Download Biomolecules

Biomolecules
Anderson
Spring 2017
College of the Redwoods
Let’s Review
• Atoms – made up of protons, neutrons, and electrons
that have the properties of a chemical element
• Molecules – result of chemical bonding between
electrons of atoms
• Macromolecules – large molecules built from smaller
molecules
• Octet Rule – elements can and want to hold 8 electrons
in their outermost shells (except the 1st ring holds just 2)
• Elements are abbreviated by capital letters: C, O, H
(sometimes 1 capital and 1 lower case, like Cl)
Biological Macromolecules
• Large molecules necessary for life
• Built from smaller organic molecules (organic = contains carbon)
• 4 major classes of biological macromolecules
1.
2.
3.
4.
•
Carbohydrates (sugars)
Lipids (fats/cholesterol)
Proteins
Nucleic acids (DNA)
Mostly carbon-based, but also include hydrogen, oxygen,
nitrogen, phosphorus, sulfur, and a few others
Carbon Bonding
Remember: Carbon has 6 protons, 6 neutrons, and 6 electrons
That means, according to the
Octet Rule, that there are 4
electrons in the outermost
ring
These are called valence
electrons
Therefore, carbon can form 4
covalent bonds with other
atoms/molecules
Simple Carbon Molecules
Remember:
1 dash between molecules
= 2 electron being shared
2 dashes = 4 electrons are
being shared
3 dashes = 6 electrons are
being shared
Scientists like shorthand
Every corner and end of line = Carbon
Carbon can form up to 4 bonds –
carbons not bound to other elements are
bonded with hydrogen
1. Carbohydrates
• Provide energy to the body in the form of starch
and sugars
• Represented by the formula (CH2O)n
• n = number of carbon atoms, n also multiplies H
and O
• The ratio of C:H:O is always 1:2:1
• 3 subtypes: monosaccharide (1 sugar ring),
disaccharide (2 sugar rings) and polysaccharide
(multiple sugar rings)
Monosaccharides
(monomers of carbohydrates)
# carbons range 3 to 6 (trioses, pentoses, and hexoses)
Glucose is most common
C6H12O6
Notice they all have 6
carbons yet they’re
different
These are called isomers
(same chemical formula,
different structurally and
chemically)
Why is glucose so important?
Photosynthesis
6CO2 + 6H2O
carbon
dioxide
light
C6H12O6
water
+ 6O2
sugar
oxygen
Cellular Respiration
C6H12O6
sugar
+ 6O2
oxygen
6CO2 + 6H2O + ATP
carbon
dioxide
water
energy
Disaccharides
• Dehydration (removal of water) of 2 monosaccharides to
covalently bond them together
Common Disaccharides
• Sucrose – table sugar
• Lactose – milk sugar
• Maltose – malt sugar
Polysaccharides
• Long chain of monosaccharides covalently linked
• May be branched or unbranched
• May contain different types of monosaccharides
• They can be very large molecules
Starch
• Stored form of sugars in
plants – plants make glucose,
then store extra as starch,
especially roots and seeds
• Made up of amylose
(unbranched) or amylopectin
(branched), which are glucose
polymers
• Broken down by enzyme
called “amylase” into maltose
(glucose disaccharide)
Glycogen, Cellulose and Chitin
• Glycogen – storage form of glucose in humans and vertebrates
• Animal equivalent to starch (made of monomers of glucose)
• Glycogen is broken down into glucose when glucose levels decrease
• Insulin stimulates the production of glycogen (without insulin, your
blood sugar would increase)
• Cellulose – makes cell walls in plant cells (providing structural
support), also made of glucose monomers
• Cellulose in our digestive system is called dietary fiber, but we can’t
actually digest it.
• Chitin – exoskeleton of arthropods (insects, spiders, crabs)
2. Lipids
• Hydrophobic (water fearing) non-polar molecules
• Mostly carbon-carbon and carbon-hydrogen bonds
• We call these hydrocarbons
• Functions
1.
2.
3.
4.
•
Long-term energy storage for cells (fats)
Insulation from environment (keep animals dry)
Building blocks of many hormones
Important constituent of plasma membrane of cells
Made of fatty acids and glycerol (monomers)
Fats
Glycerol
Saturated with hydrogen (no
double bonds)
Fatty acid tails
Each carbon does not have 2
hydrogens, has double bonds
Fatty acids =
monomers
Phospholipids
• Major constituent of plasma
membranes (phospholipid
bilayer)
• Has both hydrophobic and
hydrophilic regions
Steroids
•
4 linked carbon rings
•
Cholesterol – steroid mainly synthesized in
liver and precursor to many hormones
•
Helps to maintain cell membrane structure
3. Proteins
• One of the most abundant organic molecules in living
things
• Functions of proteins vary from:
•
•
•
•
•
catalyzing reactions (enzymes)
molecule transportation
DNA replication
hormone signaling
and many more
• What makes the functions and structure of proteins so
diverse are the sequence of the 20 chemically different
amino acids
Amino Acids
Monomers that make up proteins
Each has same fundamental structure:
1. Central Carbon
back
2. Amino group (NH2)
bone
3. Carboxyl group (COOH)
4. R group - variable
Amino group
Carboxyl group
To form proteins, amino acids attach
to each other by peptide bonds
The result of peptide bonds is
polypeptide
20 Amino Acids
20 Amino Acids
Amino Acid
3 Letters
1 Letter
Alanine
Ala
A
Arginine
Arg
Asparagine
Amino Acid
3 Letters
1 Letter
Leucine
Leu
L
R
Lysine
Lys
K
Asn
N
Methionine
Met
M
Aspartic acid
Asp
D
Phenylalanine
Phe
F
Cysteine
Cys
C
Proline
Pro
P
Glutamic acid
Gln
Q
Serine
Ser
S
Glutamine
Glu
E
Thrionine
Thr
T
Glycine
Gly
G
Tryptophan
Trp
W
Histidine
His
H
Tyrosine
Tyr
Y
Isoleucine
Ile
I
Valine
Val
V
Protein Structure
• Proteins have different shapes and molecular weights
• Some are globular, some are fibrous in shape
• Sequence of amino acids determines the structure,
the structure determines the function
• There’s an estimated 2 million different types of
proteins in the human body, all made from just 20
amino acids!
How does a protein get it’s shape?
4 Levels of Protein Structure
1. Primary
2. Secondary
3. Tertiary
4. Quaternary
Sequence and number of amino acids
What determines the AA sequence?
Genes (DNA) encode for proteins!
Any change in gene sequence can alter amino acid sequences
Sickle cell anemia
• Hemoglobin β – protein that
binds oxygen in red blood cells
• Has 600 amino acids in protein
sequence
• ONE amino acid substitution
causes red blood cell to form
crescent shape
How does a protein get it’s shape?
4 Levels of Protein Structure
1. Primary
2. Secondary
3. Tertiary
4. Quaternary
Hydrogen bonding of peptide backbone
How does a protein get it’s shape?
4 Levels of Protein Structure
1. Primary
2. Secondary
3. Tertiary
4. Quaternary
3-D folding due to side chain (R group) interactions
How does a protein get it’s shape?
4 Levels of Protein Structure
1. Primary
2. Secondary
3. Tertiary
4. Quaternary
2+ amino acid chains (called subunits)
Denaturation of Proteins
Structure determines function!
• Changes in temperature, pH, or chemical exposure can change
protein shape
• Denaturation = proteins losing their shape
• Can be reversible because amino acid sequence hasn’t changed
• Can be irreversible (can’t refold) which leads to loss of function
4. Nucleic Acids
Carry out genetic blueprint of a cell and carry instructions for
the function of a cell
Two main types:
1. Deoxyribonucleic acid (DNA)
•
Genetic material found in all living organisms
2. Ribonucleic acid (RNA)
•
•
Involved in protein synthesis
Communicator between nucleus of cell and rest of cell
DNA and RNA are made up of monomers called nucleotides
Nucleotides
3 Components of Nucleotides
1. Phosphate group
2. Pentose (5-carbon) sugar
3. Nitrogenous base
•
•
•
•
•
Adenine
Thymine
Cytosine
Guanine
Uracil
Difference between DNA and RNA is the pentose sugar
(and a nitrogenous base)
DNA Backbone
Double Helix Structure of DNA
Socrative Time
Have you been paying attention?!