Proteins

Protein Basics

• Used in variety of cellular functions

• Made of smaller amino acids

• Only 20 amino acids… but thousands of proteins

– Exact arrangement of amino acids determines protein

leucine valine glycine alanine leucine leucinehisti-dine

aspara-gine

serine proline = protein A

leucinevaline glycine alanine leucine leucinehisti-dine

aspara-gine

serine proline = protein B

leucine valine glycine alanine leucine leucine = protein C

Amino Acid Structure

• 5 basic parts

1) Central C atom

2) Amino group (NH2)

3) H

4) Carboxyl group (COOH)

5) R group• Monomer: Amino acid• Polymer: Protein

What differs between these amino acids?

Noticealanine’sdifferentR group

NoticeValine’sdifferentR group

Noticeleucine’sdifferentR group

Noticemethionine’s

differentR group

Noticeisoleucine’s

differentR group

R group for glycine

How do amino acids bond?

• Dehydration synthesis!

• Peptide Bonds: link amino acids to form a chain (polypeptide)

• Polypeptide bends & folds based on R group attractions

Enzymes

• Types of proteins• Enzyme: Lowers the energy needed to start a chemical reaction

– Breaking down food– Build other proteins

• Sensitive to pH, temp– ex: If high fever: enzymes lose ability to work

• Very specific in actions– ex: Amylase: Breaks starch into simple sugars

• Reusable

glucose glucose glucose glucose

Enzyme amylase

glucose glucose glucose glucose

Kobe Kuiz1) What are the smaller monomers that make

proteins called?

2) How many different amino acids exist?

3) How does each amino acid differ?

4) The NH2 part of the amino acid is called the ____ group.

5) The COOH part of the amino acid is called the ____ group.

6) Which group of proteins help to start chemical reactions?