THE MOLECULES OF LIFE

Chapter 2 (chapter 5 in the book)

Like all matter, life is built from atoms — the basic units of matter that link together to form molecules.

Organic molecules are the molecules of life and are built around chains of carbon atoms that are often quite long.

There are four main groups of organic molecules that combine to build cells and their parts: carbohydrates, proteins, lipids, and nucleic acids.

Definition

CARBON IS THE MAIN INGREDIENT

OF ORGANIC MOLECULES

2.1 Concept

Carbon based molecules are called organic molecules.

Non-carbon based molecules—

water, oxygen, and ammonia are inorganic molecules.

ORGANIC vs. INORGANIC

2.1.1 Atomic Structure of Carbon

Carbon has 4 electrons in outer shell.

Carbon can form covalent bonds with as many as 4 other atoms (elements).

Usually with C, H, O or N.

Example:CH4(methane)

Two or more atoms held together by

covalent bonds.

# and types of atoms in a molecule

# and types of atoms in a molecule

How atoms are linked by bonds

review MOLECULES STRUCTURE

Atoms and complexes connected by non-covalent bonds such as hydrogen bonds or ionic bonds are generally not considered single molecules

Types of carbon backbones:

- A) straight chain

- B) branched chain

- C) can form ring structures

2.1.2 CARBON BACKBONES(SKELETONS)

CARBON SKELETONS

Group of atoms within molecules—determine properties of organic molecules

React in predictable ways with other molecules

Hydrophilic molecules: molecules that are attracted water

Hydrophobic molecules: molecules that do not mix with water

2.1.3 FUNCTIONAL GROUPS

4 most common functional groups:

1) hydroxyl group: (OH)

2) carbonyl group: (C=O)

3) carboxyl group: (O=C-OH)

4) amino group: (H-N-H)

2.1.3 FUNCTIONAL GROUPS

Most biological molecules are large and are made up of smaller subunits

Monomer: molecular subunit that is building block of a larger molecule

Polymer: long chain of monomers

2.1.4 MONOMERS & POLYMERS

Also called condensation reaction Links monomers together forming

polymers or making polymer chains longer

Water molecule is removed in forming a polymer or making it longer

Same type of reaction occurs regardless of type of monomers being linked or type of polymer produced

2.1.5 DEHYDRATION REACTION

2.1.5 DEHYDRATION REACTION

Chemical reaction where polymers are broken down to their monomers

Large polymers must be broken down to make monomers available to cells

Hydrolysis breaks the chemical bonds in polymers by adding water molecules reverse of dehydration/condensation

2.1.6 HYDROLYSIS REACTION

2.1.6 HYDROLYSIS REACTION

http--faculty.pingry.org-thata-pingry_upload-movies-water_macromolecules-condensation.mov.url

DEHYDRATION & HYDROLYSIS

Short polymer MonomerHydrolysis

Dehydration

Longer polymer

Summary:

Dehydration: water is removed to build a polymer

Hydrolysis: Water is added to break down a polymer

DEHYDRATION vs. HYDROLYSIS

CARBOHYDRATES PROVIDE FUEL AND BUILDING

MATERIAL

CONCEPT 2.2

Sugars contain carbon, hydrogen, and oxygen in the following ratio:

1 carbon : 2 hydrogen : 1 oxygen

Molecular formula of any carbohydrate is a multiple of the basic formula CH2O

2.2.1 CARBOHYDRATES ARE MADE UP OF SUGAR MOLECULES

Main fuel supply for cellular work

Other uses: - Provide raw material to make other organic molecules such as fats

- Used to make energy stockpiles

- Serve as building materials

2.2.2 HOW CELLS USE SUGARS

Sugars that contain just one sugar unit or monomer

Examples: - glucose - fructose - galactose

2.2.3 MONOSACCHARIDES

“double sugars”

Produced in dehydration reactions from two monosaccharides

Most common disaccharide is sucrose – table sugar—formed by linking glucose and fructose molecules

2.2.3 DISACCHARIDES

3 common types all glucose polymers:

Starch: found in plant cells—glucose storage molecule

Glycogen: found in animal cells—glucose storage—abundant in muscle and liver cells

Cellulose: used by plant cells for building material—makes up cell walls—not digestible by humans forms “bulk” in our diet

2.2.4 POLYSACCHARIDES

2.2.5 POLYSACCHARIDES

LIPIDS INCLUDE FATS AND STEROIDS

CONCEPT 2.3

Commonly known as fats and oils

Are hydrophobic do not mix with water

Simplest fats are triglycerides

Chain of 3 fatty acids (hydrocarbon molecules) bonded to a glycerol molecule

LIPIDS

http--faculty.pingry.org-thata-pingry_upload-movies-water_macromolecules-triglyceride.mov.url

TRIGLYCERIDE: SIMPLE LIPID

Act as a boundary—they are a major component of cell membranes

Circulate in the body acting as chemical signals to cells—some are hormones

Used to store energy in the body

Act to cushion and insulate the body

FUNCTIONS OF LIPIDS

All the carbon atoms in fatty acid chains contain only single bonds

Include animal fats such as butter

Solids at room temperature

SATURATED FATS

Have at least one double bond between the carbon atoms in one of the fatty acid chains

Found in fruits, vegetables, fish, corn oil, olive oil, and other vegetable oils

Liquids at room temperature

UNSATURATED FATS

SATURATED vs. UNSATURATED

Carbon skeleton forms four fused rings

Classified as lipids are hydrophobic

Some act as chemical signals or hormones estrogen and testosterone

Some form structural components of cells cholesterol

STEROIDS

EXAMPLES OF STEROIDS

Essential molecule found in all cell membranes

Serves as base molecule from which other steroids are produced

Has bad reputation cholesterol containing substances in blood are linked to cardiovascular disease

CHOLESTEROL

PROTEINS PERFORM

MOST FUNCTIONS IN

CELLS

CONCEPT 2.4

Form structures—hair, fur, muscles

Provide long-term nutrient storage

Circulate and defend the body against microorganisms (antibodies)

Act as chemical signals—hormones

Help control chemical reactions in cells--enzymes

FUNCTIONS OF PROTEINS

Polymers formed from monomers called amino acids

Amino acids bond together to form chains called a polypeptides

Sequence of amino acids makes each polypeptide unique

Each protein is composed of one or more polypeptides

PROTEIN STRUCTURE

AMINO ACID STRUCTURE

Figure 5-12: All amino acids consist of a central carbon bonded to an amino group, a carboxyl group, and a hydrogen atom. The fourth bond is with a unique side group – called the “R” group. Differences in side groups convey different properties to each amino acid.

Functional proteins consist of precisely twisted, coiled, and shaped polypeptides

Proteins cannot function correctly if shape is altered

Sequence and types of amino acids in the polypeptides affect protein shape

Surrounding environment—usually aqueous—plays a role in protein shape

PROTEIN SHAPE

Denaturation: loss of normal protein shape

Changes in temperature, pH, or other environmental conditions may cause proteins to become denatured

If the protein shape is changed, protein cannot function normally

DENATURATION

ENZYMES ARE PROTEINS THAT

SPEED UP SPECIFIC

REACTIONS IN CELLS

CONCEPT 2.5

Activation energy: minimum energy required to start chemical reaction

Chemical bonds in reactants must be weakened to start most reactions

Catalysts: compounds that speed up chemical reactions

Enzymes: proteins that act as catalysts for chemical reactions in organisms

ACTIVATION ENERGY

Provide a way for reactions to occur at cell’s normal temperature

Enzymes lower energy requirement for a chemical reactions in cells so they can occur at normal cell temperatures

Each enzyme catalyzes a specific kind of chemical reaction

ENZYMES

Substrate: specific reactant acted on by an enzyme

Active site: specific region of the enzyme that the substrate fits into

Substrate binds to enzyme’s active site where the substrate undergoes a change

HOW ENZYMES WORK

Shape of an enzyme fits the shape of only specific reactant molecules

As substrate enters, active site of enzyme changes slightly to form snug attachment

Attachment weakens chemical bonds in substrate lowering activation energy required for reaction to proceed

HOW ENZYMES WORK

ACTIVE SITE MODEL

Once products of chemical reaction are released, enzyme’s active site is ready to accept another reactant molecule

Recycling is a key characteristic of enzymes—they are not “used up” catalyzing a single reaction

HOW ENZYMES WORK

HOW ENZYMES WORK

Enzyme Activity.url

THE END