Transcript Chapter 2-1 The Nature of Matter

Chapter 2
The Chemistry of Life
Warm-Up
Look at the following words. Place each one in the
table below and define if you think you can.
atom
electron
proton
neutron
nucleus
element
compound
Don’t know the
meaning at all
I think the meaning
is:
I know the meaning
is:
2-1 The Nature of Matter
A. Atom – The basic unit of matter
1. 3 types of subatomic particles in an atom
– a. proton (+ charge)
– b. neutron (no charge)
– c. electron (- charge)
• Protons and neutrons are in the NUCLEUS
• Electrons are in constant motion around the
nucleus.
---Atoms have a neutral charge!--
B. Elements and Isotopes
1. Element - is a pure substance that
consists entirely of one type of atom.
a. Atomic number- number of protons in an
atom (C- Carbon 6)
An atom has the same number of protons and electrons.
2. Isotopes – Atoms of the same element
that differ in the number of neutrons.
a. Mass number- sum of protons and neutrons
b. Isotopes are named by their mass number
3. Radioactive Isotopes
a. Geologists determine age of rocks
b. Radiation for cancer
c. Used as tracers to follow substances in
organisms
C. Chemical Compounds
1. A compound is a combination of two or
more elements in definite proportions
2. Use chemical formula
D. Chemical Bonds
1. Ionic – valence electrons are
transferred (ex: NaCl)
2. Covalent – valence electrons are
shared (ex: H20)
3.Van der Waals Forces – When
molecules are close together they can
develop a slight attraction to the oppositely
charged regions of nearby molecules
Warm-up
• Draw a pH scale. Then place the following
substances on the scale in the appropriate
location according to their pH values.
– Dr. Pepper
– Fantastik cleaner
– Water
Answer:
0
7
Dr.P
water
14
Fantastik
2-2 Properties of Water
A. Characteristics of Water
- It is the single most abundant
compound in most living things
- A water molecule is neutral
1. Polarity – the oxygen end of the
molecule has a slight neg (-) charge and the
hydrogen end has a slight pos(+) charge.
There is an uneven distribution of e- between O and H
2. Hydrogen Bonds - attraction between
the partial positive and the negative
charges of atoms. These bonds are not
as strong as ionic or covalent bonds.
(EX: Water)
a. Cohesion – attraction between
molecules of the same substance
b. Adhesion - attraction between
molecules of different substances.
B. Solutions and Suspensions
1. Mixture – material composed of two or
more mixed compounds that are
physically mixed together but not
chemically combined.
a. Solutions – all components are evenly
distributed (ex: salt water)
1. solute – what is being dissolved
2. solvent – substance in which the
solute dissolves
b. Suspensions – mixture with nondissolved particles (ex: blood)
Questions
• 1. How do you know whether a sample is
a mixture(physical) or a compound
(chemical)?
• Answer: a mixture can easily be separated
into the component parts
• 2. Are solutions only in the liquid state?
• Answer: No, solutions can be solids,
liquids, or gases
C. Acids and Bases
1. pH Scale – indicates the number of H+
ions in a solution. (Ranges from 1-14)
2. Acids – Contain a higher concentration of H+
ions than pure water and pH values below 7
3. Bases – Contain a lower concentration of H+
ions than pure water and pH values above 7.
They also produce OH4. Buffers – weak acids or bases that can react
with strong acids or bases to prevent sharp,
sudden changes in pH
Chapter 2-3 Carbon Compounds
What is a Valence Electron?
What is an Organic Compound?
A. Carbon
1. 4 Valence Electrons
2. Ability to bond with other elements and itself
– millions of structures
3. Compounds containing carbon are
considered ORGANIC
B. Macromolecules – “giant molecules”
1. Connecting monomers to make polymers
2. 4 groups of macromolecules
a. Carbohydrates
i. carbon, hydrogen, oxygen – 1:2:1 ratio
ii. main source of energy for organisms
iii. starch – storage molecule
iv. monosaccharides (ex. Glucose) and
polysaccharides (glycogen and
cellulose)
b. Lipids
i. not soluble in water
ii. fats, oils, and waxes
iii. glycerol + fatty acid
iv. saturated (max # of H bonds) and
unsaturated (at least one double bond=)
c. Nucleic acids
i. H, O, N, C, P
ii. Polymers of nucleotides – sugar,
phosphate, and nitrogen base
iii. Store and transmit hereditary or genetic
information
iv. RNA and DNA
d. Proteins
i. N, C, H, O
ii. Polymers of amino acids
iii.Amino group- NH2 and a carboxyl group
– COOH
iv.Proteins control rate of cell reaction(rxn),
regulate cell processes,
form bones and muscles,
transport into and out of cells, and
some fight diseases
4 levels of organization of proteins
Primary- sequence of amino acids in a
protein chain
Secondary- amino acid within a chain is
twisted or folded
Tertiary- the chain itself is folded
Quaternary- if a protein has more than one
chain
Protein Structure
Chapter 2-4 Chemical Reactions and Enzymes
A. Chemical Reactions – process that changes
one set of chemicals into another set of
chemicals
1. reactants → products
2. breaking of bonds in reactants and forming
new bonds in products
B. Energy in Reactions – released or
absorbed
1. RXNS (reactions) that release energy
are spontaneous – produce heat light
and sound
2. RXNS that absorb energy must have a
source of energy – plants (sunlight) and
animals (food)
3. Activation Energy – energy needed to
get reaction started
Catalyzed vs. Uncatalyzed
Reaction
C. Enzymes – (Proteins)
1. Are biological catalysts
2. Catalyst – speed up RXN by lowering
activation energy
3. Very specific – only one reaction
D. Enzyme Action
1. Enzyme-Substrate Complex
a. substrates – reactants of enzymecatalyzed reactions
b. active site – where substrates bind to
enzyme (lock and key)
• Catalase. It catalyzes the decomposition of
hydrogen peroxide into water and oxygen.
• 2H2O2 -> 2H2O + O2
• One molecule of catalase can break 40 million
molecules of hydrogen peroxide each second
Competitive Inhibition
Competitive inhibition
The necessity for a close, if brief, fit between enzyme and substrate explains the
phenomenon of competitive inhibition.
One of the enzymes needed for the release of energy within the cell is succinic
dehydrogenase. It catalyzes the oxidation (by the removal of two hydrogen atoms) of
succinic acid (a). If one adds malonic acid to cells, or to a test tube mixture of succinic
acid and the enzyme, the action of the enzyme is strongly inhibited. This is because
the structure of malonic acid allows it to bind to the same site on the enzyme (b). But
there is no oxidation so no speedy release of products. The inhibition is called
competitive because if you increase the ratio of succinic to malonic acid in the mixture,
you will gradually restore the rate of catalysis. At a 50:1 ratio, the two molecules
compete on roughly equal terms for the binding (=catalytic) site on the enzyme.
2. Regulation of Enzyme Activity
a. pH values
b. temperature
c. cells regulate - proteins turn
enzymes “on” or “off”
• Feedback Inhibition
• If the product of a series of enzymatic reactions,
e.g., an amino acid, begins to accumulate within
the cell, it may specifically inhibit the action of
the first enzyme involved in its synthesis (red
bar). Thus further production of the enzyme is
halted.