• Polymers (long chains) of AMINO ACIDS

– arranged in specific sequence

– linked by PEPTIDE BONDS

– range in length from a

few to 1000+

AMINO ACIDSAMINO ACIDS • building blocks of proteins • there are 20 common amino acids• structure of an amino acid: • elements included in a

protein:-carbon-hydrogen-oxygen-nitrogen-sulfur (usually)

• Amino acids are linked together through DEHYDRATION SYNTHESIS to form PEPTIDE BONDS

PROTEIN STRUCTURE

• a protein’s function depends on its specific 3-D shape

Protein Shape:Protein Shape:

• determined by environmental

conditions

• DENATURATION: protein loses its natural shape, and therefore loses its function! This can be caused by:– extreme heat– pH changes

Functions of ProteinsFunctions of Proteins

• structural support (e.g. hair, nails)

• signaling (e.g. hormones)

Functions of ProteinsFunctions of Proteins • movement (contraction

of muscles)

• transporting oxygen in the

blood

Functions of ProteinsFunctions of Proteins

• defense (antibodies of immune system)

• catalysis of reactions (ENZYMES)

PROTEINS WORKING AS ENZYMESPROTEINS WORKING AS ENZYMES

ENZYMES:

• are proteins

• control the speed of reactions (often they increase the speed of reactions)

• are not changed or “used up” by a reaction; can be used over and over

• each enzyme is specific to a SUBSTRATE

• SUBSTRATE = the substance the enzyme acts on

 

Substrate ==> enzyme-sub.==> product

+ complex +

enzyme enzyme

• ACTIVE SITE = region of an enzyme which binds to the substrate

– is usually a pocket or groove on surface

– compatible “fit” between shape of enzyme’s active site and shape of substrate

http://www.omega.dawsoncollege.qc.ca/ray/metabol/metabol.htm

Factors Affecting Enzyme Activity

1. Temperature:

– as temp increases, reaction rate increases

– BUT, if temp gets too high, enzyme

denatures and loses its shape and function

– optimal range for human enzymes: 35-40°C

2. pH:

-optimal range for most enzymes: pH 6-8

*some enzymes operate best at extremes of pH (e.g. digestive enzyme pepsin, found in the acidic environment of the stomach, works best at pH 2)

• nucleic acids store and transmit hereditary information

• Two types of nucleic acids:1. DNA

2. RNA

Structure of Nucleic AcidsStructure of Nucleic Acids

• polymers made up of monomers called NUCLEOTIDES

• Elements present:

-carbon

-hydrogen

-oxygen

-nitrogen

-phosphorus

• each nucleotide consists

of:1. a simple sugar

-deoxyribose in DNA-ribose in RNA

 

2.   phosphate group  3.   a base (e.g. in DNA, the bases are A, G,

C, and T)

• nucleotides are joined together in DEHYDRATION SYNTHESIS

• results in a “backbone” with a repeating pattern of sugar-phosphate-sugar-phosphate...

1. DNA = Deoxyribonucleic acid

• forms the genetic code - the instructions for the proteins (amino acid sequences) of an organisms’ proteins

• is copied and passed

from one generation

of cells to another

2. RNA = Ribonucleic acid

• functions in the actual

synthesis of proteins

coded for by DNA