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EOC Review
BIOCHEMSITRY/CHEMISTRY OF LIFE
Atoms
Atoms are the basic unit
of matter
Composed of:
Part
Proton
Neutron
Electron
Charge
+ Positive
0 Neutral
- Negative
Location
Nucleus
Nucleus
Circling the
nucleus
In order to be stable
Atoms need 8 valence electrons
To do this they will create bonds!
Covalent Bonds
Between ATOMS – 2
non-metals
Sharing electrons
Strong bond!
Ex: CH4, H2O
Most important in
biology!
◦ Found in the bonds of DNA
Atoms to Ions
Atoms become ions when they lose or gain
electrons (negative charge)
Lose electrons= positive ion - cation
◦ Ex: Na+, K+
Gain electrons= negative ion - anion
◦ Ex: Cl- (chlorine ion), F- (fluorine ion)
Ionic Bonds
Between ATOMS-metal and non-metal
Transferring electrons
Ex: NaCl (salt), KF
Water
One of the most important molecules on Earth!
Universal solvent: dissolves more substances than
other liquids
Helps maintain a stable global temperature
because of its high heat capacity
Ice floats! The solid is less dense than the liquid
It has high surface tension!
Water and Polarity
POLAR
Electrons are unequally
shared
Oxygen atom: more
electronegative, pulls the
electrons away from
hydrogen
O slightly negative (more e-)
H slightly positive (less e-)
Hydrogen
bonds
Hydrogen Bonds
An attractive force between polar
molecules
H atom of one molecule is
attracted to an electronegative
atom of another molecule
(especially, N, F, or O)
Weak bonds
Ex: Water, between the strands of
DNA
Properties of Water
1. Cohesion between water molecules
◦ H2O transport in plants
◦ High surface tension
2. Adhesion between water and other substances
pH
pH: measure of acidity – the amount of H+ ions in a
solution
0 -6 = acidic, 7 = neutral, 8-14 = basic
Acids contain more H+ ions
Bases contain more OH- ions
Changing the pH is exponential 10x
Organic Compounds
Organic Compounds are essential for life!
They are made of carbon and hydrogen backbone
◦ They also contain oxygen
Carbon is able to make 4 bonds which makes it a
variety of structures
All organic compounds are made from CO2 –
converted during photosynthesis!
Is Carbon Dioxide organic? Why or why not?
Organic Compounds
Organic compounds are considered
polymers (chain of identical units) because
they are made of many monomers (single
unit)
Carbohydrates
Monomer: Monosaccharide (simple sugar)
◦ Ex. Glucose
Polymer:
1. Disaccharide: 2 monosaccharide rings joined together
a) Ex: lactose
2. Polysaccharide: macromolecule consisting of simple sugars
a) Starch (plant) & glycogen (animal): store energy
b) Cellulose (plants) and Chitin (fungi): provides structure
Function – immediate energy for the organism and structural
support in plants
Lipids
Monomer: fatty acids
Polymer:
1.
Fats (triglycerides) - Glycerol + 3 fatty acids
a)
b)
Saturated – max # of H’s. Solid.
Unsaturated – have C=C double bonds. Liquid.
2.
Phospholipids - Phosphate group + 2 fatty acids
3.
Steroids – 4 fused rings
1. Cholesterol
2. Hormones
Function – long term energy storage and component of cell membranes and
hormones
Proteins
Monomer: Amino Acid (20 different ones)
Polymer:
◦ Polypeptide – made of amino acids. Bonded by a peptide
bond.
Function:
Shape = function
Make up all tissues, enzymes, muscle tissue, transport
proteins in the cell membrane, hormones, antibodies in the
immune system
Building blocks of our body!
Nucleic Acids
Monomer: nucleotide
Function:
◦ Stores genetic information
Polymer:
◦ DNA and RNA
Found in all living things
What is an enzyme?
A catalytic protein
Speed up chemical reactions
without being used in the reaction.
They lower the Activation Energy
(EA) – the energy required to start a
reaction
5.
Recyclable
and
reusable
4. bind to
specific
substrate;
lock-and-key
fit
1. Lower
activation
energy
2. Speed up
chemical
reactions
ENZYMES
(special
proteins)
Ex: Without
enzymes
digestion would
take weeks
instead of hours
3. Without
them,
reactions
would take a
long time
Enzymes are specific
Substrate : reactant that enzyme acts on
The enzyme binds to its substrate, forming an enzyme-substrate
complex
Active site : region on the enzyme where the substrate binds
Induced fit of a substrate brings chemical groups of the active site into
positions that enhance their ability to catalyze the reaction
Enzyme Activity
An enzyme’s activity can be affected by
◦ General environmental factors, such as temperature and pH
◦ Chemicals that specifically influence the enzyme
Each enzyme has an optimal temperature & pH at which it can function
Even slight changes in pH and temperature can “denature” enzymes
◦ Denature= change the shape of the protein
◦ When the shape is changed, the active site is no longer the same and the
substrate can not fit!
Practice Biochemistry
With a partner or group of 3:
Read the three statements about molecule X and Y
Analyze the evidence about organic molecules
Write a CER about which statement is the best!
*Yes this is for a grade*