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60 Cards in this Set
- Front
- Back
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Nucleus
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-major distinction that separates eukaryotic from prokaryotic cells
-contains all DNA, DNA cannot leave -> transcription occurs in nucleus |
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Nuclear envelope
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-double phospholipid bilayer that wraps the nucleus
-perforated with nuclear pores where RNA can exit but not DNA |
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Nucleolus
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-area within the nucleus where rRNA is transcribed and subunits of ribosomes are made (not separated by membrane)
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Endocytosis
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-method besides transport through membrane that allows cell to acquire substances from extracellular environment
-types: phagocytosis, pinocytosis |
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phagocytosis
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-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 |
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pinocytosis
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-type of endocytosis
- performed by most cells -extracellular fluid is engulfed in random fashion |
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Exocytosis
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-reverse of endocytossis
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Endoplasmic Reticulum
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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
envelope -small transport vehicles bud off from ER and carry proteins to the Golgi |
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Rough ER
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-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 |
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Golgi Apparatus
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-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!! |
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secretory vesicles
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-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 |
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lysosomes
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-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 |
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agranular/smooth ER
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-tubular
-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) |
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peroxisomes
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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 |
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Two sides of a cell
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-Cytosol and ER Lumen
- to reach cytosol, must cross membrane via passive diffusion or active transport -reach ER lumen via endocytosis |
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cytoskeleton
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-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 |
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microtubules
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-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) |
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flagella and cilia
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-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) |
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MTOC
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-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 |
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Microfilaments
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-smaller than microtubules
-the protein actin is a major component of microfilaments -produce the contracting force in muscle and cytoplasmic streaming |
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Cellular Junctions
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-three types:
-tight junctions -desmosomes -gap junctions |
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Tight junctions
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-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 |
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desmosomes
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-join two cells at a single point
-found in tissues that often face stress like skin or intestinal epithelium |
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Gap junctions
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-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 |
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mitochondria
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-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 |
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Endosymbiont theory
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mitochondria may have been prokaryotes
why? -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 |
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extracellular matrix
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-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 |
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Intracellular Communication
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-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) |
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neuron
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-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 |
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dendrites
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-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 |
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Action Potential
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-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 |
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voltage gated sodium channels
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-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 |
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depolarizatoin
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-when Na+ rushes into cell through voltage gated sodium channels, cell becomes less negative,
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voltage gated potassium channels
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-in membrane of neuron
-open as sodium channels close, K+ flows out of cell making inside more negative (repolarization) |
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hyperpolarization
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-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 |
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Synapse
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-space between neurons where transmission of information is slowest
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Chemical synapse
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-unidrectional
-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 |
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second messanger system
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-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
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G-protein
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-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 |
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myelin
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-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 |
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nodes of Ranvier
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-tiny gaps between myelin
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saltatory conduction
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-when action potential jumps from one node of Ranvier to next
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Sensory (afferent) neurons
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-recieve signals from a receptor cell that interacts with environment
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Interneurons
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-transfer signals from neuron to neuron
-make up 90% of neurons in the body |
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Motor (efferent) neurons
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carry signals to a muscle or gland called effector (located toward the front ventrally)
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central nervous system
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-brain and spinal chord
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periperhal nervous system
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-everything else besides brain and spinal chord
-divided into somatic nervous system and autonomic nervous system |
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Somatic nervous system
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-division of the PNS
-designed to respond to external environment -innervate skeletal muscle -cell bodies on spinal chord, use acetylcholine as neurotrasnmitter -voluntary |
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Autonomic nervous system
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-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 |
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Parasympathetic and sympathetic ANS
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-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 |
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Nicotinic, muscarinic, adrenergic receptors
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-nicotinic and muscarinic are cholinergic receptors for acetylcholine (in somatic and parasympathetic systems)
-adrenergic receptors are for adrenaline, epinephrine and norepinephrine (in sympathetic ANS) |
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central nervous system
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brain + spinal cord
lower brain: medulla,hypothalamus, thalamus, cerebellum higher brain: cerebral cortex |
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EYE
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-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 |
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ciliary muscle
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-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 |
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retina
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-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 |
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iris
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colored portion of eye that creates opening called pupil
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Ear
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divided into three parts
-outer ear -middle ear -inner ear |
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tympanic membrane
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-also called eardrum, begins in the middle ear
-contains three small bones: malleus, incus, stapes which act like lever system |
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cochlea
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-where wave in the inner ear moves through
-movement deteced by hair cells and organ of corti and traansduced into neural cells -detects sound |
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semicircular canals
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-detect orientation and movement
-contains fluid and hair cells |
