Unit 1: Microbiology Foundation
What is a pathogen?
A disease-causing microorganism
What reaction takes place to build polymers from monomers? What reaction takes place to break down polymers into monomers?
Condensation to build polymers
Hydrolysis to break down polymers
Define chemotaxis and phototaxis.
Chemotaxis: Movement of a cell or organism toward or away from a chemical stimuli
Phototaxis: Movement of a cell or organism toward or away from a light source.
What is required for a substance to move passively across a cell membrane?
A gradient is required. Substances will move passively from high to low concentration.
Where does transcription take place in a eukaryotic cell? What about translation?
Transcription occurs in the nucleus whereas translation occurs at the ribosome (either on rough ER or free-floating in cytoplasm)
How did Jenner produce the 1st vaccine?
She used cowpox to vaccinate for smallpox
Name the components of DNA
Sugar + phosphate group + nitrogenous base
What advantages do a biofilm give to a bacterium?
Many advantages, but the main advantage is that it protect bacteria from phagocytosis (being engulfed) and desiccation (drying out)
Other advantages: Adhesion/cohesion capabilities, mechanical properties, nutritional sources, cellular communication, protection and resistance to drugs
List 5 differences between eukaryotic and prokaryotic cells.
(Formatted as eukaryotes vs prokaryotes)
1.) Membrane bound organelles vs no membrane bound organelles
2.) Membrane bound nucleus vs no membrane bound nucleus
3.) Cell walls made of cellulose vs cell walls made of peptidoglycan
4.) Larger cell size vs smaller cell size
5.) Cilia or flagella vs pili, fimbriae, and flagella
6.) Slow generation time vs fast generation time
7.) Highly regulated DNA replication vs replication of entire genome at once (more mistakes)
What organisms and/or organelles can 70S ribosomes be found?
Prokaryotic cells
Chloroplasts
Mitochondria
Name all 8 taxonomic ranks used to classify organisms, from most broad to most specific.
Domain --> Kingdom --> Phylum --> Class --> Order --> Family --> Genus --> Species
Describe the three types of bonds and give an example of each.
Covalent bond: Electrons are equally shared; typically occurs between nonmetals; strongest bond (ex. O2, CO2)
Ionic bond: One atom gains electrons while another loses electrons; uneven sharing of electrons; typically between a metal and nonmetal (Ex. NaCl)
Hydrogen bond: Weak bond between the H of one molecule and an electronegative atom of another molecule (ex. H bond between H2O molecules)
What is the difference between a solution that is hypertonic, hypotonic, or isotonic? In what direction will water move if a cell is placed into each solution?
Hypertonic solution: Concentration of solutes is greater than that of the cell, so water will move out of the cell
Hypotonic solution: Concentration of solutes is less than that of the cell, so water will move into the cell
Isotonic solution: Concentration of solutes is the same between the solution and cell, so there will be no net movement of water
Why is it important for a physician to know if an infection if caused by a Gram negative or Gram positive bacterium? (Be specific)
Gram-negative bacteria have a Lipid A component, which is a potent endotoxin that can cause endotoxic shock. A physician needs to know whether or not the bacterium is Gram+ or Gram- to target the bacterium carefully in order to avoid releasing the Lipid A endotoxin.
In chronological order, list the 4 organelles associated with protein synthesis/export and describes its function in regards to protein synthesis/export.
Nucleus: Contains genetic information (DNA) to be converted into mRNA
Ribosome: Synthesizes protein from mRNA with help from tRNA
Golgi apparatus: Modifies, packages, and transports proteins
Plasma membrane: Exports proteins out of the cell
What are the steps in Koch's postulates?
Name the four complex carbohydrates essential for life and its common function.
Starch - Plant sugar storage
Cellulose - Major component of cell walls
Chitin - Exoskeletons and cell walls in fungi
Glycogen - Animal sugar storage
What are the three parts to the prokaryotic flagellum and what does each part do?
1. Filament: Contains the globular protein flagellin, arranged in several chains that intertwine and form a helix around a hollow core
2. Hook: Moves to help move flagella
3. Basal body: Anchors the flagellum to the cell wall and plasma membrane.
Explain what a capsule is, what it's made of, and the advantages it confers to bacteria. Name at least one capsule-producing organism and the disease it causes.
A capsule is a protective, hydrated layer that lies outside of the bacterial cell envelope. It consists of repeating polysaccharides. Bacterial capsules provide protection from phagocytosis as it is slippery and can hide from the immune system by mimicking host tissues. The capsule also protects the cell from desiccation.
Ex.) Klebsiella pneumoniae: Causes pneumonia
What (4) organelles are found in plants but not in animal cells? What (3) organelles are found in animal cells but not in plants?
ONLY in plant cells: Chloroplasts, central vacuole, cell wall, plasmodesmata
ONLY in animal cells: Lysosomes, centrioles, flagella
Describe the experiments of Redi, Needham, Spallanzani, and Pasteur and discern whether or not their results supported biogenesis.
All experimental results supported biogenesis.
Redi: Tested the spontaneous generation of maggots
Needham: Tested for presence of life in a broth
Spallanzani: Needham's experiment, slightly altered
Pasteur: Tested for life using an S-Flask
Between NH3 and CH4, which molecule is polar and which is nonpolar? Why?
Hint: Draw it!
NH3 is polar because the positive and negative charges are unevenly distributed. The negative end is by the N and the positive end is by the three Hs. CH4 is polar due to the equal distribution of positive and negative charges as a result of its tetrahedral structure.
Explain what an endospore is, its components, and its functions. Give the scientific name of medically important bacteria that form endospores and list the diseases they cause. Which genus tend to live in anaerobic environments?
An endospore is a dormant, tough, and non-reproductive structure produced by some bacteria. Endospores consist of the bacterium's DNA, ribosomes, remnants of the cell membrane, and large amounts of dipicolinic acid. Endospores are meant for survival and preservation until environmental conditions improve to revert into a vegetative cell.
Ex.) Bacillus anthracis: Causes anthrax;
Clostridium botulinum: Causes botulism;
Clostridium tetani: Causes tetanus
All examples are anaerobic.
Explain why Mycobacterium is medically important, how its cell wall is unique, and any advantages this bacterium has in the external environment and inside the human body. Give a specific example of a Mycobacterium and the disease it causes.
Mycobacterium are medically important because they are hard to treat. Dormant cells exist even in patients with active disease, and these cells are far less susceptible to antibiotics than metabolically active bacteria. Mycobacterium uniquely has a large amount of waxy lipid in its cell wall, making it hard to target. As it is highly adaptive to its environment, it can easily evade detection by both the immune system and antibiotics.
Ex.) Mycobacterium tuberculosis: Causes tuberculosis
Define the endosymbiont theory. What similarities do mitochondria and chloroplasts have that support this theory?
The endosymbiotic theory states that some of the organelles in eukaryotic cells (mitochondria and chloroplasts) were once prokaryotic microbes that evolved into organelles from a symbiotic relationship.
Mitochondria and chloroplasts both have circular DNA, 70S ribosomes, the ability to self-replicate, and a double membrane.