Unit 1 - Cell Physiology Flashcards

1
Q

how many types of distinct cells are there in the human body?

A

~200

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2
Q

what are the four broad categories of cells?

A

1) epithelial cells
2) connective tissue cells
3) nerve cells
4) muscle cells

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3
Q

cells are surrounded by _______ and contain specialized structures called _______.

A

membranes, organelles

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4
Q

every cell has a nucleus, except:

A

red blood cells

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5
Q

what is the largest organelle in the cell?

A

the nucleus

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6
Q

what is the primary function of the nucleus?

A

storage of DNA in the form of chromatin.

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7
Q

the nucleus is surrounded by a membrane known as the ________, with openings called _________.

A

nuclear envelope, nuclear pores

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8
Q

nuclear pores facilitate…

A
  • passage of RNA into the cytoplasm
  • entrance of proteins that modulate gene expression
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9
Q

what is the nucleolus?

A

the site of ribosomal RNA synthesis and protein components of ribosomes

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10
Q

what is the smallest cellular organelle?

A

the ribosome

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11
Q

what is the primary function of the ribosome?

A

the “protein factory” which translates RNA into protein.

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12
Q

cells that make lots of proteins will have lots of…

A

ribosomes

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13
Q

do ribosomes have a surrounding membrane?

A

no

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14
Q

what are the two types of ribosomes?

A

free ribosomes and membrane-bound ribosomes

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15
Q

which organelle is continuous with the rough ER and the nuclear envelope?

A

smooth ER

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16
Q

what is the primary function of the smooth ER?

A

fatty acid synthesis, calcium storage and release, etc.

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17
Q

what is the primary function of the rough ER?

A

site of protein synthesis

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18
Q

proteins synthesized in the lumen are…

A

distributed to other organelles or secreted

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19
Q

the orgenelles that is comprised of a series of membranous sacs called cisternae is the…

A

golgi apparatus

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20
Q

what is the function of the golgi apparatus?

A

modifies and sorts proteins arriving from the ER, and distributing them to other organelles or to the membrane for secretion.

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21
Q

the small membrane-bound vesicles spread throughout the cytoplasm are…

A

endosomes

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22
Q

what is the function of the endosomes?

A

sorting vesicular traffic in the cell

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23
Q

what is the function of the lysosomes?

A

breakdown:
- damaged/worn out organelles
- engulfed bacteria
- engulfed debris of dead cells

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24
Q

which organelle has an acidic environment and contains digestive enzymes?

A

lysosomes

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25
Q

what is the function of peroxisomes?

A

breakdown:
- fatty acids
- detoxification of alcohol

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26
Q

what is the function of the mitochondria? (i swear to god if you say the powerhouse of the cell)

A

transfers energy in the form of ATP in a process called cellular respiration.

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27
Q

what is the function of the cytoskeleton?

A

provides structural support, facilitates change in cell shape, an produces cell movement.

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28
Q

what are the three classes of the cytoskeleton?

A

1) actin filaments
2) intermediate filaments
3) microtubules

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29
Q

which class of the cytoskeleton is made of hollow tubes, and is formed of tubulin subunits?

A

microtubules

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30
Q

which class of the cytoskeleton is made up of twisted strands of proteins like keratin, desmin, and laminin?

A

intermediate filaments

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31
Q

which class of the cytoskeleton contains G-actin subunits which form a polymer of two twisting chains, forming F-actin?

A

actin filaments

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32
Q

what is ribosomopathy?

A

multiple causes of abnormal ribosomal biogenesis resulting in human disease

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33
Q

true or false: ER stress is not secondary to other diseases.

A

false. it is secondary to things like cancer, neurodegeneration, and metabolic disease.

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34
Q

what is ER stress?

A

altered ER funtion results in accumulation of unfolded/misfolded protiens, this may cause apoptosis.

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35
Q

is mitochondrial mytopathy primary or secondary?

A

haha pranked it can be both

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36
Q

what is a lysosomal storage disorder?

A

one where toxic material build up in the lysosome.

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37
Q

what are the three key components of the fluid mosaic model?

A

1) phospholipid bilayer
2) cholesterol
3) proteins

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38
Q

what does it mean for phospholipids to be amphipathic?

A

they have a hydrophilic head and a hydrophobic tail.

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39
Q

what is the main function of cholesterol in the cell membrane?

A

to maintain membrane fluidity.

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40
Q

what are the two classes of membrane proteins?

A

1) integral membrane proteins
2) peripheral membrane proteins

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41
Q

which membrane proteins are amphipathic and are embedded in the membrane/membrane spanning?

A

integral membrane proteins

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42
Q

which membrane proteins are not amphipathic and lie on the membrane surface?

A

peripheral membrane proteins

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43
Q

what are the four main functions of the membrane proteins?

A

1) link adjacent cells together
2) regulate passage of substances into and out of the cell
3) detect chemical messengers arriving at the cell surface
4) anchor cells to extracellular matrix

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44
Q

cell membranes can join together to form…

A

junctions

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45
Q

what are the three major types of cell junctions?

A

1) desmosomes
2) tight junctions
3) gap junctions

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46
Q

what are desmosomes?

A

stong links that give high structural integrity.

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47
Q

what are tight junctions?

A

forms tight barriers so things can’t get through the cells.

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48
Q

what are gap junctions?

A

pores between cells, allowing passage of ions and small molecules.

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49
Q

what are the four mechanisms that molecules use to cross membranes?

A

1) diffusion
2) protein-mediated transport
3) vesicular transport
4) epithelial transport

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50
Q

true or false: nonpolar molecules diffuse across cell membranes relatively quickly

A

true

51
Q

true of false: polar molecules diffuse across membranes relatively quickly

A

false

52
Q

what is diffusion?

A

movement of molecules from high concentration to low concentration

53
Q

the direction of diffusion is a product of the balance between one-way movement between compartments, this is referred to as:

A

net flux

54
Q

what is the equation for Fick’s First Law of Diffusion?

A

J = PA(Co-Ci)

55
Q

why is protein mediated transport necessary?

A

it is used for molecules that are not membrane permeable

56
Q

what are the two main types of protein mediated transport?

A
  • facilitated diffusion
  • active transport
57
Q

what is facilitated diffusion?

A

protein-mediated movement of ions, amino acids, and other small molecules that cannot move through the membrane by simple diffusion

58
Q

what are the two broad categories for protein-mediators used in facilitated diffusion?

A
  • ion channels
  • transporters
59
Q

true or false: ion channels and membrane transports are not selective towards specific molescules, so any molecule can move down and transporter

A

false

60
Q

what are the two forces that contribute to ion flux across membranes?

A
  • ion concentration (chemical)
  • electrical gradient between the outside and inside of a cell (membrane potential)
61
Q

what are ion channels?

A

transmembrane proteins that form pores

62
Q

how are larger molecules protected from passing through the cell membrane?

A

very small diameter

63
Q

ion channels are selectively permeable to specific ions, this selectivity is determined by:

A

1) channel diameter
2) charge of the polypeptides
3) number of water molecules associated with ion

64
Q

diffusion of ions through ion channels by a process called:

A

channel gating

65
Q

what are the three types of ion channel gates?

A

1) ligand gating
2) voltage gating
3) mechanically gating

66
Q

the binding of specific molecules to a channel that causes conformational change is called:

A

ligand gating

67
Q

a change in membrane potential which causes conformational change is called:

A

voltage gating

68
Q

a physical change in the membrane to allow ions to pass through the membrane is called:

A

mechanical gating

69
Q

what are the three basic steps of protein mediated transport?

A

1) solute binding to specific site on protein
2) conformation change in transporter
3) dissociation of solute from binding site

70
Q

magnitude of flux through transporters dependent of four factors. what are those four factors?

A

1) solute concentration
2) affinity of transporter for solute
3) number of transporters in the membrane
4) rate at which the transporter goes through conformational change

71
Q

in facilitated diffusion, solutes move ______ their concentration gradient. in active transport, solutes move _______ their concentration gradient.

A

down, up

71
Q

what is secondary active transport?

A

the use of an electrochemical gradient across a membrane to help solutes move down their concentration gradient

71
Q

what is primary active transport?

A

the direct use of ATP to help solutes move down their concentration gradient

72
Q

in the sodium-potassium ion pump, Na+ is moved ____ the cell while K+ is moved ____ the cell

A

out of, into

73
Q

how many Na+ and K+ are moved in/out of the cell for every ATP the sodium-potassium pump uses?

A

three Na+ and two K+ ions

74
Q

true or false: vesicular transport requires molecules to pass through the membrane

A

false

75
Q

what is vesicular transport?

A

transport which is achieved by enclosure of materials into vesicles that pinch off from the membrane

76
Q

the process where membrane envaginations enclose small volume of extracellular fluid, which are taken into the cell is:

A

endocytosis

77
Q

the process where intracellular membrane-bound vesicles fuse with the plasma membrane and release their contents into the extracellular fluid is:

A

exocytosis

78
Q

what are the three common types of endocytosis?

A

1) pinocytosis
2) phagocytosis
3) receptor-mediated cytosis

79
Q
  • nonspecific
  • includes water and whatever solutes are present
  • vesicle fuses with lysosome
    theses are all properties of:
A

pinocytosis

80
Q
  • specific
  • unique to specifalized immune cells (phagocytes)
  • involves uptake of bacteria or cell debris from damaged tissue
  • internalized vesicle fuses with lysosome
    these are all properties of:
A

phagocytosis

81
Q

what is receptor mediated endocytosis?

A

clustering of receptors to allow select concentrations of solutes into the vesicles, can involve the formation of clathrin coated pits

82
Q
  • restricted to small molecules
  • generates relatively small vesicles called caveolae
  • contents delivered to the cytosol
    these are all properties of:
A

potocytosis

83
Q

what are the two functions of exocytosis?

A
  • replaces cell surface membrane lost during endocytosis
  • allows secretion of membrane impermeable molecules into extracellular fluid
84
Q

epithelial cells line the cavities and surfaces of:

A

vesicles and organs

85
Q

in an epitheleal cell, the surface that faces the hollow organ/tube is called the:

A

apical membrane

86
Q

in and epithelial cell, the surface that faces the lumen is called the:

A

transcellular pathway

87
Q

the limited movement of diffusion of water and small ions across epithelial cells is called the:

A

paracellular pathway

88
Q

utilizes the processes of diffusion and protein-mediated transport and involves the flow against concentration gradient in an epithelial cell

A

transcellular pathway

89
Q

physiological homeostasis depends on:

A

communication between cells

90
Q

how do cells communicate with each other?

A

receptors

91
Q

how do cells process signals?

A
  • lipid-soluble messengers
  • water-soluble messengers
92
Q

once a cell has recieved a signal, it must be “processed”, this is called:

A

signal transduction

93
Q

how do cells recieve signals from other cells?

A

receptor proteins

94
Q
  • most common
  • bind to plasma transmembrane receptors
    these are characteristics of what type of signal?
A

water-soluble signal

95
Q
  • can diffuse through membrane
  • bind to intracellular receptors
  • generally transduce signal via change in gen expression
    these are characteristics of what type of signal?
A

lipid-soluble signal

96
Q

cell signaling depends on ligand-receptor interactions, including:

A

1) specificity
2) affinity
3) saturation
4) competition

97
Q

what is ligand-receptor specificity?

A

the ability of a receptor to only bind a limited number of ligands

98
Q

what is ligand-receptor affinity?

A

the strength of a ligand binding to a receptor

99
Q

what is ligand-receptor saturation?

A

the extent to which receptors are bound by a ligand

100
Q

what is ligand-receptor competition?

A

presence of other ligands which “compete” for receptor binding sites

101
Q
  • a lowering of the number of target cell receptors
  • can occur in response to sustained high levels of signal (negative feedback)
  • reduces cell response to frequent/intense stimulation
  • common mechanism is internalization
    these are all characteristics of:
A

down-regulation

102
Q
  • an increase in the number of target cell receptors
  • can occur in response to sustained low levels of signal (positive feedback)
  • increases cell response to low-level stimulation
  • can occur through increased insertion of receptor-containing vesicles into the cell membrane
    these are all characteristics of:
A

up-regulation

103
Q

the process of ______ translates a signal into a cellular response.

A

signal transduction

104
Q

cellular responses to signals can include changes in:

A

1) membrane properties
2) cellular metabolism
3) secretory activity
4) rate of proliferation/differentiation
5) contractility

105
Q

in the transduction of lipid-soluble signals, the response is primarily mediated by ___________, leading to a change in gene expression

A

nuclear receptors

106
Q

1) circulating signal diffuses from circulation across membrane into cell
2) signal enters nucleus and binds receptors
3) ligand-receptor complex functions as a transcription factor, changing expression (mRNA) level of target gene
4) change in mRNA abundance effects in change in protein level, leading to cellular response
these are the steps of:

A

transduction of lipid-soluble signals

107
Q

what are the two phases of signal transduction?

A

1) binding of signal to receptor (first messenger)
2) signals generated by receptor activation (second messenger)

108
Q

many second messenger systems rely on _________ to effect change

A

phosphorylating proteins

109
Q

enzymes that phosphorylate proteins are called:

A

protein kinases

110
Q

what are the four common mechanisms of water-soluble ligand signaling?

A

1) receptors that function as ion channels
2) receptors that function as enzymes
3) receptors that interact with cytoplasmic kinases
4) receptors that interact with G-proteins

111
Q

receptors that interact with cytoplasmic kinases are called:

A

janus kinases

112
Q

G-proteins “couple” receptor with effector proteins to generate:

A

second messengers

113
Q

which G-protein inhibits production of cyclicAMP?

A

Gi

114
Q

which G-protein activates the production of cyclicAMP?

A

Gs

115
Q

which which G-proteins activates phospholipase C>?

A

Gq

116
Q

PKA has multiple targets, meaning:

A

it can elicit multiple responses in the same cell

117
Q

cAMP is a potent second messenger, thus its levels are:

A

tightly regulated

118
Q

How do signals cause the cytosolic calcium concentration to increase?

A
  • activation of plasma membrane calcium channel
  • opening of calcium channel on the ER membrane
  • active transport of calcium out of the cell blocked by a second messenger
119
Q

how does increased calcium concentration elicit a cellular response?

A

typically via binding proteins and activating them

120
Q

cessation of intracellular signaling is required to:

A

prevent overstimulation of the cell

121
Q

what are the three main steps to cessation of signal transduction pathways?

A
  • decreased concentration of signal
  • change in receptor conformation
  • receptor mediated endocytosis