Chemical and Cellular Organisation of the body

Question 1

What is a Cell?

Answer 1

Basic living, the structural, and functional unit of the body

All vital life conditions are carried out in the cell
Metabolism, reproduction, movement, responsiveness growth

All derived from previous cells
- Occurs through Mitosis and Meiosis
- contains genetic and hereditary material that regulates function in the form of DNA and RNA

Question 2

What are the four basic processes of a cell?

Answer 2

• Cell metabolism
• Cell transport
• Cell communication
• Cell reproduction

Question 3

What is cell metabolism? Name three types of reactions.

Answer 3

Cell metabolism: Sum of all chemical reactions carried out by the cell to maintain life.
1. Anabolic relations focus on helping smaller molecules join to create larger macromolecules.

2. Catabolic reactions focus on breaking down macromolecules back into smaller molecules.
3. Oxidation - Reduction reactions help to convert the energy from the chemical bonds of nutrients, into energy that can be used by the cell, namely in the form of ATP ( adenosine-tri-phosphate ).

Question 4

What is Cellular Transport?
What is Cellular communication?
What is Cell reproduction?

Answer 4

1. Transport: movement of materials across cell membranes
2. Cells need to communicate with themselves, other cells and the surrounding environment and is done through a variety of methods including chemical and electrical signals.
3. Reproduction through cell division is a necessary process of growth and development as well as the replacement of old damaged cells.

Question 5

Give an Overview of Multi-Cellular Structure.

Answer 5

1. Plasma membrane
   - acts as the physical barrier
2. Nucleus
   Contains cellular genetic material
3. Cytoplasm
   - everything in between the nucleus and membrane
   Cytosol: intracellular fluid ( contains water ions, carbohydrates, lipids, and proteins)

Organelles
Subcellular structures with specific functions ie producing energy

Question 6

Cell Membrane Structure & Function

Answer 6

1. Physical outer boundary of a cell.
2. Protection, and signalling systems for cellular transport, communication and regulating cell traffic

Question 7

Nucleus Structure & Function

Answer 7

Contains Genetic information( DNA) in the form of Chromatin.

Surrounded by a porous nuclear membrane

Has a Nucleolus ( produces ribosomes)

Question 8

Mitochondria Function

Answer 8

Powerhouse Of the Cell
Converts chemical energy from food metabolism into ATP through cellular respiration.
Can replicate ( Has its own DNA ).
Rich in livers, muscles and kidneys.

Question 9

Ribosomes Function

Answer 9

Synthesise Proteins

Question 10

Endoplasmic Rectilium Function

Answer 10

Transport system connecting cell membrane, nucleus and organelles.

Smooth ER: Synthesises lipids and metabolism of toxic substances
ie alcohol and drugs

Rough ER: Covered in ribosomes produces proteins for delivery to the Golgi apparatus.

Question 11

Golgi Apparatus Structure and Function

Answer 11

Pat of the endomembrane system
Packaging and shipping centre

Vesicles from ER bring macromolecules to pass through the Cisternae ( part of the Golgi ) and are then shipped to their final destination which is often outside the cell or embedded in the cell membrane.

Question 12

Passive transport / Active Transport

Answer 12

Active requires energy for molecules. Passive does not.

Freely permeable membranes permit any substances to pass without difficulty. ie cell wall

Semi-Permeable membranes ie Plasma membrane
allow certain substances into the cell whilst preventing others.

Impermeable membranes block the movement of all substances. ie skin, eggshells

Question 13

Diffusion

Answer 13

• Passive transport
• particles from high concentration spread out to areas of low concentration.
• random mixing of particles in a solution due to kinetic energy ( solute to solvent)
• requires no energy ( until equilibrium is achieved )

Question 14

Factors affecting Diffusion

Answer 14

1. Concentration gradient
   ( Greater = faster )
2. Temperature
   ( High = faster)
3. Particle Size
   ( smaller = faster )
4. Diffusion Distance
   ( smaller = faster )
   5, Lipid Solubility
   ( more soluble lipids = faster )
5. Membrane permeability
   ( greater permeability the better)

Question 15

Osmosis

Answer 15

Passive diffusion of water ( solvent)

This happens as Water moves from a low-concentrated area to a highly concentrated area through a semi-permeable membrane.

The membrane prevents the diffusion of solutes and creates a water gradient.

Important because large changes in the volume of water in the cell can disrupt function ie altering tonicity.

Question 16

Tonicity

Answer 16

• the capability of a solution to modify the volume of cells by altering their water content.
• If the osmotic concentration occurs between two solutions and becomes equal then it is isotonic.
• However if its unequal, then the solution with less concentration of solutes is hypotonic
• the solution with a higher concentration of solutes is hypertonic.

Question 17

What are Glycoproteins?

Answer 17

molecules that consist of proteins and carbohydrate chains

Question 18

What are Fibrous proteins and what are their functions?

Answer 18

1. made up of polypeptide chains that are elongated and fibrous in nature or have a sheet-like structure.
2. provide structural support in tissues such as hair, nails, and tendons.

Examples : Collagen & Keratin