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Bio - Chemistry of Life

Mrs. Abel's notes on the chemistry of life
by

Alicia Abel

on 3 December 2013

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Transcript of Bio - Chemistry of Life

The Chemistry of Life
Atom
the basic unit of all matter
Made of subatomic particles
Protons
Neutrons
Electrons
negatively charged particles
positively charged particles
particles with no charge (neutral)
The Nucleus
contains most of the mass of the atom
contains positive protons and neutral neutrons
has an overall positive charge
The Electron cloud
where electrons orbit around the nucleus
has very little mass
contains negative electrons
has an overall negative charge
Element
A pure substance made of only one type of atom
Elements Commonly Discussed in Biology:
Carbon
Hydrogen
Oxygen
Nitrogen
C
N
H
O
Atoms are identified by how many protons they have (atomic number)
Isotope
Atoms of the same element that have a different number of neutrons
Compound
A substance made of two or more elements chemically combined
Chemical Bonds
Ionic
Covalent
Electrons are transferred from one atom to another
One atom "steals" from another
The atom that loses electrons becomes positive
The atom that gains electrons becomes negative
Electrons are shared between atoms
The attraction between the positive atom and negative atom is an ionic bond
Molecules are made when atoms are joined by covalent bonds
Molecules
Keep an "eye on it" because it steals
Sharing is Caring
Properties of Water
H
O
2
Polarity
The oxygen atom of water is more strongly attracted to electrons
Electrons are more likely to be found near the oxygen
The oxygen end of water has a slightly negative charge
The hydrogen ends of water have a slightly positive charge
When there is an uneven distribution of electrons, the molecule is called polar
Hydrogen bonds
Occur when the more negative oxygen of one water molecule is attracted to the more positive hydrogen of another water molecule
Cohesion
Adhesion
Attraction between molecules of the same substance
Attraction between molecules of different substances
Ex: water will "stick" to itself in drops
Ex: water will "stick" to the sides of a graduated cylinder
(+)
(+)
(-)
(+)
(-)
(+)
(-)
+
0
Because water is polar, it is EXCELLENT at dissolving other materials.
Solutions and Suspensions
Solution
A mixture in which one substance is dissolved in another and the molecules of each are evenly distributed.
Suspension
A mixture in which a substance is evenly distributed as small particles, but not dissolved
Solute - substance being dissolved
Solvent - substance the solute is dissolved in
Ex: In salt water, salt is the solute and water is the solvent
Ex: Blood cells are suspended in your blood plasma. The cells do not dissolve.
pH
The covalent bonds of water sometimes break.
H O
H
OH
+
2
+
-
water
hydrogen ion
hydroxide ion
In pure water, the number of hydrogen ions and hydroxide ions is the same so it is neutral
The pH scale measures the concentration of H ions in a solution.
+
The pH scale ranges from 0 to 14
Acids
Bases
Compounds that will form H ions in a solution
Compounds that will remove H ions from a solution
Have a pH that is LESS than 7
Have a pH that is GREATER than 7
Ex: hydrochloric acid (stomach acid) is a strong acid
Ex: lye is a strong base
+
+
7
0
14
strong acids
weak acids
weak bases
strong bases
neutral
Neutral
Neutral solutions have a pH of 7
Ex: pure water
Buffers
Weak acids or bases that can react with strong bases or acids to prevent a quick change in pH.
Each step on the pH scale represents a factor of ten
A substance with a pH of 5 is 100 times stronger than a substance with a pH of 7
Why we need proteins
What foods high in lipids
Enzyme graph

Carbon Compounds
Besides water, most matter in your body is made of organic compounds.
Organic compounds: contain carbon atoms covalently bonded
Also contain hydrogen and oxygen covalently bonded to carbon
Macromolecules
Giant molecules made of many smaller molecules
Made up of small units called monomers
Monomers are joined together to make polymers
Importance of Water to Life
About 70%-75% of your body is made of water
Water helps transport dissolved molecules and suspended particles
Water is important in many reactions involving energy and heat
Carbohydrates
Lipids
Nucleic Acids
Proteins
Carbon, hydrogen, and oxygen in a 1:2:1 ratio
Used as a source of energy
Monomers: sugar molecules
Monosaccharides - molecules made of one sugar
Polysaccharides - macromolecules made of many monosaccharides.
Ex: Glucose - used by most organisms to produce energy
Ex: Glycogen - used by animals to store excess sugar
Ex: Cellulose: used by plants to give the plant structure and support
Non polar molecules - will not dissolve in polar molecules (water)
Used to store energy, build membranes, make waterproof coverings, insulate
Fats, oils, waxes, steroids
Monomers: fatty acids
Many lipids are made up of three fatty acids bonded to a glycerol molecule.
Bonds between carbons and hydrogens broken to provide great amounts of energy
Saturated fatty acids - all carbons joined by single bonds, so all carbons hold the maxiumum number of hydrogens
High energy, solid at room temperature
Unsaturated fatty acids - some carbons joined by double bonds which makes it so the carbons cannot hold as many hydrogen atoms. Lower energy. Liquid at room temperatuere.
Molecules that carry genetic information
Monomers: nucleotides
DNA, RNA (ATP)
Diverse macromolecules that contain carbon, hydrogen, oxygen, and nitrogen
Monomers: amino acids
There are 20 different amino acids that can make up proteins
Proteins are different depending on the sequence of their amino acids, how the amino acids are twisted or folded into a chain, how the chain is folded
Enzymes - a special type of protein that is used to speed up the rate of a chemical reaction
Used to build body structures, regulate cell processes, transport substances, fight disease, etc.
Mostly carbon and hydrogen atoms
Hydrogen, carbon, oxygen, nitrogen, and phosphorus
-
What causes pH?
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