Chemistry of Cells. Objectives Describe the distinguishing characteristics of carbohydrates Describe the important biological functions of polysaccharides.

Chemistry of Cells

Objectives

Describe the distinguishing characteristics of carbohydratesDescribe the important biological functions of polysaccharidesExplain what distinguishes lipids from other classes of biological macromoleculesDescribe the unique properties, building blocks and biological roles of fats, phospholipids and steroidsDistinguish proteins from the other classes of macromolecules

Objectives Cont.

List the biological functions which proteins performExplain what determines protein conformation and why it is importantDefine denaturation and explain how proteins may be denaturedDescribe the characteristics that distinguish nucleic acids from the other classes of macromoleculesSummarize the functions of nucleic acids

Objectives Cont.

Briefly describe the three-dimensional structure of DNAEvaluate the importance of energy to living thingsRelate energy and chemical reactionsDescribe the role of enzymes in chemical reactionsIdentify the effect of enzymes on food molecules

MacroMolecules

Macro = largeMolecules = 2 or more atoms covalently bondedUsually referred to as polymersLike a chainMade from several repeating subunitsThe repeated subunits are called monomersLike links in a chain3 of the 4 macromolecules are polymers of monomers

Making or Breaking Polymers

The chemical mechanisms that cells use to make and break polymers are similar for all classes of macromolecules.

Making Polymers

Monomers are connected by covalent bonds via a condensation reaction or dehydration reaction.One monomer provides a hydroxyl group and the other provides a hydrogen and together these form water.This process requires energy and is aided by enzymes.

Breaking Down Polymers

The covalent bonds connecting monomers in a polymer are disassembled by hydrolysis.In hydrolysis as the covalent bond is broken a hydrogen atom and hydroxyl group from a split water molecule attaches where the covalent bond used to be.Hydrolysis reactions dominate the digestive process, guided by specific enzymes.

There are four of them.CarbohydratesLipidsProteinsNucleic acids☺ For each of these you will be expected to identify, describe, and differentiate between all four macromolecules.☺You will also be expected to describe the biological importance of each macromolecule

Function of Carbohydrates

Sugars, the smallest carbohydrates, serve as fuel and carbon sources

Polysaccharides, the polymers of sugars, have storage and structural roles

Structure of Carbohydrates

Monosaccharides generally have molecular formulas containing C,H and O in a 1:2:1 ratio.For example, glucose has the formula C6H12O6.Most names for sugars end in -ose.Monosaccharides are also classified by the number of carbons in the backbone.

Monosaccharides, particularly glucose, are a major fuel for cellular work.They are also building blocks for of other monomers, including those of amino acids (protein) and fatty acids (lipids).While often drawn as a linear skeleton, in aqueous solutions monosaccharides form rings.

2. Polysaccharides, the polymers of sugars, have storage and structural roles

Polysaccharides are polymers of hundreds to thousands of monosaccharides joined together (What is a polymer?)One function of polysaccharides is energy storage it is hydrolyzed as needed.Other polysaccharides serve as building materials for the cell or whole organism.

Starch is a storage polysaccharide composed entirely of glucose monomersGreat big chain of glucose moleculesWhat would this look like? (Draw it.)

Biological Uses of Polysaccharides

Plants store starch within plastids, including chloroplasts.Plants can store surplus glucose in starch and withdraw it when needed for energy or carbon.Animals that feed on plants, especially parts rich in starch, can also access this starch to support their own metabolism. Hey, this sounds like an objective!