CH 5 Flashcards
prokaryotes
small cell
DNA exists in nucleoid in cytoplasm
typically one circular chromosome
eukaryotes
range of sizes
membrane-bound nucleus contains DNA
linear chromosomes in nucleus
much more extensive intracellular membrane systems
complex envelope
consists of: cell membrane, cell wall, outer membrane (gram-negative), outer layers
cytoplasm
gel-like network of proeins + macromolecules
nucleoid region
system of looped DNA coils, contains one circular chromosome, DNA binding proteins
endosymbiosis theory - Lynn Margilus
theory that the orgin of eukaryotic cells was from larger cells engulfing smaller bacterial cells and becoming symbiotic
Evidence of the endosymbiotic theory
mitochondria and chloroplasts contain parts of the bacteria, parts of eukaryotes
how are mitochondria and chloroplasts like bacteria?
they have double membranes, resemble bacteria in size and shape, have circular genomes, ribsomes like prokaryotes, can divide independent of the cell
bacilli
rods
spirochetes
long corkscrew, longer flexible, axial filament
cocci
spheres
vibrio
commas
spirilla
short spirals or helical, shorter, rigid, external flagella
arrangements are often made based on
the plane of cell division
strepto…
chains
diplo…
pairs
tetrads
four pairs in a clover shape
sarcinae
double four leafed clover
staphylo…
clusters
what structure defines the existence of a cell?
cell membrane
cell membrane
phospholipid bilayer
cell wall
consists of peptidoglycan sugar chains linked covalently by peptides/amino acids
outer membrane
exists in Gram Neg cells outside of cell wall consisting of phospholipids + LPS
cell membrane protein functions
structural support for external structures (flagella, pili)
detect environmental signals
export toxins (cell-signaling)
selective transport of substances
energy storage and transfer
what molecules can easily cross the lipid bilayer?
hydrophobic molecules, small, uncharged polar molecules
what molecules are impermeable?
large, uncharged polar molecules: glucose, sucrose
ions
passive transport
moves nutrients with concentration gradient (high to low)
net movement until equilibrium is reached
types of passive transport
simple diffusion, facilitated diffusion
facilitated diffusion
rate of transport increased by a membrane protein that carries compound
simple diffisuion
across the phospholipids
active transport
moves against concentration gradient (low to high)
requires ENERGY
types of active transport
using a carrier molecule or potential across a membrane
carrier molecule
uses ATP (primary transport), High Energy Metabolite (Group translocation)
potential across a membrane
graident of another molecule -> coupled transport
how does coupled transport work?
when a molecule moves high to low, energy is released. transport proteins harness this energy to drive another molecule low to high
symport
molecules travel the same direction in coupled transport
antiport
molecules travel opposite direction in couple transport
siderophore
iron-binding molecule, helper molecule for scavenging scarce minerals
efflux
expel wastes/toxins (antibiotics)
group translocation
uses energy from a high energy organic compound in the cell (not ATP); transported molecule is chemically modified
osmosis
diffusion of water across a selectively permeable membrane
isotonic
water molecules diffuse in and out of the cell at the same rate
hypertonic
water moves outside of cell and volume shrinks as plasmolysis (net loss)
hypotonic
net gain of water in the cell, volume expands as lysis
exocytosis
vessicle fusion forms opening to release vesicle contents outside of cell
how does the eukaryotic cell secrete proteins?
exocytosis and endocytosis
endocytosis
food particles is taken in by endosomes and lysosomes and digested
bacterial cell wall
helps withstand intracellular osmotic pressure
makes cell rigid
target of penicillian
peptidoglycan, glycan chains and short peptides
beta-lactams
inhibit formation of the peptides chains (enzyme inhibitor) eg. penicillin
lysozyme
human enzyme that breaks down the glycan chain
gram staining
gram positive are purple
gram negative are pink
gram positive
thick cell wall with many layers
teichoic acids with a negative charge. aid with cell division, cell morphology
lipoteichoic acids - attach to cell membrane
gram-negative
thin cell wall with one or two peptidoglycan layers
lipoproteins attach to outer membrane
has an outer membrane with porin proteins and LPS
lipid A
anchored in outer membrane of envelope
endotoxin
endotoxin
lipid A that is a cell component that once pathogen is lysed, causes endotoxic shock
core polysaccharide
sugar chain extending outside the cell
o polysaccharide
polysaccharide chain of sugars - identification
mycoplasma
LACK a cell wall
only have a cell membrane
small
pleomorphic
close relative of gram -
stain gram -
stronger cell membrane that contains sterols
many are pathogens
archaea cell wall
diversity of cell wall structures
S-layers sheets
pseudomurein
some dont have any cell walls
gram staining is not reliable
eukaryotic cell walls
alge has cellulose or pectins
fungi has chitin
bacterial DNA
double-stranded helix
supercoiled
organized by DNA binding proteins
nucleoid region
location of bacterial DNA
organized into loops called domains
ribosomes
make proteins from mRNA
prokaryotic
odd numbers, smaller
70s = 50s + 30s
eukaryotic
even numbers, larger
80s = 60s + 40s
adherence
ability to attach to a subtrate/surface
pili
used for adherence
conjugation (sex) pilus
transfers DNA between cells, sticks a tube that connects the cytoplasm of two cells and allow for the transfer of genetic material
stalks
membrane enclosed extensions of cytoplasm
secrete adhesion factors (holdfasts)
flagella
used in most prokaytoic motility
spin like a propeller (rotary)
powered by proton motive force
photo and chemotaxis
toward/away from light
toward/away from chemicals
PMF
stores energy generated by moving protons outside the cell
powers rotary flagella
move nutrients into cell
drives synthesis of ATP
polar motility
on the poles
peritrichous
all over
eukaryotic flagella
made up of microtubules (extensions of the cytoskeleton)
whip like motion
energy source is ATP
usually has few long flagella or many cilia
S layer
protein lattice outside the peptidoglycan in some bacteria, helps strengthen cell wall
glycocalyx
“sugar shell” made mostly of polysaccharides
bacterial structures made of glycocalyx layers
capsule
slime layer
functions of glycocalyx
attachment, proteins, nutrients/prevent nutrient loss
chromosome
essential genes, most often circular, 1 per cell
plasmids
non-essential genes, muc smaller, replicate indepentently from chromosome, often transferred to other cells
what is horizontal gene transfer?
transferring of plasmids to anoter cell
chromatin
complexes or DNA and proteins in a membrane bound nucelus
the nucelus has?
two membranes: nuclear envelope
nuclear pore complexes: transport
how do bacteria move in response to stimuli?
flagella rotate CCW towards attractant; CW rotation stops forward motion, cell randomly changes direction until it detects attractant again
gas vesicles
aquatic bacteria inflate/deflate for buoyancy
storage granules
storage of nutrients
mangetosomes
store magnetite (iron oxides) for magnetetaxis (senese Earth’s geomagnetic field)
inclusions
aggregates in the cytoplasm, often proteins
