Proteins and Nucleic Acids

Amino acids are the building blocks of proteins

• Side chains (R groups) give amino acids their various properties (polar, nonpolar)

• Amino acids combine to form polypeptides (polymers) via loss of ____ molecules

Protein FunctionMost diverse of all organic compounds

• Body Structure - Hair, muscle, collagen, bones, feathers, spider webs

• Mobility/transport - actin and myosin in muscles, hemoglobin

• Defense - antibodies• Storage - Casein in milk, proteins in eggs,

seeds• Hormones - insulin • Catalysts for all reactions within cells

(enzymes)

Enzymes

• Enzymes = Organic catalysts• Speed up chemical reactions• Not changed by the reaction• Lower “start up” energy (activation

energy) required for reaction• Extremely specific

– Each chemical reaction requires a different enzyme

Enzyme Activity: Lock and Key ModelEnzyme Activity: Lock and Key Model

Substrate = molecule acted on by enzyme

Active site = surface cleft on enzyme that binds to substrate

Induced fit = enzyme changes shape of active site so substrate can bind

How do Enzymes Speed Up Reactions?

http://www.lew-port.com/10712041113402793/lib/10712041113402793/Animations/Enzyme_activity.html

Anabolic reactions

• Bring two substrates together (greater chance of reaction)

Catabolic reactions

• Stress bonds (greater chance of bonds breaking)

Factors Affecting Enzyme Activity

• Temperature

• pH

• Concentration of Substrate

Denaturing (enzyme changes shape, stops working)

Why is protein structure important for its function?

• Shape defines its function• Shape is obtained by the precise

interactions of the R groups• R groups change - protein folds

differently (sickle cell anemia)• Sensitive to changes in cell environment

- anything that will change/break H bonds, acidity/basicity

Nucleic Acids• Building blocks are

nucleotides• Each nucleotide made

up of – A 5-carbon sugar

• RNA: ribose• DNA: deoxyribose

– Nitrogenous base • Adenine, Cytosine,

Guanine, Thymine (DNA only), Uracil (RNA only)

– Phosphate group(s)Basic Structure of a

Nucleotide

Comparison of Nucleic Acids

DNA–Double

stranded

–Deoxyribose

–Bases: CGAT

RNA–Single

stranded

–Ribose

–Bases: CGAU

Function of Nucleic acids

• DNA contains all the info the cell needs to survive and carry out its functions

• RNA - carries out the job that is specified on DNA (makes proteins)

• ATP (Adenosine triphosphate) is the fuel for cell to work

• Coenzymes help enzymes do their work eg NAD, FAD

• Messengers within cell e.g. cAMP