3: cell biology

eukaryotic cells

nucleus, domain eukarya, singular and multicellular organisms, sexual and asexual reproduction, relatively large, greater structural complexity and diversity, limited metabolic diversity

prokaryotic cells

no nucleus, no organelles, domains bacteria and archae, single celled, asexual reproduction, relatively small, reduced structural complexity and diversity, tremendous metabolic diversity

eukaryotic and prokaryotic cells both have

Cell wall, cytoplasmic membrane, cytoskeleton, ribosomes, flagella

eukaryotic cell walls

Provide structural support, protection, and access a filter, defines shape of cell, hypotonic environment; composition varies - plants: cellulose, fungi: chitin (rarely cellulose or glucomannan), algae: cellulose, proteins, agar, carrageenan, silicates, algin, calcium carbonate

prokaryotic cell walls

archaea: Pseudopeptidoglycan, glycoproteins or polysaccharides

bacteria: Peptidoglycan

peptidoglycan

Parallel chains of alternating NAG and NAM linked by peptide bridges between NAMs; gram positives have more amino acids compared to gram negatives; gram-positive bacteria are more chemically resistant

gram stain

detects difference in cell wall structure

LPS (lipopolysaccharides)

Composed of a lipid (lipid A) currently bound to the sugar (O side chain); bacterial endotoxin

bacterial endotoxin

severe gram negative infection; triggers strong immune responses like fever, inflammation, shock, vasodilation, and blood clotting (in liver)

s-layer

strong protective layer composed a protein and glycoprotein found in some prokaryotes

bacteria: located outside cell wall, archaea: functions as cell wall

envelope

All structures found outside of cytoplasm (like cell wall)

cytoplasmic membrane

what are cells are surrounded by; fluid mosaic of phospholipids, sterols, embedded/associated proteins, glycoproteins and glycolipids; selectively permeable; prokaryotes utilize cytoplasmic membrane as an organizing structure more extensively than eukaryotes

archaeal cytoplasmic membranes

bacterial and eukaryotic membrane phospholipids

lipids are identical; archaeal membrane phospholipids are heat tolerant b/c of fatty acid chain “branches”’

some extremophilic archaea have monolayer membranes, two polar heads, increase melting point

membranes

impermeable to most substances (except dissolved gasses like O2, CO2, etc), chemical/voltage gradients across membranes store energy

membrane associated proteins

selective transport channel, enzyme, cell surface receptor, cell surface identify marker, cell adhesion, attachment to cytoskeleton

passive transport processes

diffusion: high to low solute movement

osmosis: water across membrane, solvent movement

osmosis -tonics

hypotonic: Solute concentration and cell lower than outside cell, water moves in

isotonic: Solute concentration equal inside and out; cells w/ no walls like it

hypertonic: Solute concentration higher in cell than outside, water moves out

facilitated diffusion

assisted with protein

channel proteins: like a pipe, flow through

carrier proteins: bind to molecule

gated channel: cant move backwards

active transport processess

Can move low to high but needs energy (going against unfavorable direction),

active transport: requires transport proteins and ATP

group translocation: transporting and modifying molecules, uses less energy, modified cell cant leave thorugh channel protein (cus its modified)

types of transporters

uniport: move on molecule in one direction

symport: move 2 molecules in same direction

antiport: molecules move in opposite directions

cotransport

use energy from gradient to move

bulk transport processess

endocytosis: bulk important; phagocytosis of solids-cell eating, pinocytosis of liquids-cell drinking

exocytosis: bulk export, also moves large molecules

cytoskeleton of eukaryotes

composed of microfilaments, intermediate filaments and microtubules; Define shape of cells lacking walls, anchorage of organelles, transported materials, movement abd motility, microtubules from centrioles, flagella and cilia

cytoskeleton of prokaryotes

Have analogs for all eukaryotic cytoskeletal proteins; cell division, polarity determination, shape determination

ribosomes

site of translation, polypeptides are here

eurkaryotic ribosomes

free floating (80S), rough ER (80S), organelle-associated (70S) - mitochondria and chloroplasts

prokaryotic ribosomes

free floating (70S), anchored to cytoplasmic membrane (70S), anchored to cytoskeleton (70S)

eukaryotic flagella

wiggle rhythmically; filament (tail) and basal body (motor)

prokaryotic flagella

spin 360 degrees; filament (tail), hook (connects filament and body), basal body (motor); allow bacteria cells to move in response to a stimulus

types of prokaryotic arrangements

monotrichous: 1 flagella at one pole

amphitrichous: 2 flagella at each pole

lophotrichous: multiple flagella at a pole

pertrichious: flagella all over

prokaryotic flagella motility

move in response to stimuli; chemotaxis -to chemical gradients, phototaxis- to light, magnetotaxis -to earth magnetic field

runs

linear movements of cell due to counterclockwise (and coordinated) flagellar rotation

short runs = wrong direction, long runs = right direction

tumbles

random changes in direction due to clockwise (and uncoordinated) flagellar rotation

nucleus (eukaryotic only)

usually largest organelle in cell, usually 1 per cell; components: nucleoplasm, DNA packaged with histone proteins (chromatin- uncondensed DNA, chromosomes-condensed DNA), nucleoli (ribosomal RNA and protein), nuclear lamina (gives nucleus shape), nuclear envelope (membrane)

endoplasmic reticulum (eukaryotic only)

flattened hollow membrane system continuous with nuclear envelope; smooth endoplasmic reticulum (SER), rough endoplasmic reticulum (RER-ribosomes, synthesis of polypeptides)

golgi apparatus (eukaryotic only)

receives, modifies, and packages lipids and proteins from ER; usually glycosylation modification; produces secretory vesicles

lysosomes (eukaryotic only)

organelle that eats foreign bacteria; recycling old organisms

peroxisomes (eukaryotic only)

cellular detoxification

vacuoles (eukaryotic only)

storage compartment

centrosomes (eukaryotic only)

Function in mitosis and meiosis (nuclear division), composed of two centrioles

mitochondria (eukaryotic only)

Site of cellular respiration; features: double membrane system, circular chromosome with bacterial genes, 70S ribosomes, replicate independently of cell

chloroplasts (eukaryotic only)

Site of oxygenic photosynthesis, differentiated form of plastic; features: triple membrane system, circular chromosome with bacterial genes, 70S ribosomes, replicate independently of cell (by dividing)

cilia (eukaryotic only)

move cells past tissues, shorter, more numerous (on a cell) than flagella; features: single celled organisms-coordinated beating allows motility, multicellular organisms-move substances past non-motile cells

Like flagella, filament and basal body composed of microtubules in “ 9 + 2” and “9 + 0” arrangement

nucleoid (prokaryotic only)

Region of cytoplasm where chromosomal DNA is found;

single circular chromosome, bacteria- NAPs organize DNA, archaea- NAPs or histone like proteins

NAP

nucleoid associated proteins

plasmids (prokaryotic only)

Small circular extra chromosomal DNA molecules, give survival advantages (bonus genes), may be hundreds per cell, can be exchanged by conjugation (with other species of prokaryotes)

pili (prokaryotic only)

Long hollow tubes used for conjugation (horizontal transfer of plasmids, gene exchange=genetic diversity)

fimbriae (prokaryotic only)

Sticky bristle like projections for adhesion, shorter than flagella, may be hundreds per cell

endospores (prokaryotic only)

Dormant durable cells formed internally by some gram positive bacteria

function: survival of species (not reproduction), can withstand: extreme temperatures, extreme desiccation (dehydration), radiation, chemicals

viability: decades to thousands of years

glycocalyx

Mucoid mute protective layer surrounding some mute protective layer surrounding some prokaryotes

forms: slime layer- water soluble, protects cells from desiccation, helps attach to surfaces, allows gliding motility; capsule- Not water soluble, protect cells from desiccation, helps attach to surfaces, interferes with immune responses, virulence (disease) factor

prokaryotic cell common shapes

coccus: circular, bacillus: rod-shaped, coccobacillus: short/oval rod, vibrio: bent once, comma shape, spirillum: bent multiple times, spiral-shaped, spirochete: long corkscrew, filamentous: long, thread-like

prokaryotic cell common arrangements

single: individual, diplo-: pairs, strepto-: chains, palisades: chain but folded, tetrads: 4 cells in squares, sarcinae: 3D cubes, staphylo-: clusters (like a grape)

histone proteins — bacteria vs. archaea

bacteria = none; archaea = histone-like proteins

RNA polymerase — bacteria vs. archaea

bacteria = one; archaea = several

pathogenicity — bacteria vs. archaea

bacteria = many pathogens; archaea = rarely pathogenic

extremophiles — bacteria vs. archaea

bacteria = rare; archaea = common

periplasmic space

space between the inner and outer membranes of gram-negative bacteria

mycolic acid

waxy substance in Mycobacterium cell walls; reduces water loss and interferes with simple staining