Download Macromolecules or biological molecules

Biological molecules
04-04-16
Announcements
• Your lab report 1 is due now
• Quiz 1 is on Wednesday at the beginning of class,
so don’t be late
Review
• Macromolecues are large molecules necessary for
life made up of smaller molecules or subunits
• The small subunits that make up macromolecules
are known as monomers
• When monomers combine together (covalent
bonds) they form polymers
• E.g. glucose monomers make up starch, glycogen,
and cellulose
How are polymers formed?
How are polymers broken down?
The four categories of
macromolecules
Carbohydrates
• Made up of carbon, hydrogen, and oxygen
• Provide energy for the short term
• Mainly as glucose
Carb subtypes
• Monosaccharides – simple sugar
• Between 3 and 7 carbons
• Glucose is essential for cell respiration
• Plants synthesize glucose
Carb subtypes
• Disaccharides – two
monosaccharides
together
• Joined by a glycosidic
bond
Carb subtypes
• Polysaccharides
• Long chains of monosaccharides
• Joined by glycosidic bonds
• Storage polysaccharides
• Starch
• Glycogen
• Structural polysaccharides
• Chitin
• Cellulose
Lipids
• Made up mainly of carbon and hydrogen
• Provide energy in the long term
• Functions/major groups:
• Provide energy
• They form waterproof coverings on plant and animal
bodies
• They serve as the primary component of cellular
membranes
• Still others are hormones
• The fat molecules,
the triglyceride, is
made up of three
fatty acids and one
glycerol molecules
Difference between this fatty acid:
and this fatty acid?
More facts about lipids
• Animals store fats in cells known as adipocytes
• Adipose tissue is found under skin, surrounding
internal organs, muscles, etc
• Plants store unsaturated fats and oils in seeds
Essential Fatty Acids (EFA)
• Essential for our development
• Humans cannot synthesize them
• Omega-3 and omega-6 fatty acids
• Humans can synthesize omega-9
• They are all polyunsaturated
• Research indicates that they:
• Reduce the risk of chronic diseases: heart disease, cancer, and
arthritis
• Reduce triglycerides in the blood
• Lower blood pressure
• Reduce inflammation
Three categories
• Oils, fats, and waxes
• Phospholipids
• Steroids containing rings of carbon, hydrogen, and
oxygen
Fats, oils, and waxes
• Oils, fats, and waxes are made of one or more fatty
acid subunits
• Fats and oils are made up of fatty acid chains
esterified to one glycerol molecule
• Energy
• Waxes are made up of long fatty acid chains
esterified to long-chain alcohols
• Insulation
Figure 3-13b Wax
Wax
Phospholipids
• Main component of plasma
membrane
• Made up of
• Glycerol
• Two fatty acid chains
• Phosphate group
• Glycerol and two fatty acids
chains  diacylglycerol
Phospholipids are amphipathic
What Are Lipids?
• Steroids contain four fused carbon rings with
various functional groups protruding from them
• They are structurally different to fats, oils, and waxes
• But they are hydrophobic
• Cholesterol is the
most common
steroid
• Synthesized in liver
• Precursor to
testosterone and
estrogen
• Component of the
plasma membrane
of animal cells
Cholesterol
Estrogen
Testosterone
Proteins
• Proteins are molecules composed of chains
of amino acids
• Most common
• Most diverse
Proteins
• Most diverse
• Proteins have a variety of functions
• Enzymes are proteins that promote specific
chemical reactions
• Structural proteins (e.g., elastin) provide support
• Defense proteins protect us from disease and
venoms
Hair
Horn
Silk
Protein shape related to function
• They have different shapes and molecular weights
• Globular vs fibrous
• Protein shape is critical to its function
• Shape is maintained by chemical bonds
• Changes in temperature, pH, and exposure to
chemicals may lead to permanent changes in the
shape of the protein, leading to loss of function,
known as denaturation
Proteins are polymers
• Proteins are molecules composed of chains of amino acids
• Proteins are polymers of amino acids joined by peptide
bonds
• All amino acids have a similar structure
variable
group (R)
amino
group
carboxylic
acid group
hydrogen
Proteins are polymers
• Amino acids are joined by dehydration synthesis
amino acid
amino
group
dehydration
amino acid synthesis
carboxylic amino
acid group group
peptide
peptide
bond
water
• Twenty amino
acids
• Grouped
according to
chemical
nature of the
side chain or R
group
Questions
• Which categories of amino acid would you expect
to find on the surface of a soluble protein, and
which would you expect to find in the interior?
• Polar or nonpolar? What about charged?
• In membrane proteins, what distribution of amino
acids would you expect to find in a protein
embedded in a lipid bilayer?
Structure of proteins
• A protein can have as many as four levels of
structure
•
•
•
•
Primary structure
Secondary structure
Tertiary structure
Quaternary structure
The four levels of
protein structure
can be observed
in these
illustrations.
The α-helix and βpleated sheet are
secondary
structures of
proteins that
form because of
hydrogen
bonding between
carbonyl and
amino groups in
the peptide
backbone.
The tertiary structure of proteins is determined by a
variety of chemical interactions. These include
hydrophobic interactions, ionic bonding, hydrogen
bonding and disulfide linkages.
Shape and function
• Precise positioning of amino acid R groups leads to
bonds that determine secondary and tertiary
structure
• Disruption of secondary and tertiary bonds leads to
denatured proteins and loss of function
Nucleotides make up nucleic acids
• Nucleotides are the monomers of nucleic acid
chains
• Deoxyribose nucleotides
• Ribose nucleotides
Nucleotides
• All nucleotides are made of three parts
• Phosphate group
• Five-carbon (pentose) sugar
• Nitrogenous base
Nucleic acids
• DNA and RNA, the molecules of heredity, are
nucleic acids
• Nucleic acids are polymers formed by monomers strung
together in long chains by dehydration synthesis
Differences
• DNA and RNA, the molecules of heredity, are
nucleic acids
• There are two types of polymers of nucleic acids
• DNA (deoxyribonucleic acid)
• Double-stranded
• Antiparallel double helix
• RNA (ribonucleic acid)
• Single-stranded
Figure 3-25 Deoxyribonucleic acid
hydrogen
bond
Worksheet for quiz 1