Download Biochemistry Carbon Compounds

Biochemistry
(Biology, Chapter 3, for Honors Chem summer work)
Carbon Compounds
Section 1
The hundreds of thousands of different molecules in living things are made mostly of just four
different elements: _____________________________________________________.
Of these, ____________ is the one that forms the basic structure, or framework of these
molecules.
Carbon is able to form large and complex molecules, allowing for great diversity of life.
Carbon Bonding
A carbon atom has ____ electrons in its outermost (highest) energy level. Therefore, a carbon
atom readily forms __________________________ with other atoms, resulting in an
enormous variety of organic compounds. By having four “connection points,” molecules made
of carbon can branch out and become very complex.
Even molecules made of just carbon and hydrogen can form a variety of shapes:
Label each shape:
Carbon rings are often simplified by just drawing a pentagon or hexagon.
=
Further variety is achieved by the types of covalent bonds that carbon can form. In a typical
covalent bond, atoms share two electrons (often referred to as one pair of electrons.)
When it shares ______________, it forms a _____________________.
When it shares ______________, it forms a _____________________.
In any combination of single, double & triple bonds, there will always be a total of four bonds
from a single carbon atom.
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Functional Groups
Functional groups are groups of atoms that are found together in the same arrangement so
often, that they are given special names. When a functional group occurs, it gives its molecule
predictable characteristics.
Analogy: If you see a person wearing a suit, carrying a briefcase and
talking on a cellphone while walking down a city street in the business
district, you might conclude he is a business administrator in a large
company. If you see a woman in a long white dress with a veil and carrying
flowers, you can tell she is getting married. In the same way, certain
combinations of elements in a molecule, tell us something about the
molecule.
The Hydroxyl Group
One important functional group is the _____________________, —OH which makes
a molecule __________.
Polar molecules are ______________, (“water-loving“) and are soluble in water.
When found on a simple carbon-based molecule, a hydroxyl group
makes that molecule into an “alcohol.” There are many kinds of alcohols.
One common alcohol is called ethanol, and this is the molecule found in
alcoholic beverages.
More functional groups are presented here. Fill in the missing information from the text.
Common Functional Groups
Name
Structure
Effect on molecule
Examples
(from the molecules on next page.)
Hydroxyl
Carboxyl
Amino
Phosphate
(mildly acidic)
(alkaline)
(acid)
Notes:
• The structure of a functional group is drawn with one bond to the side that does not appear to
be connected to anything. This is to indicate that the functional group is bonded to some larger
molecule. The functional group is not a molecule and it does not exist all by itself.
• A carboxyl group has an —OH as part of its make up. However, this —OH is not a hydroxyl
group. An —OH is only called a hydroxyl group when it is not part of a larger functional group.
• Not all molecules with an —OH are alcohols. For example, sugars such as glucose contain
many —OH, but they are not alcohols.
• A molecule is a three-dimensional object that can be drawn from any angle. Although we
usually write a functional group in one direction, such as —OH, it might be drawn on the other
end of a molecule, such as HO—. Also, the bond between the O and the H might be drawn:
x—O—H. All of these are representations of the hydroxyl group.
• A carboxyl group is sometimes drawn as —COOH, but really the two O branch out in different
directions, as shown in the text.
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Find, circle, & label the functional groups in the molecules below.
Ethanol
A fatty acid, a component of fats.
An amino acid, for making proteins
Glucose, a sugar.
ATP
Butyric acid, a fatty acid
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Large Carbon Molecules
Many large carbon compounds are made from simpler subunits joined together.
monomer:
polymer:
Analogy: if you are building
with Lego blocks, each
individual Lego would be like a
monomer. A stack of Legos or
a wall of Legos, would be like a
polymer.
Monomers
Polymers
macromolecules:
When two monomers bond together, some atoms need to be removed to provide a location
for the new bond. In the molecules of living things, the atoms that are removed are an oxygen
and two hydrogens, which form a molecule of ______________.
condensation reaction (also called dehydration synthesis):
In the diagram above, circle the H from glucose and the –OH from fructose that could be
removed to form H2O (water) when the two monomers are bonded together.
The opposite process happens when large molecules are broken down into monomers. This
happens when we digest our food. For every monomer that breaks apart from the larger
molecule, a water molecule is used from the surrounding environment (instead of created.)
Hydrolysis:
(We are skipping the section called Energy Currency.)
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Molecules of Life
Section 2
There are four main categories of organic compounds essential to living things. They are all
built primarily from carbon, hydrogen and oxygen. These atoms occur in different amounts
and in different arrangements in each category, giving each its own set of unique properties.
You are likely familiar with these names from your knowledge of nutrition.
(We are covering only carbohydrates and proteins. We are not doing Lipids and Nucleic Acids.)
Carbohydrates
(Sugars, starch, and plant fiber are common types of carbohydrates.)
carbohydrates: organic compounds composed of ________________________.
Example: glucose is C6H12O6
Draw a molecule of glucose:
Notes about Names
• Understanding the word origin of a name will help you remember the name and will also
help you remember facts about the topic.
• Look at the word “carbohydrate.”
• The first part of the word comes from “carbon.”
• The second part of the word is “hydrate.” This should make you think of water. You
already know that words like hydration, dehydration and dehydrated have to do with how
much water you have in your body. If you look at the chemical formulas of different
carbohydrates, you will see that the hydrogen (H) and the oxygen (O) are always in a 2:1
ratio, just like in water: H2O
• You will see below that carbohydrates are also called “saccharides.” This name comes
from the Greek word for sugar: saccharum.
Carbohydrates can exist as:
•
______________________: a single subunit (a monomer)
•
______________________: two monomers bonded together
•
______________________: multiple monomers in a longer chain
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Monosaccharides
Monosaccharide:
Chemical formula: usually C6H12O6
These are also called “simple sugars.” The three most common
monosaccharides are: (see diagrams in text)
•
•
•
All have the same chemical formula (
) but _____________________________.
This is a common occurrence in Chemistry. When two substances have the same
chemical formula, but the atoms are arranged differently, the two substances are
called isomers of each other.
isomers: chemical substances with the same chemical formula but different molecular
structures.
Disaccharides
disaccharide: a sugar made of two monosaccharides.
Examples:
Sucrose : this is the typical white sugar that you likely have in your kitchen at home.
Made of the monomers _______________ and ________________. (in textbook.)
Lactose : this is one of the sugars found in milk.
Made of the monomers ______________ and ________________. (research!)
Note that when two monosaccharides bond to form a disaccharide, it is done by the process
of dehydration synthisis.
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Polysaccharides
Polysaccharide : a carbohydrate made of 3 or more monosaccharides.
(Usually made of hundreds or thousands.)
Ex 1: Glycogen
Structure :
Purpose :
Ex 2: Starch
Structure: hundreds of glucose monomers.
Two forms:
§ long coiled chain.
§ Branched chain (similar to glycogen.)
Purpose: storage of glucose in plants, usually in the
fruits, roots, or seeds.
(think of foods that you might already know
are “starchy” such as grains and potatoes.)
Ex 3: Cellulose
Structure: thousands of glucose molecules linked in long
chains. The chains are then further connected to each
other by hydrogen bonding between them, making a
strong rigid structure.
Purpose:
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Proteins
proteins:
• organic compounds composed mainly of…_________________. (what 4 elements)
•
•
polymers, formed from monomers called _____________________.
Examples of proteins:
Amino Acids
There are ______ different amino acids. All have the same basic structure of four different
groups arranged around a central carbon:
1.
2.
3.
4. The “R group.” This is the part that varies among
the 20 amino acids. For example, the diagrams
below show that glycine’s R-group is “H.” And
alanine’s R-group is “-CH3”
Alphabet Analogy: The 26 letters of the English alphabet can be combined in
different ways to make hundreds of thousands of words. Depending on the choice
and order of letters, the words can have different meanings and different functions.
The similar idea with proteins is that each protein is made of a different combination
of the 20 amino acids. The choice and order of the amino acids, and the behavior
of their different R-groups, creates a variety of protein molecules with a wide variety
of functions.
Dipeptides and Polypeptides
dipeptide: two amino acids joined by a covalent bond.
peptide bond:
+ H 2O
Note that when two amino acids bond together, it is by the process of dehydration synthisis.
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polypeptide: a long chain of amino acids (100’s or 1000’s of them) bonded together to make
a protein.
A polypeptide refers simply to the long chain of amino acids, similar to the idea of beads
strung together on a necklace.
The molecule is not officially called a “protein” until the chain folds upon itself to make a threedimensional shape. Certain amino acids in the chain, depending on their R-groups, can make
a second bond with another amino acid at a distant location on the chain, causing the
molecule to be locked into a specific shape. These various shapes are what give each protein
its specific function.
Tool Analogy: many tools are made of the same few materials: steel, with a
wood or plastic handle. Examples are a hammer, screwdriver, pliers, needle,
fork, knife, and a wrench. Although they are all made of the same materials,
they have different functions because of their different shapes.
Functions of proteins: It is impossible to make a simple list of the functions of proteins. There
are thousands of proteins and thousands of functions. As with tools, there are so many
functions because of all the different shapes that can be made. A few are listed here:
• Body structures (hair, horns, skin, nails)
• Muscle movement
• Antibodies that target germs for destruction
• Hemoglobin: carries oxygen in the blood
• Hormones: cause chemical reactions in target cells
• Receptors in the cell membrane: receive the message from a hormone
• Enzymes: their shape creates a mini-environment for another chemical reaction.
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