom because oxygen is toxic to them
75
Which bacteria grow at the center of the test tube where oxygen levels are low?
Microaerophiles
76
Which bacteria grow best at moderate temperature (20-45oC)
Mesophiles
77
What is the optimal temperature range for thermophiles?
50-70 oC
78
Which bacteria can grow at low temperature but prefer slightly warmer conditions?
psychrotrophs
79
What happens to bacterial membranes at very low temperatures?
They gel leading to a stop in growth dur to reduced metabolic activity
80
81
82
How does bacterial growth respond to a temperature range of 30 oC?
It remains within an optimal range but extreme temperature reduce growth
83
Which enzyme is most affected by low pH
Amylase
84
What is the general trend of enzymatic activity as pH increases beyond the optimal level?
It decreases
85
What type of Bacteria thrive in acidic environments (pH 1-5)
Acidophiles
86
Where are alkaliphiles typically found?
Soda lakes Alkaline soils Industrial waste
87
What happens to the growth rate of alkaliphiles if the pH moves toward neutral or acidic levels?
It decrease sharply
88
Which enzymes shows optimal activity in a basic environment?
Arginase around pH 9-10
89
Why does enzyme activity decline at extreme pH levels?
Extreme pH causes enzyme denaturation altering its active sites
90
What happens when an enzyme's active site is denatured?
The substrate no longer fits and the enzyme loses its function
91
How does enzyme structure relate to its function?
The specific shape of the active site allows binding to a substrate if altered the enzyme becomes nonfunctional
92
What is the consequences of enzyme denaturation in biological systems?
It disrupts metabolic processes leading to cell malfunction or death
93
Can denatured enzyme regain their functions?
In some cases, mild denaturation can be reversible, but severe damage is usually permanent

microbiology (5 decks)

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