Microbio exam 1

Germ theory

Some diseases are caused by microorganisms that have gained access to the human body

Louis Pasteur

Conducted experiments that disproved spontaneous generation

Koch’s 1st postulate

The suspected pathogen must be present in all cases of the disease and absent from healthy animals

Koch’s 2nd poslulate

The suspected pathogen must be grown in pure culture

Koch’s 3rd postulate

Cells from pure culture of the suspected pathogen must cause disease in a healthy animal

Koch’s 4th postulate

Suspected pathogen must be reisolated and shown to be the same as the original

Evolution

Process of change over time that results in new varieties and species of organisms

All cells have

Cytoplasmic membrane, cytoplasm, ribosomes, and a genome

Resolution

Smallest distance by which two objects can be separated and still distinguished

Bright-field microscopy

Light passes through cell directly forms the image

Phase contrast and Differential interference contrast

Exploits the phase change of light passing through an object of varying thickness and density

Dark-field microscopy

Illuminating rays are directed from the side, so only scattered light rays enter the lens

Fluorescence microscopy

Uses fluorescent chemicals to absorb light at one wavelength and emits light at a specific longer wavelength. Good for viewing specific cells or components of cells

Transmission electron microscopy

Electron passes through the specimen and reveals the internal structure

Scanning electron microscopy

Electrons scan the specimen surface and reveals the external features in 3D

Coccus

Spherical or ovoid

Bacillus

Rod

Strepto

Chain

Staph

Clusters

Diplo

Pairs

Peptoglycan

Polysaccharide chains wrapped in circles around the cell wall. Main composite of bacterial cell wall

Gram positive color

Retains crystal violet

Gram negative color

Needs pink counter stain

Lipoteichoic acids

Found in gram + bacteria, increases strength of cell wall

Peptoglycan

Bacterial membrane layer. Think in gram+ bacteria, thin in gram- bacteria

Periplasm

Space between inner and outer membrane in gram- bacteria

Cytoplasmic membrane composition

Phospholipids studded with proteins. No cholesterol

Membrane function

Permeability barrier, protein anchor, energy conservation

Outer surface of membrane

Interacts with substrates or processes large molecules for transport

Inner surface membrane

Interacts with substrates involved in energy-yielding reactions and other cellular functions

Channel

Transports solute across the membrane, found in the outer membrane of gram- bacteria and some membranes of gram+ bacteria

Carrier

Transports solute across membrane, active or passive

Receptor

Binds extracellular or periplasmic molecules, conformational change

Enzyme

Facilitates chemical reactions

Simple transport

Driven by proton motive force

Group translocation

Chemical modification of transported substance driven by phosphoenolpyruvate

ABC transporter

Periplasmic binding proteins are involved, energy comes from ATP

Uniporters

Transport nutrients in one direction

Symporters

Function as cotransporters

Antiporters

Transport a molecule across the membrane while transporting another molecule in the opposite direction

Capsules/slime layers

Polysacharride layers that assist in attachment to surfaces and resist dessication

Fimbrae

Short, helical, filamentous protein structures that enable bacteria to stick to surfaces

Pili

Thin filamentous proteins that allow bacterial attachment to surface, movement via twitching motility, DNA transfer, and evasion of immune system

Flagella

Long, helical proteins that rotate to propel the cell

Monotrichous

Single polar flagellum

Amphitrichous

Flagellum at each pole

Lophotrichous

Multiple flagella localized at cell poles

Peritrichous

Multiple flagella at many locations in the membrane

Chemotaxis

Movement in response to chemicals

Endospores

Dormant, non-reproductive structure that allows survival in harsh conditions

Catabolism

Energy releasing reaction

Anabolism

Energy using reaction

Chemoorganotrophs

Generate ATP using oxidation of organic compounds

Chemolithotrophs

Generate ATP using oxidation of inorganic compounds

Phototrophs

ATP generated from harnessing light energy

Heterotrophs

Utilize carbon from organic compounds

Autotrophs

Utilize carbon from CO2

Exergonic

-delta G, releases energy

Endergonic

+delta G, requires energy

Prosthetic groups

Cofactors that are inorganic molecules

Coenzymes

Cofactors that are organic molecules

Cofactors

Small non-protein molecules found in enzymes that participate in catalysis but are not substrates

Apoenzyme

An enzyme that requires a cofactor that is not bound to it to catalyze a reaction

Holoenzyme

An active enzyme that is bound to its cofactor

Feedback inhibition

Method of hindering a metabolic pathway by having a product inhibit an earlier reaction

Noncompetitive inhibition

Inhibitor changes the shape of an active site

Competitive inhibition

Inhibitor blocks an active site

Essential nutrients

Nutrients that must be supplied by the environment

Macronutrients

Major elements in cell macromolecules and ions necessary for protein function

Mucronutrients

Trace elements necessary for enzyme function

Complex media

Chemically undefined media or media such as nutrient broth or agar

Defined/synthetic media

Chemical composition of the media is known

Selective media

Contains ingredients to inhibit growth of certain spores to allow the growth of others

MSA

Selective media for the isolation of staphylococci

Differential media

Contains specific chemicals to indicate species that possess or lack a biochemical process

B period

Cell increases in mass and size

C period

Chromosome replicates and two strands are segregated

D period

Synthesis of a septum forms two identical cells

MreB

Major shape-determining bonds around the inside of the cell underneath the cytoplasmic membrane

Autosysins

Sever pre-existing peptoglycan, creating breaks in the sugar backbone and peptide crosslinks. Happens during B phase

Ftsz

Protein that forms a ring around the center of the cell during division

ZipA

Protein anchor that connects FtsZ ring to the cytoplasmic membrane during division

FtsA

Protein that helps connect FtsZ ring to the membrane and recruits other divisome proteins

Min proteins

Proteins that facilitate the location of the FtsZ ring

Lag phase

Interval between innoculation and beginning of growth. No cell division happens while bacteria adapt to the environment

Exponential phase

Exponential growth of population occurs. cells are healthiest

Stationary phase

Population growth is limited by nutrient availability, buildup of waste, or space/ Number of viable cells is equivalent to dead cells

Death phase

Most cells die, but remaining viable cells can be transferred to a new culture

Continuous culture

Open-system microbial culture of fixed volume

Chemostat

Most common type of continuous culture device

Colony forming unit assay

A culture of bacteria is serially diluted in sterile liquid media and the dilutions are plated. Number of colonies on the plate indicate the viable cells in the original culture

Microautotrophs

Grow in low oxygen and carbon rich environments

Anaerobes

Don’t use oxygen

Facultative anaerobes

Grow with or without oxygen

Obligate anaerobes

Inhibited or killed by oxygen

Aerotolerant anaerobes

Insensitive to oxygen