Proteins Multipurpose molecules Proteins Most structurally functionally diverse

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Proteins Multipurpose molecules

Proteins Multipurpose molecules

Proteins • Most structurally & functionally diverse group • Some Functions of Proteins: –

Proteins • Most structurally & functionally diverse group • Some Functions of Proteins: – – enzymes (pepsin, DNA polymerase) Biological structures (keratin, collagen) carriers & transport (hemoglobin, aquaporin) cell communication • signals (insulin & other hormones) • receptors – defense (antibodies) – movement (actin & myosin) – storage (bean seed proteins)

Protein Structure – Monomer( 1 unit) = amino acids • 20 different amino acids

Protein Structure – Monomer( 1 unit) = amino acids • 20 different amino acids – polymer = polypeptide • protein can be one or more polypeptide chains folded & bonded together • large & complex molecules • complex 3 -D shape hemoglobin Rubisco growth hormones

Amino acids H O H | || – central carbon —C— C—OH – amino

Amino acids H O H | || – central carbon —C— C—OH – amino group (typically ionized) —N— – carboxyl group (an acid which is | H also ionized) R – R group (side chain) • Structure • variable group • different variable group makes a different amino acid • confers unique chemical properties to each amino acid Recall: Structure determines function

Amino Acids cont’d • Amino acids have both acidic (carboxyl) and basic (amino) properties.

Amino Acids cont’d • Amino acids have both acidic (carboxyl) and basic (amino) properties. • When dissolved in water, the carboxyl group donates a H+ ion to the amino group to possess an extra hydrogen and therefore a net +ve charge.

R groups • Amino acids may be polar, non-polar, or charged (acidic or basic).

R groups • Amino acids may be polar, non-polar, or charged (acidic or basic). • This depends on the nature of the side chains. • Generally, acidic aa’s possess a carboxyl group on the side chain and basic aa’s contain an amino group on the side chain.

Effect of different R groups: Nonpolar amino acids nonpolar & hydrophobic Why are these

Effect of different R groups: Nonpolar amino acids nonpolar & hydrophobic Why are these nonpolar & hydrophobic?

Effect of different R groups: Polar amino acids polar or charged & hydrophilic Why

Effect of different R groups: Polar amino acids polar or charged & hydrophilic Why are these polar & hydrophillic?

Building proteins • Peptide bonds – Formed by a condensation reaction between NH 2

Building proteins • Peptide bonds – Formed by a condensation reaction between NH 2 (amine) of one amino acid & COOH (carboxyl) of another (amide bond) – C–N bond dehydration synthesis H 2 O peptide bond

Protein structure & function • Function depends on structure – 3 -D structure •

Protein structure & function • Function depends on structure – 3 -D structure • twisted, folded, coiled into unique shape pepsin hemoglobin collagen

Now…. LETS DISCUSS LEVELS OF PROTEIN ORGANIZATION Please review pg. 27 in your textbook

Now…. LETS DISCUSS LEVELS OF PROTEIN ORGANIZATION Please review pg. 27 in your textbook tonight!

Primary (1°) Structure • Order of amino acids in chain – amino acid sequence

Primary (1°) Structure • Order of amino acids in chain – amino acid sequence determined by gene (DNA) – slight change in amino acid sequence can affect protein’s structure & its function • even just one amino acid change can make all the difference!

Sickle Cell Anemia

Sickle Cell Anemia

Secondary (2°) structure • “Local folding” – folding along short sections of polypeptide –

Secondary (2°) structure • “Local folding” – folding along short sections of polypeptide – interactions between adjacent amino acids • H bonds – weak bonds between R groups – forms sections of 3 -D structure • -helix • -pleated sheet

Secondary (2°) structure

Secondary (2°) structure

Tertiary (3°) structure • “Whole molecule folding” – interactions between distant amino acids •

Tertiary (3°) structure • “Whole molecule folding” – interactions between distant amino acids • hydrophobic interactions – cytoplasm is water-based – nonpolar amino acids cluster away from water • H bonds & ionic bonds • disulfide bridges – covalent bonds between sulfurs in sulfhydryls (S–H) – anchors 3 -D shape

Quaternary (4°) structure • More than one polypeptide chain bonded together – only then

Quaternary (4°) structure • More than one polypeptide chain bonded together – only then does polypeptide become functional protein • hydrophobic interactions collagen = skin & tendons hemoglobin

Protein structure (review) R groups hydrophobic interactions disulfide bridges (H & ionic bonds) 3°

Protein structure (review) R groups hydrophobic interactions disulfide bridges (H & ionic bonds) 3° multiple polypeptides hydrophobic interactions 1° amino acid sequence peptide bonds determined by DNA 4° 2° R groups H bonds

Protein denaturation • Unfolding a protein – conditions that disrupt intermolecuar bonds • temperature

Protein denaturation • Unfolding a protein – conditions that disrupt intermolecuar bonds • temperature • p. H • Exposure to chemicals – destroys functionality • some proteins can return to their functional shape after denaturation, many cannot

Nucleic Acids Information storage

Nucleic Acids Information storage

Nucleic Acids • Function: – genetic material • stores information – genes – blueprint

Nucleic Acids • Function: – genetic material • stores information – genes – blueprint for building proteins » DNA RNA proteins DNA • transfers information – blueprint for new cells (mitosis) – blueprint for next generation (meiosis) proteins

Nucleic Acids • Examples: – RNA (ribonucleic acid) • single helix – DNA (deoxyribonucleic

Nucleic Acids • Examples: – RNA (ribonucleic acid) • single helix – DNA (deoxyribonucleic acid) • double helix • Structure: – monomers = nucleotides DNA RNA

Nucleotides • 3 parts – nitrogen base (C-N ring) – pentose sugar (5 C)

Nucleotides • 3 parts – nitrogen base (C-N ring) – pentose sugar (5 C) • ribose in RNA • deoxyribose in DNA – phosphate (PO 4) group – enzymes facilitate the formation of covalent bonds between the phosphate group of one nucleotide and the hydroxyl group on C 3 of the adjacent nucleotide (see right). This is called a phosphodiester bond.

Types of nucleotides • 2 types of nucleotides – different nitrogen bases – purines

Types of nucleotides • 2 types of nucleotides – different nitrogen bases – purines • double ring N base • adenine (A) • guanine (G) – pyrimidines • • single ring N base cytosine (C) thymine (T) uracil (U)

Nucleic polymer • Backbone – sugar to PO 4 bond – phosphodiester bond •

Nucleic polymer • Backbone – sugar to PO 4 bond – phosphodiester bond • new base added to sugar of previous base • Polymer (aka a strand) grows in one direction – N bases hang off the sugar-phosphate backbone

Pairing of nucleotides • Nucleotides bond between DNA strands – H bonds – purine

Pairing of nucleotides • Nucleotides bond between DNA strands – H bonds – purine : : pyrimidine – A : : T • 2 H bonds – G : : C • 3 H bonds

DNA molecule • Double helix – H bonds between bases join the 2 strands

DNA molecule • Double helix – H bonds between bases join the 2 strands • A : : T • C : : G

Macromolecule Review

Macromolecule Review

Carbohydrates • Structure / monomer – monosaccharide • Function – energy – raw materials

Carbohydrates • Structure / monomer – monosaccharide • Function – energy – raw materials – energy storage – structural compounds glycosidic bond • Examples – glucose, starch, cellulose, glycogen

Lipids • Structure / building block – glycerol, fatty acid, cholesterol, H-C chains •

Lipids • Structure / building block – glycerol, fatty acid, cholesterol, H-C chains • Function – energy storage – membranes – hormones • Examples ester bond (in a fat) – fat, phospholipids, steroids

Proteins • Structure / monomer – amino acids – levels of structure • Function

Proteins • Structure / monomer – amino acids – levels of structure • Function – enzymes – transport – signals defense u structure u receptors u peptide bond • Examples – digestive enzymes, membrane channels, insulin hormone, actin

Nucleic acids • Structure / monomer – nucleotide • Function – information storage &

Nucleic acids • Structure / monomer – nucleotide • Function – information storage & transfer • Examples – DNA, RNA phosphodiester bond

RNA & DNA • RNA – single nucleotide chain • DNA – double nucleotide

RNA & DNA • RNA – single nucleotide chain • DNA – double nucleotide chain • N bases bond in pairs across chains – spiraled in a double helix

Homework: • Learning Check • Pg. 28 #19 -23 Fill in back of Macromolecule

Homework: • Learning Check • Pg. 28 #19 -23 Fill in back of Macromolecule Handout ( Proteins & Nucleic Acids) Complete Functional Group Review handout