B2.1 Membrane and Membranes Transport Flashcards

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1
Q

what are amphipathic membranes

A

Molecules that have both hydrophilic and hydrophobic parts

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2
Q

examples of other amphipathic molecules

A

Other amphipathic molecules besides phospholipids are some of the proteins like integral proteins

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3
Q

example of simple diffusion across membranes

A

movement of oxygen and carbon dioxide molecules between phospholipids

Both oxygen and carbon dioxide are small and uncharged molecules
Diffusion of these gases move from a high concentration area to a low concentration area

Oxygen and carbon dioxide can diffuse across the plasma membrane to carry out gas exchange in between the cell and the surrounding environment. This can also be carried out in the alveoli of the lungs and gill filament of different animals. Plant cells can also have diffusion of these gases for photosynthesis and respiration

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4
Q

integral proteins

A

a kind of membrane protein that is anchored in the plasma membrane with amphipathic nature. It has both a hydrophilic (interacting with the phosphate groups of the membrane) and a hydrophobic (interacting with the hydrophobic tails of the membrane)

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5
Q

Structure of Phospholipids

A

Consist of a polar hydrophilic head composed of a glycerol and a phosphate molecule
Consist of two non-polar hydrophobic tails composed of fatty acid (hydrocarbon) chains
Because phospholipids contain both _hydrophilic (water-loving) and lipophilic (fat-loving) regions, they are classed as amphipathic.

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6
Q

Arrangement of the Phospholipid Bilayer

A

Phospholipids spontaneously arrange into a bilayer
The hydrophobic tail regions face inwards and are shielded from the surrounding aqueous fluids, while the two hydrophilic head regions associate with the cytoplasm and extracellular fluids respectively

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7
Q

types of proteins

A

hormone-binding
enzymatic
cell adhesion
cell-to-cell communication
channel forming
pumps for active transport

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8
Q

hormone-binding

A

these proteins have specific shapes exposed to the exterior that fits the shape of specific hormones. the attachment between the protein and the hormone causes a change in the shape of the protein, which results in a message being relayed to the interior of the cell

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9
Q

enzymatic

A

these proteins occur on either the interior or the exterior membrane surface. they are often grouped together so that a sequence of metabolic reactions, called. metabolic pathway, is catalyzed

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10
Q

cell adhesion

A

this protein type allows temporary or permanent connections called junctions between cells. there are two types of junctions, gap junctions and tight junctions

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11
Q

cell-to-cell communication

A

most of these proteins have carbohydrate molecules attached. They provide an identification label so that organisms can distinguish between self and non-self material

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12
Q

channel forming

A

some proteins span the membrane, providing passageways for substances to be transported through

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13
Q

pumps for active transport

A

in active transport, proteins shuttle a substance from one side of the membrane to another by changing shape. This process requires the expenditure of energy in the form of adenosine triphosphate (ATP)

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14
Q

channel proteins

A

channel proteins exist to transfer large or polar substances, e.g. water

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15
Q

aquaporin

A

A type of integral proteins to allow water molecules to pass through the plasma membrane

The middle part of this protein allows water to go through but not for charged ions or solutes

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16
Q

cell junctions

A

tight junctions
desmosomes
gap junctions

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17
Q

tight junctions

A

impermeable junctions

prevent molecules from passing through intercellular space

e.g. lining of the digestive tract

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18
Q

desmosomes

A

anchoring junctions bind to adjacent cells like Velcro

form internal tension-reducing network of fibers; plaques on surface of membrane attach to protein filaments

e.g. found in tissues subject to stress like skin; heart muscle

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19
Q

gap junctions

A

allow for intercellular communication

allow ions and small molecules to pass through channels formed by connexon protein cylinders

e.g. found in electrically excitable tissue (heart; smooth muscle) to synchronize

20
Q

simple diffusion

A

substances moving from a high concentration gradient to a low concentration gradient

21
Q

hypertonic

A

net flow of water out of the cell, the cell loses volume

22
Q

isotonic

A

no net water movement

23
Q

hypotonic

A

lower concentration of solute than another solution

24
Q

plasmolyzed

A

plasma membrane and cell wall separate

25
Q

cytosol

A

fluid part of cytoplasm

26
Q

cytoplasm

A

consists of all the organelles

27
Q

cholesterol

A

Cholesterol is a component of animal cell membranes.

Cholesterol functions to immobilise the outer surface of the membrane, reducing fluidity.

It makes the membrane less permeable to very small water-soluble molecules.

28
Q

active transport

A

Active transport
Exocytosis
Endocytosis

29
Q

passive transport

A

Diffusion
Facilitated diffusion
Osmosis

30
Q

Facilitated diffusion

A

the net movement of charged particles from a region of high concentration to a region of low concentration through protein channels

31
Q

Osmosis

A

net movement of water molecules from a region of high water potential to a region of low water potential through a semipermeable membrane.

32
Q

Water potential (trident w)

A

a measure of potential energy per unit volume in water

33
Q

Active Transport

A

the movement of particles from a region of low concentration to a region of high concentration using protein pump and ATP

34
Q

Indirect active transport

A

uses the energy produced by the movement of one molecule down a concentration gradient to transport another molecule against a gradient.

E.g. Sodium-dependent glucose transporter / Sodium-glucose linked transporter (SGLT)

35
Q

Sodium-glucose linked transporter (SGLT)

A
  1. There are more Na+ ions outside the intestinal cells
  2. Na+ and glucose bind to the transport protein
  3. Na+ pass through the carrier to the inside of the cell down a concentration gradient, with the carrier capturing the energy released by this movement
  4. Using the energy from the transportation of the Na+, glucose is pumped as well.
  5. The captured energy is used to transport the glucose through the same protein into the cell.
36
Q

Exocytosis

A

The export of substances using vesicles and energy

Furthermore, as the vesicles are made of phospholipids, it can fuse with the membrane when carrying out exocytosis.

E.g. Exporting extracellular protein(the protein is first made in the rER, then using vesicle to transported to the golgi apparatus to be modified and packaged, then the vesicles will fuse with the membrane to release its content.)

37
Q

Endocytosis

A

The import of substances using vesicles and energy

Vesicles is made of phospholipid, which is important to transport substance in cell.

The fluidity of the plasma membrane allows the membrane to change shape and helps to bud off to form vesicles when carrying out endocytosis.

38
Q

Glycolipid

A

carbohydrate chain attached on the phosphate group of the phospholipid

39
Q

Membrane fluidity

A

Membrane fluidity allows vesicles to form and carry out endocytosis or exocytosis at different locations of the plasma membrane

40
Q

Different types of endocytosis

A

phagocytosis
pinocytosis

41
Q

phagocytosis

A

“cell eating”

Plasma membrane forms a pseudopodium

42
Q

pinocytosis

A

“cell drinking”

Plasma membrane wraps around and pull in to form vesicles

43
Q

Receptor-mediated endocytosis

A

Looking for a specific item to pull in
It has to fit the receptors to go into the cell

44
Q

How Extracellular Proteins Move Through the Golgi Apparatus

A
  1. Protein produced by the ribosomes of the rough ER enters the lumen of the ER. The protein is packed into a vesicle.
  2. The vesicle fuses with the cis of the Golgi apparatus.
  3. As the protein moves through the Golgi apparatus, it is modified on the trans side inside another vesicle.
  4. The vesicle moves towards and fuses with the plasma membrane, secreting the contents from the cell (exocytosis)
45
Q

Voltage-gated ion channels in neurons

A

Voltage-gated ion channel is a kind of integral protein in the plasma membrane of neuron

The channel will open and close depending on a certain rage of membrane potential due to electrical stimuli (nerve impulse)

46
Q

example of voltage-gated ion channels

A

Sodium voltage-gated channel proteins
Potassium voltage-gated channel proteins
Calcium voltage-gated channel proteins