Biochemistry

To be used with Biochemistry Guided Notes

Organic vs. Inorganic MoleculesOrganic Inorganic

Does not contain C, H, and O at same time (Example: H20)

Carbon is the key element—the element of life

Water: makes up 60 to 98% of living things—necessary for chemical activities and transport

Salts: help maintain water balance

Example: Gatorade—electrolytes

Carbon can bond with itself and form many times for bonds (single, double, triple and rings)

4 Organic Molecules:

Carbohydrates Lipids

Nucleic Acids Proteins

Contains Carbon (C), Hydrogen (H), and Oxygen (O) (Example: C6H12O6)

Acids and Bases: -pH Scale -Important for enzyme function

Carbohydrates

• Sugars and complex carbohydrates (starches)

• Contain the carbon, hydrogen, and oxygen (the hydrogen is in a 2:1 ratio to oxygen)

• End in -ose

Monosaccharides

• Simple sugars

• All have the formula C6H12O6

• Have a single ring structure

• Example: Glucose

Disaccharides

• Double sugars

• All have the formula C12H22O11

• Example: sucrose (table sugar)

Polysaccharides• Three or more simple sugar units• Examples:

– Glycogen: animal starch stored in the liver and muscles

– Cellulose: indigestible in humans: forms cell wall in plants

– Starches: used as energy storage

How are complex carbohydrates formed?

• Dehydration synthesis: combining simple molecules to form a more complex one with the removal of water

• Example:– monosaccharide + monosaccharide disaccharide + water

– C6H12O6 + C6H12O6 C12H22O11 + H2O

• polysaccharides are formed from repeated dehydration synthesis

Monosaccharide + Monosaccharide

Disaccharide

+ Water

How are complex carbohydrates broken down?

• Hydrolysis: the addition of water to a compound to split it into smaller subunits– also called chemical digestion

• Example:– disaccharide + water monosaccharide + monosaccharide

– C12H22O11 + H2O C6H12O6 + C6H12O6

Lipids

• Lipids (Fats): lipids chiefly function in energy storage, protection, and insulation– contain carbon, hydrogen, and oxygen but the

H:O is not in a 2:1 ratio– Examples: fats, oils, waxes, steroids

• Lipids tend to be large molecules

Lipids

• Lipids are formed from one glycerol molecule and 3 fatty acids

• 3 fatty acids + glycerol lipid (fat)

4 Types of Lipids1.Fats: from animals

• Saturated: solid at room temperature• All single bonds in the fatty acid tail• Very difficult to break down

4 Types of Lipids

2. Oils: from plants• Unsaturated: liquid at room temperature

• Presence of a double bond in the fatty acid tail• Ex. Vegetable oils

Four Types of Lipids

3. Waxes: ear wax, bees wax

4 Types of Lipids

4. Steroids:• One important molecule that is classified in

this category is cholesterol• High levels could lead to heart disease

Proteins

• Proteins: contain the carbon, hydrogen, oxygen, and nitrogen– Made at the ribosomes– Composed of amino acid subunits

Proteins

• Major Protein Functions: – Growth and repair– Energy

• Usually end with -in:– Example: Hemoglobin

Making Proteins

• Dehydration synthesis of a dipeptide– Dipeptide: formed from two amino acids

• amino acid + amino acid dipeptide + water

Breaking down Proteins

• Hydrolysis of a dipeptide • dipeptide + water amino acid + amino acid

Proteins

• Polypeptide: composed of three or more amino acids– These are proteins

• Examples: insulin, hemoglobin, and enzymes

• There are a large number of different types of proteins:– The number, kind and sequence of amino

acids lead to this large variety

Nucleic Acids

• Nucleic Acids: present in all cells – DNA: contains the genetic

code of instructions throughthe synthesis of proteins

• found in the chromosomesof the nucleus

– RNA: directs protein synthesis

• found in nucleus, ribosomes & cytoplasm

Enzymes

• Catalyst: inorganic or organic substance which speeds up the rate of a chemical reaction without entering the reaction itself– Examples: enzymes (organic) and heat (inorganic)

• Enzymes: organic catalysts made of protein – most enzyme names end in –ase– enzymes lower the energy needed to start a chemical

reaction (activation energy)

How enzymes work

1. Enzyme forms a temporary association with a the substance it affects• These substances are known as substrates.

2. The association between enzyme and substrate is very specific—like a Lock and Key• This association is the enzyme-substrate complex

3. While the enzyme-substrate complex is formed, enzyme action takes place.

4. Upon completion of the reaction, the enzyme and product(s) separate

5. The enzyme is now able to be reused

Enzyme-Substrate Complex

Enzyme Terms

• Active site: the pockets in an enzyme where substrate fits – Usually enzyme is larger than substrate

• Substrate: molecules upon which an enzyme acts

• All enzymes are proteins• Coenzyme: non-protein part attached to

the main enzyme– Example: vitamins

Proteins in action   enzyme

substrate -------------> product

Lock and Key Model

Factors Limiting Enzyme Action• pH: pH of the environment affects enzyme

activity– Example: pepsin works best in a pH of 2 in stomach

Amylase works best in a pH of 6.8 in mouth--saliva

Factors Limiting Enzyme Action

• Temperature: as the temperature increases the rate of enzymes increases

– Optimum Temperature: temperature at which an enzyme is most affective

• Humans it is 37 degrees C or 98.6 degrees F• Dogs between 101 and 102 F

When Temperatures Get Too High• Denature:

– Change in their shape so the enzyme active site no longer fits with the substrate

– Enzyme can't function– Above 45 C most

enzymes are denatured

• Why do we get a fever when we get sick?

General Trend vs. Denaturing

Factors Limiting Enzyme Action

• Concentration of Enzyme and Substrate

– With a fixed amount of enzyme and an excess of substrate molecules

• the rate of reaction will increase to a point and then level off

– Leveling off occurs because all of the enzyme is used up

• Excess substrate has nothing to combine with – Add more enzyme reaction rate increases again

Enzyme-Substrate Concentration