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BIO 130 > Test 2 > Flashcards

Test 2 Flashcards

0
Q

How do enzymes function?

A

By lowering the activation energy by increasing the rate of the reaction; change rate at which equilibrium is reached

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1
Q

What are enzymes?

A

Catalysts for biological reactions

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2
Q

How do temperature and pH affect enzymes?

A

Temp- as it increases so does the rate of the reaction and vice versa
pH- changing shape or charge properties or substrate so either substrate cannot bind to active site or undergo catalase

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3
Q

What is an enzymes active site?

A

The region where a substrate binds and a catalytic event occurs

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4
Q

What is an enzymes prosthetic group?

A

A small organic group of metal ions that frequently function as electron receptors

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5
Q

Oxidoreductases causes…

A

Oxidation reduction reactions

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6
Q

Transferases

A

Transfer of function groups from one molecule to another

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7
Q

Hydrolases

A

Hydrologic cleavage of

One molecule into 2 molecules

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8
Q

Lyases is?

A

Addition of a group to a molecule with a rearrangement of electrons

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9
Q

Isomerases

A

Movement of a functional group within a molecule

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10
Q

Ligases

A

Joining of 2 molecules to form a single molecule

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11
Q

How do enzymes bind to substrates to catalyze reactions?

A

Random collision, lock and key model or induced fit model

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12
Q

What is the cycle of events that an enzyme goes through?

A

Substrate binding
Substrate activation
Catalytic event
Product release

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13
Q

What is Vmax?

A

The upper limit of a reaction rate

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14
Q

What is Km?

A

Michaelis constant; a specific concentration of substrate depending on the affinity of the enzyme

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15
Q

What is saturation?

A

The relationship between the rate of reaction and concentration of substrate depending on the affinity of the enzyme

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16
Q

What are the four methods used in enzyme regulation?

A 
Alteration of temp/pH
Substrate level regulation
Competitive inhibition 
Allosteric regulation 
Covalent modification
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17
Q

What is competitive inhibition?

A

Molecules bind to the active site so that substrates CANNOT bind

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18
Q

What is allosteric regulation?

A

Facilitated by binding of regulatory molecules at the allosteric site

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19
Q

What are ribozymes?

A

RNA molecules that act as catalysts; NOT a protein

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20
Q

What is covalent modification?

A

Enzyme activity is affected by the addition of removal of chemical groups via covalent bonding

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21
Q

What are the functions of membranes?

A 
Define boundaries 
Loci for specific functions
Transport proteins 
Receptors 
Cell-to-cell communication
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22
Q

What is the fluid mosaic model?

A

Mosaic of proteins discontinuously embedded in or attached to a fluid lipid bilayer

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23
Q

How was it discovered that the membrane was composed of a lipid bilayer?

A

The lipid bilayer membrane structure in 1925

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24
Q

How is cholesterol incorporated into membranes?

A

By being found in sterols in animal cells

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25
Q

What are the 3 classes of membrane lipids?

A

Phospholipids
Glycolipids
Sterols

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26
Q

What are the ways that lipids can move within the membrane?

A
  • Rotation about their long axis
  • Lateral diffusion in the plane of the membrane
  • transverse diffusion requiring hydrophilic head to pass hydrophobic interior
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27
Q

How is lipid mobility measured?

A

Within membranes by fluorescence recovery after photo bleaching (occurs within seconds)

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28
Q

What factors affect membrane fluidity?

A

Sterols decrease fluidity above Tm(rigid, prevents movement)

Sterols increase fluidity below Tm(prevent phospholipids from fitting together)

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29
Q

What are the functions of proteins found in the membrane?

A

Transport
Receptors
Adhesion

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30
Q

What are the classes of membrane proteins?

A
  • Integral- Cyto, exo & transmembrane domain
  • Lipid anchored-one or more covalently linked lipids; GPI anchor
  • Peripheral- associated with integral & lipid head groups
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31
Q

How can scientists visualize the mobility of membrane proteins?

A
  • freeze fracture images
  • exposure to electrical field
  • mouse & human cell fusion
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32
Q

What are glycoproteins?

A

Conjugated to carbs; almost ALWAYS on exo- face

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33
Q

What are the functions of glycoproteins? (4)

A

Defense
Cellular uptake
Adhesion
Embryonic development

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34
Q

What is diffusion?

A

The movement of solutes

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35
Q

What is osmosis?

A

The movement of water across a selectively permeable membrane

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36
Q

What is facilitated diffusion?

A

The movement of diluted down the gradient mediated by proteins

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37
Q

What is active transport?

A

Moving solutes against concentration gradient

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38
Q

What is passive transport?

A

Simple/facilitated diffusion

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39
Q

What is indirect active transport?

A

One solute moving down gradient while driving the other solute up

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40
Q

Why is direct active transport?

A

Accumulation of molecules is coupled directly to an exergonic chemical reaction

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41
Q

What types of molecules can cross the membrane by simple diffusion?

A

Small, non polar molecules

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42
Q

How does water move during osmosis?

A

From low to high solutes

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43
Q

What type of diffusion exhibits saturation?

A

Facilitated diffusion

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44
Q

What is the difference between carrier and channel proteins?

A

Carrier- bonds solutes on one side of the membrane & changes the conformation which allows solutes to diffuse
Channel- forms hydrophilic channels in member and so diffusion may occur

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45
Q

What are three types of carrier transport proteins?

A

Uniport
Symport
Antiport

46
Q

What is uniport?

A

1 solute 1 direction

47
Q

What is symport?

A

2 solute same direction

48
Q

What is antiport?

A

2 solutes opposite direction

49
Q

How do plant and animal cells respond differently to hyper- iso- and hypotonic solutions?

A

Hyper- both shrivel
Iso- both are normal
Hypo- animal explodes/plant expands

50
Q

What are the different types of ATPases?

A

P, V, F, and ABC

51
Q

What is p-type?

A

Pumps Na, K, Ca ions; reversibly phosphorylated and found in plasma membrane

52
Q

What is v-type?

A

Pumps hydrogen ions into the vacuole

53
Q

What is f-type?

A

Pumps H ions using ATP hydrolysis; found in bacteria, mitochondria and chloroplasts; reversible using ATP synthase

54
Q

What is ABC-type?

A

Pumps a variety of solutes including nutrients, proteins, is also used to pump drugs out of cells

55
Q

Steps of Na/K pump? (6)

A
  1. 3 Na ions bind to a protein in the initial E1 confirmation
  2. Binding of the Na ions triggers the phosphorylated enzyme
  3. Phosphorylation results in A conformational change from E1 to E2 Na are transported in the membrane to outside the cell
  4. K ions outside cell bind to enzyme
  5. Binding of K triggers de phosphorylation and rerun to E1
  6. K transported through membrane to inside cell
56
Q

Na/glucose pump? (6)

A
  1. 2 external Na ions bind to symporter
  2. Glucose is able to bind to symporter
  3. Conformational change of protein exposed the molecule to the inside of the cell
  4. Na ions released in response to low internal Na concentration
  5. Transporters locked in conformation until glucose is released inside cell
  6. Empty transporters open to outside of cell again
57
Q

What is depolarization?

A

A change in membrane potential to a less negative value

58
Q

What is hyperpolarization?

A

Membrane potential briefly becomes more negative than normal

59
Q

What does a dendrite do?

A

Receives messages and sends them to other parts of the body

60
Q

What does the axon do?

A

Conducts impulses away from the body

61
Q

What is the role of the myelin sheath?

A

To accelerate transmission of nerve impulses

62
Q

What is the nodes of ranvier?

A

Small segments of axon between segments of myelin sheath

63
Q

What are neurotransmitters?

A

Chemicals released by neurons that transports impulse across a synapse

64
Q

How do nerve cells respond to depolarization?

A

They return to resting membrane potential

65
Q

How do voltage gated ion channels function?

A

As interval membrane proteins that form ion conducting pores who’s permeability is regulated by changes in membrane potential

66
Q

What are the 3 types of voltage gated channels?

A

Open confirmation
Closed confirmation
Channel inactivation

67
Q

What is an action potential and why are they important?

A

Membrane potential changing from negative to positive back to negative in response to stimulus. It is important bc it transmits signals along cell membranes.

68
Q

How do action potentials travel along nerve cells?

A

Via Na and K channels

69
Q

How do signals travel different in myelinated vs. non-myelinated nerve cells?

A

Myelinated travel faster and farther, non-myelinated travel in waves and take longer

70
Q

What is MS?

A

The moss of myelin sheath due to an autoimmune response. Sodium escapes and damages nerve s which reduced communication and function

71
Q

What are the 2 types of synaptic transmissions?

A

Electrical and chemical

72
Q

What is electrical transmission?

A

Neurons connected by gap junctions; spread of depolarization. The signal is immediate and is 3-5 nm

73
Q

What is chemical transmission?

A

Neurons connected by adhesion proteins; synaptic cleft 20-50 nm. Transmission requires neurotransmitters held in vesicles

74
Q

Name the 4 types of neurotransmitters

A

Acetylcholine
Amino acids
Monoamines
Neuropeptides

75
Q

What is an example of acetylcholine?

A

Cholinergic

76
Q

What are 3 examples of amino acid neurotransmitters?

A

GABA, glycine, glutamine

77
Q

What are 3 examples of monoamine neurotransmitters?

A

Nonadrenaline, dopamine, serotonin

78
Q

What is an example of the neuropeptide transmitter?

A

Endorphins

79
Q

How are neurotransmitters sent from one nerve class to another?

A

Exocytosis

80
Q

What are the types of neurotransmitters receptors that we discussed? And details of both.

A 
1. Nicotinic acetylcholine receptor 
Binds 2 molecules
Ligand gated Na+ channel 
Depolarization 
2. GABA receptor 
Binds to GABA 
ligand gated Cl- channel
Hyper polarization
81
Q

How are neurotransmitters inactivated?

A
  1. Reputable

2. Degradation

82
Q

What is re uptake?

A

Neurotransmitters pumped back into presynaptic neurons

83
Q

What is degradation?

A

Unique to acetylcholine; neurotransmitters broken down by enzymes

84
Q

What are chemical signals?

A

Molecules that bind to receptors on target cell surface and elicit a response from target cells

85
Q

What are second messengers?

A

Molecules produced in target cells that relay the signal from one part of the cell to the other

86
Q

What are Ligands?

A

Small messenger molecules

87
Q

What are high affinity receptors?

A

Ligand binds easy, low concentrations of ligand can occupy many receptors

88
Q

What are low affinity receptors?

A

Ligand DOES NOT bind easily, high concentration of ligand required to occupy many receptors

89
Q

What is auto regulation?

A

Internal adaptive mechanism that works to adjust that systems response to stimuli

90
Q

What is apoptosis?

A

Clean cell death

91
Q

What properties give receptors affinity and specificity for their Ligands?

A

Binding site shape, amino acid placement, multiple noncovalent bonds

92
Q

What is the dissociation constant and how does it relate to the receptor affinity?

A

Kd

It indicates how much ligand is needed to trigger a response in a target cell

93
Q

How do receptors adapt to prolonged exposure to Ligands?

A

Receptor- down regulation

94
Q

How are agonists and antagonists similar and different?

A

Similar by both being artificial Ligands recognized by cellular receptors
Different by agonists activate endorphins and antagonists block Ligands from binding

95
Q

What are the 2 types of plasma membrane receptors that were discussed

A

G protein linked receptors

Protein kinase associated receptors

96
Q

What are G protein linked receptors?

A

Ligand binding causes a change in confirmation that activated a G protein

97
Q

What is a protein kinase associate receptor?

A

Ligand binding activates causing phosphorylation events

98
Q

What are the structures of the G protein linked and protein kinase associated receptors?

A

G protein- 3 subunits

Protein kinase- single polypeptide chain with one transmembrane domain

99
Q

What are the subunits that make up G proteins?

A

Alpha, beta, gamma (α,β,γ)

100
Q

How are G proteins activated and inactivated?

A

Activated by lingands bonding to receptor, receptor binding to transcription protein, protein reaches nucleus and is activated
Inactivation- Gα hydrolysis GTP, GTP to GDP, Gα reassociates with Gβγ

101
Q

What is the difference between Gs and Gi proteins?

A

Gs- stimulatory; activated adenylate Cyclades for ^ in cAMP

Gi- inhibitory; inhibits adenylate Cyclades for decrease in cAMP

102
Q

What enzyme is responsible for synthesis of cAMP?

A

Adenine Cyclase

103
Q

How does the cell get rid of cAMP once the stimulatory ligand is no longer bound to the receptor?

A

Phosphodiesterase to AMP

104
Q

What are 2 diseases that affect signal transduction pathways?

A

Cancer and diabetes

105
Q

How are calcium ions utilized in signal transduction?

A

In apoptosis when cytochrome C is activated and released from the mitochondria, it stimulates calcium

106
Q

What types of receptors do growth factors generally bind to? And what specific type does EFG bind to?

A

EFG; tyrosine kinase

107
Q

How are tyrosine kinases activated?

A

Ligand binding-> clumped receptors phosphorylated each other -> auto phosphorylation

108
Q

How are hormones different than other Ligands?

A

Hormones can act from a long distance away, Ligands must touch to react

109
Q

What are the important molecules of apoptosis?

A

P53
Bcl2
Cytochrome C

110
Q

What is the role of p53 in apoptosis?

A

Triggers apoptosis in response to DNA damage

111
Q

What is Bcl2 in apoptosis?

A

Anti-apoptosis proteins found in mitochondrial surface

112
Q

What is the role of cytochrome C in apoptosis?

A

Release from mitochondria to promote apoptosis

BIO 130 (1 decks)

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