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cell Flashcards

1
Q

cell

A

functional unit of a living organism

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2
Q

all cells contain:

A
  • plasma cell membrane
  • cell organelles
  • nucleus
  • cytoplasm
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3
Q

plasma membrane

A

surrounds the cell surface

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4
Q

cell organelles

A

compartmentalize the cell and perform specific functions
- membrane bound or non membrane bound

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5
Q

cytoplasm

A

interior of the cell, region outside the nucleus and is composed of cytosol (a gel-like fluid in which organelles are suspended)

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6
Q

nucleus

A

the largest organelle in the cell

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7
Q

4 functions of the plasma membrane

A
  1. physical barrier between the icf and ecf (maintains homeostasis)
  2. cell-to-cell communication (contains receptors which bind signaling molecules)
  3. structural support (connections composed of proteins which anchor cells to each other or to extracellular materials)
  4. transport (selectively permeable)
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8
Q

phospholipid bilayer

A

2 layers of phospholipids with embedded proteins

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9
Q

amphipathic molecule

A

contains polar and non polar regions
- phospholipids, cholesterol, glycolipids

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10
Q

structure of a phospholipid

A

polar head group - phosphate attached to glycerol, a nitrogen containing chemical group and glycerol backbone (hydrophilic)
nonpolar tail - 2 fatty acid chains composed of carbon and hydrogen atoms - saturated = no double bonds - unsaturated = 1 or more double bonds (hydrophobic)

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11
Q

cholesterol

A

amphipathic steroid lipid found in plasma membrane
functions to maintain proper fluidity of membrane 1 cholestrol:1phospholipid
polar group - hydroxyl group
nonpolar group - carbon-hydrogen rings and a carbon-hydrogen group attached to one of the rings

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12
Q

glycolipids

A

lipids with carbohydrate attached, amphipathic due to presence of sugar
found in outer leaflet of the plasma membrane form the glycocalyx

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13
Q

glycocalyx

A

a layer of carbs linked to lipids or membrane proteins

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14
Q

2 types of membrane proteins

A

integral (intrinsic)
peripheral (extrinsic)

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15
Q

intrinsic membrane proteins

A

amphipathic
inserted into phospholipid bilayer of cell membrane and partially span membrane or are transmembrane proteins
- transporters or channels

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16
Q

peripheral membrane proteins

A

not amphipathic
attached at the outer or inner surface of the membrane

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17
Q

glycoproteins

A

proteins facing the extracellular surface with carbs attached

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18
Q

cell junctions

A

specialized connections that stabilize interactions and promote communication between cells

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19
Q

desmosome

A

adhering junctions that anchor cells together in tissues subject to considerable stretching or mechanical stress
- made of plaques, cadherins, intermediate filaments

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20
Q

plaques

A

on cytoplasmic surface of cell; anchor cadherins

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21
Q

cadherins

A

link cells together

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22
Q

intermediate filaments

A

anchor cytoplasmic surface of desmosome to components inside cell to provide structural support

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23
Q

tight junctions

A

found in epithelial tissue specialized for molecular transport
made of occludins

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24
Q

epithelial tissue

A

composed of cell laid together in sheets with cells tightly connected to one another
have two surfaces that differ in structure and function

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25
4 functions of occludins
1. form nearly impermeable junction 2. link adjacent cells together 3. limit the movement of molecules between cells 4. limit the movement of integral membrane proteins and lipids
26
gap junctions
transmembrane channels linking the cytoplasm of adjacent cells made of connexons electrically and metabolically couple cells
27
function of nucleus
transmission of genetic info to next gen of cells and contains info needed for protein synthesis
28
what does nucleus contain
chromatin - DNA and associated proteins nuclear envelope - double layered porous membrane surrounding nucleus nuclear pores - pores in nuclear envelope that allow molecules to move in and out of nucleus nucleolus - site of synthesis of ribosomal RNA
29
what cells dont have one nucleus
red blood cells - none skeletal muscle - many
30
ribosomes
function: protein synthesis composed of small and large subunit found free in the cytoplasm or bound to the rough er
31
endoplasmic reticulum
fluid filled membranous system
32
function of rer
synthesize proteins and perform post-translational modification needed to produce a functional protein
33
function of ser
synthesize lipids, stores calcium (in muscle called the sarcoplasmic reticulum), drug detoxification (liver)
34
golgi apparaatus
composed of cisternae (flattened sacs) receives vesicles which contain proteins that were made at the rer function: post-translational modification of proteins from rer, sorts and packages proteins into vesicles (secreted, become integral membrane proteins, or become lysosomes, er, or golgi)
35
lysosomes
contain hydrolytic enzymes which break large molecules into small subunits
36
peroxisomes
contains oxidative enzymes which use oxygen to remove hydrogen from molecules, breaking them down - break down fatty acids, alcohol drugs - hydrogen peroxide a by-product
37
mitochondria
make atp or energy - important for cellular respiration contain double phospholipid membrane have their own DNA
38
two organelles with double phospholipid membranes
nucleus and mitochondria
39
cytoskeleton
non membrane bound organelle composed of protein filaments or cytoskeletal filaments function: maintain cell shape, maintain the position of organelles in the cell, mediated cell and organelle motility
40
cytoskeletal filaments include
microfilament - made of protein actin intermediate filament microtubules - made of protein tubulin
41
vesicular transport
a form of transport that uses vesicles to move substances across biological membranes
42
3 types of endocytosis
phagocytosis pinocytosis receptor mediated endocytosis
43
phagocytosis
cell eating
44
pinocytosis
cell drinking plasma membrane simply indents below the particles to be brought into the cell
45
steps of phagocytosis
recognition attachment pseudopodia reach around substance and form a phagosome inside the phagocytic cell fusion of the phagosome to a lysosome to form phagolysosome destruction of ingested substance by lysosomal enzymes release of end products by exocytosis
46
receptor mediated endocytosis
specific process that involves receptors which bind to specific ligands to be brought into the cell involves clathrin
47
chemical driving force for non vesicular tranport
different conc of a substance on either side of a membrane move passively from high to low conc
48
electrical driving force of non vesicular transport
any substance that is charged will be affected by the electrical driving force exists due to membrane potential - different in the electrical potential or voltage across a cell membrane
49
electrochemical driving force of non vesicular transport
the sum of the electrical and chemical driving forces acting on an ion
50
which substances move across a phospholipid bilayer by simple diffusion, what cant
small, nonpolar, uncharged - large and polar will not cross - has charge will not cross
51
3 factors influencing the rate of simple diffusion
1. magnitude of driving force 2. membrane surface area 3. membrane permeability
52
4 factors affecting membrane permeability
1. the lipid solubility of the diffusing substance (nonpolar crosses more readily) 2. size and shape of the diffusing substance (small and regular shaped cross more readily) 3. temp (high temp diffuses faster) 4. diffusing distance (how thick)
53
mediated transport
the use of a protein to cross the cell - facilitated diffusion and active transport
54
facilitated diffusion
specific transport process, passive transport proteins involved are carriers (specific binding sites) or channels (specific ions)
55
active transport
capable of move a substance against its conc gradient involves transport proteins with specific binding sites for the substances to be transported
56
primary active transport
energy source to drive the transport process is atp - na/k pump
57
secondary active transport
energy source to drive the transport process is movement of an ion down its electrochemical gradient - na/glucose cotransporter
58
chemical messengers
a form of intercellular communication may be lipid-soluble of lipid insoluble used for the process of signal transduction
59
transcription factors
alter the rate of transcription of mRNA in the nucleus by binding to a response element (specific sequence of dna ner the beginning of a gene alters the rate of protein synthesis
60
3 types of membrane bound receptors
channel, enzyme, g-protein linked receptors
61
first messenger
extracellular chemical messenger that binds to a specific membrane-bound receptor
62
second messenger
a substance that enters of is generated in the cytoplasm of a cell following the binding of the first messenger to its receptor
63
protein kinase
an enzyme that phosphorylates another protein or adds phosphate groups to the protein alters the activity of another protein
64
steps of signal transduction
1. a first messenger binds to binding sites on the receptor 2. an ion channel in the receptor protein opens 3. ions move through the channel. as the ions have a charge, they alter the electrical properties of the cell and produce a response
65
ligand-gated ion channels
receptor with binding sites for a chemical messenger and an ion channel component
66
membrane bound receptor that functions as enzymes
receptor with binding sites for a chemical messenger and intrinsic enzyme activity
67
g-protein linked receptors
membrane bound receptor that binds extracellular chemical messengers
68
g-protein
found at the cytosolic surface of the plasma membrane bind guanosine nucleotides made of 3 subunits: alpha, beta, gamma function as a link between the receptor in the plasma membrane and an effector protein
69
alpha subunit when inactive binds
GDP
70
alpha subunit when active binds
GTP
71
how does binding of a first messenger alter the activity of an effector ion channel - actions of g-proteins on ion channels
1. binding of first messenger to receptor causes conformational change in receptor 2. affinity of alpha-subunit for GTP increases; GDP dissociates, GTP binds 3. GTP-bound alpha-subunit dissociates from b and y; moves to ion channel 4. ion channel opens or closes, alters flow of ions across membrane
72
how does binding of a first messenger alter the activity of an effector enzyme - actions of g-proteins on enzymes
1. binding of first messenger to receptor causes conformational change in receptor 2. affinity of a-subunit for GTP inc; GDP dissociates, GTP binds 3. GTP-bound a-subunit dissociates from b and y; moves to enzyme 4. different types of g-proteins: Gs - stimulates or activates the enzyme, Gi - inhibits the enzyme 5. altering the activity of the enzyme alters the production of a second messenger by the enzyme in the cytosol
73
cAMP messenger system
most common second messenger system found in the cells in out body
74
steps involved in production of cAMP
1. binding of first messenger causes conformational change; GTP binds 2. activated a-subunit of Gs protein separates and binds to adenylyl cyclase, activating it 3. adenylyl cyclase catalyzes conversion of cytosolic atp into cyclic amp 4. cAMP acts as a second messenger and diffuses through the cytoplasm 5. cAMP binds to and activates protein kinase A 6. activates PKA catalyzes the phosphorylation of proteins in the cell by transferring a phosphate group from atp to proteins 7. once cellular proteins have been phosphorylated, activity is altered, results in cellular response

physiology (12 decks)

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