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Biology 1B > Membrane Transport > Flashcards

Membrane Transport Flashcards

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1
Q

What are membranes? Where are they found?

A

phospholipid polymers of fatty acids, glycerol,
phosphate and a terminal amine or alcohol group. They are amphipathic and spontaneously assemble mono/bilayers in water. Found as boundaries around organelles.

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2
Q

How do membranes form cell boundaries?
How do they support bioenergetics?

A

Ion (charge) gradients across membranes are used to generate
biological energy. Supported through the controlling of gradients

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3
Q

What are organelles and what are their roles?

A

membrane-delimited compartments in
eukaryotic cells. Cells and organelles are highly dynamic

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4
Q

What is Phosphatidyl choline?

A

-It is a phospholipid
-choline, a phosphate linkage to
glycerol which is esterified with
two fatty acids

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5
Q

What is the hydrophilic head group comprised of?

A

Choline

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6
Q

Are the fatty acid tails on a phospholipid hydrophilic or hydrophobic?

A

Hydrophobic

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7
Q

What is GFP?

A

Green Fluorescent Protein. Produces fluorescent proteins which can be used in

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8
Q

How do chloroplasts communicate within cells?

A

Through Stromules (messenger projections)

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9
Q

Which organelles undergo independent division?

A

chloroplasts and mitochondria

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10
Q

Transport proteins in the cell membrane allow for the ‘___’ interaction of the cell with the environment

A

controlled

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11
Q

What are transport proteins for?

A

-To create a hydrophilic passage
-Create a filter
-Provide possibility for energy coupling
-Provide possibility for regulation

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12
Q

What are the different levels of permeability in a cell membrane?

A

high permeability - small hydrophobic molecules and gases (e.g. O2)
Limited permeability - water
Very low permeability - ions (e.g. K+) and large solutes (e.g. glucose)

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13
Q

What is facilitated diffusion?

A

a hydrophilic pore created by transport proteins in which molecules diffuse through

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14
Q

What is the electrochemical gradient?

A

The net driving force for a molecule’s movement is due to chemical and electrical gradients. Direction depends on the relative sizes of chemical and electrical gradients, has an energy gain

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15
Q

What are the transport proteins used for active transport?

A

pumps and co-transport systems

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16
Q

What are the transport proteins used for passive transport?

A

Channels and carriers

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17
Q

What is ATPases in relation to energy coupling?

A

a group of enzymes that catalyze the hydrolysis of a phosphate bond in ATP to ADP.. harnessing the energy

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18
Q

How do pumps work?

A

ions bind to cytoplasmic high-affinity binding sites in protein pumps. Pumps establish electrochemical gradients which can be used to drive the active transport of other molecules.

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19
Q

How do co-transport systems operate?

A

Couple the downward movement of one ion (driver) to the uphill movement of another solute (substrate). One molecule is used to carry another across the membrane.

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20
Q

What is a symport?

A

A driver ion and substrate move in the same direction (‘piggyback’ principle). e.g Amino acid and Na+

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21
Q

What is an antiport?

A

Driver ion and substrate move in the opposite direction (‘revolving door’ principle)

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22
Q

How does passive transport work?

A

Moves substrates down the electrochemical gradient without the input of energy but relies on previously established electrochemical gradients

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23
Q

How does a carrier work?

A

Undergoes a conformational change that exposes ion binding sites to different sides of the membrane.. following electrochemical gradients

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24
Q

How do ion channels exert control of passage?

A

-They are selective using filters
-They are ‘gated’ = they open and close upon specific stimuli

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25
How are ion channels measured?
Using a patch clamp to measure how single channel proteins gate. Requires a suction pipette, current amplifier
26
Identify the essential characteristics of stem cells
Unspecialised cells that can reproduce indefinitely and can differentiate into one or more specialised cell types (potency). There are embryonic and adult cells.. can generate tissues, organs or organisms.
27
explain stem cell potencies and how these relate to research applications
-Totipotent: generates all the embryo and extra-embryonic tissues, such as the placenta. (e.g. Zygote) -pluripotent: generate cells all three germ layers but not the extra-embryonic tissues (e.g. embryonic stem cells) -Multipotent: ability to differentiate into multi-lineages but not to all germ layers (ADULT) -Unipotent: ability to differentiate along only one lineage (ADULT)
28
Explain stem cell use in research
Basic research Drug testing - disease and patient-specific cells Toxicology - normal, human cell supply Drug discovery Therapy -Therapeutic cloning is used to produce Patient-specific cell lines, designed to replace injured/diseased tissues. Regenerative medicine.
29
What are some of the ethical implications associated with stem cell research?
Derived from an embryo: Very early stage, when is it a life? Range of policies for use of hESC across the world. Sometimes based on religious belief
30
Explain the potential of stem cell derived products for therapeutic use
-Heart and blood vessels -Liver and pancreas -eye -blood -CNS and peripheral nerves -blood -Bone and cartilage -hair and skin -Type 1 diabetes
31
Where can stem cells be isolated from?
Adult tissues and organs, Umbilical cord blood, foetal tissues and organs
31
What is induced pluripotency?
-Somatic cells can be reprogrammed into induced pluripotent stem -Re-program differentiated cells to act like Embryonic Stem cells
31
What does autologous mean?
Taken from an individual and returned to the same person
31
What does allogeneic mean?
Taken from an individual and returned to a different person
32
How is somatic cell nuclear transplantation achieved?
-Remove nucleus of egg, becomes enucleated egg -nucleus removed from somatic cell -Morula is produced after development
32
What are the properties of hESC and where are they derived from?
-Self renew and expand indefinitely in culture -They are pluripotent -Taken from (ICM) inner cell mass of blastocyst
32
What is the second law of thermodynamics?
-Every energy transfer increases the entropy of the Universe -Takes the environment into account
32
Energy fixes, such as secondary metabolites in plants for taste/odour, are reversible/irreversible
Irreversible
32
What is anabolism?
where energy is used to build complex molecules
33
What is catabolism?
where energy is released through molecule breakdown
34
A reaction or transport process only occurs spontaneously if..
Delta G is negative
35
What is the equation for Gibbs free energy?
Delta G = enthalpy - temperature x entropy
36
What is an exergonic reaction?
A release of energy due to a metabolic or chemical process, ΔG < 0
37
What is an endergonic reaction?
When energy is required in a metabolic or chemical process, ΔG > 0
38
If absolute amount of ΔG is smaller for B than for A then the energy released during A can be used for B. True or false?
True
39
Where is the chemical energy stored in ATP?
In the inorganic phosphate (Pi) because the negative charges repel each other. Produces ΔG = -7.3 kcal/mol
40
what are the two ways to form ATP?
Substrate-level phosphorylation, transfer of phosphate group Oxidation phosphorylation (chemiosmosis), movement of ions down their gradient across a semipermeable membrane. Produced by substrate-level and oxidative phosphorylation of ADP.
41
What reaction allows NADH to be used as an electron currency?
Redox reaction
42
What is produced during Glycolysis?
4 ATP, 2 NADH + 2 H+, 2 Pyruvate + 2 H2O (in the energy payoff phase)
43
What energy is invested in Glycolysis?
2 ATP
44
What occurs during glycolysis? Where does it take place?
Glucose form is changed and then split into two smaller 3-carbon molecules, phosphate group comes from molecule. In the Cytosol
45
What does 'kinase' refer to in enzyme nomination?
Adds phosphate
46
What does 'isomerase' refer to in enzyme nomination?
converts molecule from one isomer to another
47
What does 'dehydrogenase' refer to in enzyme nomination?
oxidizes a substrate by reducing an electron acceptor
48
What does 'enolase' refer to in enzyme nomination?
a hydro-lyase type enzyme
49
Does the Citric Acid Cycle require O2?
YES! will not proceed without oxygen as it is crucial for electron gradient so the 2 pyruvate can progress into the mitochondrion.. is not required as part of the reaction.
50
What occurs if there is no Oxygen present during glycolysis?
Fermentation: Pyruvate will be: -plants- turned into ethanol and yields 2 ATP -Animals- turned into lactate which is reversible
51
What is the second stage of cellular respiration known as? Where does it take place?
The Citric Acid Cycle. In the Mitochondria
52
What enzyme is needed to start the citric acid cycle?
Acetyl CoA
53
What is produced in the citric acid cycle using 2 pyruvate?
Is conducted in 2 cycles: 6 NADH, 2 FADH2, 2 ATP
54
What occurs during the electron transport chain? What is the process called?
Takes place in the inner mitochondrial/chloroplastal membrane; where a proton gradient is established. This acts as a 'high-energy' intermediate between redox potential and ATP synthesis. Feeds through protein complex of electron carriers and H+ flow back through ATP Synthase. Produces about 26 or 28 ATP. Oxidative phosphorylation.. chemiosmosis.
55
What is the maximum yield of ATP per glucose?
~30 or 32 ATP
56
What is the overall reaction of cellular respiration?
C6H12O6 + 6O2 -> 6CO2 + 6H2O, DELTA G = -686 kcal/mol (-2870KJ/mol)
57

Biology 1B (7 decks)

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