Cell Surface Membrane Structure Flashcards

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1
Q

What does a cell surface membrane do?

A

Controls the movement in and out of the cell.

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2
Q

What does the cell surface membrane form a boundary between?

A

The cytoplasm and environment

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3
Q

What is the bilayer made up of?

A

Phospholipids with hydrophilic phosphate heads on both sides as they are attracted by water and hydrophobic tails in the centre of the membrane which are repelled by water.

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4
Q

What are the 3 functions of the phospholipid bilayer?

A
  1. Allow lipid soluble substances to enter and leave the cell
  2. Prevent water soluble substances entering and leaving the cell
  3. Makes the membrane flexible and self sealing
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5
Q

What are found embedded in the phospholipid bilayer throughout the membrane?

A

Proteins

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6
Q

What do proteins do that never cross it?

A

Provide mechanical support or act as receptors

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7
Q

What are the two types of proteins called that span the whole membrane?

A

Channel or carrier proteins

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8
Q

What are channel proteins?

A

Water filled tubes that allow water soluble ions to diffuse across.

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9
Q

What are carrier proteins?

A

Bind to larger molecules like glucose and amino acids then change their shape in order to move them across the membrane.

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10
Q

What are the 5 functions of proteins?

A
  1. Structural support
  2. Act as channels allowing water soluble molecules through
  3. Carrier proteins allow active transport across membranes
  4. Act as receptors to identify cells
  5. Help cells adhere together
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11
Q

What molecules add strength to the membrane?

A

Cholesterol

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12
Q

How does cholesterol add strength to the membrane?

A
  1. Very hydrophobic prevents water and dissolved ions being lost
  2. Pulls together fatty acid tails limiting movement
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13
Q

What are the 3 functions of cholesterol?

A
  1. Reduce lateral movement of phospholipid molecules
  2. Makes membranes less fluid at high temperatures
  3. Prevent leakage of water and dissolved ions frok the cell
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14
Q

What are glycolipids made up of?

A

A carbohydrate covalently bonded with a lipid

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15
Q

What do glycolipids do?

A

Carbohydrate part extends from the phospholipid bilayer into watery environment outside where it acts as a cell-surface receptor

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16
Q

What are the three functions of glycolipids?

A
  1. As recognition sites
  2. Help maintain stability of membrane
  3. Help Cells attached to one another to form tissues
17
Q

What are glycoproteins is made up of?

A

Carbohydrate chains attached to intrinsic proteins on the outer surface of the membrane

18
Q

What do glycoproteins act as? What is. 2 examples?

A

Cell surface receptors e.g. hormones and neurotransmitters

19
Q

Are the three functions of glycoproteins?

A
  1. Act as recognition sites
  2. Help Attach cells to one another and form tissues
  3. Allow cells to recognise each other
20
Q

What molecules can’t pass through the cell surface membrane due to its permeability?

A

Non - lipid soluble molecules, too large molecules molecules with the same charge as protein channels and polar charged molecules

21
Q

How do you large molecules have to pass across the cell surface membrane?

A

Channel and carrier proteins.

22
Q

What model is used to describe cell surface membranes?

A

Fluid-mosaic model

23
Q

Why are cell-surface membranes referred to as fluid Mosaic models?

A

Fluid-Visual phospholipid molecules can move making it flexible and constantly change shape
Mosaic- Proteins embedded in phospholipid bilayer vary in shape size and pattern like the tiles of a mosaic