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cells and phys > exam 2 > Flashcards

exam 2 Flashcards

1
Q

nuerons

A

cells capable of transmitting signals across relatively long distances using electrical current
these signals = nerve impulses

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2
Q

Cell membranes regulate

A

ion movement in/out of cell which Maintains different concentrations of various ions inside and outside of the cell; maintains gradient

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3
Q

Ion gradient is also known as

A

electrical potential

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4
Q

changing ion gradient along length of membrnae =

A

electrical current

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5
Q

Sympathetic

A

Sometimes described as the “fight or flight” nerves; movement of skeleton/muscles

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6
Q

Parasympathetic

A

Sometimes described as internal organ function nerves; responsible for every day functions (“Feed and Breed”)

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7
Q

Sympathetic and parasympathetic nerves work in

A

concert to govern involuntary (visceral) functions in body

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8
Q

Two systems in opposition to each other

A

maintains careful equilibrium

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9
Q

Organ Systems

A 
Cardiovascular
Respiratory
Digestive
Urinary
Reproductive
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10
Q

afferent

A

Sensor neuron input

Activated by reflex centers in the CNS

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11
Q

efferent

A

Motor neuron output

Activated by reflex centers in the CNS

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12
Q

refex arc

A

complete circuit of nerves involved with involuntary response; from the incoming stimulus to the final effector organ

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13
Q

Brain (conscious) can

A

override many reflex arcs

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14
Q

what are the two types of cells in the nervous system?

A

neurons (highly Specialized) and glial cells (supportive)

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15
Q

neuron types

A

sensory, motor and interneurons

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16
Q

sensory neurons

A

Provide information about environment from body to brain

Sight, smell, touch, pressure, pain, temperature

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17
Q

motor neurons

A

Provide movement information from brain to muscles (skeletal and smooth) and glands
Somatic
Autonomic (Sympathetic, Parasympathetic)

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18
Q

interneurons

A

Receive signals from one neuron and transmit them to another

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19
Q

what do Glial cells do? what kinds are there?

A

Most abundant in central nervous system (CNS)
Glia = “glue” (supportive)
the kinds are microglial, oligodendrocytes, schwann and astrocytes

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20
Q

Microglial cells

A

phagocytosis of infectious material, debris

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21
Q

Oligodendrocytes

A

form myelin sheath in CNS

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22
Q

Schwann cells

A

form myelin sheath in PNS

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23
Q

Astrocytes

A

control access of brain cells to blood( blood-brain-barrier)

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24
Q

Neurons are capable of signal transduction which is

A

Receive a signal of one type, transmit a signal of another
Ex: when someone steps on your foot
Peripheral pressure-sensitive neurons in foot activated
Pain-sensing neurons activated as well
Two different signals must be transduced/ converted into an electrical signal that travels from foot  spinal cord  brain
Neurons in brain respond

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25
Q

Membrane Potential

A

difference in electrical potential between the inside and the outside of a cell this is a property of all cells

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26
Q

Electrical potential

A

the potential energy possessed by electric charges by virtue of their position in an electrostatic field; electricity property of all cells

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27
Q

All Living Cells at Rest

A

Disparity / inequality of charge inside to outside
Due to differing [ions] inside to outside
Produces Resting Membrane Potential (Vm)
= -60mV (net negative)

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28
Q

Neurons also have Electrical Excitability which is limited to

A

specialized cells ex. Nerve and muscle

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29
Q

Stimulation generates Action Potential (AP) which is

A

change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell

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30
Q

In nerve cells, positive charge can “flow” along the

A

axon; transmitting a signal across distance Made possible because of differential opening/closing of gated ion channels

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31
Q

gradiets excist across

A

cell membrane

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32
Q

contribute most to membrane potential

A

Na+, K+, Cl-

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33
Q

Degree of gradient

A

electrical potential (voltage)

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34
Q

When - / + charges put into motion

A

current (amp)

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35
Q

In the Steady-State:

A

Differing [ions] on either side of membrane determines resting membrane potential
“Leakage” occurs (ions leak down the gradient)

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36
Q

“leakage” must be managed otherwise..

A

K+ goes out ; cytosol = more negative(HYPERPOLARIZATION)
Na+ goes in ; cytosol less negative ; (DEPOLARIZATION)
Cl - goes in ; cytosol more negative; (HYPERPOLARIZATION)

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37
Q

If cell became suddenly highly permeable to Na+ in

A

purposeful depolarization

neurons take advantage of this

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38
Q

If cell becomes suddenly highly permeable to K+ out

A

purposeful hyperpolarization

neurons take advantage of this

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39
Q

Na+ and K+ flow can rapidly change through

A

ion channels

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40
Q

Integral membrane proteins
Form pores
Channels are “gated” – opened/closed by changes in voltage
Some are “leaky”

A

Ion Channels

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41
Q

Voltage-Gated Ion Channels

A

Channels for Na+, K+, (Ca+2) that are Structurally similar (but not identical) it is a Rectangular “tube” with 4 walls
The potassium channel = multimeric (4 subunits)
The sodium channel = monomeric (4 domains)
One wall has voltage sensor
 Channel Gating
Each wall has inactivation particle
 Channel Inactivation

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42
Q

potassium channel

A

Multimeric; 4 subunits
Negatively charged amino acids concentrated at cytosolic entrance to the channel
Attracts positively charged ions
Repels negatively charged ions

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43
Q

vestibule

A

Below the selectivity filter is a widened area which accomodates hydrated ions

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44
Q

potassium channel contains

A

Each subunit contains 2 αhelices which tilt, forming a cone/pore (called pore helices)
Loop of amino acids jutting off of pore helices forms selectivity loop

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45
Q

The selectivity loops together form the

A

selectivity filter

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46
Q

Carbonyl oxygens that line the filter are what charged

A

negatively
K+ is relatively large; all 4 carbonyl oxygens are spaced to accommodate
Na+ is relatively small; carbonyl oxygens too far apart to interact uniformly  only 2 carbonyl oxygens interact  energetically unfavorable

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47
Q

Channel inactivation

A

Involves inactivating particle
Allows channels to close rapidly and stay closed (despite electrical stimulation) until membrane potential returns to resting state

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48
Q

what states can ion channels be in

A

open closed and inactivated

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49
Q

Different concentrations of various ions inside and outside of the cell

A

electrical potential

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50
Q

allow for flow of ions

A

electrical current

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51
Q

change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell

A

Action potential (AP)

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52
Q

types of synapses

A

electrical and chemical

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53
Q

electrical synapes

A

Presynaptic neuron + postsynaptic neuron
Connected by gap junctions
Composed of (6) connexin protein subunits (= connexon)
Connexons from pre- and post-synaptic neurons = gap junction
Allow for passage of ions, small molecules
Provides for cell-cell transmission with virtually no delay
Occurs where speed of transmission is essential
ex: cardiac cells

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54
Q

chemical synapse

A

Presynaptic neuron + postsynaptic neuron
Separated by 20 – 50nm space
Space = Synaptic Cleft
AP must be converted to chemical signal to cross the cleft, then converted back to AP
Chemical signal = Neurotransmitters

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55
Q

Neurotransmitters (NT)

A

Stored in terminal bulbs / synaptic knobs
located in pre-synaptic neuron
AP arrives  stimulates vesicles containing NT to fuse with pre-synaptic membrane  releasing NT into cleft

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56
Q

NT binds

A

postsynaptic membrane receptors

Binding of NT alters membrane potential  either stimulate or inhibit AP in next neuron

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57
Q

Excitatory post-synaptic potential =

A

EPSP (depolarization)

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58
Q

Inhibitory post-synaptic potential

A

IPSP (hyperpolarization)

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59
Q

Ligand-gated / Ionotropic =

A

= direct action
Act as ion channels
NT binds  changes confromation  ions pass through
Can stimulate or inhibit post-synaptic AP

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60
Q

Metabotropic

A

indirect action
Binding of NT activates intracellular messengers
Second messengers open ion channel  ions pass through
Can stimulate or inhibit post-synaptic AP
Slower response than ionotropic

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61
Q

Neurotransmitters

A

Relay molecules - relay signals across synapses
“Signaling Molecules”
Must elicit a response when released into the cleft
Must be released at the right time / with right stimulus

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62
Q

neurotransmitter examples

A

Ex: acetylcholine
catecholamines – dopamine, norepinephrine, epinephrine
amino acids / derivatives – histamine, seratonin, etc.
neuropeptides - enkephalins

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63
Q

Acetylcholine (Ach)

A

Most common neurotransmitter in vertebrate PNS
and neuromuscular junction
Excitatory  stimulates post-synaptic APs
When Ach binds  increased permeability of postsynaptic membrane to Na+
Synapses that use Ach = cholinergic

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64
Q

Catecholamines

A

Derived from tyrosine
(dopamine, norepinephrine, epinephrine)
Synthesized in adrenal gland
Effects are complex; excitatory or inhibitory
Used in nerves, smooth muscles in the intestines;
certain nerve-nerve transmissions in brain

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65
Q

Synapses that use catecholamines

A

adrenergic

66
Q

Amino Acids / Derivatives

A 
Ex:
Histamine
Seratonin
Gamma-aminobutyric acid (GABA)
Glycine
Glutamate

Actions are complex – excitatory or inhibitory

67
Q

Neuropeptides

A

Short chain amino acids
Hundreds identified
Differ from other NTs  act on groups of neurons
Long-lasting

Ex: enkephalins = inhibitory - stop pain in CNS during shock, stress
substance P = excitatory

68
Q

NTs must be inactivated quickly to prevent

A

overstimulation of the post-synaptic neuron

69
Q

Degradation

A

Ex: acetylcholinesterase degrades acetylcholine
Consider: acetylcholinesterase inhibitors (organophosphates – pesticides, herbicides, nerve gas)
increased cholinergic effects  muscle overstimulation

70
Q

Re-uptake

A

Membrane pumps

Consider: Selective seratonin reuptake inhibitors (SSRIs) (zoloft, paxil, lexapro, prozac)

71
Q

protein trafficing

A

process involving all movement of proteins from one part of the cell or compartment to another

72
Q

Protein targeting/sorting

A

type of trafficking whereby protein signals dictate where a protein will be located, how it will be sorted

73
Q

peptide

A

<50 amino acids in primary structure

74
Q

polypeptide

A

> 50 amino acids in primary structure

75
Q

protien

A

one or more polypeptides

76
Q

4 stages of protein structure

A 
Primary = sequence of amino acids
Secondary = alpha helices; beta sheets
Tertiary = folded 
Quaternary = multiple polypeptides assembling together
77
Q

how many common amino acids are there?

A

20
Grouped into polar, nonpolar, acidic/basic (charged)
Bound together with peptide bond
Amino end = N-terminus, Carboxyl end = C-terminus

78
Q

process of translation

A

mRNA exits nucleus through nuclear pore complex
Ribosome binds mRNA
composed of protein, rRNA
contains mRNA binding site (small subunit)
large subunit contains active site for peptide bond formation
Individual codons exposed
Large subunit binds
Charged tRNAs interact with:
Aminoacyl site (A site)
Peptidyl site (P site)
Exit site (E site

79
Q

There are differences between bacterial and

A

eukayotic translation

80
Q

mutation alter DNA

A

change mRNA  might change protein

81
Q

Point mutations –

A 
base substitutions (silent, missense, nonsense)
insertions, deletions (frame shift)
82
Q

Chromosomal mutations

A

Gene duplication, deletion
Gene inversion
Gene translocation

83
Q

“musts” of Post-translational Processing

A

Proteins must be modified
Proteins must fold – structure relates to function!
Proteins must be sorted/trafficked to destination

84
Q

Organelles involved in post-translational processing

A

Endoplasmic reticulum
Golgi apparatus
Transport vesicles

85
Q

cleavage

A

Proteins transported across membranes have block of amino acids removed (signal sequence)

86
Q

splicing

A

modification of the nascent pre- messenger RNA (pre-mRNA)

87
Q

mRNA

A

introns, exons; proteins = inteins, exteins

88
Q

Inteins get removed,

A

exteins bind together

89
Q

glycosylation

A

Carbohydrate side-chains added to protein

90
Q

CHemical modifications

A

Small molecules added onto amino acids

91
Q

multimeric (quaternary structure)

A

Single polypeptides combined with other polypeptides to create complete proteins

92
Q

Targeting proteins to specific compartments of cell using signal sequence:

A

Co-translational Import
and
Post-translational Import

93
Q

Cotranslational import into ER lumen

A

Ribosomes become bound to ER
Protein released into ER lumen  processed
Packaged into vesicles to exit ER
To Golgi  further processing
Packed into vesicles  vesicles, lysosomes, plasma membrane

94
Q

Signal Hypothesis (Blobel&Sabatini, 1971)

A

ER signal sequence itself doesn’t contact ER

Instead signal recognition particle (SRP) mediates

95
Q

Cotranslational Import to the er

A

translated protein is released in to ER (review steps) followed by folding I to quaternary structure

96
Q

Abnormal Folding

A

Unfolded protein response
Sensors in ER membrane detect misfold
Triggers a temporary stop of translation for most other proteins
Enhances translation of chaperones and degradation proteins (proteosomes)
Misfolded protein then unfolded and refolded
ER associated degradation (ERAD)
Recognizes misfolded proteins
Retranslocates them from the cell for degradation

97
Q

Cotranslational Import to Folding to?

A

Glycosylation

98
Q

Some proteins translated on free ribosomes (cytosol)

After translation these proteins:

A 
May remain in cytosol
May be taken into certain organelles (post-translational import)
nucleus
mitochondria
chloroplasts
peroxisomes
99
Q

Co-translational import

A 
Folded
Glycosylated
Trafficked to:
Plasma membrane
**Outer organelle membranes
100
Q

Integral Membrane Proteins: (IMPs)

A 
Most common type= transmembrane
Spans entire membrane
Less common = integral monotopic protein
Emerges from the membrane on 1 side only
Essentially held in membrane with αhelical segments
101
Q

Proteins destined to become IMPs have

A

specific signal tags that identify their final membrane destination
Carbohydrates attached to amino acid side chains

102
Q

Remember: several membranes are targets

A

Plasma membrane

Outer organelle membranes

103
Q

Anchoring IMPs in ER membrane

A

Similar to regular translocation into ER (cotranslational)

104
Q

Anchoring IMPs to ER Membrane:

A

The N-terminus is in ER lumen

The C-terminus (and most of the protein) is in cytosol

105
Q

Also possible to anchor to ER membrane using internal start-transfer sequence

A

No ER signal sequence
SRP interacts with internal sequence on protein
Hydrophobic region
Binds translocon

106
Q

For multipass proteins:

A

Contain alternating stop-transfer and start-transfer signals

107
Q

Note that ER membrane is where ALL

A

membrane proteins are first assembled (all-co-translational import)

108
Q

4 essential needs of the cell

A

Genetic information to guide protein production (central dogma)
Molecular building blocks (nucleotides, amino acids, simple sugars, fatty acids, etc.) to build macromolecules
Chemical catalysts (enzymes)
Energy

109
Q

traditional definition of energy

A

capacity to do work

110
Q

another deffintion of energy

A

capacity to cause physical or chemical change

111
Q

energy is required for

A

Synthetic Work
biosynthesis = formation of new chemical bonds
Mechanical Work
physical change in position or orientation of cell or some part of cell
Gradient Work
Maintaining concentration gradients (ex: pumps)
Electrical Work
Electrical signaling
Production of heat – homeotherms

112
Q

1st Law of Thermodynamics

A

The law of conservation of energy

Energy can neither be created nor destroyed; only altered in it’s form

113
Q

2nd Law of Thermodynamics

A

Law of Thermodynamic Spontaneity

The universe always tends toward greater disorder or randomness (entropy) –

114
Q

free energy

A

measure of spontaneity = G

ΔG = free energy change in a reaction

115
Q

When ΔG is negative

A

spontaneous reaction, exergonic

116
Q

When ΔG is positive =

A

= nonspontaneous reaction, endergonic

117
Q

energy is released when

A

chemical bonds are broken

118
Q

ATP

A 
adenosine triphosphate
(3) components
Ribose
Adenine
(3) Phosphate groups
Energy “currency”
Releases 7.3kcal/mol

Has high potential energy (PE)
Three phosphate groups

119
Q

there is no life without

A

ATP

120
Q

ATP production

Site:

A

mitochondria and chloroplast

121
Q

ATP production process

A

Substrate-level phosphorylation
Oxidative phosphorylation
Photophosphorylation
Requires: a “food source” and oxidation-reduction rxns

122
Q

Sources of “food” in ATP production

A 
Autotrophs = self-feeders
and Heterotrophs (organotrophs) = “other-feeders”
123
Q

type of autotrophs

A

Phototrophs  capture light energy from sun  convert light energy into chemical energy (carbohydrate)  perform cellular respiration – oxidation

124
Q

types of heterotrophs

A

Chemotrophs  break chemical bonds in macromolecules recovered from other organisms; primarily through oxidation (of carbohydrate, glucose)
Lithotrophs  feed on inorganic material

125
Q

LEO” goes “GER”

A

Lose-electron-oxidation

Gain-electron-reduction

126
Q

RedOx Reactions:

A

usually accompanied by a proton (H+)
Molecule that contains the reduced atom gains a hydrogen (H) atom
has higher potential energy (PE)
Molecules that are oxidized often lose a proton along with an electron
have lower potential energy (PE)
“Follow the proton”

127
Q

Electron Transport Chain

A

Fed by oxidation of NADH and FADH2
Electrons stepped down in energy along ETC
Proteins, cytochromes, quinones, Fe-S complexes, etc
Energy released used to produce proton gradient
Protons flow down the concentration gradient through ATP Synthase
Drives formation of ATP = oxidative phosphorylation
26 ATP / mol glucose

128
Q

All eukaryotic cells use cellular respiration

A

Animals use Cellular Respiration

Plants use Photosynthesis and Cellular Respiration

129
Q

how do Bacteria, Archaea make ATP

A

use ETC, ATP Synthase to make ATP

130
Q

Fermentation

A

Without oxygen or another electron acceptor available, electrons carried by NADH have nowhere to go
ETC stops Any NAD+ in cell quickly goes to NADH

Fermentation is a metabolic pathway that:
Regenerates NAD+ from stockpiles of NADH
Allows glycolysis to continue producing ATP

131
Q

Photosynthesis

A

Light-dependent Reactions
Generate ATP
(Photophosphorylation)
Generate NADPH

132
Q

exocytosis

A

expulsion or secretion of material from a cell by fusion of a vesicle with the plasma membrane

133
Q

endocytosis

A

uptake of extracellular materials into a cell by infolding of the plasma membrane to form a vesicle

134
Q

Phagocytosis

A

= form of endocytosis; large particles or whole organisms (>0.5um) taken into the cell for digestion

135
Q

Vesicle

A

general term for small organelle compartment brought into cell through endocytosis

136
Q

early endosome

A

small organelle compartment emerging from TGN; mildly acidic in chemistry; fuses with vesicles; can continue to mature into lysosome, or travel to other parts of cell and fuse with plasma membrane

137
Q

late endosome

A

maturing early endosome; changing in contents and chemistry (more acidic)

138
Q

lysosome

A

mature form; containing digestive hydrolases

139
Q

exocytosis

A

Final step in the secretory pathway for proteins
Involves microtubule “tracks” that lead vesicles to plasma membrane
Fusion of secretory vesicle with plasma membrane triggered by second messengers

140
Q

Colchicine

A

microtubule inhibitor  inhibition of exocytosis

141
Q

Exocytosis:Special case = polarized secretion

A

Allows for secretion from only one side/surface of cell
Intestinal epithelium
Nerve cells
Involves proteins gathered in subdomains of plasma membrane

142
Q

endocytosis

A

Plasma membrane progressively folds inward
Pinches off and encloses material from outside of cell
removes plasma membrane from around cell

143
Q

Vesicle that folds inward from plasma membrane fuses with

A

early endosome from trans golgi network (TGN)

144
Q

Early endosome matures to late endosome

A

Late endosome to lysosome

145
Q

Phagocytosis

A

“eating,” taking in large molecules

146
Q

Pinocytosis

A

“drinking,” taking in liquid/dissolved material

147
Q

Phagocytosis Mechanism

A

Material binds to plasma membrane
Pseudopods reach up, around material
Material gets pulled into cell in phagocytic vacuole
Binds with early endosome  late endosome  matures into lysosome  degrades, breaks apart material

148
Q

Receptor-Mediated Endocytosis

A

Certain soluble, suspended materials coming into cell tansport by vesicle

Vesicle pinches off = coated vesicle

149
Q

Different “Fates” of RME materials

A

Endosome matures to lysosome  ligand broken apart
Receptor recycled to membrane, ligand in endosome taken to destination in cell
Endosome carried to TGN for retrograde transport through endomembrane system
Endosome travels to another portion of membrane; releases ligand in exocytosis; called transcytosis

150
Q

Coat Proteins:

A

Must be able to rapidly assemble and round out the invaginating vesicle
Must be able to rapidly disassemble so uncoated vesicle can then bind early endosome, etc.

151
Q

signal transduction

A

any process by which a biological cell converts one kind of signal or stimulus into another

152
Q

A system of messages (first, second, etc.) that produces

A

a cascade of events within and between cells  tissues  organs

153
Q

First message must be received by cell – by a receptor

Three types of receptors:

A

Plasma membrane receptor; with intrinsic enzyme capability (ex: tyrosine kinase linked receptors)
Plasma membrane receptor; coupled to GTP binding and hydrolyzing proteins (ex: G-protein coupled receptors, GPCRs)
Intracellular receptor; migrates to nucleus when bound to it’s ligand  alters gene transcription (ex: glucocorticoid receptor)

154
Q

in signal transduction he first message can

A

can bind receptor inside and outside the cell

155
Q

fist message in signal transduction is

A

ligand

156
Q

Ligand + receptor

A

ligand-receptor complex

157
Q

PTKs can be classified as

A

receptor or non-receptor associated

158
Q

PTKs:

A

Phosphorylate tyrosine residues on proteins (often enzymes)
Role in many regulatory processes
Differentiation
Growth
Cell migration
Proliferation
Abnormal signaling  disease (cancer, inflammation, diabetes, etc.)

159
Q

G-protein coupled receptor pathways

A

A membrane-associated receptor complex

7-pass transmembrane protein

160
Q

Glucocorticoids

A

class of steroid hormones released from adrenal gland / adrenal cortex
Named for role in regulating glucose metabolism
Involved in immune response to inflammation
Inhibitory - quiet the immune response

cells and phys (4 decks)

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