PORTAGE MICROBIOLOGY FINAL EXAM
Microbiology is the study of what
✅ - microorganisms/viruses and there biological processes
What is the smallest
... [Show More] biological unit of life?
✅ - cell
What is a macromolecule?
✅ - a molecule containing a very large number of atoms, such as a protein, nucleic acid, or synthetic polymer.
What are the 4 main types of macromolecules
✅ - proteins, carbohydrates, lipids, polysachrides
What various functions do proteins have in a cell
✅ - Proteins may facilitate the movement of materials in or out of a cell.
Some can act as enzymes that catalyze, or speed up, biochemical processes.
Others play a structural role while other proteins, such as filaments, enable movement.
What are the two major types of nucleic acids and their roles?
✅ - There are two major types of nucleic acids: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). Nucleic acids are chemical molecules that carry genetic information within the cell. DNA contains a vast amount of hereditary information and is responsible for the inheritable characteristics of living organisms. RNA is responsible for deciphering the hereditary information in DNA and using it to synthesize proteins.
What is the plasma membrane and what is it made up of?
✅ - The plasma membrane serves the cell as a surrounding barrier that separates the inside of the cell from the outside surrounding environment. The plasma membrane also restricts the movement of materials (water, nutrients, etc) either in or out of the cell, thus allowing a cells to absorb and keep what is needed (influx) while also preventing the escape (out flux) of essential nutrients. The plasma membrane is composed of lipids (hydrophobic hydrocarbons).
What are the three main components of polysaccharides?
✅ - Polysaccharides are composed of carbon, hydrogen and oxygen atoms.
Examples would include, C6H12O6 (glucose) C12H22O11 (sucrose) and C6H10O5 (cellulose).
What is the primary difference between prokaryotic and eukaryotic cells?
✅ - Eukaryotic cells contain a nucleus, a membrane enclosed region within the cell that contains the genetic material.
Prokaryotic cells do not have a nucleus and can be further classified as either Bacteria or Archaea.
What are the main morphologies of bacteria?
✅ - Bacteria can be described as coccus (round/spherical),
bacillus (rod),
vibrio (curved rod)
spirillum (spiral/corkscrew).
Which group (classification) of bacteria is noted for its ability to survive under harsh conditions?
✅ - Archaea. They are able to survive in extremely harsh environmental conditions such as high salt levels, acid conditions, high temperatures and oxygen-poor conditions.
What are the 4 main classifications of Eukarya
✅ - Eukaryotic microorganisms are classified as either belonging to Animalia, Plantae, Fungi or Protista.
Can viruses be classified as either prokaryotic or eukaryotic?
✅ - No. Viruses are considered neither prokaryotic nor eukaryotic. Viruses are not considered living and do not replicate on their own, meaning they must replicate within a host.
The lipid bilayer of the plasma membrane is composed of what?
✅ - The cell membrane is a bilayer composed primarily of amphipathic phospholipids, meaning they contain a polar hydrophilic (water loving) head group and a non-polar hydrophobic (water fearing) tail region. The lipid bilayer is situated in such a way where the non-polar tail groups face inward thus orienting the polar head groups to interact with water both outside and inside of the cell.
What are the primary cellular organelles described in this module? Be sure to know the roles of each.
✅ - Ribosomes (protein synthesis)
ER (site of protein synthesis)
Golgi (protein modification and distribution) lysosomes (waste disposal),
mitochondria (ATP generation)
chloroplasts (plants only; site of photosynthesis).
True or False: Metabolism is a controlled set of biochemical reactions that occur in living organisms in order to maintain life.
✅ - True
True or False: Enzymes are polysaccharides that catalyze chemical reactions.
✅ - False. Enzymes are proteins that catalyze chemical reactions
What are usually metal ions known to assists enzyme during the catalysis reaction?
✅ - Cofactors are usually metal ions and assist enzyme during the catalysis reaction.
Define catabolism
✅ - the breakdown of complex molecules in living organisms to form simpler ones, together with the release of energy; destructive metabolism.
Upon cellular injury, which metabolic process is involved during the growth and repair phases of the cell?
✅ - The anabolic process would be active as it (by definition) is involved in the building up of small complexes into larger complexes.
Describe the energy transfer process relative to both ATP and ADP.
✅ - ATP has the energy (phosphate group) to donate while ADP can accept energy in the form of a phosphate group. Thus, ATP can be reduced (ATP →ADP + Pi) while ADP can be built into ATP (ADP + Pi →ATP).
An organism that derives its energy (generates ATP) from photons of light is called a _________
✅ - Phototrophic microorganism.
An organism that derives its energy by removing electrons from elemental sulfur would be classified as a __________?
✅ - Lithotroph
A reactive intermediate would be present in which phosphorylation process?
✅ - The chemical compound losing the phosphate group is referred to as the phosphorylated reactive intermediate.
Identify the products of the following chemical equation:
Glucose + 2NAD+ → 2 NADH + 2 Pyruvate + 2 ATP
✅ - The products are to the right of the arrow: 2NADH, 2 Pyruvates and 2 ATP
What is the primary byproduct of the TCA cycle? Select all that apply.
A. NAD+
B. FAD
C. NADH
D. FADH2
✅ - C and D. The TCA cycle produces an abundance of reduced electron carriers (NADH and FADH2).
True or False. The reactants of the TCA cycle directly enter and fuel the electron transport system.
✅ - False. The products of the TCA cycle (reduced electron carriers) enter and drive the production of ATP via the electron transport system.
In the absence of glucose, which of the following can be used as alternative energy sources? Select all that apply.
A. Lactose
B. Nucleic acids
C. Carbohydrates
D. Lipids
✅ - A, C, D can all be used as alternative energy sources.
For the catabolism of proteins and lipids, which of the following enzymes are used? Select all that apply.
A. Ligases
B. Proteases
C. Transferases
D. Lipases
✅ - Proteases and lipase
True or False. The β-oxidation pathway catabolizes the fatty acid chains of lipids.
✅ - True
True or False. Plants, algae and bacteria all contain chloroplasts.
✅ - False. Chloroplasts are specific to algae and plants only.
The process of carbon fixation begins with which of the following reactants: select all that apply.
A. ATP
B. Glyceraldehyde-3-phosphate
C. CO2
D. NADPH
E. H2O
✅ - A, C, D, and E. Carbon fixation uses the ATP/NADPH produced during light reactions to convert CO2 and H2O into useful sources of energy (carbohydrates).
What is one of the main functions of light reactions?
✅ - Similar to the electron transport chain, one of its main functions is to generate a proton concentration gradient to generate ATP.
True or False: Dark reactions can occur in the presence or absence of light.
✅ - True. The term 'dark reactions' (also known as the Calvin Cycle) simply denotes the second stage in photosynthesis—dark reactions do not actually require darkness in order to occur.
How many turns (or repititions) of the Calvin Cycle are required to generate one molecule of glucose?
✅ - Six.
Complete the following equation by placing the appropriate numbers where indicated.
__CO2 + __ATP + __NADPH + __H20 → __C6H12O6 + __ADP + __NADP+
✅ - 6 CO2 + 18 ATP + 12 NADPH + 12 H20 → C6H12O6 + 18 ADP + 12 NADP+
Match the following reactions to its corresponding enzyme:
1. A + B → A-B
2. A-B → A + B
3. A- + B →A + B-
4. Ab + C → A + Cb
A- Lyases
B- Transferases
C- Oxioreductaces
D- Hydrolases
E- Ligases
F- Isomerases
✅ - 1E 1. A + B → A-B Ligases
2A 2. A-B → A + B Lyases
3C 3. A— + B → A + B— Oxioreductaces
4B 4. Ab + C → A + Cb Transferases
A micrometer is defined as
A. 10-3
B. 10-6
C.10-9
D. 10-12
✅ - B. A micrometer is one-millionth of a meter.
True or False: A nanometer is longer than a micrometer.
✅ - False. A nanometer is 1,000 times smaller than a micrometer.
Resolution and contrast are two critical factors that influence your ability to see an object. Explain each.
✅ - Resolution refers to the distance between two objects at which the objects still can be seen as separate. Poor or low resolution means two (or more) objects may appear as one.
Contrast is the difference in light absorbance between two objects. Poor contrast gives a high background and makes the visualization of multiple objects difficult. For instance, trying to identify 2 dark colored objects at night (low light = low contrast) versus the same 2 objects in the middle of a sunny afternoon (bright light against 2 dark objects = high contrast).
Assuming a fixed ocular, identify the part of the microscope you would adjust to enhance the magnification of a sample.
A. Objective
B. Condenser
C. Iris diaphragm
D. Eye piece
✅ - A. Only the oculars (eyepiece) and the objectives contribute to the magnification of the sample. Since the eyepiece is fixed, only the objectives could be altered.
What is the total magnification (relative to your eye) of a sample imaged with a 20x objective and a 15x eyepiece? Show your math.
✅ - 20 x 15 = 300x magnification
True or False: A cell that is adherent, flat (thin) and unstained is easily identified using bright field microscopy.
✅ - False. Adherent, flat cells are almost invisible due to the limits on both resolution and contrast.
Which of the following could be seen clearly by the unaided eye? Select all that apply.
A. Bacteria with diameter of 24 μm
B. Protozoa with diameter of 150 μm
C. Virus with a diameter of 0.2 μm
D. Skin cell with diameter of 1500 μm
✅ - B and D. The unaided eye can, on average, clearly resolve objects > 100 μm
For each of the following questions select from the list below the single best answer:
Phase-Contrast
Dark Field
Fluorescence
Confocal
This type of microscope is best suited for visualizing GFP, RFP and YFP proteins.
✅ - Fluorescence
This type of microscope can provide detailed images of live cells without staining.
✅ - Phase-Contrast
This type of microscope is used to greatly increase the contrast between samples and background by reflecting light off of the specimen.
✅ - Dark Field
This type of microscope is capable of capturing images in multiple focal planes, rendering a specimen in 3D
✅ - Confocal
Gram-Positive cells appear _______ in color due to a ______ peptidoglycan layer in the cell wall.
✅ - Purple; Thick
Gram-Negative cells appear _______ in color due to a ______ peptidoglycan layer in the cell wall.
✅ - Pink; Thin
True or False: Following the decolorization step of the Gram stain, Gram-Negative bacteria will appear colorless.
✅ - True. Even together, the LPS and thin peptidoglycan layer are unable to retain the crystal violet dye during decolorization.
Name one substance capable of chemically fixing cells to a slide.
✅ - Any of the following are true: Paraformaldehyde, ethanol or methanol.
You want to observe the size and shape of a cell. What is the easiest staining technique that you could perform? Name at least one dye you would use during this process.
✅ - Simple stain. You could use any of the following: methylene blue, crystal violet, safranin or fuschin.
You suspect a patient may have TB. Once a sample has been obtained it is sent off to the lab for an acid-fast stain. If the patient were infected with TB, describe what you would expect to see on the stained slide. [Show Less]