Chemical Compounds of Life
4.1 Organic Compounds
Contain the element carbon
Occur naturally in living things or their products
Some produced in chemistry laboratory
Also contain H, N, O
Do not contain carbon
CO2 ( carbon dioxide )
CaCO3 ( calcium carbonate )
Contained in living organisms
Reactions are complicated
Water – An Important Inorganic Compound
Most important of all
65 % of body
Survive for weeks without food
Biological processes take place only in water
Adhesion and cohesion both play important roles in the transport of water in plants.
Forces help water to rise up through the roots
Cohesion– polar molecule
oxygen end has a partial negative charge
hydrogen end has a partial positive charge
Holds water molecule together
How and why water can store heat?
Protects organisms from damaging changes in temperature
Adhesionattraction between the molecules of one substance and the molecules of another substance
Best solvent – why?
Capillary action or capillarity
Two slides dipped in water
Structure and Types of Organic Compounds
Difference inorganic and organic compounds
Greater size and complexity of many organic compounds
Number of carbon atoms
4 valence electrons
figure 4-4, p. 59
figure 4-5, p. 60
Long chain bonds
Usually double bonds formed
Sometimes triples bonds occur
Four types of organic compounds
Carbohydrates, lipids, nucleic acids, and proteins
Types of Hydrocarbon Bonds
Carbohydrates and Lipids
Carbohydrates – compounds of carbon, hydrogen, and oxygen
Same ratio of H and O as water
2 H for ever 1 O
Simplest carbohydrates are Monosaccharides ( simple sugars )
Figure 4-6, page 61 shows structural formulas for C6H12O6
Glucose, fructose, and galactose all of which have the same chemical formula but different structural formula
Chemical names of sugars always end in – ose
Sugars contain large amounts of energy
Nearly all organisms use glucose as a source of energy
Sugar molecules can be put together by DS.
Synthesis – putting together
Dehydration – removing water
OH group in each molecule of water.
Figure 4-7, page 61.
Living cells DS brought about by action of enzymes ( see p. 68 )
Two simple sugars
A double sugar
Formed by DS
Figure 4.7 is maltose
Several simple sugars joined by DS or long chains of repeating sugars units.
Polymers– large molecules consisting of long chains of repeating sugar units.
Polysaccharides are sugar polymers
Largest polysaccharides may contain hundreds or thousands of sugar units.
Organisms store excess sugar in the form of polysaccharides.
In plants, stored as starch.
In humans, stored in liver as glycogen ( polysaccharide ) sometimes called animal starch
Other polysaccharide types
cellulose found in plants
Chitin makes up shells of insects
Disaccharides and polysaccharides may be broken apart by HYDROLYSIS.
Figure 4.8, page 62
Maltose + water à Glucose + Glucose
Two simple sugar bonds broken and OH groups restored.
In living organisms brought about by different enzymes action.
Are substances that are commonly called fats, oils, and waxes.
Made up of C, H, O
Less O2, less than in carbohydrates.
Lipids serve as reserve energy supply.
Lipids supply twice the amount of energy than the same amount of carbohydrates.
Fats and oils are chemically similar.
Oils remain liquid at room temperature
Plants: oils in seeds
Peanut oil, corn oil, castor oil.
Mammals: fat under skin
Cushions helps stop heat loss
Storage product but, not stored long
Broken down and replaced
Mice – replace about ½ each week.
The Formation of Lipids
Waxes – combination of fatty acids and compounds that are similar to glycerol.
Fats and oils – formed when fatty acids combine with glycerol.
Glycerol is a 3-carbon chain with an OH group bonded to each carbon.
1. A chain of carbon atoms to which hydrogen atoms are bonded
2. Carboxyl group
Consists of 1 carbon bonded to 1 O by a double bond and to an OH group.
See figure 4-9, page 62 and figure 4-10, page 63.
All single bonds
Evidence: found in animal products like butter and meat, increase cholesterol production in the body.
Build up of deposits that harden and narrow arteries.
Heart attack and strokes.
Cholesterol:normally synthesized in the body, mainly in the liver. Is a structural component of nerve tissue and cell membrane. It also is used to make various steriod hormones, including progesterone, testosterone, estradiol, and cortisol. Bile salts are breakdown products of cholesterol.
One or more pairs of carbon atoms in the fatty acid molecules are joined together by a double bond or even a triple bond.
Polyunsaturated – fat that has chains with more than one double or triple bond.
Figure 4-11, page 63.
Can be changed to saturated fats, add a hydrogen. Process called hydrogenation.
Tend to be oils.
Many processed foods contain partially hydrogenated fats.
Found in plant products tend to decrease blood cholesterol levels.
Nucleic Acids and Proteins
Contain P, N, C
Two kinds: both found in nucleus
DNA ( deoxyribonucleic acid )
RNA ( ribonucleic acid )
More information in Chapter 26
The Structure of DNA
Molecule of long chain of repeating nucleotides
has 5-carbon sugar ribose or deoxyribose bonded to PO4 and a nitrogenous base
Only 4 nitrogenous bases in DNA molecule
Adenine, thymine, cytosine, guanine
Adenine is always bonded to a thymine
Cytosine is always bonded to a guanine
Shape of a ladder, figure 4-12a and 12b, page 65
Chain of nucleotides
Each rung consists of 2 bases
Human cell has 3 million pairs of bases
Sequence of the bases acts as codes that determines what protein is made in the cell.
DOUBLE HELIX – coiled and fits in cell
The Structure of RNA
Similar to DNA
One chain or bases
Sugar RNA is ribose
Thymine is replaced by uracil
RNA is involved in protein synthesis
Contains N, C, H, O
Some contain S and P
Numerous range of properties
Makes life possible by its complexity
Found throughout living organisms
cartilage, bones, muscles
Enzymes are proteins
Structural units of proteins
Figure 4-13, page 66.
Are simple compound and consists of
1 carboxyl group ( COOH )
1 amino acid ( NH2 )
1 Hydrogen atom
1 side chain, ( R ) which is different in each amino acid
Glycine, side which is another H
Alanine, side is another CH3
20 amino acids are commonly found as parts of proteins
The Peptide Bond
Figure 4-14, page 66
Peptide : a bond between two amino acids
Resulting Molecule called dipeptide.
Amino acids added to either end of a dipeptide by dehydration synthesis.
polypeptide – long chain of amino acids
All proteins are made up of one or more polypeptides bonded together.
The Structure of Proteins
Linked together in any sequence and in varying lengths
Making different proteins.
Cross-links: creates enormous variety
Smallest protein molecule has about 50 amino acids or about 1000 atoms
The largest over 100,000 amino acids and millions of atoms.
Ordering is difficult
Insulin is the first protein structure
1954 by Frederick Sanger
Noble Prize Winner
Hormone that controls blood-glucose levels.
Technology now, in the present.
Methods to identify structures of proteins is painstaking.
Break molecule into smaller and smaller pieces
Identify the amino acid at the end of each broken section.
STM – scanning tunneling microscope (page.67)
The Importance of Enzymes
Are protein substances necessary for chemical reactions in living cells.
Burning of gasoline
Life chemical reactions are different.
Dozen of steps
Small part of molecule is removed
Small groups of atoms is added
Atoms rearranged in molecules
Steps must occur with great precision and in correct order.
Ordinary temperatures inside cell
Not give off great amounts of heat
Cell will be destroyed
Catalyst and Substrate
Catalyst: a substance that brings about a reaction without being changed itself.
Enzymes are organic catalysts.
Fore each step there is a specific enzyme
Enter a chemical reaction temporarily.
Used again and again.
Made by cells of living organism
Substrate:the substance that an enzyme acts upon.
End in suffix – ase
Rest of name derived from substrate.
Example: maltase, which splits maltose into 2 glucose molecules. ( - ose, sugars )
Protease – breaks down proteins
Lipase – breaks down lipids
Pepsin – made inside cells of stomach wall.
Leaves cells and mixes with food, breaks down proteins in food into simpler substances
How Enzymes Work
Depends on shape.
Active site – on surface of enzyme.
Substrate fits active site
figure 4-15, page 69.
Forms temporary union
Break bonds within substrate molecule
Substrate separated into 2 smaller molecules
Two molecules join, two substrates
Each fit into active site
Key and one lock shape fits only one substrate
Each enzyme can catalyze a reaction only of those substrates
Figure 4-15a, page 69
Enzyme is not a rigid shape
Changes shape slightly
Figure 4-15b, page 69
Grasping a baseball
Factors Affecting Enzyme Action
Small amounts of an enzyme can cause the reaction of large quantities of ___________.
Enzymes enable _____ reactions to take place at normal ___________________.
Enzymes work best at certain ___________.
At still higher _________, however, the _________ itself starts to breakdown. This process is called ____________________.
Each enzyme works best at a certain _____.
The rate of an enzyme-controlled reaction depends on the __________________ of the enzyme and _________________.
Some enzymes need substances called _______________ in order to function.
_________ are organic substances but not _____________.
In the past, it was believed that organic compounds existed only on Earth. Using modern technology, organic compounds, such as methane, have been, detected in the atmosphere of planets and in interstellar clouds of gas. Organic compounds have been found in meteorites.
Many students believe that carbohydrates taste sweet. Although carbohydrates that are classified as sugars usually taste sweet, others such as polysaccharides do not.
Sucrose and lactose are two common disaccharides. Lactose, or milk sugar, is formed from glucose and galactose. Sucrose, or table sugar, is made of glucose and fructose.
Most fatty acids have an even number of carbon atoms.
Stearic acid C18H36O2
Palmitic acid C16H32O2
Oleic acid C18H34O2
Nucleotides are building blocks of nucleic acids.
Enormous variety of proteins can be produced by different combinations of the 20 amino acids.
More Background Information
Many enzyme-catalyzed reactions involve the transformation of energy. Such reactions occur in photosynthesis and cellular respiration. Energy from ATP is used in muscle contraction and active transport processes.
Most of the chemical reactions of living cells will not occur without enzymes. Enzymes increase the rates of reactions they catalyze by at least 1 million times.
Enzymes are highly specific in their actions. Each enzyme catalyzes only one particular reaction, involving specificsubstrates.
Name: Section: Lab Date:
Title: The Effect of Enzyme Concentration on Reaction Rate
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