UNIT 3 1A: Plasma Membrane

Question 1

Define Cell Theory

Answer 1

The theory that all living things are made up of at least one cell, and that these cells are the basic unit of life and came from pre-existing cells

Question 2

Four common factors of Plant, Animal, Bacteria and amoeba cells

Answer 2

1. Genetic Material
2. Cytosol
3. Ribosomes
4. Plasma membrane

Question 3

What is Cytosol

Answer 3

The liquid inside a cell, between the organelles (doesn’t include the organelles)

Question 4

What is a Ribosome

Answer 4

A non-membrane-bound organelle involved in the synthesis of proteins

Question 5

What is the Plasma Membrane

Answer 5

A membrane made up of two layers (known as a bilayer) of phospholipids that encloses the contents of a cell

Question 6

Function of the Plasma membrane (rsc)

Answer 6

1. Recognising other cells when forming tissue, or determining whether cells are foreign during an immune response
2. Communication with other cells
3. Selectively controlling which substances are transported into or out of the cell.

Question 7

Define hydrophobic

Answer 7

Water-repelling; does not dissolve readily in water

Question 8

Define Hydrophillic

Answer 8

Water-attracting or water-soluble; dissolves readily in water

Question 9

Define semi-permeable membrane

Answer 9

A membrane that only lets certain substances cross it; also called partially permeable, differentially permeable or selectively permeable

Question 10

What are the 4 components of the plasma membrane

Answer 10

1. Phospholipids
2. Proteins
3. Carbohydrates
4. Cholesterol

Question 11

Parts of the phospholipids

Answer 11

1. Hydrophillic glycerol and phosphate head
2. Hydrophobic Fatty acid tail

Question 12

Types of proteins in a cell membrane

Answer 12

1. Integral/Transmembrane protein
2. Peripheral protein

Question 13

Functions of proteins in a cell membrane (TSC)

Answer 13

1. Transport
2. Signalling
3. Cell-to-cell recognition

Question 14

Role of carbohydrates in a cell membrane

Answer 14

1. Adhesion between cells
2. Cell recognition

Question 15

Types of carbohydrate chains

Answer 15

1. Glycoprotein (when attached to a protein)
2. Glycolipid (when attached to a phospholipid head)

Question 16

Role of cholesterol in the cell membrane

Answer 16

1. Cholesterol helps to increase the stability of the plasma membrane without affecting the membrane’s fluidity (ability to flow)
2. Increases membrane permeability

Question 17

Define Fluid Mosaic Model

Answer 17

A model that represents the plasma membrane as a combination (mosaic) of phospholipids, proteins, cholesterol and carbohydrates that gives the membrane its fluid nature.

Question 18

What defines a saturated lipid

Answer 18

When the fatty acids have only one bond between each carbon atom, which causes the lipids to pack together lightly

Question 19

What defines an unsaturated lipid

Answer 19

Unsaturated fatty acids in the tails of a lipid have double bonds between some carbon atoms, which causes the lipids to pack together less tightly.

Question 20

Benefits of unsaturated lipids in the plasma membrane

Answer 20

The presence of unsaturated lipids in the bilayer increases the fluidity of the plasma membrane