B2.1 Flashcards

1
Q

State that phospholipids naturally form continuous sheet-like bilayers in water

A

When added to water phospholipids naturally form bilayers

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2
Q

List locations of lipid bilayers in cells

A

Nucleus, mitochondria, and chloroplast

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3
Q

Outline the location of aqueous solutions in relation to the lipid bilayer

A

The cytoplasm is located within the lipid bilayer and other aqueous solutions are located outside the lipid bilayer

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4
Q

State the primary function of the cell membrane

A

Separating the cytoplasm and cell contents from the environment

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5
Q

Explain why the hydrophobic core of a lipid bilayer has low permeability to large molecules and hydrophobic particles

A

In order to not ruin the internal chemistry of the cell

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6
Q

Describe simple diffusion

A

the passive transport of particles from a region of high concentration to low concentration

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7
Q

Outline the impact of concentration gradient, particle size and polarity or charge of molecules on the rate of diffusion across a lipid membrane

A

Higher concentration gradients, smaller particle sizes, and non-polar characteristics promote faster diffusion and vice versa

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8
Q

Outline how the hydrophobic and hydrophilic structures of proteins impact their anchoring to the membrane

A

The hydrophobic section of the integral protein anchors the protein in the bilayer, whereas the peripheral protein has no hydrophobic part and isnt anchored to the protein

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9
Q

Explain two examples of simple diffusion of molecules into and out of cells

A

Oxygen moves from an area of higher concentration (such as the external environment or capillaries) to an area of lower concentration (inside the cell).

The higher concentration of carbon dioxide inside the cell creates a concentration gradient, and CO2 molecules move from inside the cell to an area of lower concentration (such as the bloodstream or extracellular space)

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10
Q

Compare the location of integral and peripheral proteins in the membrane

A

Integral proteins are permanently attached to the plasma membrane, peripheral proteins are temporarily attached to one side of the membrane

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11
Q

List at least four functions (with example) of membrane bound proteins

A

Transport GLUT2
Cell signalling EGFR
Enzymatic activity ATP
Cell adhesion Cadherin

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12
Q

Define osmosis.

A

Osmosis is the passive transport of water molecules from a region of low solute to a region of high solute concentration

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13
Q

Outline the structure and function of aquaporin proteins

A

Aquaporins are integral channel proteins that selectively transport water rapidly through membranes

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14
Q

Describe the structure and function of channel proteins

A

Channel proteins are specific to the molecule that can pass through them making cell membranes more selective

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15
Q

Define facilitated diffusion

A

The passive transport of molecules from a region of high concentration to a region of low concentration through channel proteins

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16
Q

Outline the specificity of channel proteins for ions

A

size, charge, and coordination chemistry

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17
Q

List types of gates on channel proteins

A

Gated channels open in response to stimuli whereas voltage gated channels open and close based on potential difference across membranes

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18
Q

Describe one example of facilitated diffusion through a protein channel

A

GLUT1 a transmembrane protein that facilitates the passive transport of glucose molecules across the cell membrane

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19
Q

Explain one example of active transport of molecules into and out of cells through a protein pump

A

The sodium potassium pump an integral membrane protein that transports three sodium ions out of the cell while also moving 2 potassium ions into the cell

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19
Q

Describe the structure and function of pump proteins, including the role of specificity, conformational change and ATP

A

Pump proteins are integral membrane proteins that function as active transporters by utilizing energy from ATP to move ions against their concentration gradient with high specificity

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20
Q

Compare active transport using a pump protein to facilitate diffusion using a channel protein

A

Channel proteins requires no energy, has no conformational change, goes with the concentration gradient and are a lot less selective

21
Q

Define selective permeability

A

Allowing certain substances to pass while restricting others from crossing

21
Q

Outline how channels and pumps in the membrane allow for selective permeability.

A

Because they only allow specific particles to pass or transport through

21
Q

State the simple diffusion is not selective and depends only on the concentration gradient, particle size and polarity or charge of molecules

A

Simple diffusion is not selective and depends only on concentration gradient, particle size and polarity or charge of molecules

22
Outline the structure of glycoproteins and glycolipids
Glycoproteins are membrane proteins with a carbohydrate chain attached Glycolipids are phospholipids with a carbohydrate chain attached
23
Describe the role of glycoproteins and glycolipids in cell adhesion and cell recognition
glycoproteins are sometimes responsible for direct attachment between neighboring cells. The carbohydrates of glycoproteins and glycolipids can form an extracellular matrix with their neighboring cells, leading to stable cell adhesion The carbohydrate chains that form on glycoproteins and glycolipids have specific shapes allowing the immune system to recognise the cells as self. Glycoproteins and glycolipids act as antigens if the carbohydrate chain isn’t recognized
24
Compare and contrast the structure, melting point and relative fluidity of saturated and unsaturated fatty acids in lipid bilayers
Saturated fatty acids have no C-C double bonds resulting in a straight and close packing of phospholipids, with a higher melting point and a higher viscosity. Unsaturated fatty acids have C-C double bonds, resulting in kinks in the fatty acid tails, with lower melting points and lower viscosity
25
Outline an example of adaptation in membrane composition in relation to habitat
As the temperature decreases steelhead trout have a higher concentration of unsaturated fatty acid
26
Describe the structural placement of cholesterol within the cell membrane
Cholesterol is located between fatty acid tails of phospholipids in cell membranes
27
Outline how temperature affects cell membrane fluidity
Higher the temperature the less fluid the cholesterol is and vice versa
28
Describe the function of cholesterol as a modulator of membrane fluidity
It allows for the stability of the membrane as at higher temperatures it increases the melting point and at lower temperatures it maintains the fluidity
29
Outline the structure and function of vesicles in cells
Vesicles are small membrane bound structures involved in the transport of materials within cells
30
Describe the formation of a vesicle via endocytosis
The large particle is entering the cell and is surrounded by the plasma membrane, which buds off inside the cell to form a vesicle
30
State that the fluid properties of the cell membrane allow for the formation of vesicles
The fluid properties of the cell membrane allows the formation of vesicles
31
Outline the formation of a vesicle within the cell
Through the enclosing of materials required to be transported or stored
32
Describe the transport of materials within a cell using vesicles
Proteins to be secreted are synthesized by ribosomoes and attached to the RER The RER forms a vesiclle containing protein and sends it to the Golgi Apparatus The vesicle then fuses with the Golgi Apparatus and the Golgii modifies the protein, it packages the protein in a secretory vesicle which moves towards the plasma membrane, where it fuses with plasma membrane releasing it outside of the cell.
33
Outline two examples of materials brought into the cell via endocytosis
bacteria and viruses to eat and destroy
34
Outline two examples of materials released from a cell via exocytosis
Neurotransmitters released from neurons for intercellular communication. Hormones released from endocrine cells to regulate body functions
34
Describe the release of materials from cells via exocytosis.
Exocytosis involves the fusion of a vesicle with the plasma membrane releasing content outside of the cell
35
State the effect of endocytosis and exocytosis on the area of the cell membrane
Endocytosis increases, exocytosis decreases the cell membrane area
36
Contrast secretion with excretion
Secretion is the release of specific substances synthesized by cells into body fluids or external environment, whereas excretion is the elimination of waste products or excess substances from the body.
37
Outline the structure, function and specificity of voltage-gated channels
Integral proteins allowing specific ions to pass through facilitated diffusion in response to changes in membrane potential difference
38
Describe the function of the voltage-gated potassium channel
A voltage gated channel located along the neurons
39
Outline the structure, function and specificity of ligand-gated channels
Integral proteins allowing specific ions to pass through facilitated diffusion in response to a ligand attached to the channel
40
Describe the function of the ligand-gated sodium channel in the postsynaptic cell membrane (AKA the nicotinic acetylcholine receptor)
It allows sodium ions to enter a neuron
41
State the function of an exchange-transporter proteins
To facilitate silmutaneous movement of 2 different molecules or ions across a membrane in opposite directions
42
Describe the structure and function of the sodium-potassium pump
An integral membrane protein which allows 3 sodium ions out of the cell and 2 into the cell against their respective concentration gradients
43
Outline the role of the sodium-potassium pump in maintaining neuronal resting potential
By contributing to the negative charge inside the cell and the positive charge outsidem which is crucial for proper electrical signalling in neurons
44
Outline the function of cotransporters in indirect active transport
They facilitate the transport of molecules across cell membranes by harnessing the energy stored in the electrochemical gradient of one molecule to drive the transport of another molecule against it’s concentration gradient
45
Describe the role of glucose cotransport proteins in the small intestine and kidney nephron
SGLT1 in the small intestine and SGLT2 in the kidney nephron play a vital role in contributing to the homeostatis of glucose in the body
46
Outline the role of CAMs in the formation of tissues
They mediate cell-cell adhesion and cell-matrix interactions. They also regulate tissue dvelopment, differentiation and maintenanc of tissue architecture
47
State that the loss of CAM function can lead to metastasis of cancer cells.
the loss of CAM function can lead to metastasis of cancer cells