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
cilia
- hair-like projections from cell surface (like a larger microvilli)
- beat rhythmically to move fluids across cell surface
- 9 pairs of microtubules surrounding a central pair (9+2 array)
- anchored to compact basal body at base
flagella
- move cells thru fluid
- like a tail
- only cell with flagellum in humans is sperm cell
ribosomes
- manufacture proteins; can be either fixed or free
- large and small subunits
mitochondria
- produces most energy (ATP) in the cell
- double-layered membrane
- inner membrane folded into cristae, increasing surface area (++ATP!)
- cristae: crest and valleys in the mitochondria
nucleus
- control center
- stores DNA
- surround by the nuclear envelope which protected the nucleus (in places connected to endoplasmic reticulum)
- filled with nucleoplasm, which suspends contents of nucleus (enzymes, proteins, RNA, DNA, filaments)
- nuclear envelope pierced by nuclear pores that allow communication btw cytosol and nucleus
endoplasmic reticulum
- network of intracellular membranes that form flat sheets (cisternae)
- cisternae: chambers that exist within these sheets and tubes
- synthesis of carbohydrates, lipids, and especially proteins occurs in ER
- storage location of certain synthesized molecules
- transport mechanism of other molecules
Rough ER
has fixed ribosomes for protein synthesis and export out of the cell
Smooth ER
synthesis of lipids and carbohydrates (no ribosomes)
golgi apparatus
- series of membranous sacs (cisternae) that give rise to lysosomes and secretory vesicles
- important for the synthesis and packaging of secretions (esp. proteins)
- packaging warehouse
lysosomes
- vesicles derived from golgi apparatus that remain in the cell’s cytoplasm
- removes bacteria and organic debris from cytoplasm and isolate it into vesicles because they contain hydrolytic or digestive enzymes
- contain digestive enzymes, digests (lyses) what’s in or fuses with the lysosomes
- releases nutrient components into cytosol and expels waste by exocytosis
gap junctions
permit free diffusion of ions and small molecules btw two cells
hemidesmosomes
resemble half of a spot desmosome: attach to basement membrane
tight junctions
formed from fusion of two cell membranes; block diffusion of fluids and solutes btw cells
(spot) desmosomes
plasma membranes linked by proteoglycans and cell adhesion molecules
how proteins move in the golgi apparatus
- Proteins synthesized in rough ER
- ER packages proteins into vesicles that bud off of ER
- Transport vesicles fuse to the forming (Cis) face of the Golgi and empty into cisternae
- Each cisterna physically moves from forming face to maturing face, carrying proteins with it (cisternal progression)
- Maturing (trans) face generates vesicles that carry proteins away from golgi
