BIO 245 Module 2 Study Guide

Inoculation

introducing microbes into a growth medium

Medium (media)

the environment containing nutrients

Inoculum

the microbes you add first

Incubation

letting them grow (often at 37 degrees C for human bacteria)

Culture

the resulting population of microbes growing in the medium

Photoautotroph

Carbon source - CO₂, energy source - light

Photoheterotroph

Carbon source - organic compounds, energy source - light

Chemolithoautotroph

Carbon source - CO₂, energy source - inorganic chemicals

Chemoorganoheterotroph

Both carbon and energy come from organic compounds

Aerobic

top growth

Microaerophilic

growth just below surface

Facultative anaerobic

growth throughout

Aerotolerant anaerobic

some growth in O₂

Anaerobic

bottom growth

Direct cell counts

counts total cells

Turbidity

measures cloudiness, counts live & dead cells

Colony counts (most accurate)

Counts living cells only

Lag Phase

• Earliest period of growth

• Appears “flat” on the graph = slowed growth

• Cells have to adjust to their new environment

• Reproduction has not reached its maximum rate

• Population may be too small for sampling to be accurate

Exponential Phase

• Maximum rate of cell division

• The phase when you can calculate the generation time

• Will continue until nutrients start to run out

Stationary Phase

• Population size limit has been reached

• Rate of reproduction matches or falls below death rate

9.9 mL

10^-2

9.0 mL

10^-1

0.9 mL

10^-1

Eukaryotic Chromosomes

• Location: nucleus

• Shape: linear

• Number: multiple (humans = 46)

• Proteins: wrapped around histones

• Extra DNA: Mitochondria, chloroplast

Prokaryotic Chromosomes

• Location: no nucleus

• Shape: circular

• Number: usually one

• Proteins: no histones

• Extra DNA: plasmids

How do large genomes fit into small cells?

DNA is supercoiled and tightly packed

Semiconservative

Each new DNA molecule has 1 original strand and 1 new strand

When lactose IS present

Repressor: OFF

Transcription: ON

When lactose is NOT present

Repressor: ON

Transcription: OFF

Missense

different animo acid

Nonsense

early STOP

Silent

no change

Frameshift

entire sequence changes

Inversion

bases swapped

Back mutation

returns to normal

Spontaneous mutation

random errors

Induced mutation

Chemicals, radiation

Conjugation

Cell-to-cell contact, uses phili, live - live

Transformation

Uptake of free DNA, dead - live

Transduction

Via bacteriophage (virus)

Glycolysis inputs and outputs

input: 6 glucose, 2 ATP, 2 NAD+

output: 2 pyruvate, 2 NADH, 2 ATP (net)|4 total

Krebs cycle inputs and outputs

input: 2 acetyl-CoA, 2 NADH, 2 CO2

output: 8 NADH, 2 FADH, 6CO2, 2 ATP (net)|4 total

Electron transport chain inputs and outputs

input: 10 NADH, 2 FADH2, O2

output: H2O, 34 ATP (net)|38 total

What are NADH and FADH2? Why are they important and when are they made?

NADH and FADH2 are electron carriers. They hold high-energy electrons and hydrogen that can later be used in the electron transport chain to make ATP

Substrate-level phosphorylation

-       ATP is made by directly transferring a phosphate from a substrate molecule to ADP

-       Happens in glycolysis and the Krebs cycle

Oxidative phosphorylation

-       ATP is made using energy from electron transport and the proton gradient

-       Requires the ETC and ATP synthase

-       This is where most ATP is made in aerobic respiration

Aerobic respiration

Uses oxygen as the terminal electron acceptor

Anaerobic respiration

Uses the same general pathways, but uses a terminal electron acceptor other than oxygen, such as nitrate, nitrite, or sulfate

Alcoholic fermentation

-       Pyruvate is converted to ethanol

-       Used in making alcoholic beverages

-       Performed by yeast or some bacteria

Acidic fermentation

-       Produces acidic end products

-       Includes lactic acid-related pathways in organisms like Lactobacillus and Streptococcus

Chemotherapy

using a drug to control infection without harming host cells

Antimicrobial drugs

compounds that kill or inhibit microbes

Antibiotics

natural antimicrobial drugs

Synthetic drugs

man-made antimicrobials

Selective toxicity

ability to kill/inhibit microbes without harming host cells

Prophylaxis

preventative drug treatment

Combined therapy

using 2 or more drugs together

Synergy

drugs working together for enhanced effort

Cell wall synthesis

Weakens wall - lysis (penicillin)

Cell membrane

Disrupts permeability - leakage (polymyxins)

Nucleic acids

Blocks DNA/RNA synthesis (quinolones, rifampin)

Protein synthesis

Targets ribosomes (tetracyclines, aminoglycosides)

Metabolic pathways

Blocks enzyme activity (competitive inhibition) (sulfonamides, trimethoprim)

Drug resistance

When microbes survive exposure to drugs they were previously sensitive to

Drug resistance (acquired resistance)

-       Develops after exposure to an antimicrobial

-       Microbes were originally susceptible, but change over time

-       Happens through:

• Mutations

• Gene transfer (plasmids)

-       Major clinical problem because it leads to treatment failure

Natural resistance (intrinsic resistance)

-       Microbe is already resistant before exposure

-       Due to natural features like:

• Cell structure (gram- outer membrane)

• Being an antibiotic-producing organism

-       This is not caused by drug use and is less of a concern clinically