Lecture AP Biology Chapter 5 The structure and function of large biological molecules

In this chapter, you should be able to: List and describe the four major classes of organic molecules; Explain: monomers, polymers, dehydration synthesis with the type of covalent bond for each; distinguish between monosaccharides, disaccharides, and polysaccharides.

1 What are the 4 classes of

macromolecules? Give an example of

each.

2 Draw and label the parts of an amino acid.

3 How are 2 amino acids put together?

Name the process and describe what

happens.

4 Draw a tripeptide (Use Google for help)

Label the peptide bonds.

Peptide Bonds

Ch 5 Warm-Up Activity

In your family groups,

complete #1-5 on Activity 4/5.1: “How can you identify organic macromolecules?”

1 What are the 4 levels of protein

structure? What bonds are formed

in each level?

2 Which protein was involved in the

curds & whey lab yesterday?

3 Explain what happened to the milk

to form the curds and whey

Chapter 5

The Structure and Function of Large Biological Molecules

You Must Know

• The role of dehydration synthesis in the

formation of organic compounds and hydrolysis

in the digestion of organic compounds.

• How to recognize the 4 biologically important

organic compounds (carbs, lipids, proteins,

nucleic acids) by their structural formulas.

• The cellular functions of all four organic

compounds.

• The 4 structural levels of proteins

• How proteins reach their final shape

(conformation) and the denaturing impact

that heat and pH can have on protein structure

Monomers Polymers Macromolec ules

•Giant molecules

•2 or more polymers bonded together

ie amino acid  peptide  polypeptide

 protein

Dehydration Synthesis

Hydrolysis

I Proteins

• “Proteios” = first or primary

• 50% dry weight of cells

• Contains: C, H, O, N, S

Myoglobin protein

Protein Functions (+ examples)

Overview of protein

functions

Overview of protein

functions

Four Levels of Protein

Four Levels of Protein Structure (continued)

Basic Principles of Protein

Folding

A Hydrophobic AA buried in interior

of protein (hydrophobic

interactions)

B Hydrophilic AA exposed on surface

of protein (hydrogen bonds)

C Acidic + Basic AA form salt bridges

(ionic bonds)

D Cysteines can form disulfide bonds

Four Levels of Protein Structure

(continued)

3 Tertiary

 Bonding between side chains (R groups) of

amino acids

 H bonds, ionic bonds, disulfide bridges, van

der Waals interactions

Four Levels of Protein Structure (continued)

4 Quaternary

 2+ polypeptides bond together

amino acids  polypeptides 

protein

Bonding (ionic & H) can create asymmetrical attractions

Chaperonins assist in proper folding of proteins

• Protein structure and function

are sensitive to chemical and

physical conditions

• Unfolds or denatures if pH and

temperature are not optimal

change in structure = change

in function

II Nucleic Acids

Function: store hereditary info

Nucleotides: monomer of DNA/

RNA

Nitrogen Base

phospha

te

5-C sugar

Information flow in a cell: DNA  RNA  protein

III Carbohydrates

• Fuel and building material

• Include simple sugars (fructose) and polymers

(starch)

• Ratio of 1 carbon: 2 hydrogen: 1 oxygen or CH 2 O

• monosaccharide  disaccharide  polysaccharide

• Monosaccharides = monomers (eg glucose,

ribose)

• Polysaccharides:

 Storage (plants-starch, animals-glycogen)

 Structure (plant-cellulose, arthropod-chitin )

Differ in position &

orientation

of glycosidic linkage

The structure and

classification

of some

monosaccharid es

Linear and ring forms of

glucose

Carbohydrate synthesis

Cellulose vs Starch

Two Forms of Glucose:  glucose & 

glucose

Cellulose vs Starch

• Starch =  glucose monomers

• Cellulose =  glucose monomers

Storage polysaccharides of plants (starch) and animals (glycogen)

Structural polysaccharides: cellulose & chitin

(exoskeleton)

II Lipids

Saturated Unsaturated Polyunsatura ted

“saturated” with H Have some C=C, result in kinks

Solid at room

Cholesterol, a steroid

The structure of a

phospholipid

Hydrophobic/hydrophilic interactions make a

phospholipid bilayer