Macromolecules

1
Macromolecules

• 4 major classes
• Carbohydrates
• Lipids
• Proteins
• Nucleic acids

2
Carbohydrates

• Serve as fuel and and source of carbon
• They can be small single sugar molecules or long
  chains of single sugar molecules strung together.
• Simple sugars (monosaccharides) ? Complex sugars
  (polysaccharides)

3
Monosaccharides

• Simplest sugars
• Contain carbon, hydrogen, and oxygen
• 121 ratio
• Ex. glucose C6H12O6
• Short life span in cell, either broken down for
  energy or lined through dehydration synthesis to
  form disaccharides or polysaccharides

4
Disaccharides

• Consist of two monosaccharides
• Short-term energy storage
• Sucrose (table sugar glucose fructose)
• Lactose (milk sugar glucose galactose)
• Lactose intolerance?
• When cells need energy these are broken down into
  monosaccharides subunits to release energy

5
LACTOSE INTOLERANCE

• Disaccharides cannot be absorbed through the wall
  of the small intestine.
• Lactose found in milk/dairy products
• In absence of lactase (enzyme), lactose not
  digested.
• Enteric bacteria switch to lactose
• metabolism. Result of fermentation?
• Normal mammalian condition?
• Lactase production declines 90
• within the first 4 years of life.

6
Polysaccharides

• Store energy
• Starch (plants)
• Glycogen (animals)
• Provide support
• Cellulose (plant cell walls)
• Chitin (exoskeleton of insects, spiders, crabs,
  and lobsters, also in fungi cell walls)

7
What Are Carbohydrates?

• Cellulose is the most abundant organic molecule
  on Earth
• Provides cell wall support for all plant cells
• Cellulose is made of long chains of glucose
  subunits
• Like cellulose, starch is made of long chains of
  glucose subunits
• Most animals can digest starch but not cellulose
  (roughage or fiber)

8
Cellulose structure
wood is mostly cellulose
plant cell with cell wall
close-up of cell wall
Hydrogen bondscross-linkingcellulose molecules
CH2OH
CH2OH
H
H
OH
OH
O
O
H
H
H
H
O
OH
H
H
H
OH
H
O
OH
OH
H
H
H
H
O
O
O
H
H
H
H
cellulosefiber
individualcellulosemolecules
bundle ofcellulosemolecules
O
O
Fig. 2-15
H
H
OH
OH
CH2OH
CH2OH
9
Macromolecules

• 4 major classes
• Carbohydrates
• Lipids
• Proteins
• Nucleic acids

10
Lipids

• Large molecules of mostly hydrogen and carbon
• Insoluble in water (hydrophobic)
• 3 major groups
• Fats, oils and waxes
• Phospholipids
• Steroids

11
Lipids Group 1 Oils, fats, and waxes

• Contain only carbon, hydrogen, and oxygen
• Contain one or more fatty acid subunitslong
  chains of C and H with a carboxyl group(COOH)
• They usually do not have a ring structure.

12
Dehydration synthesis

• Fats and oils Called triglycerides
• Form from three fatty acid subunits and one
  molecule of glycerol.
• used for long-term energy storage
• in both plants and animals

13
Saturated vs. Unsaturated
14
Fat Facts

• Functions
• Energy store
• Cushion for organs
• Insulation
• 1 gram of fat stores 2x the energy as a gram of
  starch
• Fats store energy in less weight than
  carbohydrates

15
Energy Storage

• Plants are immobile use starch
• Mobile forms (seed)- use oils
• Animals are mobile - use fats

16
Lipids Group 2. Phospholipids

• They are like oils except one fatty acid is
  replaced by a phosphate group attached to
  glycerol.
• Polar head- water soluble (hydrophilic)
• Fatty acid tails- insoluble in water (hydrophobic)

17
Phospholipid Structure

• Bilayer in cell membranes

18
Lipids Group 3.Steroids

• 4 carbon rings with various functional groups
• Signal Molecules for regulation (many hormones)
• Testosterone
• Estrogen
• Cortisol
• Cholesterol
• Found in cell
• membranes

Cholesterol
19
Macromolecules

• 4 major classes
• Carbohydrates
• Lipids
• Proteins
• Nucleic acids

20
Proteins

• Amino acids are the building blocks of protein
• Unique sequence of amino acids
• Polypeptide chain

21
Three-dimensional shapes give proteins their
functions.
(a) Primary structure Thesequence of amino
acids linkedby peptide bonds
(b) Secondary structureFolding usually
maintainedby hydrogen bonds
leu
H
R
H
C
N
C
N
val
H
C
O
H
C
H
C
lys
N
O
C
N
O
C
lys
H
H
C
C
N
C
N
gly
O
C
O
H
C
H
his
C
N
C
O
N
hydrogenbond
O
C
ala
H
H
C
C
C
N
N
lys
O
C
O
val
C
H
C
(c) Tertiary structure Foldingresults from
bonds withsurrounding water moleculesand
between amino acids
O
N
O
lys
helix
pro
(d) Quaternary structureIndividual polypeptides
are linkedto one another
Fig. 2-24
22
Proteins

• Proteins have many structures, resulting in a
  wide range of functions

23
Functions of proteins

• Some proteins are structural and provide support
  in hair, horns, spider webs, etc.
• Proteins act as enzymes to catalyze many
  biochemical reactions.
• They can act as energy stores.
• They are involved in carrying oxygen around the
  body.
• They are involved in muscle movement.

24
Macromolecules

• 4 major classes
• Carbohydrates
• Lipids
• Proteins
• Nucleic acids

25
Nucleic Acids

• Nucleic acids are long chains of similar, but not
  identical, subunits called nucleotides.
• All nucleotides have three parts.
• A five-carbon sugar (ribose or deoxyribose)
• A phosphate group
• A nitrogen-containing molecule called a base

Figure 3.26
26
Nucleotide chain
base

• Types of nucleotides
• Those that contain the sugar ribose.
• Those that contain the sugar deoxyribose.
• Nucleotides string together in long chains as
  nucleic acids with the phosphate group of one
  nucleotide bonded to the sugar group of another.

sugar
phosphate
Fig. 2-26
27
Nucleic Acids

• DNA (deoxyribonucleic acid)
• Double strand of nucleic acids
• Provides direction for building proteins
• RNA (ribonucleic acid)
• Single strand of nucleic acids

Figure 3.26
28
The reaction shown below?

• hydrolysis.
• dehydration synthesis of a disaccharide.
• synthesis of DNA.
• breakdown of a fat molecule.

29
Glucose is to starch as _______ is to _______.

• oil fat
• chitin lipids
• RNA DNA
• amino acid protein

30
The diagram below illustrates

• the formation of a polysaccharide.
• the four levels of protein structure.
• the breakdown of a nucleic acid.
• the synthesis of a saturated fat.