Lecture Exam 2 Flashcards
1
Q
Prokaryotic Cell
A
Simple structure
No organelles, No nucleus
DNA is in cell wall
Peptidoglycan in cell wall
Diameter Size <1-5m
Reproduce process: Binary fission
2
Q
Eukaryotic Cell
A
Complex structure
Many organelles
DNA inside nucleus
No Peptidoglycan
Diameter size 10-100m
Reproduce process: Mitosis
3
Q
The cell wall of a bacterial cell is
A
Complex and semirigid
4
Q
The 3 major groups of bacteria:
A
Gram-positive bacteria, Gram-negative bacteria, and Mycoplasmas
5
Q
How do the 3 major groups of bacteria differ?
A
The structure of their cell walls
6
Q
Gram-negative bacteria has the most complex wall structure
A
7
Q
The cell wall of gram-negative bacteria is composed of
A
An OUTER MEMBRANE component and a THIN layer of peptidoglycan molecule.
8
Q
The outer membrane is a bilayer composed of an outer layer and an inner layer.
A
Outer layer consists of: LPS, phospholipids, and membrane protein molecules
Inner layer consists of: phospholipid and membrane protein molecules
9
Q
Each phospholipid molecule has a
A
Hydrophilic HEAD and 2 hydrophobic tails
10
Q
The liquid portion of the LPS molecule
A
Lipid A
11
Q
Endotoxin
A
LPS
12
Q
Bacterial toxin
A
Endotoxin
13
Q
Connects the outer membrane to the layer of peptidoglycan molecules
A
Lipoprotein molecule
14
Q
The cell wall of gram positive consists of
A
A THICK layer of peptidoglycan molecules
NO outer membrane component
15
Q
Mycoplasmas
A
DO NOT contain a cell wall
16
Q
Mycoplasmas shapes:
A
are irregular or undefined due to lack of cell wall
17
Q
Bacteria Mycoplasmas pneumoniae causes
A
Atypical pneumonia (pneumonia without its typical clinical symptoms
18
Q
Why are mycoplasmas considered the third group of bacteria?
A
Because the lack of cell wall
19
Q
Why do mycoplasmas stain PINK at the end of Gram-staining even though they are Gram-Positive?
A
The lack of cell wall makes it difficult for them to retain the purple crystal violet dye. The CV-I complex can be easily washed out of the cell after alcohol wash during the Gram Staining.
20
Q
What are the functions of a bacterial cell wall?
A
Protection, Cell shape, Turgor pressure
21
Q
What are the major cell shapes of bacteria?
A
Coccus, bacillus, and spiral shape (vibrio, spirillum, or spirochete)
22
Q
What is turgor pressure?
A
aka osmotic pressure (water pressure inside a cell)
23
Q
Cytoplasmic membrane (Plasma membrane)
A
The membrane that encloses the cytoplasm (the interior of the cell).
24
Q
What is the function of the cytoplasmic membrane?
A
To regulate what comes in and out of the cell
25
Selective permeability
Specific and selective
26
What is the structure of cytoplasmic membrane?
A bilayer of phospholipid molecules with membrane proteins in between.
27
A fluid-filled space found between the outer membrane component and the cytoplasmic membrane.
Periplasm
28
Periplasm is ONLY found in
Gram-negative bacteria
29
What are the bacteria appendages?
Fimbriae, pili and flagella
30
Sit on the ends of the cell or are evenly distributed
Shorter, straighter and thinner than flagella
Fimbriae
31
Longer than fimbriae
Pili
32
Protein molecules that make up Fimbriae and Pili
Pilins
33
Joining two bacterial cells
Sex pili
34
Functions of Fimbriae and pili
For attachment purpose
35
Functions of Flagella
For locomotive purposes
36
Single flagellum at one end
Monotrichous
37
One or more flagella at both ends of cell
Amphitrichous
38
Many flagella at one end of cell
Lophotrichous
39
Flagella all over the surface of a cell
Peritrichous
40
A slippery mucoid substance that forms the outermost layer
Glycocalyx
41
Organized and firmly attached
Capsule
42
Unorganized and loosely attached
Slime layer
43
Function of a capsule
Protection of drying out and protection from phagocytosis
44
Forms inside the cell when environmental conditions are not favorable for growth
Endospore
45
Can be released to outside once formed
Endospore
46
Belonging to bacterial special genus Clostridium and genus Bacillus
Endospore
47
Do not form endospores
Vegetative cells
48
Formed by the process of sporulation
Endospore
49
The differences between endospores and spores tbc
Endospores are dormant, resting, and non-growing structures formed by certain bacterial species when environmental conditions are not favorable for growth. When conditions become favorable the endospores will germinate to form actively growing vegetative cells. Endospores are infectious and cause disease.
50
Staining
Coloring
51
Why do we need to stain microorganisms?
Because most microbes are colorless, and we use brightfield microscope in out lab to observe microbes. A stain must be used in order to create a light dark contrast between the background and the microbial specimen.
52
What are stains?
Stains are dye-molecules that bind to microbial cells or microbial cellular structures.
53
Stains are chemical salts
composed of a positively charged ion and a negatively charged ion. One of the two is responsible for the actual color in the dye.
54
Chromophore
The colored portion of a stain.
Could be negative or positive.
55
When color is in the positive ions
basic dye
56
when color is in the negative ions
acidic dye
57
Bacterial cells are
negatively charged and pH7
58
How does the basic dyes work?
Basic dyes are attached to the negatively charged bacteria and binds to the surface due to opposite electrical charges
59
How does the acidic dyes work?
Two negatives repel each other, therefore, the acidic dye stains the background.
60
Procedure for basic staining
1. Prepare a microbial smear on a microscope slide
2. Fix it
3. Apply the stain
4. Rinse with tap water
5. Blot dry
6. Observe
61
Why do we need to fix the microbes before staining?
Fixing is to kill the microbes and to attach them to the slide.
62
How do we fix the microorganisms?
By using heat provided by bacti-cinerator
63
What are the staining techniques?
Simple, Differential, and Special
64
What is the purpose of simple staining?
To highlight the entire microorganism so the cell shape and basic structures are visible.
65
What are the 2 most frequently used differential staining techniques?
Gram staining and Acid-fast staining
66
What does the Gram staining technique do?
It differentiates gram-positive bacteria from gram-negative bacteria
67
Gram staining procedure
1. Apply Crystal violet to Heat fixed bacteria smear
2. Rinse
3. Cover with iodine
4. Rinse
5. Wash with alcohol
6. Rinse
7. Apply safranin
8. Rinse
9. Blot dry
10. Observe
68
A stain that will stain ALL microbes the SAME color
Primary dye
69
What is a mordant?
a color intensifier
70
What is an example of a mordant?
Iodine
71
What is an example of a decolorizing agent?
Alcohol
72
A secondary stain is
also known as a counterstain
73
At the end of Gram-staining,
Gram-Positive bacteria RETAIN the primary dye. Gram-Negative RETAINS the counterstain. Gram-negative stays PURPLE. Gram-positive is not PINK
74
What is the concept behind Gram-Staining?
The results are dependent upon the structure of the cell wall of the bacteria.
75
How does acid-fast staining work?
Acid-fast bacteria can RETAIN the carbolfuchsin (red primary stain) in their waxy cell walls. Non-acid fast bacteria appears blue after alcohol wash and being stained with counterstain methylene blue.
76
What are examples of acid-fast bacteria?
Mycobacterium tuberculosis and Mycobacterium leprae
77
What is the purpose of special staining?
To color, detect, and demonstrate the presence of various structures in bacteria like capsule, endospore, and flagella.
78
How do we stain capsule itself?
We use a technique called negative staining
79
Negative staining procedure:
1. Use a basic dye to stain the bacterial cell itself.
2. Then use an acidic dye to stain the background.
80
What is microbial growth?
An increase in the numbers of a microbial cell
81
What is media?
The nutrients
82
What is Culture?
When microbes grow in the presence of nutrients
83
What are the requirements for the medium?
1. Must provide an energy source
2. Must be sterile
84
How many forms can medium come in?
2; solid and liquid
85
What is a broth?
a liquid form of medium
86
How can a medium come if in solid form?
as a deep or slant in a test tube or a petri dish
87
What is agar?
A polysaccharide (a polymer of sugar molecules)
88
Agar itself is a
solidifying agent
89
What are the advantages of using agar medium?
1. Microorganisms do not break down the structure of agar.
2. It is easier to observe microbial growth, as colonies.
3. Provides an increased surface area for microbial growth
90
What is a colony?
a visible mass of microbial cell growth belonging to a single microbial species
90
What does fastidious bacteria require?
Special culturing conditions such as longer incubation time, special media requirements, or anaerobic environment.
91
What are the 4 types of media?
Complex, Enriched, Selective, and Differential
92
What is the purpose of using complex media?
For cultivating bacterial sample collected from the environment or culturing bacteria in a lab on a regular basis.
93
What are examples of complex media?
Nutrient broth, nutrient agar and tsa, or tryptic soy broth
94
What is the purpose for using enriched media?
For cultivation of pathogenic bacteria from human clinical samples such as urine, blood, sputum, nose sample etc.
95
Why use enriched media to cultivate human clinical samples?
Enriched medium is used to encourage the growth of a particular microbial species of interest from a mixed population.
96
What is an example of enriched media?
Blood agar
97
What are the chemical components of blood agar?
5-10% animal blood
98
What is the purpose of using selective media?
To select for a particular type of bacteria or microorganism due to its chemical ingredients.
99
What are examples of selective media?
Sabouraud dextrose agar
100
What are the chemical components in Sabouraud dextrose agar?
acidic pH and antibiotics
101
MacConkey agar selects for which bacteria using which chemicals?
Gram-negative bacteria;
Bile salt and crystal violet
102
What is an example of gram-negative bacteria?
E.coli
103
What is an example of gram-positive bacteria?
Staphylococcus
104
What does EMB agar select for and using which chemical components?
Gram-negative bacteria;
Eosin and methylene blue
105
What does HE agar select for and which chemicals does it contain?
Gram-negative bacteria;
Bile salt
106
MacConkey agar, EMB agar and HE agar all 3
Selects for Gram-Negative bacteria first then Differentiates among them based on lactose fermentation or not.
107
Blood agar differentiates bacteria based on
hemolyzation of red blood cells or not.
108
What color does lactose-fermenting bacteria turn on MacConkey agar and why?
Pink;
Because MacConkey agar contains a pH indicator called Neutral Red. Neutral red is colorless and neutral pH and turns PINK at acidic pH.
Lactose fermenting gram-negative bacteria are able to ferment sugar lactose and produce lactic acid which turns neutral red pink.
109
HE agar can also differentiate
genus Salmonella from genus Shigella
110
How can HE agar differentiate bacteria belonging to genus Salmonella from bacteria belonging to genus Shigella?
Based on sulfur to sulfide conversion
111
What are examples of lactose-fermenting gram-negative bacteria?
E.coli and genus Klebsiella
112
What are examples of non lactose-fermenting gram-negative bacteria?
genus Salmonella, Proteus and Shigella
113
What is alpha-hemolysis?
The partial breakdown of rbc
114
Name an example of an alpha-hemolytic bacteria
Streptococcus pneumonia
115
What is beta-hemolysis?
The complete breakdown of rbc
116
Name an example of a beta-hemolytic bacteria
Staphylococcus aureus
117
What is gamma-hemolysis?
No breakdown of rbc
118
What is an example of gamma-hemolysis bacteria?
Staphylococcus epidermis
119
What is metabolism?
The sum of all chemical reactions
120
What does Catabolic reactions do? (Energy-yielding)
Releases energy by breaking down complex organic molecules into simple ones
121
Examples of Catabolic Reaction
Starch (a complex carb) ----> Glucose (a simple carb) + energy released
Protein (a complex molecule) ---> Amino acids (simple molecules) + energy released
122
What does Anabolic reactions do? (energy-consuming)
Build complex organic molecules from simple ones.
123
What are some examples of Anabolic reactions?
Glucose (a simple carb) + Energy consumed ---> Starch (a complex carb)
Amino acids (simple molecule) + Energy consumed ----> Protein (a complex molecule)
124
What is energy coupling?
Energy released from a catabolic reactions can be used to drive anabolic reactions
125
What is responsible for carrying out energy coupling?
ATP molecules
126
ATP stands for
Adenosine triphosphate
127
What is ATP?
A chemical molecule
128
What is ATP composed of?
1. a 5 carbon sugar called Ribose
2. a Nitrogenous base (opposite of acid) called Adenine
3. 3 phosphate groups
129
The chemical bonds formed between the phosphate groups of ATP molecule are rich in
energy and CAN be broken to yield energy ONLY in the presence of water molecule.
130
What is the terminal phosphate bond?
The very last phosphate bond.
131
What happens when the terminal phosphate bond is broken?
The terminal phosphate group (Pi) is removed from the rest of the ATP molecule. This is when ATP becomes ADP in the presence of water and energy is released.
132
What is ADP
Adenosine Diphosphate
133
What is ATP hydrolysis?
When ATP is broken down into ADP and Pi in the presence of water. Energy is released at the end of this chemical reaction
134
ATP hydrolysis is an example of which reaction?
Catabolic reaction (energy-yielding)
135
What is ATP recycling?
When an ATP molecules is recycled back from ADP and Pi, which requires energy.
136
Which of these require energy?
A. ATP recycling
B. ATP generation
C. ATP synthesis
D. ATP formation
All of them
137
ATP recycling, ATP generation, ATP synthesis and ATP formation are examples of which reaction?
Anabolic reaction because it is energy consuming
138
What is the ATP cycle?
When combining ATP hydrolysis with ATP recycling.
139
What are enzymes?
Protein molecules
140
What do enzymes do?
Speed up chemical reaction without becoming involved.
141
What is a chemical reaction about?
Chemical bond breaking and bond formation.
142
What is a typical chemical reaction?
Reactants----->Products
143
In a typical chemical reaction
the OLD bonds of the Reactant molecules will break to form the NEW bonds in the Products
144
How much energy is enough to break the bonds?
Depends upon the reactant molecules
145
What is activation energy (Ea)?
The amount of energy needed for bond breaking. Different reactant molecules require different amount of energy for bond breaking.
146
What does an energy profile of a typical chemical reaction show you?
Shows the progress of a chemical reaction going from its REACTANTS to PRODUCTS
147
How can enzyme fit into an energy profile of a typical chemical reaction?
An enzyme can speed up a chemical reaction by reducing the activation energy.
148
What are substrates?
Reactant molecules in the presence of enzymes.
149
Enzymes speed up a chemical reaction by doing what 1st?
by binding to it substrate molecule
150
Are enzymes substrate specific?
Yes, they will only help their own substrate
151
what size protein molecules and what kind of shape are proteins?
Large protein molecules
Specific 3-d shape
152
Where does the enzyme molecule bind with the substrate molecule?
The active site of an enzyme
153
Shape-Shape recognition
Specificity and compatible fit
154
Apoenzyme
The protein portion of an enzyme
155
Cofactor
The non protein part of an enzyme
156
The apoenzyme is INACTIVE by itself until it joins with
The cofactor
157
What is the active holoenzyme?
The apoenzyme and cofactor join
158
What are the 2 types of cofactors?
Organic molecule (containing carbon) and Inorganic molecule metal ion
159
What are some example of inorganic cofactors
zinc, iron, copper
160
Coenzyme
When a cofactor is organic
161
What are examples of coenzymes?
NAD+, FAD, CoA
162
What are the factors that can influence enzyme action?
Temperature, pH, substrate concentration and enzyme inhibitors
163
What happens if the temperature goes up too high?
The enzyme gets denatured (shape is changed) and the speed will slow down.
164
What does "enzyme in saturation" mean?
When the active site of an enzyme is ALWAYS occupied by its substrate.
165
How does competitive inhibitor work?
They resemble and compete with the substrate molecule for the active site.
166
How does non competitive inhibitors work?
They do not compete with the substrate and they do not fit into the active site of enzyme.
167
What is the allosteric site?
Any other site that is not the active site.
168
What is carbohydrate catabolism?
THe breaking down of carbs
169
Glucose molecules provide what?
A good source of energy for microbial cells
170
What are the 2 ways microbes break down glucose?
By Cellular respiration and Fermentation
171
Cellular respiration and Fermentation share what?
The first stage of glycolysis
172
Does cellular respiration take place in Aerobic Respiration or Anaerobic Respiration?
Takes place in both
173
Does fermentation take place in presence of oxygen or not?
Takes place in the absence of oxygen
174
Aerobic Respiration is
the breakdown of sugar glucose in the presence of oxygen
175
Energy is released or yielded at the end of
Aerobic respiration
176
What is the chemical reaction for Aerobic Respiration?
6CO + 6H O + energy yielded
2 2
177
THe 3 sequential stages of Aerobic Respiration are:
1. Glycolysis
2. Krebs Cycle
3. Electron Transport Chain
178
What are the reactants for Glycolysis?
1 molecule of glucose (6 carbons)
179
What are the products for Glycolysis?
2 molecules of pyruvate (3 carbons each)
180
How much energy does Glycolysis yield?
2 ATP molecules and 2 NADH molecules
181
What does pyruvate convert to before entering the Krebs cycle?
acetyl CoA
182
What are the reactants for Krebs cycle?
2 pyruvate molecules
183
What are the products for Krebs cycle?
2 Acetyl CoA
184
How much energy does Krebs cycle yield?
2 ATP molecules and 6 NADH molecules
185
What is oxidation?
electron losing
186
What is reduction?
electron gaining
187
During the Electron Transport Chain stage of Aerobic Respiration,
glucose is oxidized and oxygen is reduced.
188
What is the initial electron acceptor?
NAD+
189
NAD+ reduces to form NADH
190
What is the final electron acceptor?
Oxygen
191
Once oxygen accepts electrons coming down the electron transport chain
Oxygen is reduced to form water
192
How much energy does the Electron Transport Chain stage yield?
34 ATP molecules
193
How much energy is yielded during the entire Aerobic respiration of one molecule of glucose?
38 ATP
