Amino Acids & Proteins The Molecules in Cells Ch 3.

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Amino Acids & Proteins The Molecules in Cells Ch 3

description

Protein Mammalian hair is composed of structural proteins Proteins have a broad size range  RNA digesting enzyme ribonuclease A (molecular weight of 5733 and 51 amino acids long)  Cholesterol transport protein apolipoprotein B (molecular weight of 513,000 and 4636 amino acids long) Enzymes regulate chemical reactions

Transcript of Amino Acids & Proteins The Molecules in Cells Ch 3.

Page 1: Amino Acids & Proteins The Molecules in Cells Ch 3.

Amino Acids & Proteins

The Molecules in CellsCh 3

Page 2: Amino Acids & Proteins The Molecules in Cells Ch 3.

Overview of Protein Function

Proteins are involved in cellular structure movement defense transport communication catalysis (enzymes) regulation

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Protein

Mammalian hair is composed of structural proteins

Proteins have a broad size range RNA digesting enzyme ribonuclease A

(molecular weight of 5733 and 51 amino acids long)

Cholesterol transport protein apolipoprotein B (molecular weight of 513,000 and 4636 amino acids long)

Enzymes regulate chemical reactions

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Proteins

Made from 20 different amino acids Proteins are the most structurally and

functionally diverse of life’s molecules Their diversity is based on different

arrangements of amino acids

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Amino Acid Structure

Amino Group Carboxyl Group

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Amino Acid Structure

Each amino acid contains: an amino group a carboxyl group an R group, which distinguishes each of

the 20 different amino acids Each amino acid has specific chemical

properties

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Properties of Amino Acids

Determined by the R group Amino acids may be:

Non-polar Neutral, polar Positively charged, polar Negatively charged, polar

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Properties of Amino Acids

Leucine (Leu)

HYDROPHOBIC

Serine (Ser) Cysteine (Cys)

HYDROPHILIC

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Protein Synthesis: Amino acids can be linked by peptide bonds

A protein is a chain of amino acids linked by peptide bonds

Peptide bond Type of covalent bond Links amino group of one amino acid with

carboxyl group of next Forms through dehydration synthesis reaction

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Peptide Bond Formation

Amino acid Amino acid

PEPTIDEBOND

Dehydration Synthesis Reaction

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Primary Structure of Proteins

A protein’s primary structure is its amino acid sequence

Unique for each protein Two linked amino acids = dipeptide Three or more = polypeptide

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Primary Structure & Protein Shape

Primary structure influences shape in two main ways: Allows hydrogen bonds to form between

different amino acids along length of chain

Puts R groups in positions that allow them to interact

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Protein Shapes

Fibrous proteins Polypeptide chains arranged as strands or

sheets

Globular proteins Polypeptide chains folded into compact, rounded

shapes

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Secondary Structure of Proteins

Hydrogen bonds form between different parts of polypeptide chain

These bonds give rise to coiling or folding pattern

Helix or pleated sheet

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Examples of Secondary Structure

Alpha helix

Pleated sheet

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Tertiary Structure of Proteins

Folding as a result of interactions between R groups

coiled and twisted polypeptide chain of one globin molecule

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Quaternary Structure of Proteins

Some proteins are made up of more than one polypeptide chain

Hemoglobin

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Polypeptides With Attached Organic Compounds

Lipoproteins

Proteins combined with cholesterol, triglycerides,

phospholipids

Glycoproteins

Proteins combined with oligosaccharides

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Denaturation

Disruption of three-dimensional shape Breaking of weak bonds Causes of denaturation:

pH Temperature Salinity

Destroying protein shape disrupts function

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In review ….

What are the similarities & differences between amino acids?

Describe each type of protein structure.

How does shape influence protein function?