Glossary of MMG Chemotaxis and Organelles
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- What is chemotaxis?
- -when a chemical interacts with a protein on the cell surface and signals the flagellum to spin one way or another
- What is temporal sensing?
- -bacteria continually sample the encironment and move through increased runs and less tumbles (attractant) or decreased runs (repellent)
- What is taxis?
Why do cells do this?
- -moving of a cell
-the sense gradients of chemicals or physical agens such as light and move to or away from them
- What is phosphorylation of CheY called?
How about mehtylation of MCP?
- What indicates an attractant and what movement results?
- -low CheA kinase activity which means the cell has de-phosphorylated CheY
-this is attractant so it needs to run (towards it) so the cell would have de-methylated MCP
- What chemotaxis signal transduction occurs in a repellent signal?
- -high CheA kinase activity leads to phosphorylated CheY. To tumble, repellants must be bound so we have methylated MCP
- During mehtylatation of MCP, which binds attractants?
How about repellants?
- -de-methylated MCP (run)
-methylated MCP (tumble)
- During Phosphorylation of CheY, which one indicates a clockwise spin (tumble)?
How about CCW (run)?
- -phosphorylated CheY (tumble)
-de-phosphorylated CheY (run)
- What are fimbriae and pili?
- -numerous hair-like structures over the surface of a cell for attaching to other cell surfaces
-composed of protein pilin
- What are "F" or "sex pilus"?
- -a specialized form of pili
-a single pilus forms a bridge between two cells through which DNA from donor cell can move (conjugation)
- What is the glycocalyx made of?
- -polysaccharides and glycoproteins secreted by cells to accumulate on surface
- What two types of glycocalyx are there?
- -capsule (well formed and more rigid)
-slime layer (more loosely aggregated)
- What functions does the glycocalyx serve?
- -attachment to surfaces
-anti-phagocytic (increases pathogenicity)
- What are some types of inclusions in bacteria?
What are these used for?
- -Glycogen (energy, carbon [polymerized glucose])
-Poly-Beta-hydroxybutyrate (energy, carbon [lipids])
-Polyphosphates (inorganic phosphate [nucleic acids])
-Sulfur [amino acids]
-Iron magnetite (magnetotaxis [Fe3O4])
- What are inclusions?
- -granules used to store nutrients, energy, and structural building blocks
- What is an endospore?
- -spores formed in Gram+ soil bacteria for the purpose of survival when nutrients are low or conditions become intolerable
- What makes endospores so sucessful?
- -resistant to heat, desiccation, and harsh chemicals
*can remain dormant for thousands of years
- What compound is found in endospores that gives it heat resistance?
- -dipicolinic acid (not found in vegetative cell) that complexes with calcium to be effective
- How does sporulation occur if its genes are inactive?
- -cell enters vegetative growth (can take up to 8 hours)
-vegetative genes are turned off and sporulation genes are turned on
- Describe steps 1-4 of sporulation
- 1)DNA replicated
2)DNA align on x-axis
3)cyto membrane invaginates forming forespore
4)membrane grows and engulfs forespore in 2nd membrane: veg cell DNA disintegrates
- Describe steps 5-8 of bacterial sporulation
- 5)cortex of Ca and dipiclinic acid deposited between membranes
6)spore coat forms around endospore
8)endospore released from original cell
- What is the function of microtubules?
- -vesicle transport and structural integrity
- What is the function of mitochondrion?
- -energy production
- What is the function of ribosomes?
- -protein synthesis
- What is the function of nuclear pores?
- -protein trafficking
- What is the function of the Golgi complex?
- -protein trafficking and glycosylation
- What is the function of the nucleolus?
- What is the function of peroxisomes?
- -H2O2 synthesis
- What is the function of nucleus?
- -DNA replication transcription
- What is the function of Chlorosplasts?
- What is the function of lysosomes?
- -portein degradation
- What is the function of microfilaments?
- -vesicle transport
- What is the function of smooth ER?
- -protein trafficking
- What is the endosymbiosis theory?
- -postulate that membrane-bound organelles in eukaryotes evolved from symbiotic bacteria residing in cytoplasm of primitive eukaryotes
- What might have given rise to mitochondrion?
- -aerobic bacteria
- What may have given rise to chloroplasts?
- -phototropic bacteria
- What does the smooth ER do?
- -plays role in lipid synthesis
-protein synthesis from ribosomes on its surface. It transports these
- How does the Golgi Body process molecules for transport out of cell?
- -creates secretory vesicles that fuse with cytoplasmic membrane
- Where does respiration occur in eukaryotic cells?
- Where does oxidative phosphorylation occur and what is it known as?
- -mitochondria (in cristae)
- What is a choloroplast in more depth?
- -found in algae
-site of photosynthesis
-contains outer membrane and flattened membrane discs (thylakoids) where ATP is produced
- What are 5 functions of a eukaryotic cytoskeleton?
- 1) anchor organelles
2) cytoplasmic streaming and movement of organelles
3) cell contraction
4) movement during endocytosis and amoeboid action
5) provides basic shape
- What is the eukaryotic cytoskeleton made up of?
- -tubulin microtubules
-intermediate filaments (composed of various proteins)
- What is microbial growth?
- -an increase in number of microbes rather than size
(such as reproduction)
- What is bacterial division?
- -equal division into two replicates through binary fission after all cellular constituents are doubled
- How can fungus divide?
-filament (hyphae) elongation
- What is cell division called?
- -cytokinesis (partitioning of cellular constituents into two cells and then separating them)
- How does cytokinesis occur?
- -bacterial Fts proteins interact to form a divisome
-FtsZ molecules form a ring structure and directs a new cell wall (septum) and subsequent constriction of walls
*this process is actively being pursued as an antibacterial drug target
- In eukaryotes, how does cytokineses occur?
- -results from contraction of an actin-myosin contractile ring
-in eukaryotic microbes with walls, this is followed with septum formation (algae, fungi)
- How can exponential growth be expressed methematically?
- -as a geometric progression
g= generation time
n=# of doublings
t-total time of expo growth
- Problem: You inoculate a culture of 1 x 103 (N0) bacteria and grow them under exponential growth conditions with a generation time of 30 minutes (g). At what time (t) will the number of bacteria equal 1 x 106 (N) ?
- t = g x n = 30 min. x 3.3 ( log N - log N0) = 30 x 3.3 (6 - 3) = 300 min
- n is the number of doublings/generations. What is an equation for this if we have N and N nought?
- n = 3.3 ( log N - log N0)
- What are three ways to measure microbial growth?
- 1) viable cell count
2) total cell count
- How do you perform a viable cell count?
- -use serial dilutions of 10 and plate each one
- What are the pros of viable cell count?
How about disadvantages?
- -plate count: only live cells can grow
-very sensitive and accurate
+tedious and time consuming
- What are the pros and cons of total cell counts? How are they done?
- -microscope count
-no pros (besides cheap)
-disadvantages: dead cells can look like live cells, tedious and time consuming
- What does a turbidity test measure?
- -measure reflected light off cells and finds O.D.
- How do you create data using turbidity measurements?
- -By taking O.D. reading at time 't' AND doing a plate count you can get actual cell number
ADVAN: quick and easy
DIS: larger cells bias and dead cells scatter light too
- What are the 4 stages of a typical growth curve?
- 1) lag phase
2) exponential phase
3) stationary phase
4) death phase
- What is the lag phase?
- -adjustment to new environment; length of lag phase depends on growth state of starting culture; increases in ribosomal synthesis, RNA, DNA
- What is the exponential (log) phase?
- -rapid uniform growth; alsmot all cells are alive optimally using nutrients and producing waste
- What is stationary phase?
- -number of living cells equal number of dead cells: running out of nutrients and buidling up wastes; no net change in cell number but metabolism continues
- What is the death phase?
- -cells are dying due to lack of nutrients and waste build-up; decrease in viable cell count but no change in O.D; eventually O.D. will decrease-lysis of cells
- What is catabolism?
- biological reactions that produce energy and carbon flow used by anabolic reactions
- What is anabolism?
- all the biosynthetic reaction in the cell; they require energy and carbon flow
- What is meant by a cell being an 'open system'?
- -nutrients needed for anabolism flow in and waste products from catabolism flow out
- What two major things do microbes need for nutrition?
- -a carbon source
-an energy souce (ATP)
- Why are carbon source needed for nutrition? What type of carbon do heterotrphs use? Autotrophs?
- -needed for making macromolecules
-hetero: organic carbon-sugars and proteins
-auto: inorganic carbon-CO2
- What energy sources are needed for making ATP?
- -light (photoautotrophs)
-inorganic molecules like NH4, Fe, H2S (lithotroph)
-organic molecules like sugars and proteins (organotroph)
- What types of nutrition classes can eukaryotic microbes be?
-saprophytes (fungi protozoa): feed on other organisms
-photoautotrophs (algae): use light and inorganic carbon
- What are 6 major macronutrients?
- 1) Carbon
- What macronutrients make up the backbone of all organic molecules (sugars, lipids, proteins, DNA, RNA)?
- -Carbon, Hydrogen, and Oxygen
- What is Nitrogen used for in anabolism?
- -proteins, DNA, RNA, derived from ammonia(NH3), nitrate (NO3), or N2 gas
- What is Phosphorus used for in anabolism?
- -DNA, RNA, lipids
- What is Sulfur used for in anabolism?
- -Amino acids, vitamins
- What 5 ions (salts) are important in anabolism?
- 1) K
- What are the 5 major ions in anabolism used for?
- -cofactors for enzymes, stabalize protein and cell wall structures, regulate osmolarity, etc
- What are micronutrients and growth factors needed for in anabolism?
- -required in small amounts
-metals or vitamins needed as co-factors for enzymes (chromium, Mn, Ni, etc.)
- What are 4 environmental factors affecting bacterial growth?
- How does temperature affect bacterial growth?
- Affects enzyme reactions (metabolism):
-membrane structures and permeability
- What are some ways temperature is used to control bacterial growth?
- -refrigeration for mesophiles
-freezing for psychrophiles
-heating/boiling to sterilize
- In what order would you put the 4 thermophiles from freezing to boiling temperatures
- What thermophile is the source of Tag DNA polymerase and what is this used for?
- -Thermus aquaticus
-enzyme used in polymerase chain reaction (PCR) experiments
- How does pH affect bacterial growth?
- -affects protein structure and proton gradient (which is essential for bacterial ATP synthesis)
- How do osmotic effects change bacterial growth?
Why is this important to human life (food)?
- -if Na content changes more outside cell, water will leave. Too high and cell can't compensate: inhibited growth
*basis of salt and sugar preservation
- What halotolerant bacteria will contaminate preserved food and give food poisoning?
- -Staphylococcus aureus
- How does oxygen affect bacterial growth?
- -lethal to some anaerobes
- What are 5 classes of oxygen use for bacteria?
- 1) obligate/strict aerobe
2) obligate/strict anaerobe
3) facultative aerobe
5) aerotolerant anaerobes
- Describe each of the following:
- -grow under aerobic or anaerobic conditions
-only use O2 at lower concentrations than air
-tolerate and grow in O2, but can't use it
- What broth is used to reduce O2?
What dye is added to show oxidation?
- What are four molecules formed by a host defense cell to kill invading microbes?
- What do superoxides kill?
- -destroys lipids and other organics
-damaging but not as toxic
-oxidizes any molecule in cell
- Which bacterium (aerobes or anaerobes) have enzymes that can destroy certain toxic intermediates?
What are they?
c) superoxide dismutase
d) superoxide dismutase/catalase in combination
e) superoxide reductase
- Why can't anaerobes be around oxygen?
- -They don't have enzymes to destroy oxygen intermediates, so they build up to toxic levels
- Does Staph or Streptococci produce catalase?
- -staphylococci does
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