Exam #1 Review

General Study Suggestions:

1) Begin by reviewing your lecture notes. If there is anything that you

do not understand, make an appointment with me, attend office

hours or review the content in your book.

2) Next, carefully review the questions that we discussed during

lecture and the homework questions. **The exam questions will be

Download Microbiology Lab Exam Question and Answers and more Lab Reports Microbiology in PDF only on Docsity!

Exam #1 Review

**General Study Suggestions:

Begin by reviewing your lecture notes. If there is anything that you do not understand, make an appointment with me, attend office hours or review the content in your book.**
**Next, carefully review the questions that we discussed during lecture and the homework questions. The exam questions will be similar to the homework questions!
Finally, go through this review as it may serve as a reminder of the overarching content of the exam. Format and composition: There will be 25 multiple choice questions. These are followed by 7 - 8 short answer, matching or fill-in-the-blank questions worth 10 points a piece. All students must answer #26 regarding Gram-positive and Gram-negative cell wall structure. Then, choose to answer any four of the remaining questions. Circle the questions that you would like to answer. Topics covered by these free response questions:

**- Macromolecules

The cell membrane / transport
Vocabulary (macromolecules / cell components)
Basic cell structure and function** **_The exam is worth 100 points. Your overall score will be determined in one of two ways depending on which leads to the highest overall total:

Multiple Choice Score * 2 + Free Response Score
Multiple Choice Score + Free Response Score * 1._** All of the following is in your notes but here it is in review format: Microbiology is the study of life forms and agents that are too small to be seen with the unaided eye. Although humans utilized microorganisms to make bread and beer as early as 2100 B.C., it was not until 1673 that Antony van Leeuwenhoek , using a hand-crafted microscope, viewed and thoroughly described these tiny organisms which he called “animalcules”. I. The origin of microorganisms (lecture #1) A. Scientists struggled for over a hundred years to reject the idea of spontaneous generation and support the idea that all forms of life arise from other living things of the same kind ( biogenesis ). Be familiar with all the scientists involved in this debate and understand their contributions. Practice: The idea of spontaneous generation postulated that a. organisms could evolve into the next generation of organisms. b. organisms could spontaneously combust. c. organisms could spontaneously arise from other living organisms. d. living organisms could arise from nonliving material.

B. Review and understand Koch’s Postulates! II. Microbiology: Implications and Applications (lecture #1) A. Fixing nitrogen, replenishing oxygen and degradation (decomposition) are essential (vital) activities of microorganisms. B. Microorganisms also have a very big economic impact. Practice: Microorganisms are involved in a. Food production b. Food preservation c. Production of vaccines d. Production of antibiotics e. All of the above C. Bioremediation - The use of microorganims to clean up waste (e.g. degrade oil spills, detoxify compounds that are harmful to the environment). D. Genetic Engineering = Introduction of genes from one organism into another to give it new features or abilities. E. Medical Microbiology = The study of disease-causing microorganisms (called pathogens).

In 1906, the three leading causes of death were infectious diseases (cdc.gov) Now, many infectious diseases have been eradicated.
Despite the eradication of many infectious diseases we must fight newly emerging diseases, the resurgence of old diseases and microorganisms that are becoming resistant to current treatment techniques. We are also just beginning to understand that many conditions, such as peptic ulcers, are caused by bacteria and cancers, such as cervical cancer, are caused by viruses. Practice: Which of the following is a reason for the resurgence of old diseases? a. A decline in the vaccination of children b. An increase in international travel c. both a and b d. none of the above F. ** Despite the disease-causing potential of some microorganisms, most microorganisms are not pathogenic. In fact, those covering our body play a protective role by competing with pathogenic microbes. ** G. Bacteria are good model organisms for study. Why? III. Macromolecules (proteins, carbohydrates, nucleic acids and lipids) *Be sure to review and understand the game questions for this section. A. Proteins Practice: Which one of the following is NOT a protein function? a. Transporting molecules from one location to another. b. Coordinating motion. c. Providing the genetic code for all of a cell’s properties. d. Providing mechanical support in eukaryotic cells.

Practice: Which is/are TRUE of carbohydrates? a. They may serve as a source of food. b. They are hydrophilic. c. They may be bonded to proteins to form glycoproteins. d. They are a component of some bacterial capsules. e. all of the above. Practice: What is the difference between cellulose and glycogen? C. Nucleic Acids

DNA and RNA - composed of nucleotides which are composed of a 5 carbon sugar, a nitrogenous base and a phosphate group. Practice numbering the carbon atoms on the 5-carbon sugar. Why are these numbers so important to understanding the structure of not only nucleotides but the nucleic acids which they form? Practice: DNA contains a. sugars b. 3’-5’ phosphodiester bonds c. triacylglycerols d. peptide bonds e. c and d
Bases Purines - adenine and guanine (double-ring structure) Pyrimidines - cytosine, thymine and uracil (single ring) Practice: Which of the following is found in RNA but not in DNA? a. adenine b. cytosine c. thymine d. uracil
In nucleic acids, the nucleotide subunits are bound covalently (the 5’ phosphate binds to the 3’ hydroxyl). This linkage is termed a 3’,5’- phosphodiester linkage.
Covalent bonding of many nucleotides forms a single strand of nucleotides which, in DNA, then binds to a complementary strand via hydrogen bonds. The complementary strand runs in the opposite direction (antiparallel) to the first strand. Together they form a double-stranded helix. a. A single strand of nucleotides joined by 3’,5’-phosphodiester bonds always has polarity/directionality. It always has a 3’ end and a 5’ end. b. When the H-bonds that hold the two strands of DNA together are broken, this is called denaturation or melting. c. **If given a DNA sequence, be sure that you understand how to determine its correct complimentary sequence!!

D. Lipids Practice: Which is/are TRUE about lipids? a. They are a major structural component of all cell membranes. b. They can serve as energy stores. c. They function in cell signaling and recognition. d. All of the above.

Triacylglycerols, steroids, sterols, waxes and phospholipids *Know the basic structure of a triacylglycerol **Be able to recognize the structure of a phospholipid.
ALL CELL MEMBRANES ARE SEMIPERMEABLE PHOSPHOLIPID BILAYERS. Know how phospholipids come together to form a PL bilayer. Be able to draw and label the hydrophilic and hydrophobic portions of a phospholipid bilayer. Practice: Why are fats packed with power? IV. Classification and Nomenclature A. Domains Practice: Which of the following is/are not domains into which all living organisms can by classified? a. Helminths b. Bacteria c. Archaea d. Eucarya
Members of the domain Bacteria and Archaea are prokaryotes, they vary in size but are often 0.3 to 2 micrometers; they are single-celled and have no membrane-bound nucleus or organelles. Their genetic material is simply stored in a region called the nucleoid. Prokaryotes are surrounded by a cell membrane and generally a rigid cell wall. They multiply by binary fission and some move using flagella. Bacteria differ from archaea in that their cell wall is composed of peptidoglycan. Archaea have a different overall cell wall composition that LACKS PEPTIDOGLYCAN. While bacteria live in all environments, archaea are frequently found in extreme environments.
Members of the domain Eukarya can be either single-celled or multicellular. They always have a membrane-bound nucleus and organelles. Some eukaryotic cells have a cell wall but it is NEVER MADE OF PEPTIDOGLYCAN. On average, eukaryotic cells are larger than prokaryotic cells (5 to 50 micrometers). Are there exceptions? B. Nomenclature. Practice: In binomial nomenclature, the scientific name of an organism includes its a. family and genus. b. first name and last name. c. genus and species. d. domain.

Inclusions a. Generally used for storage (backup food supply) and include granules that store phosphate, glycogen, and amino acids. Some storage granules are bound by a single-layered membrane. b. Microcompartments are thought by some scientists to be functionally analogous to organelles. These include carboxysomes that store CO2. c. Magnetosomes What do magnetosomes allow bacteria to do? d. Gas vacuoles = aggregates of large numbers of gas vesicles. Practice: Which one of the following microorganisms is most likely to have gas vacuoles? a. Bacillus subtilis (a soil bacterium) b. Escherichia coli (a gut bacterium) c. Anabaena flos-quae (an aquatic, photosynthetic cyanobacterium)
Cytoplasmic membrane Practice: Which is not true of the cytoplasmic membrane? a. it defines the boundaries of the cell. b. It is a semipermeable barrier. c. It consists mainly of a fixed, static phospholipid bilayer. d. It uses proteins as selective gates and sensors. e. all of the above are true. *IMPORTANT: There will be a question regarding the cytoplasmic membrane and the Fluid Mosaic Model. a. Transport - small hydrophobic molecules and small gas molecules can diffuse across the membrane (simple diffusion) but large, hydrophilic molecules and charged molecules require transporters. b. Energy transfer across the plasma membrane. Prokaryotic cells that are capable of some type of respiration or photosynthesis have the components of the electron transport chain across their membrane. These components are electron carriers. They transfer electrons from one to the other and this leads to the ejection of protons. As protons are ejected out of the cell, a proton gradient forms across the membrane. This proton gradient is called the proton motive force (PMF). This PMF is like reserve energy (like a battery). When the protons are allowed to flow back through a protein into the cell, the reserve energy can be harnessed to make ATP!! In prokaryotes, this battery-like energy can also be used to power other cellular processes (e.g. flagella rotation and certain transport systems).
The cell wall a. Contains peptidoglycan in bacteria. Peptidoglycan contains glycan chains of alternating NAM and NAG. A tetrapeptide chain is attached to each NAM (composed largely of unusual amino acids). These tatrapeptide chains are then joined (directly in most Gram-negative bacteria, whereas Gram-positive bacteria are more likely to have a (glycine) peptide interbridge).

b. The peptidoglycan layer in bacteria can be thought of like a wire mesh. It is very rigid, yet it is porous. c. Because eucaryotic cells do not contain peptidoglycan, it makes a good target for antimicrobial substances (penicillin and lysozyme). Practice: Which is/are true about the cell wall of bacteria? a. It determines the shape of the bacteria. b. It prevents the bacteria from bursting in hypotonic solutions. c. It contains peptidoglycan. d. It may be targeted by antimicrobials. e. all are true.

Practice: Draw the cell wall of both a Gram-positive and a Gram-

negative bacteria. Be certain to note which molecules are

responsible for the cells’ overall negative charges as well as being

recognized by our body’s immune system. ** There will be an

important question about this!**

Practice: What is the difference between teichoic and lipoteichoic acid? Practice: The cell wall of a Gram-negative bacterium a. has a thick peptidoglycan layer. b. has a thin peptidoglycan layer. c. is characterized by an outer membrane containing LPS. d. has gel-like fluid between the inner and outer membranes called the periplasm. e. b, c and d f. none of the above. *Note- An LPS molecule has three regions. The upper region, the O-specific polysaccharide, is recognized by host defense systems. It also changes in some bacteria (e.g. Salmonella ) allowing them to evade the immune system. The central region contributes to the negative charge of the cell wall. The lowest lipid A region is the toxic region that allows LPS to act as an endotoxin (elicits fever and shock). Also in Gram-negative cell walls, lipoproteins join the outer membrane to the peptidoglycan layer. Porin proteins span the outer membrane to form pores through which small molecules can pass. d. The cell wall protects bacteria from destruction by osmotic pressure. Practice: The simple diffusion of water is called a. permeosis b. osmosis c. aquaosis d. turgorperosis If the concentration of solutes inside a cell is less than that outside the cell = a hypertonic enviroment. Water flows out of the cell, the cytoplasmic membrane shrinks and pulls away from the cell wall (plasmolysis). Practice: Describe what happens when a cell is placed in a hypotonic environment. What is the difference between a spheroplast and a protoplast?

Microbiology Lab Exam Question and Answers, Lab Reports of Microbiology

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Download Microbiology Lab Exam Question and Answers and more Lab Reports Microbiology in PDF only on Docsity!

Exam #1 Review

Practice: Draw the cell wall of both a Gram-positive and a Gram-

negative bacteria. Be certain to note which molecules are

responsible for the cells’ overall negative charges as well as being

recognized by our body’s immune system. ** There will be an

important question about this!**