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60 Cards in this Set

  • Front
  • Back
-major distinction that separates eukaryotic from prokaryotic cells
-contains all DNA, DNA cannot leave -> transcription occurs in nucleus
Nuclear envelope
-double phospholipid bilayer that wraps the nucleus
-perforated with nuclear pores where RNA can exit but not DNA
-area within the nucleus where rRNA is transcribed and subunits of ribosomes are made (not separated by membrane)
-method besides transport through membrane that allows cell to acquire substances from extracellular environment
-types: phagocytosis, pinocytosis
-type of endocytosis
-cell membrane protrudes outward to engulf particle
-only few specialized cells possess capability
- in humans initiated by antibodies or complement proteins binding to macrophages and neutrophils
-type of endocytosis
- performed by most cells
-extracellular fluid is engulfed in random fashion
-reverse of endocytossis
Endoplasmic Reticulum
maze of membranous walls separating the cytosol (aqueous solution inside cell) from the ER lumen or cisternal space (extracellular) Contigous with space between double bilayer of the nuclear
-small transport vehicles bud off from ER and carry proteins to the Golgi
Rough ER
-Endoplasmic reticulum close to the nucleus that many ribosomes attached to it on its cytoplasm side.
-synthesizes all proteins not used in cytosol
-translation on the ER propels proteins into the ER lumen towards the Golgi apparatus/complex
Golgi Apparatus
-series of flattened membrane bound sacs
-golgi organizes and concentrates proteins based upon their signal sequence and carbohydrate chains
-can change proteins by glycosylation (adding carb chains) or by removing amino acids
-end product is a vesicle full of proteins that are expelled from the cell as secretory vesicles which mature into lysosomes or transported to other parts of cell
-modifies and packages proteins!!
secretory vesicles
-bud off golgi bodies
-become part of the cell membrane and supplies membrane with integral proteins and lipids
-releases contents via exocytosis
-can be recycled by golgi
-contain acid hydrolases enzymes that function best in acidic environment which are capable of breaking down every type of macromolecule in the cell
-generally have a pH of 5
-fuse with endocytotic vesicles and digest contents
-degrade cytosilic proteins in an endocytotic proces
-come from the golgi
agranular/smooth ER
-contains enzyme to hydrolyze glucose 6-phosphate to glucose
-produce triglycerides and store in fat droplets contained in adipocytes
-synthesize most of phospholipid
-important for temperature regulation
-DETOX: oxidizes foreign substances (drugs, toxins)
in the cytosol
- grow by incorporating proteins and lipids from the cytosol
-inactivate toxic substances such as alcohol, regulate oxygen concentration, play a role in synthesis and breakdown of lipids and in metabolism of nitrogenous bases and carbohydrates
-self replicate
Two sides of a cell
-Cytosol and ER Lumen
- to reach cytosol, must cross membrane via passive diffusion or active transport
-reach ER lumen via endocytosis
-network of filaments that determines structure and motility of a cell

-anchors some membrane proteins and other cell components, moves components within cell, and moves cell itself

-major types of filaments that make of cytoskeleton: microtubules and microfilaments
-larger than microfilaments

-rigid hollow tubes made from tubulin protein

-compose flagella and cilia

-makes up mitotic spindle during mitosis

-have + end and - end, - end attaches to microtubule organizing center (MTOC)
flagella and cilia
-specialized structures made from microtubules

-major portion called axoneme which contains 9 pairs of microtubules forming a circle around two lone microtubules in 9+2 arrangement

-crossbridges made from dynein connect outer microtubules to neighbor
-this creates whip action in flagella and cilia (only in eukaryotes, in prokaryote flagella rotate)
-microtubule organizing center in cell

- negative end of microtubule attaches to MTOC while positive end grows away from it

-centrosome is major MTOC in animal cells

-centrioles in centrosome function in making cilia and flagella but are not necessary for microtubule production
-smaller than microtubules

-the protein actin is a major component of microfilaments

-produce the contracting force in muscle and cytoplasmic streaming
Cellular Junctions
-three types:

-tight junctions


-gap junctions
Tight junctions
-form watertight seal from cell to cell that can block water, ions, and other molecules from moving around and past cells

-tissues held together by tight junctions act as fluid barrier
-join two cells at a single point

-found in tissues that often face stress like skin or intestinal epithelium
Gap junctions
-small tunnels connecting cells

-allow small molecules and ions to move between cells

-in cardiac muscle allow for the spread of action potential between cells
-powerhouse of the eukaryotic cell

-home to the KREB cycle
in matrix of mitochondria

-possess two phospholipid bylaers: inner membrane where electron transport chain occurs and outer membrane
Endosymbiont theory
mitochondria may have been prokaryotes

-they have circular DNA with no histones or nucleosomes just like prokaryotes that replicates independently from eukaryotic cell

-genes in mitochondrial DNA code for mitochondrial RNA, mitochondria have their own ribosomes with sediment of 55-60s

-some of codons in mitochondria differ from codons in rest of cell presenting exception to universal genetic code
extracellular matrix
-holds cells of tissue in place

-may be liquid like blood or solid like bone

-basal lamina- thin sheet of matrix material that separates epithelial cells from support tissue, allows passage of some molecules not others
Intracellular Communication
-accomplished by
-neurotransmitters (released by neurons, rapid direct and specific)
-local mediators
-hormones (affects many cells in tissues in different ways, slower, spread throughout the body)
-functional unit of nervous system

-highly specialized, cannot divide

-depends on glucose for chemical energy

-depend heavily on aerobic respiration but has low stores of glycogen and oxygen
-part of neuron that receive signal to be transmitted

-transferred directly to axon hillock, if it is strong enough it is transmitted down axon and then to synapse
Action Potential
-disturbance of electric field across membrane of a neuron

-resting potential is -70mv established by Na+/k+ pumps which pump out 3 Na for 2 K that it brings into cell so cell inside is less positive than outside

-originates at the hillock

-all or nothing effect, if it reaches threshold it will create same size AP, if not nothing will happen
voltage gated sodium channels
-in the membrane of a neuron

-change configurationwhen voltage across membrane is disturbed

-allow Na+ to flow into cell

-cell then reverses polarity and depolarization occurs
-when Na+ rushes into cell through voltage gated sodium channels, cell becomes less negative,
voltage gated potassium channels
-in membrane of neuron
-open as sodium channels close, K+ flows out of cell making inside more negative (repolarization)
-when K+ channels are letting K+ out of cell during repolarization, they are slow to close, so it goes more negative than the resting potential

-passive diffusion returns membrane to its resting potential
-space between neurons where transmission of information is slowest
Chemical synapse

-small vesicles filled with neurotransmitter rest just inside the presynaptic membrane

-membrane near synapse allows Ca+ to come in when action potential arrives which causes neurotransmitter vesicles to be released
second messanger system
-system in which receptors may be ion channels which are opened when their respective neurotransmitter attaches or they may act via a second messanger system activating another molecule into the cell to make changes
-common initiated second messanger system

-attached to the receptor protein along the inside of the postsynaptic membrane

-when receptor is stimulated, alpha subunit breaks free and may
-activate separate ion channels
- activate a second messanger
-activate intracellular enzymes
-activate gene transcription
-myelin wrap around axons to speed up signals through insulation

-produced by schwann cells in peripheral nervous system

-only in vertebrates

-appear white while neuronal cell bodies are gray
nodes of Ranvier
-tiny gaps between myelin
saltatory conduction
-when action potential jumps from one node of Ranvier to next
Sensory (afferent) neurons
-recieve signals from a receptor cell that interacts with environment
-transfer signals from neuron to neuron

-make up 90% of neurons in the body
Motor (efferent) neurons
carry signals to a muscle or gland called effector (located toward the front ventrally)
central nervous system
-brain and spinal chord
periperhal nervous system
-everything else besides brain and spinal chord

-divided into somatic nervous system and autonomic nervous system
Somatic nervous system
-division of the PNS

-designed to respond to external environment

-innervate skeletal muscle

-cell bodies on spinal chord, use acetylcholine as neurotrasnmitter

Autonomic nervous system
-division of the PNS, sister of the somatic

-involuntary functions

-divided into sympathetic and parasympathetic

-controlled mainly by hypothalamus

-innervates cardiac and smooth muscle and some glands
Parasympathetic and sympathetic ANS
-innervate most intestinal organs by working antagonistically

-Sympathetic: fight or flight
-increase beat rate and stroke volume in heart
-constricts blood vessels around digestiv and excretory systems in order to increase blood flow to skeletal muscles
-signals originate in spinal cord
-use noradrenaline, norepinephrine, adrenaline

Parasympathetic ANS: rest and digest
-slows heart
-increases digestive and excretory activity
-signals originate in brain and spinal cord neurons
-use acetylcholine
Nicotinic, muscarinic, adrenergic receptors
-nicotinic and muscarinic are cholinergic receptors for acetylcholine (in somatic and parasympathetic systems)

-adrenergic receptors are for adrenaline, epinephrine and norepinephrine (in sympathetic ANS)
central nervous system
brain + spinal cord

lower brain: medulla,hypothalamus, thalamus, cerebellum

higher brain: cerebral cortex
-light first strikes eye on cornea
-light enters lens which would have spherical shape but is controlled by ligaments conneced to ciliary muscle

-image is real and inverted because eye is converging lens
ciliary muscle
-when contracts, the opening of the circle decreases allowing the lens to become more like a sphere and bring focal point closer

-when relaxed focal point increases
-covers inside of the back of the eye
-has rods and cones
-rods can sense all visible light and cannot distinguish color while cones are specialized and can distinguish color
colored portion of eye that creates opening called pupil
divided into three parts
-outer ear
-middle ear
-inner ear
tympanic membrane
-also called eardrum, begins in the middle ear
-contains three small bones: malleus, incus, stapes which act like lever system
-where wave in the inner ear moves through
-movement deteced by hair cells and organ of corti and traansduced into neural cells

-detects sound
semicircular canals
-detect orientation and movement
-contains fluid and hair cells