Cell Biology (Exam 1)

Nucleus

control center of the cell, contains DNA & synthesizes RNA

DNA (recipe book)

deoxyribonucleic acid, info for synthesis of proteins, directions for cell function, genetic transfer

RNA (copier of recipe book)

ribonucleic acid, single strand w/ a different sugar and different pyrimidine base (U instead of A)

cytoplasm

colloid solution outside of nucleus, protein synthesis location (water, proteins, glucose, lipids, electrolytes, organelles)

ribosomes (attached and free)

made of ribosomal RNA/proteins/messenger RNA, free ribosomes in cytoplasm responsible for protein synthesis

DNA pyrimidine bases

thymine, cytosine

DNA purine bases

adenine, guanine

transcription

RNA polymerase “unzips” the DNA, mRNA strand forms, comes across stop codon releasing completed RNA strand

translation

happens at ribosome to synthesize proteins from mRNA, tRNA brings amino acids according to genetic code to make a protein

rough endoplasmic reticulum (factory for protein synthesis)

factory for synthesis & transport of proteins, proteins destined for cell membrane export out of cell or to become lysosomal enzymes

smooth endoplasmic reticulum

synthesizes different steroid hormones, lipoproteins, and lipids, regulates intracellular calcium , stores glucose as glycogen, drug metabolism

golgi apparatus (UPS store of cell)

makes vesicles to package proteins, enzymes, and hormones from the ER so they can leave via phospholipid bilayer

lysosomes

engulfs waste, breaks it down + makes it not harmful + excretes it (contains digestive enzymes)

peroxisomes

contain enzymes that degrade peroxides, control free radicals (can cause cellular damage) created by metabolism

mitochondria

transforms organic compounds into ATP using oxygen to carry out cellular respiration, self-replicating (tells itself to replicate bc need more ATP) , regulates apoptosis

cytoskeleton (made up of actin, myosin, microtubules, and intermediate filaments)

maintains cell shape + movement

microtubules

involved in transport, maintain shape, enable transport, form cilia (help keep bad things out), form flagella

microfilaments

muscle contraction, microvilli (help absorb nutrients)

cell membrane

lipid bilayer w/ hydrophilic heads and hydrophobic tails, proteins embedded in bilayer (receps, ion channels, transport, cell recognition, cell adhesion)

membrane protein: receptor

bind to chemical messengers, activate cells (open ion channels, trigger muscle contractions, activate enzyes, trigger release of hormones)

membrane protein: antigens

recognition of self vs foreign

autocrine signaling

cell talking to self

paracrine signaling

cell talking to another cell nearby

endocrine signaling

messenger from gland sends hormone to talk to cells

passive transport

no energy required, driven by differences on sides of membrane (high to low concentration)

simple diffusion

through membrane or through pores/spaces in membrane, must meet 3 criteria: small, uncharged, lipid soluble exs: O2, CO2, N, urea, alcohol, FAs

facilitated diffusion through ion channels

water filled channel formed by proteins, down gradient, does not meet one of the simple diffusion criteria

facilitated diffusion w/ transport protein

down gradient, very specific substance is transported by any one protein, ex: gluose

filtration

movement of water + solutes through a membrane bc of pushing power on one side of membrane is stronger than the other (hydrostatic pressure influenced by oncotic)

osmosis

movement of water “down” a concentration gradient from high water concentration to low water concentration (membrane is not permeable to solutes so water moves) *water moves to make soup less salty

osmolality

concentration of particles per wt. of water

active transport

low to high, requires energy (therefore requires oxygen)

active transport: enzyme pumps

Na+/K+ pump, 3Na/2K move for each molecule of ATP hydrolzyed

vesicular transport

membrane engulfs substance to include or remove it, requires energy, exs: phagocytosis, hormone secretion, uptake of cholesterol into cells

membrane potentials

cells are slightly negative inside (due to high K) and positive on outside (due to high Na)

action potentials overview

sudden change in the resting membrane potential, results in nerve impulse transmission and muscle contraction, triggered by electrical or chemical stimulation

action potenial specifics

1. stimulus causes Na channels to open

2. depolarization - more Na rushes in than K rushed out

3. nerve impulses conducted + muscle cells contract

4. repolarization - Na channels close, K channel open (K rushed out restoring membrane potential), Na/K pump restores balance of ions

energy metabolism

conversion of nutrients into energy needed for cell function

anaerobic

glycolytic pathway which occurs in cytoplasm, no oxygen

aerobic

occurs in mitochondria after anaerobic when oxygen is available

glycolysis and anaerobic metabolism

one glucose yields 2 ATP (important during hypoxia), O2 present = pyruvic acid moves into mitochondria and enters citric acid cycle, O2 not present = pyruvic acid → lactic acid

citric acid cycle

pyruvic acid converted to acetyl-CoA, 2 molecules of ATP, NADH and FADH

ETC

32 atp, total 34 atp generated in aerobic metabolism

epithelial tissue

attached to basement membrane, line body external and internal surfaces, includes squamous, cuboid, and columnar cells, simple or stratified

connective tissue

most abundant tissue, supports body tissues, common types: loose connective, adipose, dense connective, exs: tendons, ligaments, bones, fat

muscle tissue

long contractile cells: myocytes

nerve tissue

high specialized cells which receive and transmit impulses

exocytosis

out

endocytosis

in