Microbiology Midterm I

flashcards created from Dr. Whiteley's midterm I in-class notes.

beginning of life

3.8 billion years ago

great oxygenation

2.2 billion years ago

eukaryotic origin

2.1 - 1.5 billion years go

origin of animals

600 million years ago

origin of humans

200,000 years ago

how do we know the origin of life?

zircons

zircons

oldest mineral; traps smaller, degradable molecules

oldest zircons

4.6 billion years old

stromatolites

layers of prokaryotes and rocks; mat fossils

how to know stromatolites were living

contain 12C

evidence for earlier life

cell shapes in old hydrothermal vents

how to know when oxygenation happened

iron banding

how to know when eukaryotes emerged

nucleus; cholesterol derivatives

biomarker

entity/molecule whose presence indicates an organism

Lucretius

diseases are caused by invisible creatures

Fracastoro

seeds of disease spread through possessions

fomites

things that can transmit diseases with out the infected person present

Hooke

sees first cell

Leeuwnhoek

invented microscope; teeth scrapings

Pasteur

1861; no spontaneous generation

Pasteur flask

open and closed to air; boiled beef broth did not show growth

Redi

disproved spontaneous generation before Pasteur

Woese

split domain into bacteria and archaea

red blood cell size

larger than most bacteria

microscopic sizes

virus < bacteria < eukarya

pandora virus

visible to naked eye

social amoebae

form spores to find new food

number of human cells

10^13

number of bacterial cells in humans

2 * 10^13

highest density of bacterial cells in humans

mouth, large intestine

E. coli

bacteria we know the most about

E. coli makeup in gut

commensal; 2%; produced vitamins; NOT anaerobic

E. coli doubling time

15 minutes

bacillus

1 x 4 um

coccus

sphere

syphillus

squiggly

Staphylococcus aureus

main cause of cavities; 30% have it in nasal pharynx

bacterial size

70-100 microns

why are bacteria small

surface area/volume ratio should be large

Claustridium dificil

hospital sickness; 8-10 minute doubling time

slowest growing bacteria

years; in ice cores

human body bacteria doubling time

generally 1 hour

bacterial cytoplasm H2O

80%

ion concentration in cytoplasm

300 mMol

potassium ion concentration in cell

250 mMol

glucose concentration in cell

1-2 mMol

ribosomes in cytoplasm

main energy sink; 7-50k

determines amount of ribosomes

amount of food cell has

cytoplasm viscosity

\> olive oil, < glycerin

cytoplasm electronic environment

reducing environment; everything wants electrons

viscosity of cytoplasm

mostly because of unbound DNA

E. coli DNA

4.5 million basepairs; 1 millimeter if DNA is stretched

DNA arrangement in cytoplasm

supercoiling around proteins

most antibiotics mechanism

targets ribosome; inhibit replication

antibiotic issue

permeating cytoplasmic membrane

lipid bilayer width

8nm

protein percentage of membrane

50 - 70% of dry weight

membrane protein structure

amphipathic

membrane fluidity

lateral movement; hardly any flipping; affected by temperature

most common bacterial phospholipid

phosphatidylethanolamine, + charge

lipid bilayer charge

NON neutral; + or -

membrane viscosity

olive oil; but VERY stable

interactions between nonpolar parts of membrane

Van der Waals

disrupt Van der Waals interactions

heat, ethanol (solubilises membrane)

proton motive force

bring protons in on concentration gradient; gain energy for transport

why do bacterial cells not lyse in non isotonic environments?

cell wall

Hans Christian Gram

gram stain with light microscopy

gram positive color

purple; crystal violet

gram negative color

red; safranin

cell wall biomarker

peptidoglycan

penicillin

inhibits peptidoglycan synthesis; DOES NOT DESTROY; only works if cells are growing; leaves behind shells for immune response

peptidoglycan structure

2 sugars linked by amino acids

cell wall transport via

pores

ways to increase membrane fluidity

add double bonds to phospholipid tails to add kinks; add sterols

sterols in membrane

keeps membrane rigid in hot temperatures, fluid in cold

bacterial cell wall exceptions

mycoplasma

acid fast bacteria

waxy cell wall; needs to be stained in acid

leprosy

cannot be grown on plate

gram + cell wall

60-80 nm peptidoglycan cell wall (30 - 40 layers); techoic acids covalently attached

techoic acid

negatively charged; anchors cell wall to membrane

component of peptidoglycan linkage

N-acetylglucosamine and N-acetylmuramic acid attached to amino acid chain that form repeating structure when linked to other units

N-acetylmuramic acid

biomarker for bactera

D amino acid chain

microbes

L amino acid chain

mostly in humans

break peptide bonds in cell wall

proteases

lipotechoic acid

long sugar with lipid in cell membrane

gram negative cell wall

double membrane with thin (2 - 4 nm) peptidoglycan layer in between

lipoprotein

stabilize outer membrane; covalently attached to peptidoglycan

periplasm

gel between inner and outer membrane in gram - cells

periplasm volume

20% of cell; 30-50 nm wide

bacteria protein volume

2.5 million proteins/cell

bacteria lipoprotein volume

600,000/cell (25% of cellular proteins)

asymmetric bilayer composed of

oligosaccharide

oligosaccharide

lipopolysaccharide, Lipid A

Lipid A

very toxic to humans; must be tested for in all human products

lipopolysaccharide

O-antigen (very variable), core oligosaccharide (generally quite conserved)

gram + cells cell wall assembly

some outside enzymes; peptidoglycan synthesis inhibitors work best here

porin length

600 Daltons; 3 glucose molecules

penicillin in gram - cells

encounters resistant proteins

P. aeruginosa Lipid A

can add sugars and proteins quickly and adaptively