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Proteins and Nucleic Acids

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Page 1: Proteins and Nucleic Acids - MS. BAGBY AP BIOLOGYbagbyapbio.weebly.com/.../proteins_and_nucleic_acids.pdfNucleic Acids • Function: o Store & transmit hereditary information • Examples:

Proteins and Nucleic Acids

Page 2: Proteins and Nucleic Acids - MS. BAGBY AP BIOLOGYbagbyapbio.weebly.com/.../proteins_and_nucleic_acids.pdfNucleic Acids • Function: o Store & transmit hereditary information • Examples:

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Chapter 5 Macromolecules: Proteins

Proteins

• Most structurally & functionally diverse group of biomolecules.

• Function:

o Involved in almost everything

o Enzymes

o Structure (keratin, collagen)

o Carriers & transport (membrane channels)

o Receptors & binding (defense)

o Contraction (actin & myosin)

o Signaling (hormones)

o Storage (bean seed proteins)

• Structure:

o Monomer = amino acids

� 20 different amino acids

o Polymer = polypeptide

� Protein can be 1 or more polypeptide

chains folded & bonded together.

� Large & complex molecules

� Complex 3-D shape

• Amino Acids

o Structure:

� Central Carbon

� Amino Group

� Carboxyl Group (acid)

� R Group (side chain)

• Variable group

• Confers unique chemical properties of the amino

acid.

• Nonpolar Amino Acids (Hydrophobic) WHY?

Page 3: Proteins and Nucleic Acids - MS. BAGBY AP BIOLOGYbagbyapbio.weebly.com/.../proteins_and_nucleic_acids.pdfNucleic Acids • Function: o Store & transmit hereditary information • Examples:

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• Polar Amino Acids (Hydrophilic) WHY?

Building Proteins

• Peptide Bonds: dehydration synthesis

o Linking NH2 of 1 amino acid to COOH of

another.

o C–N bond

• Polypeptide Chains

o N-terminal = NH2 end

o C-terminal = COOH end

o Repeated sequence (N-C-C) is the

polypeptide backbone

� Grow in one direction

Page 4: Proteins and Nucleic Acids - MS. BAGBY AP BIOLOGYbagbyapbio.weebly.com/.../proteins_and_nucleic_acids.pdfNucleic Acids • Function: o Store & transmit hereditary information • Examples:

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Protein Structure & Function

• Function depends on structure.

o 3-D structure

� Twisted, folded, coiled into unique shape.

• All starts with the order of amino acids.

o What determines that order of amino acids?

Primary (1°) Structure

• Order of amino acids in chain

o Amino acid sequence determined by DNA

o Slight change in amino acid sequence can affect

protein’s structure & it’s function

� Even just one amino acid change can make

all the difference!

Secondary (2°) Structure

• Folding along short sections of polypeptide

o interaction between adjacent amino acids

o H bonds between R groups

o α-helix

o β-pleated sheet

Tertiary (3°) Structure

• Determined by interactions between R

groups

o Hydrophobic interactions

� Effect of water in cell

o Anchored by disulfide bridges

(H & ionic bonds)

Page 5: Proteins and Nucleic Acids - MS. BAGBY AP BIOLOGYbagbyapbio.weebly.com/.../proteins_and_nucleic_acids.pdfNucleic Acids • Function: o Store & transmit hereditary information • Examples:

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Quaternary (4°) Structure

• Joins together more than 1 polypeptide chain.

o Only then is it a functional protein.

Protein Structure Review

Denature a protein

• Disrupt 3° structure

o pH salt temperature

� Unravel or denature protein.

� Disrupts H bonds, ionic bonds & disulfide bridges.

• Some proteins can return to their functional shape after denaturation, many cannot.

Page 6: Proteins and Nucleic Acids - MS. BAGBY AP BIOLOGYbagbyapbio.weebly.com/.../proteins_and_nucleic_acids.pdfNucleic Acids • Function: o Store & transmit hereditary information • Examples:

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Chapter 5 Macromolecules: Nucleic Acids

Nucleic Acids

• Function:

o Store & transmit hereditary information

• Examples:

o RNA (ribonucleic acid)

o DNA (deoxyribonucleic acid)

• Structure:

o Monomers = nucleotides

Nucleotides

• 3 parts

o Nitrogen Base (C-N ring)

o Pentose Sugar (5C)

� Ribose in RNA

� Deoxyribose in DNA

o PO4 group

• 2 Types of Nucleotides

o Different Nitrogen bases

o Purines

� Double ring N base

� Adenine (A)

� Guanine (G)

o Pyrimidines

� Single ring N base

� Cytosine (C)

� Thymine (T)

� Uracil (U)

Page 7: Proteins and Nucleic Acids - MS. BAGBY AP BIOLOGYbagbyapbio.weebly.com/.../proteins_and_nucleic_acids.pdfNucleic Acids • Function: o Store & transmit hereditary information • Examples:

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Nucleic Polymer

• Backbone

o Sugar to PO4 bond

o Phosphodiester bond

� New base added to sugar of previous base

� Polymer grows in one direction

o N bases hang off the sugar-phosphate backbone

RNA & DNA

• RNA

o Single nucleotide chain

• DNA

o Double nucleotide chain

� N bases bond in pairs across chains.

o Spiraled in a double helix.

� Double helix 1st proposed as structure of DNA in 1953 by James Watson & Francis

Crick.

• Pairing of Nucleotides

o Nucleotides bond between DNA

strands

o H bonds between purine AND

pyrimidine

� A :: T

• 2 H bonds

� G :: C

• 3 H bonds

Information Polymer

• Function

o Series of bases encodes information

� Like the letters of a book

o Stored information is passed from

parent to offspring

� Need to copy accurately

o Stored information = genes

DNA Molecule

• Double helix

o H bonds between bases join the 2 strands

� A :: T

� C :: G

� Why is it important that the strands are bonded by H bonds?

• Copying DNA

o Replication

� 2 strands of DNA helix are complementary

• Have one, can build other

• Have one, can rebuild the whole

� Why is this a good system?

� When in the life of a cell does replication occur?

• mitosis

• meiosis

Page 8: Proteins and Nucleic Acids - MS. BAGBY AP BIOLOGYbagbyapbio.weebly.com/.../proteins_and_nucleic_acids.pdfNucleic Acids • Function: o Store & transmit hereditary information • Examples:

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Cool Beans

• Ratio of A-T::G-C affects stability of DNA molecule.

o 2 H bonds vs. 3 H bonds

• More G-C = need higher T° to

separate strands.

• High T° organisms have more G-

C.

• Parasites have many A-T (don’t

know why).

ATP Adenosine Triphosphate

• Modified nucleotide

o Adenine ribose + Pi + Pi +

Pi

Macromolecule Review

1) Carbohydrates

• Structure / monomer

o monosaccharide

• Function

o Energy

o Raw materials

o Energy storage

o Structural compounds

• Examples

o glucose, starch, cellulose, glycogen

Page 9: Proteins and Nucleic Acids - MS. BAGBY AP BIOLOGYbagbyapbio.weebly.com/.../proteins_and_nucleic_acids.pdfNucleic Acids • Function: o Store & transmit hereditary information • Examples:

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2) Lipids

• Structure / building block

o Glycerol, fatty acid, cholesterol, H-C chains

• Function

o Energy storage

o Membranes

o Hormones

• Examples

o Fat, phospholipids, steroids

3) Proteins

• Structure / monomer

o Amino Acids

o Levels of structure

• Function

• Enzymes, Defense, Transport, Structure,

Signals, Receptors

• Examples

o Digestive enzymes, membrane channels,

insulin hormone, actin

4)Nucleic Acids

• Structure / Monomer

o Nucleotide

• Function

o Information storage & Transfer

• Examples

o DNA, RNA