Chapter 3 (Cell Structure & Function) Flashcards
What are the characteristics of living things?
Cellularity: organized membrane bound structure that
performs life fxns
Growth: ↑ in size by assimilation (taking in nutrients & using
compounds to make new cell parts)
accumulation: packing material onto cell to make
bigger ex: like build snowman
Metabolism: ability to take in nutrients & use them to provide
energy & build structures
Reproduction: ↑ in number; asexual: prokaryotes single cell
(budding)
Sexual: 2 parental cells
Responsiveness: make changes due to environment
Short term: taxis, enzyme concentrations, transport
Long term: adaptation and evolution of species
What is natural selection?
How does natural selection lead to change in a species? (Hint: think about the antibiotic-resistance example)
some individuals will produce more offspring. Traits of those that reproduce more will predominate in future generation
Natural selection leads to adaptation & evolution of species
When apply antibiotics to a population you get chance to see which cells are resistant to antibiotics
Describe the cell theory
-the cell is the basic unit of like
-all living things are composed of one or more cells
-all cells come from other cells
Prokaryote Cells
o Size
o Nucleus? Organelles?
o Cell wall chemistry
o Ribosomes
o External structures
o DNA
Size: smaller
No Nucleus & organelles
Cell Wall: provide structure & shape protect from osmotic forces
Bacterial cell wall: composed of peptidoglycan- long strings
of alternating N- acetylglucosamine
(NAG) & N-acetylmuramic(NAM)
Ribosome: 70S
External Structures:
Eukaryote cells
o Size
o Nucleus? Organelles?
o Cell wall chemistry
o Ribosomes
o External structures
o DNA
Size: bigger than prokaryotes
Nucleus & organelles: yes
Ribosomes: 80S
External structures:
Eukaryote flagellum
o Structure (basal body-hook-filament vs. 9+2 or 9+0 arrangements)
o Function – how does the flagellum move? How does the organism move?
Basal body & filament, no hook b/c don’t rotate
Basal body: 9+0 (none in center) arrangement in 3s
Filament: 9+2 (2 in middle) arrangement in pairs
Function: Moves in undulation (waving) no run and tumble
Prokaryote flagellum
o Structure (basal body-hook-filament vs. 9+2 or 9+0 arrangements)
o Function – how does the flagellum move? How does the organism move?
Basal body: extend into the cell through cell membrane
through cell wall. Operates like motor
Hook: ridged hook creates bend in flagellum & filament- spins
around & around drives cell a lot better
Filament: majority of the structure
Function: “run & tumble”
Run- move straight line flagellum (CCW)- tufts of
flagella bundle & rotate together
Tumble- abrupt movement of flagellum (CW)- tufts
of flagella become unbundled
What do these words mean?
Monotrichous, lophotrichous, amphitrichous (these are all polar)
Monotrichous: one flagellum (@ one end of cell)
Lophotrichous: tuft/multiple flagella together (@one end of
cell)
Amphitrichous: one or more flagellum @ both end of the cell
What do these words mean?
o Peritrichous
cover the cell
What do these words mean?
o Taxis, chemotaxis, phototaxis, geotaxis, magnetotaxis
Define: Positive taxis & Negative taxis
Taxis: movement in response to stimulus (dif. external
environment stimulus)
-Postive taxis: movement toward stimulus ↑ # of Runs
(CCW)
-Negative taxis: movement away stimulus ↑ # of tumbles
(CW)
Chemotaxis: chemicals
Phototaxis: light
Geotaxis: gravity
Magnetotaxis: magnetic field
Phospholipid bilayer cell membranes:
o Describe the structure of a biological membrane.
o What can cross?
o What cannot cross?
-proteins up to 50%
-Fluid mosaic model: uneven distribution of proteins ( adding
& removing Proteins & phospholipids)
Functions:
1) barrier: separates inside of the cell from the outside
-semi-permeable –> not everything can cross the
bilayer
2) Respiration: location for the conversion of chemical energy
to cellular energy in some prokaryotes
-in order for respiration in membrane need to
have ETC: protons move electrons between one another
- e- get passed on to proteins in the membrane & some
proteins move a proton( hydrogen ion) across
membrane lots of changes on one side of membrane
What CAN cross: (all small & ionic, not too strongly charged)
-water
- small lipid soluble compounds (steroids)
- oxygen & CO2
What CANNOT cross:
-most hydrophilic substances
-charged compounds & ions
-ions
Phospholipid bilayer cell membranes:
Diffusion, facilitated diffusion, osmosis, active transport
Passive Transports: doesn’t require energy, just use
concentration (DFO)
Diffusion: no energy occurs across membrane from high–>low
concentration
Facilitated Diffusion: requires protein
Carrier (permease): specific to chemical
Pore(channel): general, multiple chemicals can cross the
membrane
Osmosis: diffusion of water across membrane w/ or w/o a
pore
Active Transport: use cell energy=ATP to move material from
low to high concentration(ATP broken down
to ADP + phosphate
-Uniport: just 1 molecule move across membrane
-Antiport: 1 molecule in 1 direction other
molecule in other direction against ea. other
-Symport: moves both molecules in same direction
-Coupled transport: 2 transport working together to achieve
active transport (ex: uniport & symport)
What is group translocation? Who does it?
Only occurs in bacteria- chemical is altered as it crosses the membrane (EX: E. coli & glucose)
Describe the Bacterial structures (describe structure and function)
o Glycocalyx
EXTERNAL STRUCTURE
sugar cup
function: to protect cell/allow for attachment
composed of: polysaccharides, proteins or both
2 types of glycocalyces:
1) Capsule- firmly attached to cell surface in some
pathogens protects from immune cells
2) Slime layer- loosely attached- hold more H2O used
to attach to surface & protect against
dehydration
Describe the Bacterial structures (describe structure and function)
o Flagellum
EXTERNAL STRUCTURE
Motility: ability to move through the environment
Basal body: extend into the cell through cell membrane
through cell wall. Operates like motor
Hook: ridged hook creates bend in flagellum & filament- spins
around & around drives cell a lot better
Filament: majority of the structure
Function: “run & tumble”
Run- move straight line flagellum (CCW)- tufts of
flagella bundle & rotate together
Tumble- abrupt movement of flagellum (CW)- tufts
of flagella become unbundled
Describe the Bacterial structures (describe structure and function)
o Fimbria
EXTERNAL STRUCTURE
-nonmotile structures used for attachment
-short, numerous bristle-like surface projections, made of
protein
-stick cells to one another or to a surface( biofilms) or to a host
cell(pathogen)
Describe the Bacterial structures (describe structure and function)
o Pilus
EXTERNAL STRUCTURE
- longer than fimbriae( shorter than flagella)
-hollow tube: allow DNA to be transferred donor to receptor
- “sex pilus” (conjugation pilus): DNA transfer from one cell to
another
Describe the Bacterial structures (describe structure and function)
o Cell wall
EXTERNAL STRUCTURE
Gram +: Thick- many layers of peptidoglycan
-Teichoic acids: help ions pass through wall
-Lipoteichoic acids: link cell wall to cell membrane
-Some can be acid-fast bacteria (mycobacterium)
-additional layer of mycolic acid: hydrophobic waxy
material, prevents staining with crystal violet
Gram - : Thin cell wall of peptidoglycan
-extra membrane –> outer membrane
-From inside—> out: cell membrane->thin cell wall->outer
membrane (periplasmic space-periplasm-)
-Outer membrane: phospholipids, channel proteins,
LPS: lipopolysaccharide (lipid A+ polysaccharide)
-lipid A: also an endotoxin- when gram - bacteria are killed
endotoxin is releases into body which cause fever,
vasodilation, shock, blood clotting
-antibiotics: w/gram- infection want to stop
infection but antibiotic complicated
Describe the Bacterial structures (describe structure and function)
o Cytoplasm
INTERNAL STRUCTURE
- the liquid & structures inside the plasma membrane
Cytosol: the liquid portion of cytoplasm contains:
water, ions, carbs, proteins, lipids, waste
Describe the Bacterial structures (describe structure and function)
o Nucleoid
INTERNAL STRUCTURE (cytoplasm)
Contains DNA + proteins usually forms on single circular chromosome
Describe the Bacterial structures (describe structure and function)
o Inclusions
INTERNAL STRUCTURE
Storage deposits; varies with species
-contains : starches, lipids, sulfur (energy storage for
metabolism of cell), magnetic (allow organism to
figure out magnetic field & figure where to move),
gases, bouncy allow to float
-Polyhyroxybutyrate: PHB= lipid material used to make
biodegraded plastic
Describe the Bacterial structures (describe structure and function)
o Ribosomes
INTERNAL STRUCTURE (cytoplasm)
Site of protein synthesis
-Location throughout cytoplasm
-Size:70S s=sedimentation (how dense)
-Structure: 2 subunits (large & small: made of protein +
ribosomal RNA rRNA -rRNA backbone to subunit-)
Describe the Bacterial structures (describe structure and function)
o Cytoskeleton
INTERNAL STRUCTURE
-simple network of fibers beneath cell membrane- provide shape to cell
-not all bacteria have this structure
Describe the Bacterial structures (describe structure and function)
o Endospores
INTERNAL STRUCTURE
-made during period of starvation
-extremely resistant to: desiccation ,heat ,radiation, chemicals
-can survive for decades
-once food is available, they “wake up” or germination
-Bacillus & Clostridium
-Start as vegetative cells then starve and endospores then when nutrient available germinate and back to vegetative cells
Describe the Bacterial structures (describe structure and function)
o DNA
nucleoid
