Chap 2

Chemical Composition of Cells

Key Knowledge

• General role of the enzymes in biochemical activities of cells

• Composition of cells– Major groups of organic or inorganic substances

• Carbohydrates• Lipids• Nucleic Acids• Water • Minerals• Vitamins• Their general role in cell structure and function

Inorganic Versus Organic

• Organic– Complex carbon-containing molecules – C, H,

O, sometimes N, P. Carbohydrates, lipids, proteins, and nucleic acids

• Inorganic– All other compounds that are not organic– Water, minerals

– CO2 – (no H)

Table 2.3 – Organic Compounds in cell

• A3 – Poster – Put information onto table into Poster

Plasma Membrane

• Membrane forms the boundary between the inside the of the cell and the environment on the outside of the cell.

• It must be able to allow substances to pass across it.

• Cellular respiration – oxygen and glucose move into the cell, waste products carbon dioxide and water move out

• Photosynthesis – carbon dioxide and water move into the plant cell for photosynthesis, glucose and oxygen move out.

Plasma Membrane

• Flexible structure – change shape• Able to grow and expand• Reseal punctures in the membrane• Able to break and reassemble• Double layer of phospholipid molecules –

phospholipid bilayer.• Cholesterol interspersed between phospholipid

molecules – strong bonds – flexibility.• Water – loving (hydrophilic)• Water-hating (hydrophobic)

Lipids

• Fats and Oil

• Fats are solid at room temperature

• Oils are liquid

• Triglyceride – tri – 3 fatty acids, one glycerol.

• Fatty acid contains only one single bonds – saturated fat. (animal fats) – also withstand higher temperatures

Lipids

• Double bonds between carbon atoms – unsaturated.

• Many double bonds between carbon atoms described as polyunsaturated.

• Double bonds more easily broken down by cells in your body than single bonds.

Vitamins

• Essential• Organic molecules• Needed in minute amounts• Help body grow, assist in normal functioning of

many metabolic processes and change food into energy.

• Water – soluble– B, C

• Fat-soluble – A,D,E and K

Minerals

• Produce a poster on the vitamins and minerals.

• Why they are important, what happens if you are not getting enough.

Proteins

• Protein booklet – What is a protein, What are proteins made up of, draw the chemical diagram of an amino acid, essential amino acid, non-essential amino acid, structural proteins, enzymes, properties of enzymes, concept map of proteins. Denaturation, what is it, why is it important.

Enzymes

• Work rapidly• Ends in –ase• Not destroyed or altered by the reactions that they

catalyse, so they can be used• Action depends on shape, can be changed by

temperature, acidity• Can work in either direction • Affected by temperature – optimal range – below

optimum they do not function effectively. Above they are denatured – change shape.

• Sensitive to pH• Specific to particular reactions• Enzyme substrate complex

Enzymes

• Enzyme + substrate(s) enzyme – substrate complex enzyme + end product

• Active site

• Lock and key mechanism

• Induced fit

• Organic catalysts

Denaturation

• 3D shape

• Change in shape caused by environmental conditions

The cell wall

• Plant cells – cellulose – carbohydrates

Carbohydrates

• C,H,O• 1:2:1• Glucose C6H12O6

• Monosaccharides • Disaccharides – two sugars• Polysaccharides – many sugars• Starch• Glycogen

Cytoplasm

• Cells approximately 80% water

• Fluid medium for substances to move about within the cells

Water

• Solvent – a substance in which other substances can be dissolved, the most common being water

• Extracellular fluids – fluids surrounding and bathing a cell.

• Temperature – stablilising effects of water

• Water’s cohesion – surface tension

Concept Poster

• Cell Wall

• Cytoplasm

• Cytoskeleton

• Mitochondrion

• Endoplasmic Reticulum

• Golgi Apparatus / Lysosomes

• Nucleus / Nucleic Acids