Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Biochemistry > Transport I&II > Flashcards

Transport I&II Flashcards

(58 cards)

Start Studying
1
Q

List the components of a plasma membrane.

A

integral membrane proteins

intracellular proteins

extracellular components

lipid bilayer - amphipathic

extracellular matrix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What facilitates movement of specific molecules across the plasma membrane?

A

membrane transport proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

True or False, the plasma membrane is semi-permeable.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

True or False, transport proteins are mostly polytopic, transmembrane, integral membrane proteins.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the plasma membrane permeable to and how do they move through the membrane?

A

lipophilic molecules (steroids); via simple diffusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the plasma membrane impermeable to and how do they move through the membrane?

A

hydrophilic (polar) molecules; via specific transport mechanism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What determines the ionic composition of the cell?

A

the activity and protein levels of specific transporters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is one way of regulating metabolism?

A

alteration in expression levels of transporters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which ion has a 10,000 fold difference between the extracellular and intracellular matrix of cells?

A

Calcium ion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

True or False, ATP consumption per gram per minute used for signaling in the brain is equal to the energy used by a human leg muscle running a marathon.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the 2 types of transport?

A

passive and active

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Define passive transport.

A

molecules move down a concentration gradient by using energy stored in the gradient e.g., ion channels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Define active transport.

A

molecules move against a gradient by using biochemical energy stored in ATP e.g., pumps/ATPases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

List and describe the 2 types of passive transport.

A

simple diffusion: (unaided) molecules that are small, non-polar, and uncharged diffuse freely across the membrane; the steeper the gradient the faster the diffusion

facilitated: (with assistance of proteins) molecules that are large and charged are unable to cross the membrane alone, they need a facilitator (protein); proteins function as channels or transporters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

True or False, the energy across a semi-permeable membrane is minimum when the concentration is equal.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the 2 types of ATP utilizing proteins?

A

P type ATPases and ATP binding cassette transporters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

List examples of P type ATPases.

A

Na+/K+/ATPase

Plasma Membrane Ca2+ ATPase (PMCA)

Sarcoplasmic reticulum Ca2+ ATPase (SERCA)

H+/K+/ATPase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe P type ATPases.

A

use energy form ATP hydrolysis to drive transport against gradient

transporter forms a covalent bond with the phosphate to form an enzyme-phosphate intermediate (E1P)

phosphorylation on a conserved aspartate residue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe the sodium pump.

A

sets up Na+ and K+ gradients across plasma membrane

stoichiometry: 3Na+: 2K+/mole ATP

Makes neurons and muscle cells electrically excitable, controls cell volume, drives the active transport of sugars and amino acids

25-40% of brain ATP used by Na+ pump

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

List some inhibitors of the Na+ pump.

A

digitoxigenin and ouabain

inhibit dephosphorylation of E2P

called cardiotonic steroids due to strong effect on heart

used in treatment of congestive heart failure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the function of calcium pumps?

A

to reduce cystosolic calcium concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Describe PMCA.

A

transports calcium from cytosol to extracellular side

maintains 10,000 fold gradient across PM

uses ATP to pump Ca2+ uphill

stimulated by the calcium binding protein calmodulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Describe SERCA.

A

transports calcium from cytosol to ER

80% of SR membrane protein

uses ATP

plays a role in relaxation of contracted muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

List an example of an ATP binding cassette transporter.

Study These Flashcards
A

ABC transporter

25
Describe ABC transporters.
Have common architecture multi-drug resistance protein/P glycoprotein pumps a wide range of small molecules out of cells uses ATP as energy source when broken, pump molecules in then right back out discovered through the use of tumor cells
26
Describe secondary transporters.
active transport mediators not directly driven by ATP thermodynamically unfavorable flow of one species of ion against a gradient coupled to favorable flow of another species down a gradient
27
List and describe the types of secondary transporters.
Antiporters - ions move in opposite directions (Sodium calcium exchanger) Symporters - ions move in same direction (lactose permease) Uniporter - ions can move in both directions, depending upon the concentration (mitochondrial calcium transporter)
28
Describe lactose permease.
is a symporter uses the proton gradient generated by oxidation of fuel molecules to drive lactose and other sugars against concentration gradient
29
A researcher mutated a critical domain on the Na+/K+ - ATPase gene. When expressed in cells, the mutated protein was unable to form the E-P intermediate in the reaction cycle of the enzyme. Which of the following amino acids was most likely altered in the mutant protein?
Aspartate
30
A 60 year old man arrived to the Emergency Room complaining of chest pain, shortness of breath, and swelling of the legs. Echocardiography results showed evidence of congestive heart failure. The attending physician immediately started him on Digitalis. Which ion transporter/channel is the primary target of this drug?
Na+/K+ ATPase
31
Describe ion channels.
integral, polytopic membrane proteins mediate facilitated passive transport transport ions 1000X faster than pumps highly selective and specific for ions respond to physical and chemical changes in their environment and undergo precisely timed conformational changes opening and closing of channels shapes the membrane potential
32
List and describe the types of ion channels.
voltage gated: respond to change in membrane potential chemically gated: responds to ligands such as neurotransmitters mechanically gated: respond to mechanical stimuli, found in sensory neurons
33
What is the purpose of patch clamping?
measure conductance across membrane
34
During his summer vacation in Hawaii, Dr. OshKosh was bit on his left arm by a puffer fish as he was swimming in the beautiful blue waters. His entire left arm was immediately numb. Which type of transport protein was impacted by the toxin in the puffer fish?
sodium channel
35
What does lidocaine do?
pain blocker - inhibits sodium channel
36
Through what animal was the sodium channel discovered?
electric eel
37
How was the structure of the potassium channel studied?
gene cloning; used structural biochemistry to predict function
38
What is the amino acid signature selectivity filter for the potassium channel?
TVGYG
39
What area is the voltage sensor in the potassium channel?
S1-S4
40
What is the pore in the potassium channel?
S5-S6
41
What unit is the "switch" for the potassium channel?
S4
42
Why does the ion selectivity work for the potassium channel?
K+ gain energy bound to channel; favorable reaction; net negative delta G Na+ loses energy when bound to channel; unfavorable reaction net positive delta G
43
How does the potassium channel transport molecules?
due to repulsion of like charges
44
Which step in the function of the K+ channel is controlled by the ball and chain mechanism?
Inactivation
45
Describe acetylcholine receptor.
ligand is the neurotransmitter present on post-synaptic side binding of Ach to its receptor opens the channel channel equally permeable to K+ and Na+ Pentamer of 4 kinds of membrane spanning subunits arranged in the form of a ring that creates a pore through the membrane
46
In what animal was acetylcholine observed?
electric rays
47
What are the subunits of Ach?
2 alphas, 1 beta, gamma, delta
48
Describe neurotransmission.
most important manifestation of membrane transport - the basis for communication in the nervous system nerve impulse is an electrical signal produced by the flow of current across the plasma membrane of a neuron inside of neuron has high K+ and low Na+ generated by Na+/K+ ATPase
49
Describe an action potential.
arises from large transient changes in the permeability of the axonal membrane to ions the conductance for Na+ changes first due to opening of sodium channels depolarization increases permeability to Na+ which begin to flow in via the Na+ channel due to high concentration outside depolarization then opens the K+ channels and K+ move out
50
List the 9 steps of an action potential.
1. resting membrane potential (-60mV) 2. depolarizing stimulus 3. Na+ channels open 4. rapid Na+ entry - further depolarization 5. Na+ channels close, K+ open 6. K+ move out 7. membrane hyperpolarization 8. K+ channels close 9. cells return to resting potential
51
List steps in synaptic transmission.
1. action potential reaches presynaptic terminal 2. depolarization opens up the VGCC 3. calcium enters cell 4. Causes fusion of synaptic vesicles 5. exocytosis - release NT in synaptic cleft 6. NT bind to receptor on post-synaptic side 7. opens up a ligand-gated channel
52
Describe gap junctions.
special form of ion channels called cell to cell channels passages between contiguous cells important role in cell to cell communication
53
List the properties of gap junctions.
small hydrophilic molecules and ions can pass through these channels sugars, amino acids and nucleotides can pass through proteins, polysaccharides and nucleic acids cannot pass through
54
Describe the structure of gap junctions.
each channel is made up of 12 molecules of a transmembrane protein = connexin 6 connexin molecules are hexagonally arrayed to form a half channel called connexon 2 connexons join end to end in the intercellular space to form a functional channel
55
What is the physiological relevance of gap junctions?
very important in cardiac tissue as it ensures a synchronous response to stimuli induction of labor, all muscle cells contract in synchrony important in lens and bone tissue - distribute nourishment sealed by high Ca2+ and H+ regulated by membrane potential and hormone-induced phosphorylation
56
What is the difference between ion channels and gap junctions?
traverse 2 membranes connect cytoplasm to cytoplasm synthesized by 2 different cells remain open for seconds to minutes
57
Describe water channels (aquaporins).
increase rate of water flow across membranes found in rbc, kidney, cornea have 6 transmembrane alpha helical domains
58
What does digitalis inhibit?
Na+ K+ ATPase pump

Biochemistry (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions