Human Biology Chapter 3

What is metabolism, and it is made up of two different chemical reactions

metabolism: all the chemical reactions occurring in a living organism

catabolic metabolism and anabolic metabolism

catabolic metabolism

Processes by which larger molecules are broken down into smaller ones

anabolic metabolism

The process in which larger molecules are built from smaller ones; it requires enery.

Nutrients

a substance that provides nourishment essential for growth and the maintenance of life.

organic compounds

Compounds that contain carbon eg. carbohydrates, amino acids, protiens and lipids.

Carbohydrates

organic molecules that are the main source of enery for cells

Monosaccharides

1 sugar molecue: eg. glucose, fructose, galactose

Disaccharides

2 sugar molecules: eg. sucrose, lactose, maltose

Polysaccharides

many sugar molecules: eg. glycogen or cellulose

Lipids

large organic molecules made up of fatty acids and glycerol.

Triglycerides

the most common form of lipid, made up of glycerol and 3 fatty acids

Proteins

very large organic molecues made up of amino acids

Amino Acids

building blocks of proteins

peptide bond

The chemical bond that forms between the carboxyl group of one amino acid and the amino group of another amino acid

Dipeptide

Two amino acids linked by a peptide bond.

Polypeptide

10 or more amino acids bonded together

Nucleic Acids

molecules containing many nucleotides forming a chain; including DNA and RNA

inorganic compound

A compound that does not contain carbon eg. water, oxygen. or having small molecules eg. carbon dioxide

aviation energy

energy needed to start a reaction

catalyst

substance that speeds up the rate of a chemical reaction

Enzyme

an organic substance that increases the speed of a chemical change without being altered or destroyed in the change

Substrate

Molecule upon which an enzyme acts.

active site

the part of a molecule that combines with the substrate

enzyme-substrate complex

the structure formed when an enzyme and substrate combine

What is the effect of enzyme concentration on reaction speed?

When there are more enzymes, reactions happen faster because more enzyme molecules can react with substrates.

What happens to reaction speed when substrate concentration increases?

Increasing substrate concentration makes the reaction faster at first, but eventually stops increasing due to saturation of enzyme activity sites.

What is the effect of product buildup on enzyme reactions?

If products build up, the reaction slows down because substrates cannot easily reach the enzymes.

How does temperature affect enzyme activity?

Higher temperatures increase reaction speed up to an optimum of about 30-40 degrees Celsius in humans; above 40-50 degrees, enzymes denature and stop working.

What is the effect of pH on enzyme activity?

Enzymes work best at a specific optimum pH; if the pH is too high or too low, enzyme activity decreases.

Cofactor

the ions or inorganic molecules required by enzymes to catalyse a reaction

Coenzyme

non - potien organic molecules that are essential for the functioning of an enzyme

enzyme inhabitor

a substance that slows or stops an enzyme's activity

cellular respiration

The chemical reactions that make energy available for the cell

ADP (adenosine diphosphate)

The substance formed when the end phosphate group is removed from a molecule of ATP

ATP (adenosine triphosphate)

a molecule that stores energy in cells; the energy is stored in the bond between the end phosphate group and the rest of the molecule.

Glycolysis

The breakdown of glucose by enzymes, releasing energy and pyruvic acid.

Anaerobic Respiration

Respiration that does not require oxygen

aerobic respiration

Respiration that requires oxygen

1st step in cellular resperation

pyruvate -> Acetyl CoA - pyruvate is converted into acetyl CoA before entering the next stage. No ATP is produced in this step.

2nd step in cellular resperation

citric acid cycle (Krebs cycle) - Acetyl CoA enters the cycle, carbon atoms are released as carbon dioxide and 1 ATP is produced per acetyl CoA (2 per glucose)

3rd step in cellular resperation

electron transport system—electrons move through a chain using oxygen, forming water and producing most of the energy (about 26-34 ATP); total aerobic respiration can produce up to 38 ATP per glucose.