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MCAT Biology > Chapter 4 > Flashcards

Chapter 4 Flashcards

1
Q

nucleus

A

only in eukaryotes ; DNA can only be the in the nucleus

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2
Q

nuclear envelope

A

wraps the nucleus

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3
Q

nucleolus

A

where rRNA is transcribed and the subunits of ribosomes are assembled

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4
Q

endocytosis

A

how cells can acquire substances from the extracellular environment

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5
Q

phagocytosis

A

a few cells are capable of this , proteins binding on the particular matter to protein receptors on the phagocytotic cell

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6
Q

pinocytosis

A

ECF engulfed by small invaginations of the cell membrane, performed by most cell and it is a random process

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7
Q

receptor mediated endocytosis

A

specifiic uptake of macromolecules, ligand binds to a receptro protein on the cell membrane and is then moved to a clathrin coated pit, the pit invaginates to form a coated vesicle, this process absorbs the ligands

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8
Q

exocytosis

A

reverse of endocytosis

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9
Q

phospholipid bilayer

A

membrane invaginates and forms individual membrane bound organelles

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10
Q

ER

A

separates the cytosol from the ER lumen, in many places it is contiguous in places with the space between the double bilayer of the nuclear envelope

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11
Q

rough ER

A

ER near the nucleus that has ribsomes attached,

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12
Q

Golgi appartus

A

series of flattened membrane bound sacs, transport vescicles bud off from the ER and carry the proteins from the ER to the Golgi appartus, organizes and concentrates the proteins as they shuttled by tansport vesicles progressively outward from compartment or cisterna of the Golgi to the next. Golgi may change proteins chemically by glycosylation or by removing AA. end product is a vesicle full of proteins. can be released to mature into proteins or transported to other parts of the cell, secretory vesicles form the protein filled vesicles are expelled from the cell,

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13
Q

secretory vesicles

A

may contain enzymes, growth factors, or ECF matrix components , release contents through exocytosis, supply membrane with its integral proteins and lipids and as the mechanism for membrane expansion. regulated secretion–only release in response to a certain stimulus, some proteins are activated within the secretory vesicles

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14
Q

lysosomes

A

contain acid hydrolases–can break down every major type of macromolecule, have interior pH of 5 , fuse with endocytotic vesicles and digest their contents, any material not degraded by lysosomes is ejected by the cell. Autolysis– lysosome bursts and kills the cell

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15
Q

smooth ER

A

resembles flattened sacs, contains glucose-6-phosphate which is hydrolyzed to glucose. triglycerides are produced in smooth ER and stored in fat droplets, phospholipids are orginially synthesized there

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16
Q

adipocytes

A

cells contains predominately fat droplets

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17
Q

peroxisomes

A

vesicles in the cytosol, grow by incorporating lipds and proteins from the cytosol, self -replicate, produce and breakdown hydrogen peroxide , inactivate toxic substances, regulate ocygen concentration, play a role in the synthesis of breakdown of lipids, and in tthe metabolism of nitrogenous bases and carbohydrates

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18
Q

cytoskeleton

A

structure and motility of a cell is determined by a network of filaments

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19
Q

microtubles and microfilaments

A

microtubules are larger than microfilaments;rigid hollow tubes from a protein called tubulin; 13 of these filaments lie alongside each other to form the tube

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20
Q

mitotic spindle

A

made from microtubules

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21
Q

flagella and cilia

A

specialized structures also made from microtubules

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22
Q

axoneme

A

the major portion of each flagella and cilium, contains 9 pairs of microtubules forming a circle around 2 lone microtubules in an arrangement 9+2

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23
Q

crossbridges

A

made from dynein connect each of the outer pairs of microtubules to their neighbor,cause microtubule pairs slidge along their neighbors creating a whip action in cilia causing fluid to move laterally, or a wiggle action in flagella causing fluid to move directly away from the cell

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24
Q

MTOC in animal cells

A

centrosome

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25
centrioles
function in the production of flagella and cilia
26
Actin
major component of microfilaments
27
microfilaments
contracting force in muscle as wll as being active in cytoplamic streaming (responsible for amoeba-like movement), phagocytosis and microvilli movement
28
tight junctions
form a watertight seal from cell to cell that can block water, ions and other molecules from moving around and past cells, --complete fluid barrier, hold together epithelial tissue in organs , barrier to protein movement between the apical and the basolateral surface of a cell
29
desmosomes
two cells at single point, attach directly to the cytosketeleton, don't provent fluid from circulating, found in tissues that normally experience a lot of stress
30
gap junctions
small tunnels connecting cells, allow small molecules and ions to move between cels, in cardiac muscle provide for the spread of the action potential from cell to cell
31
mitochondria
own circular DNA that replicates independently from the eukaryotic cell, no histones or nucleosomes genes in mitochondrial DNA code for mitochondrial RNA that is distnct from the RNA in the rest of the cell, DNA passed maternally even in organisms whose male gamete contributes to the cytoplasm
32
endosymbiont theory
mitochondria may have evolved from a symbiotic relationship between ancient prokaryotes and eukaryotes
33
mitochondria
surrounded by 2 phospholipid bilayers; inner membrane -- invaginates to form cristae, inner membrane that holds the electron transport chain, between inner and outer membrane in the intermembrane space
34
Tissue
cells that work together for a common purpose-- epithelial tissue, muscle tissue, connective tissue and nervous tissue
35
Extracellular Matrix
constitute most of the tissue as in bone, surrounds the cell and that is formed by the cell itself
36
epithelial tissue
simple -- one layer thick, stratified -- two or more layers thick
37
connective tissue
blood, lymph, bone cartilige,
38
neuronal communication
rapid, direct, specific
39
hormonal comunication
slower, spread throughout the body, affects many cells and tissues in many different ways
40
inerstital fluid
where local mediators are released
41
neuron
functional unit of the nervous system is the neuron ; send electrical signal from one cell to another
42
dendrites
recieve signal to be transmitted
43
axon hillock
where the signal goes next then the axon if th esignal is strong enough and then to the synapse
44
depolarization
cell becomes positive on the inside -- sodium channels open
45
repolarization
sodium channels are closing, potassium channels opening cells becomes negative a gain
46
hyperpolarization
potassium channels take longer to close so for a brief period the cell is more negative than its resting potential
47
all-or-nothing
the membrane completely depolarizes or no action potential is generated
48
threshold stimulus
stimulus of the membrane must pass this
49
synapse
how neural impulses are passed from one neuron to another either chemically or eletrically
50
electrical synapse
uncommon; gap junction between cells -- cardiac muscle -- very fast
51
chemical synapse
unidirectional; small vesicles with neurotransmitter in the presynaptic membrane; AP comes, Calcium voltage channels open; calcium flows into cell--neurotransmitter vesicles release in the synaptic cleft ; then postsynaptic neuron becomes permeable to the neurotransmitters
52
Brownian Motion
how the neurotransmiter diffuses across the synaptic cleft (random motion of the molecules)
53
neurotrasmitter
attaches to its receptor for only a fraction of a second and is released back into the synaptic cleft; either excites or inhibits not both
54
second messenger system
activating another molecule inside the cell to make changes -- receptors
55
EPSP or IPSP
change in cell potential due a synapse
56
microglia
arose from white blood cells -- phagocytize microbes and cellular debris in the CNS
57
ependymal cells
epithetial cells that line the space containing the cerebrospinal fluid -- use cilia to circulate the cerebro spinal fluid
58
satellite cells
support ganglia
59
astrocyes
star shaped neuoglia in the CNS , physicial suppor to neurons, maintain minerals and nutrient balance in the interstital space
60
oligodendrocyes
wrap around axons creating myelin sheeaths
61
Schwann cells
produce myelin in the PNS
62
myelin
increases the rate at which an axon can trasmit signals -- white matter or grey matter; only in vertebrates
63
nodes of Ranvier
gaps between myelin
64
saltatory conduction
AP jumping from one node of Ranvier to the next
65
sensory (afferent) neurons
recieve signals from the receptor cells that interacts with its environment then transfers this signal to other neurons; 99% of sensory input is discarded by the brain; located dorsally from the spinal cord
66
interneurons
transfers signals from neuron to neuron
67
motor (efferent) neurons
carry signals to a muscle or a gland called the effector, located near front of the spinal cord
68
nerves
neuron process bundled together
69
CNS
brain and spinal cord -- integrate nervous signals between sensory and motor neurons
70
PNS
everything else -- handles senstory and motor function of the nervous system
71
somatic nervous system
respond to external enviornment -- contains senstory and motor function, its motor neurons innervate only skeletal muscle -- neurons are located in the ventral horns of the spinal cord, located in the dorsal root ganglion
72
autonomic nervous system
recieves signal from the viscera
73
sympathetic NS
fight of flight; cell bodies found in spinal cord ; epinephrine or norepinephrine
74
parasympathetic NS
rest or digest ; cell bodies found in brain and spinal cord ; cell bodies of postganglionic neurons lie in ganglia inside or near their effectors; use acetylcholine
75
lower brain
medulla, hypothalamus, thalamus, cerebellum -- respriatory system, arterial pressure, salivation, emotions and reaction to pain and pleasure
76
higher brain
cerbrum and cerebral cortex -- cerebral cortex can't function w/o the lower brain -- contains memories and thoughts
77
sensory receptors
physical stimulus to neuraal signals ,
78
cornea
where light first strikes the anterior cavity
79
lens
suspensory ligaments tug on lens on faltten it -- connected to the ciliary muscle
80
retina
covers back of the eye has rods and cones -- rods have rhodopsin -- eye cell hyperpolarizes after the photon hits
81
cones
color
82
iris
colored portion of the ye that creates the opening called the pupil, in the dark sympathetitic NS, contracts the iris and dilates the pupil allowing more light to enter; bright environment contracts iris constricts pupil
83
ear
outer, middle, inner ear
84
tympanic membrane
external auditory canal carries the wave to the ____ or eardrum
85
middle ear
mallus, incus and stapes, act as a lever system -- increase force allows wave to be transferred from the air in the outer ear to a more resistant fluid within the inner ear
86
cochlea
wave of the inner ear moves to the ___- to the center of the sprial then spirals back out
87
hair cells ; organ of Corti
detects movement of wave and tranduces them to neural signals -- hair actually is microvilli that detect movement
88
semicircular canals
in the inner ear; responsible for balance ; each canal contains fluid and hair cells
89
taste
bitter; sour; salty and sweet

MCAT Biology (7 decks)

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