anatomy quiz 2 ch 3 cell

cell theory

cells are the smallest unit of life, all organisms are made of one or more cells, cells only arise from other cells

three basic components of any cell

plasma membrane, cytoplasm, nucleus

plasma membrane

thin structure composed of a bilayer of lipid molecules with protein molecules embedded through it

physical barrier, selective permeability, communication, cell recognition

integral proteins

proteins firmly inserted into the lipid bilayer, some protruding from one side, but most as transmembrane that span the entire membrane width

peripheral proteins

proteins not embedded into the lipid bilayer, instead, attach loosely to integral proteins or are otherwise anchored to the membrane

functions of membrane proteins

transport, receptors, enzymes, cell-cell recognition, cell-cell joining, attachment to cytoskeleton

glycocalyx

sticky carb-rich area of the cell surface created by the sugars of glycoproteins and glycolipids

lipid rafts

rafts with cholesterol and sphingolipids that make cell processes more efficient by clustering specific proteins and lipids

tight junction

integral protein molecules fuse like a ziploc bag, forming an impermeable junction that encircles the cell

desmosomes

anchoring junctions, couplings scattered like rivets along the sides of adjacent cells to prevent separation with plaques, velcro

gap junction

communicating junction, adjacent plasma membranes are very close, and cells are connected by hollow cylinders (connexons)

diffusion

the movement of particles from an area of higher concentration to an area of lower concentration

simple diffusion

substances diffuse directly through lipid bilayer, such as nonpolar small molecules that are lipid soluble

facilitated diffusion

transported substance moves with carrier protein (carrier mediated fd) or through water-filled channel (channel mediated fd)

osmosis

the movement of water through a selectively permeable membrane

osmotic pressure

the tendency of water to move into the cell by osmosis

osmolarity

the total concentration of all solute particles in a solution

hypertonic

higher concentration of nonpenetrating solutes in the cell

lose water; crenate

hypotonic

lower concentration of nonpenetrating solutes than cells

gain water; lyse

isotonic

solutions have the same concentrations of nonpenetrating solutes as those found in cells

active transport

move solutes, ions, against concentration gradient with the requirement of ATP

primary active transport

pumps that hydrolyze ATP for energy

secondary active transport

pumps that use energy stored in concentration gradients of ions

na+/k+ pump

primary active transport system, each molecule of ATP yields 3 Na+ out and 2 K+ in 1:3:2

muscle and nerve cells, operates continuously

symport

two transported substances move in the same direction

antiport

two transported substances wave to each other crossing in opposite directions

i.e. cotransporter that uses cells to regulate intracellular pH

vesicular transport

cellular energy used to move large substances, or large amounts, across cellular membranes inside vesicles, endo/exocytosis

vesicular trafficking

moves substances from one area/membranous organelle to the other

SNARE proteins

membrane proteins that control fusion of membranes, specifically with fusion of synaptic vesicles with axon terminal

SNARE proteins at chemical synapse

an action potential arrives, causes Ca2+ to enter, Ca2+ sensing protein binds Ca2+, which interacts with SNARE and brings vesicle to axon terminal, vesicle fuses with membrane and releases neurotransmitter into synaptic cleft

resting membrane potential

voltage across plasma membrane during resting state of excitable cell; —50 to —90 millivolts depending on cell

K+ most responsible

role of sodium potassium pump in rmp

Na+ and K+ constantly leak in and out, pump maintains concentration gradients, and maintain isotonicity in cell, stabilizing membrane at —70mV

cell adhesion molecules (CAMs)

membrane proteins that help cells bind to each other and to ECM

ex: cadherins and integrins

second messenger system

messengers connect plasma membrane events to internal metabolic machinery of the cell

i.e. cyclic AMP and ionic calcium that activate protein kinase enzymes, which then transfer phosphate groups from ATP to other proteins, activating enzymes

g-protein second messenger system

1) ligand binds to receptor

2) activated receptor binds to G-protein and activates

3) activated G-protein activates/inactivates effector protein by causing its shape to change

4) activated effector enzymes catalyze reactions that produce 2nd messengers in cell

5) 2nd messenger activate other enzymes or ion channels

6) kinase enzymes activate other enzymes

steps of er —> golgi packaging

vesicles move from er to golgi

proteins modified

proteins distributed (secretion, membrane, digestive)

microfilaments

strands made of actin, cell motility and shape

intermediate filaments

tough, woven fibers composed of tetramer fibrils, attach to desmosomes and act as cables to resist pulling forces on cell

microtubules

hollow tubes of tubulin protein, determine overall cell shape as well as distribution or organelles

cilia

hairlike extensions that move substances

flagella

tail-like projection to propel cell itself rather than substances

interphase

period from cell formation to cell division/metabolic phase

G1 of interphase

synthesizes proteins and lasts longest

S phase of interphase

DNA is replicated

G2 phase of interphase

brief final phase where enzymes and other proteins are synthesized and moved to proper site

replication steps (see notes)

uncoiling, separation, assembly

topoisomerase

shape relaxer

helicase

unzip helix from 5’ to 3’

single-stranded binding proteins

keeps strand open from 5’ to 3’

RNA primase

+3 RNA bases as primer, marks spot for replication

DNA polymerase

synthesize leading strand, adds bases 5’ to 3’

ligase

seals okazaki fragments

semi-conservative

½ original DNA, ½ new DNA

the genetic code

DNA —> RNA —> protein

protein synthesis

tRNAs line up, amino acids join and form polypeptide, start codon to stop codon, protein formed

mRNA

messenger RNA, carry coded info to cytoplasm for protein synthesis

rRNA

ribosomal RNA, form ribosomes for protein synthesis

tRNA

transfer RNA, small, L-shaped molecules that take amino acids to ribosomes