Cliff's - Chapter 2 - Cells Flashcards
cell
basic functional unit of all living things
plasma membrane (cell membrane)
bounds cell
encloses nucleus and cytoplasm
cytoplasm consists of
organelles suspended in fluid matrix, cytosol
organelles
specialized bodies
cytosol
is
consists of
fluid matrix,
water, dissolved substances - proteins + nutrients
plasma membrane
function
- separates internal metabolic events from external environment
- controls movement of materials into and out of cell
plasma membrane
composition
- double phospholipid membrane
- (liquid bilayer)
- polar hydrophlic heads form two outer surfaces
- nonpolar hydrophobic tails point inwards
Peripheral proteins
attach loosely to inner or outer surface of membrane
integral proteins
extend into membrane
transmembrane proteins
type of integral protein
span across membrane (surface to surface)
integral proteins
form
amphipathic
amphipathic
hydrophobic + hydrophilic regions
fluid mosaic model
mosaic
scattered proteins within flexible matrix of phospholipid molecules
phospholipid membrane is selectively permeable
only these may freely pass:
small, uncharged, polar molecules
e.g. H2O, CO2
hydrophobic molecules
e.g. nonpolar mlc like O2, lipid-soluble mlc like hydrocarbons
phospholipid membrane
impermeable molecules:
large polar molecules
e.g. glucose
all ions
Channel proteins
(plasma membrane)
certain hydrophilic (water-soluble) mlc
polar + charged molecules
Ion channels
(plasma membrane)
ions
gated channels
ion channels in nerve and muscle cells
open and close in response to chem or electric stimuli
passge of specific ions (K+, Na+)
Porins
(plasma membrane)
certain ions
small polar molecules
aquaporins
(plasma membrane of certain cells)
e.g. kidney, plant roots
dramatically increase flow of H2O
Carrier proteins
(plasma membrane)
bind to specific mlc
mlc transferred across membrane after carrier proteins change shape
e.g. glucose via carrier protein
Transport proteins
(plasma membrane)
use ATP (energy)
active transport
e.g. Na+-K+ pump
active transport
ATP used to transport materials
Na+-K+ Pump
uses ATP to maintain higher conc of Na+ and K+ on opp. sides of plasma membrane
recognition proteins
function
(plasma membrane)
give each cell type unique ID
rec b/w self types
self cells vs. foreign cells
normal cells vs. infected cells (viruses)
recognition protein
(plasma membrane)
form
glycoproteins
oligosaccharide attached
oligosaccharide extends away from surface of membrane
oligosaccharide
short polysaccharide chains
glycoproteins
proteins with oligosaccharides covalently bonded to polypeptide side chains
adhesion proteins
(plasma membrane)
attach cells to neighboring cells
or
provide anchors for internal filmanets and tubules of cell
internal filaments and tubules of cell provide…
stability to cell
receptor proteins
(plasma membrane)
binding sites for hormones, trigger mlc
when hormones, trigger mlc bind to receptor proteins..
specific cell response activated
Cholesterol mlc distributed throughout plasma membrane provide
rigidity to membrane (animal cells)
sterols
function as cholesterol in plasma membrane in plant cells
provide rigidity to membrane
glycocalyx
def and function
carb coat
covers outer face of cell wall (bacteria)
covers outer face of plasma membrane (animal)
glycocalyx
form
oligosaccharides attached to glycolipids and proteins
glycolipids
membrane phospholipids
glyocalyx
depending upon cell, may provide (3):
adhesive capabilities
barrier to infection
markers for cell-cell recognition
Organelles
bodies within cytoplasm
serve to physically separate various metabolic reactions
nucleus bouned by
nuclear envelope
nuclear envelope consists of
two phospholipid bilayers (sim. to plasma membrane)
DNA form
spread out within nucleas in form of chromatin
when cell begins to divide, chromatin…
condenses into chromasomes
before dividing, chromosomes made up of
two long DNA molecules
various histone molecules
histones
protein
organize - coil DNA into nucleosomes
nucleoli
in nucleus
concentrations of DNA
manufacture subunits of ribosomes
during cell division, chromsomes separate in the
nucleus
ribosome
made up of…
RNA molecules and protein
2 subunits
ribosome subunits and unification
40S + 60S
manufactured in nucleoli
subunits move nuclear envelope —> cytoplasm
combine –> 80S in cytoplasm
ribosome function
in cytoplasm - help assemble amino acids —> proteins
S Value
(Svedberg unit)
how readily product forms sediment in centrifuge
larger values = heavier products
Endoplasmic Reticulum
(ER)
form
2 types
stacks of flattened sacs
cross section: series of maze-like channels
rough (with ribosomes)
smooth (without ribosomes)
ER
function (general)
production of various materials
rough ER
has ribosomes on surface
creates glycoproteins
how does rough ER create glycoproteins?
attaches polysaccharide groups to polypeptides as they are assembled by ribosomes
smooth ER
function
various activities
synthesis of lipids and hormones
esp in cells that produce these for export from cell
smooth ER in liver cells
breakdown of toxins
drugs
toxic by-products from cellular rxns
Golgi apparatus
(golgi complex, golgi body)
form
group of flattened sacs
arranged like stack of bowls
gogli
fxn
modify and pack proteins and lipids into vesicles
vesicles
form
small
spherically shaped sacs
bud from outside surface of golgi
vesicles
fxn
merge with plasma membrane
release contents to outside of cell
Lysosomes
form
vesicles from golgi that
contain digestive enzymes
lysosomes
fxn
break down food
cellular debris
foreign invaders (bacteria)
lysosomes
characteristics (pH)
low pH (favorable to enzymes)
lysosomes occur in
animal cells
NO plant cells
if an enzyme escapes from lysosome
it will be inactive in neutral pH of cytosol
Peroxisomes
fxn
break down various substances
e.g. H2O2, fatty acids, amino acids
peroxisomes are common in these kinds of cells
liver and kidney
peroxisomes fxn in liver and kidney cells
break down toxic substances
peroxisomes in plant cells
modify by-products of photorespiration
photorespiration
CO2 diverted from use in photosynthesis
glyoxysomes
peroxisomes in germinating seeds
break down fatty acids —> energy for growth
Mitochondria
carry out aerobic respiration
aerobic respiration
energy (ATP) obtained from carbs
chloroplasts
carry out photosynthesis
photosynthesis
plant process
incorporate energy from sunlight into carbohydrates
three protein fibers, in decreasing diameter
microtubules
intermediate filaments
microfilaments
microtubules
intermediate filaments
microfilaments
protein fibers involved in shaping or coordinating movements of cytoskeleton
cytoskeleton
internal structure of cytoplasm
microtubules made of
protein tubulin