Transcript 2.3 Carbon-Based Molecules

2.3 Carbon-Based Molecules
KEY CONCEPT
Carbon-based molecules are the foundation of life.
2.3 Carbon-Based Molecules
Carbon atoms have unique bonding properties.
• Carbon forms covalent bonds with up to four other atoms,
including other carbon atoms: building block of life
• Carbon-based molecules have three general types of
structures
– straight chain
– branched chain
– ring
2.3 Carbon-Based Molecules
• Many carbon-based molecules are made of many small
subunits bonded together.
– Monomers are the individual subunits.
– Polymers, large molecules or macromolecules, are
made of many monomers
2.3 Carbon-Based Molecules
Four main types of carbon-based molecules are found in
living things.
• Carbohydrates are made of carbon, hydrogen, and
oxygen, and include sugars and starches
2.3 Carbon-Based Molecules
Four main types of carbon-based molecules are found in
living things.
• Carbohydrates are made of carbon, hydrogen, and
oxygen.
– Monomer is called a
monosaccharide or
simple sugar: glucose
– Disaccharide is TWO
monosaccharide: sucrose
– Polysaccharides include
starches, cellulose, and
glycogen.
2.3 Carbon-Based Molecules
• Function: Carbohydrates can be broken down to
provide energy for cells.
• Function: Some are part of cell structure.
Polymer (starch)
Starch is a polymer of
glucose monomers that
often has a branched
structure.
Polymer (cellulose)
monomer
Cellulose is a polymer
of glucose monomers
that has a straight, rigid
structure
2.3 Carbon-Based Molecules
Four main types of carbon-based molecules are found in
living things.
• Lipids are nonpolar molecules made of carbon,
hydrogen & oxygen & include fats, oils, and cholesterol.
– Many contain carbon chains called fatty acids.
– Fats and oils contain fatty acids bonded to glycerol.
Triglyceride
2.3 Carbon-Based Molecules
• Lipids have several different functions.
– broken down as a source of energy
– make up structure of cell membranes
– used to make hormones
2.3 Carbon-Based Molecules
• Fats and oils have different types of fatty acids.
– Saturated: maximum # of H possible in the chain;
solid animal fats like butter & in meat
– Unsaturated: NOT saturated with H; liquid oils like
plant oils (olive, peanut, corn, etc.)
2.3 Carbon-Based Molecules
• Phospholipids make up all cell membranes.
– Polar phosphate “head”
– Nonpolar fatty acid “tails”
• Cholesterol is a lipid with a ring structure.
– A certain amount of cholesterol is necessary for life
– Hormones: Control stress (e.g. cortisol) and sexual
development (e.g. testosterone & estrogen)
Phospholipid
2.3 Carbon-Based Molecules
Four main types of carbon-based molecules are found in
living things.
• Proteins are polymers of amino acid monomers and are
the most varied of the carbon-based molecules.
– contain carbon, hydrogen, oxygen, nitrogen and
sometimes, sulfur.
2.3 Carbon-Based Molecules
• Proteins are polymers of amino acid monomers.
– Twenty different amino acids are used to build proteins
in organisms. The body can make 12; others come
from foods like meat, beans & nuts.
– Amino acids have similar structure: an amine group
(NH2) and a carboxyl group (COOH) but differ in side
groups, or R groups.
2.3 Carbon-Based Molecules
• Proteins are polymers of amino acid monomers.
– Amino acids form covalent bonds, called peptide
bonds, between C-N
– Amino acids are linked into chains called polypeptides
– A protein is one or more polypeptides
2.3 Carbon-Based Molecules
• Proteins differ in the number and order of amino acids.
– Amino acids interact to give a protein its specific shape
(structure) and, therefore, function (job)
Hemoglo
bin
hydrogen bond
– Incorrect amino acids change a protein’s structure
and function.
2.3 Carbon-Based Molecules
• A protein can have just about any function, depending on
its structure
– Contractile proteins actin and myosin function in
muscle movement
– Hemoglobin is a protein, globin, bonded to a pigment,
heme, which binds & transports oxygen in the body
– Skin, hair & nails contain the protein keratin which
provides structure, strength & water-proofing
– Enzymes are protein catalysts for chemical reactions
in all living things
2.3 Carbon-Based Molecules
Four main types of carbon-based molecules are found in
living things.
• Nucleic acids are polymers of monomers called
nucleotides composed of C, H, O, N and phosphorus (P).
2.3 Carbon-Based Molecules
• Nucleic acids contain the instructions or code to build
proteins.
– Nucleotides are made of a sugar, phosphate
group, and a nitrogen base.
A phosphate group
deoxyribose (sugar)
nitrogen-containing molecule,
called a base
2.3 Carbon-Based Molecules
• Two basic types of nucleic acids
– DNA stores genetic
information
– Basis for genes &
heredity
DNA
– Several kinds of
RNA
RNA molecules
build proteins based
on the DNA code