Studied by 3 peoplesurface area -to- volume ratio
as organisms increase in size, their ratio will decrease
a higher SA:V ratio leads to (smaller cells)
more efficient exchange of materials
a SA:V decrease leads to
a difficulty for large cells to perform properly
prokaryotic cell
single-celled organism w/o nucleus
what is inside a prokaryotic cell?
cytoplasm
what is the only membrane in prokaryotes?
plasma membrane
plasma membrane
prokaryotes have a cell wall that surrounds the lipid layer
example of a eukaryote
fungi, protists, plants, animals
organelles
small structures in eukaryotic cells
plasma membrane in eukaryotic cells
outer envelope of cell, made up of phospholipids + proteins
what does the plasma membrane do?
regulates movement of substances in + out of cell
fluid-mosaic model
arrangement of phospholipids + proteins in membrane
adhesion proteins
form junctions between adjacent cells
receptor proteins
serve as docking sites for arrivals at cell
transport proteins
form pumps that use ATP to transport solutes across membrane
channel proteins
form channels that selectively allow the passage of certain ions or molecules
nucleus
largest organelle; directs what goes in cell + responsible for cell’s ability to reproduce
what is the nucleus home to?
DNA - which is organized into large structures called chromosomes
ribosomes
sites of protein synthesis; manufacture all proteins required/secreted by cell, composed of ribosomal RNA (rRNA) + proteins
endoplasmic reticulum (ER)
continuous channel that extends into many regions of cytoplasm, provides support + transportantion
what does the smooth ER lack?
ribosomes
what does the smooth ER do?
makes lipids, hormones, steroids, breaks down chemicals
what do the ribosomes on the rough ER do?
make proteins
golgi complex
modifies, processes, + sorts products
what is the golgi complex called?
packaging and distribution centers (package products in sacs/vesicles)
mitochondria
powerhouse of the cell, converts energy from molecules into useful energy for cell
what is the most common energy molecule?
ATP
lysosomes
carry digestive enzymes, important for apoptosis
what are digestive enzymes used for?
used to break down old organelles or large ingested particles
apoptosis
programmed cell death
vacuoles
fluid-filled sacs that store water, food, wastes, salts, or pigments
cytoskeleton
shape of cell is determined by protein fibers in this
what do plant cells have that animal cells lack?
cell wall > provides support
what do plant cells posses that make them look green?
chloroplasts, which contain chlorophyll
what do plant cell not contain?
centrioles
the ability of molecules to move across the cell depends on :
semipermeability of plasma membrane + size/charge of particles
what size substances can cross membrane with no issue
small substances
what is the outside of the lipid bilayer
hydrophilic
what is the inside of the lipid bilayer
hydrophobic
what kind of substance can pass through the lipid bilayer?
only hydrophobic substances
facilitated transport
helps hydrophilic molecules pass through
aquaporins
water-specific channels
passive transport
if there is high concentration in one area, substance will spread out + diffuse into area of low concentration
what is diffusion?
when a substance moves down the concentration gradient
simple diffusion
when the diffusing molecule = hydrophobic
facilitated diffusion
diffusion requires help of channel-type protein
tonicity
used to describe osmotic gradients
isotonic environment
solute concentration is same inside + outside
hypertonic environment
more total dissolved solutes than cell
hypotonic environment
lower concentration of solute, water will flow out of solute into cell
water potential
measure of potential energy in water; describes eagerness of water to flow from high > low water potential
what is water potential affected by?
solute potential + pressure potential
formula for solute potential of a solution
-iCRT
what does the i stand for?
ionization constant
what does the c stand for?
molar concentration
what does R stand for?
pressure constant
what does T stand for?
temp in Kelvin (C + 273)
active transport
movement against natural flow
primary active transport
when ATP is directly utilised for transport
secondary active transport
when something is actively transported using energy captured from another substance moving DOWN concentration gradient
endocytosis
when particles are too large to enter cell, the cell uses a portion of the cell membrane to engulf substance (membrane forms pocket, pinches in + forms vacuole or vesicle)
bulk flow
one-way movement of fluids brought about by pressure
dialysis
diffusion of solutes across selectively permeable membrane
exocytosis
cell ejects waste products
Note
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