the cell Flashcards
what are the two types of cells?
- sex cells/gametes/germ cells (sperm and ovum)
- somatic cells (relating to the body)
extracellular fluid
watery medium cells float in and it’s also btw cells. high in sodium ions, chloride ions
cell membrane
- what the edge of the cell is limited by. (bag that encloses the cell)
- also called plasma membrane/plasmalemma
cytoplasm
material within the cell
cytosol
intracellular fluid (fluid w/in the cell) high in potassium, proteins, amino acids. low concentration Na+, carbohydrates. mostly exists outside of the cell
phospholipid bilayer
effectively isolates cellular content from surrounding fluids by being hydrophobic
what are the heads on the surface of plasma membrane?
hydrophilic (water loving)
what are the tails on the inside of the plasma membrane?
- provides a physical barrier and controls what comes in and out of the cell
- also provides a chem barrier
- repels water
integral proteins (aka transmembrane proteins)
- span the membrane
- integrity of the membrane
- part of it
- like channels
- allow communication btw the extracellular env and the intracellular env
peripheral proteins
- attached to either the inner or outer surface, but can detach
- have diff fxns throughout the cell
- attach to proteins
the cell membrane is what?
selectively permeable (lets some particles in but not all things)
passive mechanisms
energy: do not require energy
types: diffusion, osmosis, facilitated diffusion
concentration gradient: moves from high to low concentration
active mechanisms
energy: require energy
types: endocytosis, exocytosis
concentration gradient: moves from low to high concentrations
diffusion
- molecules leave from an area of high concentration to an area of low concentration
osmosis
movement of water across the membrane to equilibrate impermeable solute concentration.
facilitated diffusion
- movement of solute across the membrane using a transport protein as a passageway
- solutes passively transported across plasma membrane by carrier protein
- bind to receptor site, which causes a conformational change in carrier protein
active transport
- needs ATP
- moves substances across plasma membrane despite opposing concentration gradient (moving against concentration gradient)
Ex: sodium potassium pump: too much Na+ in the cell = pump it out and if you need more you pump it in
Active: endocytosis
- pinocytosis: cell “drinking”
- phagocytosis: cell “eating”
- receptor-mediated endocytosis: target molecules bind to receptor proteins on membrane surface to trigger vesicle formation
- all of these processes involve packaging extracellular material into vesicle (membrane-bound sac)
active: exocytosis
- release of fluids or solids from cells when intracellular vesicles fuse with plasma membrane (wastes, secretions)
- form vesicles inside the cell -> bind to plasma membrane -> break apart -> release
microvilli
- finger-like projections of plasma membrane
- increase surface area of the cell = more absorption of extracellular fluids
- strengthened by cytoskeletal proteins
- allows us to have more receptors
- lots of intestinal cells have microvilli bc that’s where we do a lot of absorbing
non-membranous organelles
- cytoskeleton, microvilli, centrioles, cilia, flagella, ribosomes
- not enclosed by membrane, in contact with cytosol
membranous organelles
- mitochondria, nucleus, endoplasmic reticulum, golgi apparatus, lysosomes, peroxisomes
- enclosed by membrane to keep away from cytosol
cytoskeleton
- network of filaments that gives strength and flexibility to cell
centrioles
- collection and tube like structures made of microtubules
- 9 sets of 3 microtubules (9+0 array)
- centrioles bound tgthr = centrosome