Proteins and Nucleic Acids

Nucleic Acids - Function

• Food sources: high protein foods like nuts, meat, fish, milk, beans

• There are 2 types of nucleic acids:1. DNA - Deoxyribonucleic Acid

Location - inside nucleus Function – genetic instructions to make RNA

2. RNA - Ribonucleic AcidLocation - in nucleus and cytoplasm

Function – converts DNA instructions into proteins

Nucleic Acids - Structure

• Nucleic acid monomers are nucleotides.• All nucleotides are made of three parts:

1. A pentose sugar, deoxyribose for DNA and ribose for RNA

2. Phosphate3. One of five nitrogen containing bases

a. In DNA, either adenine, thymine, guanine, or cytosineb. In RNA, uracil replaces thymine

Nucleotide - Structure

- DNA is a large polymer made of many nucleotides.- Two strands of DNA hydrogen bond between the nitrogen bases and coil together.- RNA is a single stranded nucleic acid.

Nucleic Acid Polymers

Proteins - Functions

• Food sources: high protein foods like nuts, meat, fish, milk, beans

• Four main functions:1. Major structural component of all cells, organs

and tissues2. Enzymes that speed up all chemical reactions

are all proteins3. Transport substances within and between cells4. Chemical messengers and protein based

hormones

Proteins - Monomers

• All proteins are made of the same 20 amino acids connected in different combinations.

• 10 amino acids are considered essential in the diet of adult humans and our bodies can make the remaining 10 from the amino acids that we eat.

• Infants and children need more amino acids because their bodies cannot make as many.

TWENTY AMINO ACIDS

All amino acids have a nitrogen functional group, an acid functional group and a side functional group that makes each amino acid unique.

Proteins – Forming Polypeptides• Amino acids bond by

dehydration synthesis between the amino and acid functional groups of two amino acids.

• This forms a covalent peptide bond.

• Polypeptides have from 40 to 1000 amino acids in a long chain.

Protein Folding and Structures

• Proteins are only functional when the polypeptide folds into the correct 3D shape.

• A polypeptide is a primary protein structure.• The secondary protein structure involves

forming hydrogen bonds – helix folds forming a spiral– pleated folds forming sheetshttp://www.youtube.com/watch?v=lijQ3a8yUYQ

More Protein Folding

• A tertiary protein folding occurs to make an active protein.

• The tertiary structure is a complex shape.• Bonds are formed between the functional

groups on the different amino acids. Some R groups are hydrophilic and will be on the outside of the protein, hydrophobic groups will be inside the protein, as well cations are attracted to anions.

Even More Protein Folding• Often a tertiary protein is

complete and works.• Sometimes two or more

tertiary proteins bind to form a quaternary protein like hemoglobin.

• Hemoglobin has two alpha and two beta chains all joined together. Each of the tertiary proteins has one iron atom that binds to oxygen.

Hemoglobin – A Quaternary Protein

Keratin – Structural Protein in hair

Lactase – Enzyme Protein

YiiP Zinc Transporter Protein

Insulin – A Chemical MessengerThe left side is a space-filling model of the insulin monomer. On the right side is a ribbon diagram of the insulin hexamer, thought to be the stored form. A monomer unit is highlighted with the A chain in blue and the B chain in cyan. Yellow denotes disulfide bonds, and magenta spheres are zinc ions.