Transcript 2.1 Molecules and Metabolism

Essential idea:
Living organisms control their composition by a
complex web of chemical reactions.
Understandings:
• Molecular biology explains living processes in
terms of the chemical substances involved.
– This is a reductionist approach --(breaking things
down into their component parts)
– This approach has given us insights into whole
organism
– However, this approach is limited because when
components are combined unique and possibly
unpredicatble properties arise (emergent
properties)
Understandings:
• Molecular biology explains living processes in
terms of the chemical substances involved.
–
Below is an example of one chemical reaction that take place in the body,
that is the formation of urea, which the primary constituent of urine
Understandings:
•
Carbon atoms can form four covalent bonds allowing a diversity of stable
compounds to exist.
Matter consists of chemical elements in pure form and
in combinations called compounds
• Organisms are composed of matter
• Matter is anything that takes up space
and has mass
• Matter is made up of elements
Elements and Compounds
• An element is a substance that cannot be
broken down to other substances by chemical
reactions
• A compound is a substance consisting of two
or more elements in a fixed ratio
Sodium
Chlorine
Sodium chloride
An element’s properties
depend on the structure of its atoms
• Each element consists of unique atoms
• An atom is the smallest unit of matter that still
retains the properties of an element
Essential Elements of Life
• About 25 of the 92 elements are essential to
life
• Carbon, hydrogen, oxygen, and nitrogen
make up 99% of living matter
• Most of the remaining 1% consists of calcium,
phosphorus, potassium, iron and sulfur
Organic Compounds
• Organic Compounds are compounds
containing carbon found in living things
– BUT there are exceptions are classified as
NON-organic
• Carbon dioxide (CO2)
• Carbon Monoxide(CO).
• Hydrogen Carbonates (HCO3- )
Overview: Carbon—The Backbone of Biological
Molecules
• Although cells are 70–95% water, the rest consists
mostly of carbon-based compounds
• Carbon is unparalleled in its ability to form large,
complex, and diverse molecules
• Proteins, DNA, carbohydrates, and other
molecules that distinguish living matter are all
composed of carbon compounds
Concept 4.2: Carbon atoms can form diverse
molecules by bonding to four other atoms
• Electron configuration is the key to an atom’s
characteristics
• Electron configuration determines the kinds and number of
bonds an atom will form with other atoms
• Remember the OCTET RULE!! All atoms lose/ gain/ share
electrons so they can get 8 electrons on their outer shell
The Formation of Bonds with Carbon
• With four valence electrons, carbon can form four
covalent bonds with a variety of atoms
• This tetravalence (4 valence electrons) makes
large, complex molecules possible
• In molecules with multiple carbons, each carbon
bonded to four other atoms has a tetrahedral
shape
• However, when two carbon atoms are joined by a
double bond, the molecule has a flat shape
•
In molecules with multiple carbons, each carbon bonded to four other
atoms has a tetrahedral shape
•
However, when two carbon atoms are joined by a double bond, the
molecule has a flat shape
Molecular
Formula
Structural
Formula
Ball-and-Stick
Model
Space-Filling
Model
Molecular Diversity Arising from Carbon Skeleton
Variation
• Carbon chains
form the
skeletons of most
organic
molecules
Ethane
Propane
Butane
2-methylpropane
(commonly called isobutane)
Length
Branching
• Carbon chains
vary in length and
shape
1-Butene
2-Butene
Double bonds
Cyclohexane
Rings
Benzene
Hydrocarbons
• Hydrocarbons are organic molecules consisting
of only carbon and hydrogen
• Many organic molecules, such as fats, have
hydrocarbon components
• Hydrocarbons can undergo reactions that
release a large amount of energy
Combustion of Hydrocarbons
• Hydrocarbons can undergo reactions that
release a large amount of energy
Understandings:
•
Metabolism is the web of all the enzyme-catalysed reactions in a cell or
organism.
–
Enzymes are biologically synthesized proteins that speed up a chemical reaction
without changing/ reacting themselves.
What is an Enzyme?
• globular proteins
• catalysts which speed up biological
reactions
• unchanged by the reaction
• specific to their substrate
• active site is the position on the
enzyme occupied by the
substrate
• affected by temperature and pH
Organization of the Chemistry of Life into
Metabolic Pathways
• A metabolic pathway begins with a specific
molecule and ends with a product
• Each step is catalyzed by a specific enzyme
What is an enzyme animaiton:
http://www.northland.cc.mn.us/biology/biolo
gy1111/animations/enzyme.swf
Understandings:
•
Anabolism is the synthesis of complex molecules from simpler molecules
including the formation of macromolecules from monomers by condensation
reactions.
•
Catabolism is the breakdown of complex molecules into simpler molecules
including the hydrolysis of macromolecules into monomers.
Hydrolysis vs. Condensation
Hydrolysis
Condensation
• Adds water
• Removes water
• Breaks down polymers
into monomers
• Forms new bonds
between monomers
forming polymers
• Catabolic
• Breaks down complex
molecules into simpler
molecules
• Example: Breaks down
starch into glucose
• Anabolic
• Forms more complex
molecules from simpler
ones.
• Example: glucose and
fructose are bonded
together to form sucrose
4 Types of Condensation (dehydration) Reactions
1. Occurs between monosaccharide and forms
disaccharides and polysaccharides
2. Occurs between glycerol and fatty acids and
forms monoglycerides
3. Occurs between monoglycerides and forms diand tri-glycerides
4. Occurs between amino acids and forms
polypeptides (proteins)
Condensation (dehydration) Reaction
in carbohydrates
glucose
glucose
glucose
Fructose
Starch
Sucrose
Condensation reaction of amino acids to form
polypeptides (proteins)
Condensation monoglycerides
4 types of hydrolysis reactions
1. Breakdown of disaccharide or polysaccharides
into monosaccharide
2. Breakdown of monoglycerides into glycerol
and a fatty acid
3. Breakdown of diglycerides and triglycerides
into monoglycerides
4. Breakdown of a polypeptide (protein) into
amino acids.
Hydrolysis of sucrose (dissacharide)
Hydrolysis of Maltose
Hydrolysis of a dipeptide
Understandings
• Life is based on carbon compounds including
carbohydrates, lipids, proteins and nucleic
acids.
Below is the structure of a LIPID
Ester linkage
Fat molecule (triacylglycerol)
Molecular Protein Structure
Carbohydrate structure
Nucleic acid Structure
Skills & Applications
• Application: Urea as an example of a
compound that is produced by living organisms
but can also be artificially synthesized.
• Skill: Drawing molecular diagrams of glucose,
ribose, a saturated fatty acid and a generalized
amino acid.
• Skill: Identification of biochemicals such as
sugars, lipids or amino acids from molecular
diagrams.
Nature of Science
• Falsification of theories—the artificial synthesis
of urea helped to falsify vitalism.