2.3: Carbon-Based Molecules

Carbon-based molecules are the foundation of life.

Bonding Properties of Carbon

• Carbon forms covalent bonds with up to four other atoms, including other carbon atoms.

1

23, 4

Structure of carbon-based molecules…

• Three general types:1. straight chain H H Cl H H

| | | | |H - C- C - C - C - C - H | | | | | H H H H H

3-chloropentane

Structure of carbon-based molecules…

• Three general types: 2. Branched chain

Structure of carbon-based molecules…

• Three general types: 3. Ring

• Many carbon-based molecules are made of many small subunits bonded together.– Monomers are the individual subunits.– Polymers are made of many monomers.

Four Types of Carbon-Based MoleculesCarbohydrates

LipidsProteins

Nucleic AcidsALL four are found in LIVING

things.

Carbohydrates• Organic molecules

made of the elements carbon, hydrogen, and oxygen (CHO)

• Includes sugars and starches

• Pasta, bread, and fruit are high in carbohydrates

Structure of Carbohydrates

• Monomer• Monosaccharides – “saccharide” means

sugar– simple sugars– Glucose, galactose,

fructose

Structure of Carbohydrates

• Disaccharide• Two

monosaccharide molecules bonded together

• Sucrose, or table sugar, made of one glucose and one fructose molecule

Structure of Carbohydrates

• Polymer • Polysaccharides – Chains of

monosaccharides– starches,

cellulose, and glycogen

Function of Carbohydrates• Can be broken down to

provide energy for cells.– Glucose-main source of energy

for cells, product of photosynthesis

• Provide us with energy– Sugar rush then crash

• Some carbohydrates are part of cell structure.– Cellulose-makes up the cell wall

of plant cells

LIPIDS• Organic molecules made

of the elements carbon, hydrogen, and oxygen (CHO)• Nonpolar molecules–Do not dissolve in water

• Include fats, oils, cholesterol, and wax

Structure of Lipids

• Fatty acids bonded to glycerol.–Glycerol-3 hydroxyl

groups–Fatty acids-long carbon

chains Two different types of

fatty acids found in fats and oils:oSaturated fatty acidsoUnsaturated fatty acids

Two Types of Fatty Acids

Functions of Lipids

• Used for long term energy storage

• Make up cell membranes– Phospholipid bilayer

• Used to make hormones– Testosterone (males) & estrogen

(females)

• Insulate and waterproof organisms– Cutin-waxy substance that

coats leaves of plants to help prevent water loss

Lipid Polymer-Phospholipid

• Consists of glycerol, two fatty acids (nonpolar tails) and a phosphate group (polar head of molecule)

• Makes up ALL cell membranes

Lipid Polymer-Triglycerides

• Consists of glycerol and three fatty acids

• Type of fat found in your blood.– Your body uses them for

energy.

• You need some triglycerides for good health. – But high triglycerides can

raise your risk of heart disease and may be a sign of metabolic syndrome

Nucleic Acids

• EXTREMELY long carbon-based molecules made of carbon, hydrogen, oxygen, nitrogen, and phosphorus (CHONP)

Structure of Nucleic Acids• Monomer– Nucleotide• made of a five-carbon

sugar, phosphate group, and a nitrogen base.• 5 kinds: Adenine,

Thymine, Cytosine, Guanine, & Uracil

• Polymers– DNA-Deoxyribonuleic

Acid– RNA-Ribonucleic Acid

A phosphate group

nitrogen-containing molecule,called a base

deoxyribose (sugar)

Function of Nucleic Acids

DNA

RNA

• DNA stores genetic information

• RNA builds proteins using information from DNA

Proteins

• Large organic molecules made of carbon, hydrogen, oxygen, and nitrogen (CHON)

• Essential to all life• Foods high in proteins:– Poultry, fish, eggs,

beans, nuts, peanut butter, milk

Structure of Proteins

• Monomer– Amino acid

• Contain an amino group and a carboxyl group

• Interact to give a protein its shape and function

• Peptide bonds form between amino acids to form chains

• Organisms use 20 different amino acids to build proteins– Your body makes 12,

others come from food you eat

Structure of Proteins• Polymer– Protein– Also called polypeptide

• Each protein has a different arrangement of amino acids

• Incorrect amino acid sequence and/or arrangement changes the protein’s structure and function

Function of Proteins• Building and connecting materials of living

things– Collagen-forms bones, tendons, ligaments, and

cartilage• Take part in chemical reactions and transport

materials– Hormones, antibodies, and enzymes

Function of Proteins

• Longer-lasting energy source than carbohydrates because broken down more slowly

• Involved in eyesight, digestion, etc. as well

2.5: Enzymes Enzymes are catalysts for chemical reactions in

living things.

Chemical Reactions • Substances are changed

into different substances by breaking and forming chemical bonds– Reactants are changed to form

products

• Cell growth, reproduction, interaction with the environment, and response to stimuli are the result of a chemical reaction

Reactants Products

Catalysts• Lowers activation energy• Speed up chemical reactions

Activation Energy

• Energy that needs to be absorbed for a chemical reaction to start–Energy reactants need in order to react• Break bonds and form new ones

Rate of Chemical Reactions

• Biochemical reactions must occur at certain speeds, or rates, in order to be useful.

• Rate of a reaction depends on:– Temperature– Concentration of the chemicals– Surface area

Enzymes as Catalysts

• Enzymes are proteins• Makes reactions that happen in cells possible– Lower activation energy and speed up reaction

rate• Without enzymes, many reactions would not

happen– Others would occur too slowly for the organism to

survive• Enzyme will not be used up or changed during

the reaction

Structure of Enzymes• Gives reactants a site where

they can come together to react– Substrates-reactants affected

by enzyme

• Substrates bind to the active site

• Shape of substrate and active site are complimentary, or opposite– Fit together like a lock and key

substrates (reactants)

enzyme

Substrates bind to anenzyme at certain places called active sites.

Lock and Key Model Illustrates how enzymes function

Substrates bind to anenzyme at certain places called active sites.

The enzyme bringssubstrates together and weakens their bonds.

The catalyzed reaction formsa product that is releasedfrom the enzyme.

Structure of Enzymes

• Allows only certain reactants to bind to the enzyme– An organism may have thousands of different

enzymes– Each is specific to one chemical reaction

• An enzyme’s function depends on its structure.

Functions of Enzymes

• Energy-releasing enzymes power cell functions• Enzymes in nerve cells produce

neurotransmitters to carry impulses from nerves to muscles

• Muscle cells have enzymes that are triggered in response to the neurotransmitters

Functions of Enzymes

• Blood contains enzyme carbonic anhydrase– Catalyzes reaction in your blood where carbon

dioxide combines with water to form carbonic acid– Makes reaction one million times faster so that

carbon dioxide does not build up in your blood, which could be fatal

• Enzyme lipase in the pancrease– Speeds up digestion of lipids

Functions of Enzymes

• Disruptions in homeostasis can prevent enzymes from functioning.– Enzymes function best in a small range of

conditions.– Changes in temperature and pH can break

hydrogen bonds.– Destroyed at temperatures above 50˚C– Work best at pH of 7