Chapter 2



Notes: Carbon Compounds

Chapter 2-3 and 2-4

Chemistry of Carbon

1. Carbon can form 4 covalent bonds

2. Carbon can bond with Carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur,

Bonding Symbols

A single bond is signified by a solid line between symbols; shares 2 electrons

A double bond is signified by two solid lines between symbols; shares 4 electrons

A triple bond is signified by three solid lines between symbols; shares 6 electrons

Macromolecules

1. Macromolecules are “Giant molecules”

2. Consist of monomers (smaller units) that join together to form polymers (large molecules of repeating units- monomers- bonded together by covalent bonds

a. The process of bonding monomers together is called polymerization.

b. Synthesizing covalent bonds between the monomers involves losing a water molecule- dehydration, or condensation reaction

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c. Breaking the covalent bond within the polymer to break off a monomer involves breaking a water molecule and inserting its pieces – hydrolysis

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Types of macromolecules

1. carbohydrates

2. lipids

3. nitrogenous bases

4. proteins

Carbohydrates

1. Composition: made of C, H and O atoms

2. Monomer unit: monosaccharides

3. Uses: Main source of energy for organisms, structural purpose in cell membrane, and exoskeleton of insects.

4. Examples:

a. Sugars

1. Monosaccharide = simple sugar compound

2. Dissacharides = two monosaccharides bonded together by a glycosydic bond

b. Starches: Complex carbohydrates that store extra sugar

1. In animals, starch is called glycogen, structural is called chitin

2. In plants, “plant starch”, structural is called cellulose

Lipids

1. Composition: C, H, O atoms

2. Subunits: glycerol and fatty acids

3. Not soluble in water- nonpolar

4. Function: energy storage, main part of cell membrane, hormones

5. Examples: fats, oils, waxes, steroids, cholesterol

6. Types of fatty acids:

a. Unsaturated fatty acids are found in lipids that are liquid at room temperature, C=C bonds

Example: Olive oil

b. Saturated fatty acids are found in lipids that are solids at room temperature, no C=C bonds

Example: Shortening, butter

Proteins

1. Composition: C, H, O, N

2. Uses: structure, storage, transport of other substances, movement, immunity, catalyze reactions, and making chemical reactions happen

3. 4 levels of structure

a. Made of monomers called amino acids, 20 types

b. Same general structure, but different R group

c. Primary- order of amino acids- makes a polypeptide chain

d. Secondary- α-helix or β- pleated sheet

e. Tertiary- 3D structure, interactions along different parts of the amino acid chain

f. Quaternary- interactions between 2 amino acid chains

Nucleic Acids

1. Composition: _C_, _H_, _O_, N_, _P_

2. Uses: store and transmit _genetic information__

3. Two types

a. DNA (deoxyribonucleic acid)

b. RNA (ribonucleic acid)

4. Made of monomers called nucleotides. A nucleotide has three parts:

a. 5-carbon sugar

b. phosphate group

c. nitrogenous base (adenine, guanine, cytosine, thymine, or uracil)

Chemical reaction: A change of one set of chemicals into another.

1. Can be slow or fast

2. Chemical reactions require collisions between molecules

3. Involves changes in chemical bonds

A + B ( C + D

a. Reactants are elements or compounds that enter a chemical reaction.

Bonds are broken in the reactants.

b. Products are elements or compounds that result from a chemical reaction.

Bonds are formed

Chemical Reaction Example: CO2 in the body

1. Cells produce CO2, then blood carries CO2 from cells to lungs (exhale)

Problem: CO2 is not soluble in water.

Solution: A chemical reaction converts CO2 to a soluble compound

2. In blood, CO2 is converted to soluble compound:

CO2 + H2O → H2CO3

3. In the lungs, reaction is reverse to exhale CO2

H2CO3 → CO2 + H2O

Chemical reactions involve energy

1. Breaking and forming chemical bonds requires energy release and absorption.

2. Reactions that release energy can occur spontaneously (but not all do)

a. Energy is released as heat

3. Reactions that absorb energy will not occur without an energy source.

4. What is activation energy? The energy needed to get a reaction started

Some chemical reactions are really slow or require lots of energy and cannot occur on their own.

Endergonic/ Endothermic Reaction Exergonic/ Exothermic Reaction

Enzymes are catalysts.

1. Catalyst: a substance that speeds up the rate of a chemical reaction by lowering the activation energy of the reaction.

a. An enzyme is a protein that act as biological catalysts

b. Enzymes speed up reactions that take place in cells

c. Enzymes provides a site (activation site) where reactants can be

brought together to react. This decreases the activation energy

d. Substrate” the reactants in a reaction involving an enzyme

e. Enzymes can be reused, but can only have one type of substrate

f. The enzyme-substrate relationship is like that of a “lock and key”

g. Enzymes can have an allosteric inhibitor in which another molecule can turn the enzyme on or off by binding to it (make the key work or not)

h. Enzymes can be affected by:

1. pH

2. Temperature

3. Other Proteins

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