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Pathophysiology > Cell structure and function > Flashcards

Cell structure and function Flashcards

1
Q

Large quantities of ATP are stored in all cells. T/F

A

False: ATP must be continuously synthesized to meet energy needs.

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2
Q

glycolysis occurs where

A

in the cytosol and is an anaerobic process

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3
Q

lipid bilayer is highly permeable to?

A

lipid soluble and non-charged molecules.

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4
Q

channel proteins allow

A

passive transport of ions

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5
Q

intercellular communication is accomplished by 3 principal means:

A

Gap junctions
Direct cell-to-cell
Chemical mediators.

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6
Q

List functions of the plasma membrane (8)

A

endocytosis– highly selective shield
exocytosis– recognition
active transport– communication
membrane potentials– growth regulation

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7
Q

3 types of membrane lipids are

A

cholesterol
phospholipids
glycolipids

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8
Q

define amphipathic

A

lipids have a hydrophillic charged end and a hydrophobic non-polar end.

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9
Q

Proteins filaments that comprise the cellular skeleton

A

actin filaments
microtubules
intermediate filaments

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10
Q

Largest cytoplasmic organelle

controls production of cellular enzymes. membrane receptors and structural proteins.

A

Nucleus

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11
Q

converts energy to forms needed to drive cellular reactions. Oxidative phosphorylation occurs here, generating most of the cell’s ATP

A

Mitochondria

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12
Q

membrane bound bags of degradative enzymes.

A

Peroxisomes

many found in liver and kidneys.

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13
Q

coated with ribosome and their primary role is the synthesis of proteins for membrane components, and synthesis of products to be excreted from the cell.

A

Rough ER

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14
Q

gathers simple molecules and combines them to make complex molecules which are then packaged and transported out of the cell.

A

Golgi Apparatus

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15
Q

involved in lipid metabolism and are found in large quantities in cells specializing in the production of steroid hormones or lipoproteins

A

Smooth ER

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16
Q

organelles containing acid hydrolases capable of digesting organic molecules.

A

lysosomes

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17
Q

small, lipid insoluble molecules are transported across plasma membrane by

A

transporter proteins

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18
Q

calcium against its concentration gradient is transported across plasma membrane by

A

membrane calcium transporter

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19
Q

large, lipid insoluble molecules are transported across plasma membrane by

A

endocytosis

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20
Q

ions moving down concentration gradient are transported across plasma membrane by

A

membrane channel proteins

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21
Q

glucose is transported across the plasma membrane by

A

passive transport carrier

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22
Q

tissue with synchronized function use this type of cell signaling

A

gap junctions

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23
Q

ligand signaling

A

target cells respond to ligands signaling through specific protein receptors.

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24
Q

synaptic signaling

A

nerve cell releases neurotransmitter into gap junction where it binds to target cell to cause an effect.

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25
Q

paracrine

A

affect localized cells.

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26
Q

endocrine

A

hormone released through bloodstream.

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27
Q

autocrine

A

cell responds to its own signals.

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28
Q

Active transport

A

transports substances against concentration gradient

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29
Q

sodium-potassium pump

A

transports 3 sodium ions out of the cell in exchange for 2 potassium ions.

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30
Q

major determinant of resting potential is

A

potassium ion concentration across the membrane

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31
Q

Binding of a ligand to a G-Protein receptor stimulates

A

adenylyl cyclase to produce a second messenger within the target cell

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32
Q

saturated lipids

A

straight tails that pack together and tent to stiffen membrane

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33
Q

unsaturated lipids

A

bent tails tend to increase fluidity

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34
Q

glycolipids and glycoproteins

A

found in outer half of lipid bilayer, with the sugar groups exposed at the cell surface.
Glycolipids involved in cell recognition and cell to cell interations

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35
Q

tight junctions

A

connect neighboring cells like a fence to confine proteins to a certain area.

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36
Q

actin filament

A

movement, information transfer

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37
Q

microtubules

A

organization, orderly transport within cell, equal distribution of chromosomes during division.

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38
Q

intermediate filament

A

strong, ropelike

39
Q

nucleus inner membrane

A

unbroken sphere around DNA and contains protein binding sites that help organize chromosomes.

40
Q

nucleus outer membrane

A

continuous with endoplasmic reticulum and closely resembles it in structure and function

41
Q

nuclear pores

A

holes in membrane allowing proteins into the nucleus.

- mediate export like RNA and ribosomes

42
Q

nucleolus

A

manufactures ribosomes

43
Q

Endoplasmic reticulum

A

central role in the synthesis of membrane components, proteins, and lipids for the plasma membrane, organelles, and synthesis of products to be secreted.

44
Q

ribosomes

A

synthesis of proteins, can free float or ind to the ER.

-signal recognition particles bind to leading sequence of the protein

45
Q

translocon

A

pore in the ER that protein chain pushed through.

46
Q

cisternae

A

stack of smooth membrane bound compartments

47
Q

3 processing compartments of golgi

A

cis face
middle compartment
final compartment

48
Q

cis face of golgi cisternae

A

next to ER, receives newly synthesized proteins and lipids from transport vesicles which bind and become part of golgi

49
Q

middle compartment of golgi cisternae

A

modify proteins and lipids

50
Q

final comartment of golgi cisternae

A

depart for final destination

51
Q

lysosomes obtain materials to digest in 3 ways

A

endocytosis
autophagy
phagocytic cells

52
Q

autophagy

A

damaged/obsolete parts of cell destroyed

53
Q

phagocytic cells

A

WBC engulf particles then fuse with lysosome

54
Q

peroxosomes

A

use oxidative enzymes to perform degradative functions

55
Q

oxidative enzymes

A

use molecular oxygen to breakdown organic substances- byproduct is hydrogen peroxide which is then used to degrade other molecules by catalase enzyme.

56
Q

Mitochondria inner membrane

A

forms enclosed space called matrix, contains a concentrated mix of enzymes

57
Q

cristea

A

highly convoluted structure with multiple folds of inner membrane of mitochondria, provides large surface area for membrane bound enzymes of respiratory chain; production of ATP.

58
Q

mitochondria outer membrane

A

numerous porin transport proteins forming large aqueous channels making membrane porous

  • large proteins can pass through freely
  • specific protein transporters need to shuttle across inner mitochondrial membrane.
59
Q

anabolism

A

energy using metabolic processes that results in synthesis of complex molecules; fats

60
Q

catabolism

A

energy releasing breakdown of. nutrients such as glucose to produce ATP.

61
Q

glycolysis

A

10 enzymatic steps to break the six-carbon glucose molecule into a pair of three-carbon pyruvate molecules

  • requires 2 ATP in early stage
  • produces 4 ATP in later stage; net gain of 2 ATP and 2 NADH
  • anaerobic process
62
Q

lactic acidosis

A

may result after prolonged anaerobic conditions; leading to glycolysis.

63
Q

pyruvate

A

product of glycolysis; converted to lactate and excreted in blood stream.

64
Q

NADH

A

Product of glycolysis; contain high-energy electrons that are transferred to electron transport chain in mitochondria

65
Q

citric acid cycle

A

results in complete oxidation of glucose to final products; CO2 and H2O.

  • pyruvate and fatty acid enter mitochondrial matrix and are converted to acetyl CoA
  • acetyl CoA (2 carbon) transferred to oxaloacetate molecule (4 carbon) creating citrate (6 carbon)
  • 2 carbons cleaved to create 2 CO2 molecules for each turn of the cycle.
  • produces one ATP molecule per cycle but captures a great deal of energy in form of H-
  • H- combines with NAD+ and FAD to create NADH and FADH2 which got into oxidative phosphorylation
66
Q

oxidative phosphoylation

A

results in ATP by reaction of ADP + inorganic phosphate (Pi) ADP + Pi = ATP

67
Q

oxidative phosphorylation steps

A
  • hydrogen transported to electron transport chain by carrier molecules NADH and FADH2.
  • enzymes of transport chain harness energy from the transported protons (H+) gradient.
  • proton gradient used to power synthesis of ATP
  • ATP synthase: enzyme in the inner mitochondrial membrane allows protons to flow back into mitochondria down their gradient
  • About 30 ATP are form ed from complete oxidation of glucose into CO2 and H2O.
  • – 2 from glycolysis
  • – 2 from citric acid cycle
  • — remainder from oxidative phosphorylation
68
Q

transporter proteins

A

highly specific to transport specific molecules

69
Q

Active transport pumps

A

move solutes across the membrane against the concentration gradient

70
Q

Membrane transport carriers

A

bind molecules then move across membrane

71
Q

Na+ driven carrier

A

Na+ gradient produced by Na+-K+ pump is used to power a variety of transporters by secondary active transport.

72
Q

passive transport carrier

A

move substances across membrane passively

73
Q

membrane channel proteins

A

water filled pores in membrane.

  • transport ions passively
  • highly selective
  • open and close according to membrane signals.
74
Q

voltage gated membrane channel

A

respond to change in membrane potential

75
Q

mechanically gated membrane channel

A

respond to mechanical deformation

76
Q

ligand gated membrane channel

A

responds to binding of a signaling molecule

77
Q

resting potential

A

electrical charge present in side cell when there is no ion movement across the membrane

78
Q

K+ remains inside cell due to

A

active transport

attraction of negatively charged ions inside cell

79
Q

action potential

A

cells are electrically excitable

  • react to changes in voltage across membrane
  • influx of positive ions causes shift in membrane potential to a less negative value: depolarization
  • threshold: reached when membrane patch becomes approx. -65mV
    • activate volate-gated Na+ channels allowing rapid influx of Na+.
  • – influx in one patch causes membrane depolarization of next patch, opening more Na+ channels
  • repolarization: Na+ inflow is stopped by closing channels and K+ outfow is increased: passive and channels open.
80
Q

gap junction

A

connecting channels between adjacent cells, allows passage of small molecules.

81
Q

direct cell to cell contact

A

cell membrane receptors with signaling molecules present on another molecule.
- important for development of immune response.

82
Q

chemical mediators

A

synaptic
paracrine
endocrine
autocrine

83
Q

cell surface receptor-mediated responses

A

ion channel linked receptor
enzyme linked receptors
G-Protein-coupled receptors (GPCR’s)

84
Q

ion channel linked receptor

A

bind neurotransmitter causing ion channels in membrane to open or close

85
Q

enzyme linking receptors

A

catalyze enzyme reaction when activated.
- function as protein kinases: mediate transfer of phosphate groups from ATP or GTP to proteins and thus affect activity of target protein

86
Q

G-Protein-coupled receptors (GPCR’s)

A

controls production of 2nd messenger

  • most hormones and drugs have effects here
  • activated subunits influence activity of target enzymes.
  • 3 types: G- proteins, Gq and Gi
87
Q

G-proteins (GPCR’s)

A

subunit stimulates production of cAMP

88
Q

Gq (GPCR’s)

A

subunit stimulates enzyme phospholipase C.

  • cleaves a membrane phospholipid to form 2 secondary messengers
    • inositol 1,4,5-triphosphate (IP3)
    • diacylglycerol (DAG)
89
Q

Gi (GPCR’s)

A

inhibitory to the production of cAMP

90
Q

secondary messengers (5)

A 
cAMP
IP3
DAG
Ca2+
cGMP
91
Q

intracellular receptor mediated response

A

specific for particular ligand, must be lipid soluble and able to pass directly through cell membrane.

92
Q

Proliferation

A

G1
S phase- synthesis
G2
M phase- mitosis and cell division

93
Q

pRb

A

Rb protein important in preventing a cell form proceeding through cell cycle.
- bind to E2F and gene transcription factor, rendering it unable to bind to DNA and begin replication.

Pathophysiology (80 decks)

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