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54 Cards in this Set
- Front
- Back
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how do cells vary?
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in shape, function, ability to multiply, and mobility
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microvilli
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fingerlike, hollow, tubular extensions of the cell membrane that increase surface area
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molecular architecture of plasma membrane (types of molecules)
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lipids- phospholipids, cholesterol, & glycolipids
proteins- integral/transmembrane carbohydrates- in glycolipids & glycoproteins |
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lipid bilayer permeable to what?
impermeable to what? |
permeable- lipid soluble substances like O2 and CO2
impermeable- water soluble substances like sugars, amino acids, ions (need channels) |
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what controls fluidity of plasma membrane?
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fatty acids--> unsaturated makes a more fluid membrane; saturated makes it more rigid
and cholesterol |
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glycolipids
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lipids with carbs attached to them
found in outer half of bilayer; contain monosaccharides |
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peripheral proteins
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bound to surface of membrane, many on the interior
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integral/transmembrane proteins
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embedded in membrane/span it
serve as enzymes, carriers, channels, transporters, or receptors |
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glycoproteins
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proteins containing carbohydrates
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carbohydrate role in lipid bilayer
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project outward; cell-cell interactions & cell recognition
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tight junctions
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seal space between cells by fusing membranes; in epithelial sheets
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desmosomes
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spot-welds adjacent cells that reinforce tissue
between skin cells |
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gap junctions
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couple cells electrically & chemically
important in cardiac muscle |
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ER
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network of interconnected membranes that form flattened sacs, canals, and vesicles; important to synthesize proteins & lipids
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ribosomes
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may be attached to ER or free in cytoplasm; made of rRNA & 80 ribosomal proteins; make proteins
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Golgi
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flattened membranes formed from ER; near the nucleus; packages proteins; prominent in cells that secrete proteins AKA schtuff
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mitochondria
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oxidize glucose & fatty acids; lock energy into ATP
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lysosomes
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digest stuff with enzymes
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peroxisomes
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bags of enzymes
abundant in liver & kidney break down fatty acids, make cholesterol, make parts of myelin sheath |
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Centrosome
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microtubule-organizing center; pair of centrioles
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microfilaments & microtubules (function & made of?)
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microfilaments- cellular movement; actin
microtubules- internal skeleton (& move organelles); tubulin |
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inclusions
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lipid droplets, glycogen granules, & melanin granules
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# human chromosomes
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46 (23 pairs)
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physical processes that do NOT require energy from the cell
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diffusion, facilitated diffusion (uses carrier proteins), osmosis
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physical processes that require energy from the cell
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active transport (uses carriers), endocytosis, exocytosis
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types of cells that rarely divide
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skeletal and cardiac muscle cells, differentiated neurons
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cell cycle
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M phase (PMAT), G1, S, G2
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cytokinesis starts when?
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during anaphase
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interphase
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consists of G1, S, G2
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what splits cells?
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contractile ring of microfilaments that forms over the equatorial plate
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where are cell cycle checkpoints?
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at G1, G2, and M
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some checkpoints involve which tumor suppressor gene?
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p53
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what phase do cells go into when they are withdrawn from the normal phases?
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G0
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immortal strand hypothesis
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new strands of DNA segregate together in daughter cells, so stem cells keep old DNA that is less likely to have errors
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totipotent v. pluripotent cells
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totipotent- can differentiate into anything (embryonic stem cells)
pluripotent- can differentiate into most things (bone marrow) |
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metastasis
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when cancer cells break away from the tumor, are carried to another part of the body, and form a secondary tumor
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tumor suppressor genes
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inactivation of these causes cancer (both copies must be inactivated for cancer to develop)
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proto-oncogenes
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activation causes cancer
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causes of activation/inactivation of tumor suppressor/proto-oncogenes
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mutations, rearrangements of DNA, incorporation of viral DNA
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tumor suppressor genes produce what?
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proteins called cell cycle checkpoint determinants
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what do cell cycle checkpoint determinants do?
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arrest cell division, often in G1 (& sometimes in S) to allow cell to repair DNA
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retinoblastoma tumor suppressor gene
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loss of this gene causes retinoblastoma- due to the loss of a protein called pRB, which suppresses cell division
suppress gene by putting phosphate on it |
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p53 tumor suppressor gene
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MOST FREQUENTLY MUTATED GENE IN HUMAN CANCER
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neutrophils
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white blood cells that commit suicide (ex. of apoptosis)
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consequences of improper apoptosis
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too much- parkinson's, alzheimer's
too little- cancer |
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process of apoptosis
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cells shrink & round up
DNA breaks up; chromatin condenses nucleus breaks up cell develops "blebs" on surface, which break away in apoptotic vesicles vesicles are phagocytized by macrophages |
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caspases
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"executioner enzymes" involved in apoptosis
proteases that break down cellular proteins & DNA |
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necrosis
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accidental cell death
cells lose shape, swell, lose function membranes break down cells & organelles undergo lysis substances released cause inflammation |
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nuclear transfer cloning
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nucleus removed from oocyte, donor cell fused using electric pulses
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number of cells in body
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> ten trillion (1 x 10^13)
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number of cells that die each day
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60-70 billion
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3 types of endocytosis
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phagocytosis
pinocytosis receptor-mediated endocytosis |
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what is used in phagocytosis to kill engulfed particles?
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superoxide (O2-)
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example of exocytosis
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release of neurotransmitters by neurons
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