Transcript 2.3 Carbon-Based Molecules

2.3 Carbon-Based Molecules
2.3 Carbon Based Molecules
What are carbon-based molecules and
why are they so important to life?
2.3 Carbon-Based Molecules
KEY CONCEPT
Carbon-based molecules are the foundation of life.
•
•
Carbon atoms (symbolized by “C”) are the “building
blocks of life because most life on Earth is “carbonbased”.
Carbon atoms are the basis for the molecules that
make up all living things on Earth.
- Molecules that contain carbon are called organic
molecules.
2.3 Carbon-Based Molecules
Which of the following is considered an organic molecule?
A.
B.
C.
D.
E.
F.
H2O
CO2
H2
CaPO4
NaCl
[Option 2]
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Carbon atoms have unique bonding properties.
• Carbon atoms are special because they can form bonds
with up to four other atoms, including other carbon atoms.
• Carbon-based molecules have three general types of
structures.
– straight chain
– branched chain
– ring (will always have carbon in the corners)
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• Carbon chains can bond with other carbon chains or
rings to make very long, complex molecules.
• Many carbon-based molecules are made of many small
subunits bonded together.
– Monomers are the individual subunits.
– Polymers are made of many monomers.
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• All monomers in a polymer can be the same, as in starch,
or they can be different as they are in proteins.
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The picture is an example of which type of carbon-based
monomer?
A. Chain
B. Branched
C. Ring
2.3 Carbon-Based Molecules
Four main types of carbon-based molecules are found in
living things.
1. Carbohydrates are molecules made of carbon,
hydrogen, and oxygen.
– They include sugars and starches
– Are found in fruits and grains
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• The most basic carbohydrates are called
monosaccharides, or simple sugars.
– Usually contain 5 or 6 carbon atoms.
– Ex:
- Fructose (found in fruits)
- Glucose (found in plants)
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• Many monosaccharides can be combined together to form
polysaccharides.
– Ex. Two sugars bonded together form table sugar.
– Polysaccharides include
starches, cellulose, and
glycogen.
Polymer (starch)
Polymer (cellulose)
monomer
Starch is a polymer
of glucose
monomers that often
has a branched
structure.
Cellulose is a
polymer of glucose
monomers that has
a straight, rigid
structure
2.3 Carbon-Based Molecules
• Starches are made by plants and are broken down to
provide energy for plant cells. It is also eaten by other
animals.
• Cellulose is a part of plant cell structure. It makes up the
tough, stringy part of plants
2.3 Carbon-Based Molecules
2. Lipids are nonpolar molecules that include fats, oils, and
cholesterol.
– fatty acids are the chains of carbon bonded to
hydrogen atoms that make up lipids
– Fats and oils contain fatty acids bonded to glycerol.
Triglyceride
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• Fats and oils have different types of fatty acids.
– saturated fatty acids
– unsaturated fatty acids
- Monounsaturated
- Polyunsaturated
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• saturated fatty acids
– Each carbon atom s attached to two carbon
atoms and two hydrogen atoms
– They form a straight chain that is easily
stacked in your blood stream.
– Can cause blockages.
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• unsaturated fatty acids
– Carbon atoms are not saturated with
hydrogen atoms.
– Some form double bonds with another
carbon instead.
– This causes a “kink” in the chain and makes
the fat less likely to stack and block.
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Polyunsaturated fats have more double bonds
and kinks than monounsaturated fats. This means
that they are even less likely to stack than
monounsaturated fats.
2.3 Carbon-Based Molecules
Which type of fat would you want to avoid most?
A. Polyunsaturated fat
B. Saturated fat
C. Monounsaturated fat
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• Lipids have several different functions.
– broken down as a source of energy
– make up cell membranes
– used to make hormones
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• Phospholipids make up all cell membranes.
– “head” is polar and made of a phosphate group
– “tails” are nonpolar fatty acids
Phospholipid
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• Phospholipids naturally come together in the
arrangement seen below to make up our cell membranes
(the boundary that protects our cells)
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3. Proteins are polymers of amino acid monomers.
– Amino acids are molecules that contain carbon,
hydrogen, oxygen, nitrogen, and sometimes sulfur.
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• Twenty different amino acids are used to build proteins in
organisms.
– All amino acids have similar structures.
– Each amino acid monomer has a carbon that is
bonded to four other parts. Three of these parts are
the same in ALL amino acids:
- A hydrogen atom
- An amino group (NH2- a part that contains nitrogen (N))
- And a carboxyl group (COOH)
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• Amino acids differ only in side groups, or R groups.
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• Amino acids are linked by peptide bonds.
– The bonds form between the amino group of one amino
acid and the carboxyl group of another amino acid
• Through peptide bonds, amino acids are linked in chains
called polypeptides (a chain of amino acids)
• A protein is one or more polypeptides.
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• Proteins differ in the number and order of amino acids.
This gives a protein its structure and function.
Hemoglobin
hydrogen bond
– Incorrect amino acids change a protein’s structure
and function.
- One wrong amino acid of the 574 in hemoglobin causes
sickle cell anemia
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Proteins are polymers made of monomers of
A.
B.
C.
D.
Nucleotides
Fatty acids
Sugars
Amino acids
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4. Nucleic Acids
• Nucleotides are made of a sugar, phosphate group,
and a nitrogen base.
A phosphate group
deoxyribose (sugar)
nitrogen-containing molecule,
called a base
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Nucleic acids are polymers of nucleotides (many
nucleotides come together to make a nucleic acid)
• There are two general types of nucleic acids:
– DNA
– RNA
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– DNA stores genetic
information.
DNA
– RNA builds proteins. RNA
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• Carbohydrates, lipids, and proteins have large numbers
of structures and functions.
• In contrast, nucleic acids have one function: to work
together to make proteins
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What are the four main groups of organic molecules?
A.
B.
C.
D.
carbohydrates, nucleotides, fatty acids, and amino acids
proteins, lipids, carbohydrates, and nucleotides
lipids, nucleic acids, carbohydrates, and proteins
nucleic acids, saccharides, proteins, and lipids
2.3 Carbon-Based Molecules
Lipids are polymers made of monomers of
A.
B.
C.
D.
Nucleotides
Fatty acids
Sugars
Amino acids
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Peptide bonds hold these monomers together in chains
A.
B.
C.
D.
Nucleic acids
Fatty acids
Sugars
Amino acids
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These are made of one or more polypeptides
A.
B.
C.
D.
Proteins
Lipids
Carbohydrates
Nucleic acids