Cells membrane

Question 1

Passive vs active proceses

Answer 1

Passive processes – do not require energy to pass through the membrane
Diffusion, osmosis, facilitated diffusion

Active processes – do require energy to pass through the membrane
Carrier-mediated transport (active transport), vesicular transport

Question 2

3 Types of Movement Across Cell Membrane

Answer 2

1. Diffusion: simple diffusion (passive ions / molecules) and osmosis
2. Facilitated Diffusion/Transport: proteins in cell membrane (channel or carrier), passive or active
3. Vesicular Transport: materials moved in membrane bound sacs, active

Question 3

What is simple diffusion?

Answer 3

The movement of particles from an area of HIGH to an area of LOW concentration (With the concentration gradient), PASSIVE process (does not require energy), Eg water, oxygen, carbon dioxide

Question 4

What is osmosis?

Answer 4

Diffusion of a solvent (usually water) through a differentially permeable membrane, From an area of HIGH water concentration to an area of LOW water concentration, Passive process

Question 5

What is facilitated diffusion?

Answer 5

Facilitated diffusion is when a substance needs assistance to pass across the cell membrane going from a high concentration to a low concentration (passive – no energy needed). The Carrier or channel proteins are what assist with this movement.

Question 6

Carrier protein

Answer 6

is specific to the molecule it is transporting across the membrane. the carrier protein facilitates diffusion.

Question 7

Channel protein

Answer 7

A channel protein, acts like a pore in the membrane that lets water molecules or small ions through quickly.

Question 8

Active transport

Answer 8

a process that involves the movement of molecules from a region of lower concentration to a region of higher concentration against a gradient

Question 9

Vesicular Transport (endo and exocytosis)

Answer 9

Movement of materials in and out of a cell in a vesicle. (Bubble like structure surrounded by a membrane.)
Active process – against the concentration gradient, requires energy.

Question 10

Endocytosis, phagocytosis and pinocytosis.

Answer 10

The process of capturing a substance or particle from outside the cell by engulfing it with the cell membrane through a vesicle, and bringing it into the cell.
Phagocytosis- cell eating (solids) Only specialised cells do this.
Pinocytosis- cell drinking (liquids) All cells.

Question 11

Exocytosis

Answer 11

where contents of a vesicle are pushed out through the cell membrane

Question 12

The phospholipid bilayer

Answer 12

A two-layered arrangement of phosphate and lipid molecules that form a cell membrane, the hydrophobic lipid ends facing inward and the hydrophilic phosphate ends facing outward.

Question 13

Cell Membrane

Answer 13

seperates the cell contents from the enviroment outside the cell and from neibouring cells. it encloses the contents of the cell and controls what is able to leave and enter the cell.

Question 14

Cell membrane functions

Answer 14

1. Acts as a physical barrier – separates cytoplasm and extracellular fluid.
2. Regulates passage of materials- materials entering + leaving cell.
3. Sensitivity to changes – receptors sensitive to particular molecules. eg hormones, antigens.
4. Support – internal part of cell membrane attached to microfilaments of cells cytoskeleton, giving support to the whole cell. Also have connections between the membranes of adjacent cells, supporting the whole tissue

Question 15

Carrier meditated transport

Answer 15

transport of ions or molecules across a cell membrane by special carrier protines