Transcript Chapter 3 PowerPoint

How are organic compounds different
from inorganic compounds?
 Why is water so important to living
things?
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Inorganic Compounds – derived from
nonliving things
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Organic Compounds – derived from living
things and contain “C” - “H” & “O”
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So, what would water (H2O) be??
A source of hydrogen & some
oxygen
2. A medium for dispersal &
transport
3. Most common solvent
1.
Water’s biological functions stem from its
chemical structure
 In a water molecule the 2 hydrogen
atoms are covalently bonded to the
oxygen atom
 Although electrons are shared, they are
not shared equally
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The oxygen atom has 8 protons in its
nucleus to attract electrons
 The hydrogen atom only has one proton
 The nucleus of the oxygen atom more
strongly pulls the shared electrons
 As a result the electrical charge is
unevenly distributed
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The 3 atoms in a water molecule are not
arranges in a straight line
 The 2 hydrogen atoms bond with the
oxygen atom at an angle
 The total electrical charge on the
molecule is zero
 But the area where oxygen is located is
slightly negative and the areas where
the 2 hydrogens are located are slightly
negative
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Makes water effective at dissolving
many other substances
› Sugars
› Some proteins
› Ionic compounds
**NaCl – ionic compound that dissociates into
Na+ ions and Cl- ions in water.
**Important for essential body functions such
as muscle contraction and the sending of
nerve impulses
Polar water molecules are attracted to
eachother
 A hydrogen bond forms between a
slightly positive H atom in one water
molecule and a slightly negative oxygen
atom in another water molecule
 So, water clings to itself and to other
substances
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Cohesion – attractive force between
particles of the same kind
Water molecules are cohesive
The hydrogen bonds cause water to
act as if it has a skin on its surface
This is called surface tension
Water appears to bulge from the
sides of objects
Adhesion is the attractive force between
unlike substances
 Capillary Action - Adhesion + Cohesion
allows water molecules to move up
through narrow tubes against the force
of gravity
 You can observe the flow of colored
water up through a stem and into a
flower
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 Contain
carbon atoms that are
covalently bonded to other carbon
atoms
 Carbon atoms are usually bonded to
other atoms as well – H, O and N
 The chemistry of carbon is the
chemistry of life
Has four electrons in outer shell:
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It wants to fill its outer shell with 8
electrons
It can form four covalent bonds with itself
or other elements
It can combine in many ways(chains,
branches, and rings)
It can form double or triple bonds
Functional groups – clusters of atoms
attached to the carbon determine the
characteristics of a compound (OH)
Large molecules are built up from smaller
molecules – monomers
 Monomers bond together to form
polymers (larger molecules of repeated,
linked units)
 Large polymers are called
macromolecules
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Monomers link together to form polymers
in a chemical reaction called a
condensation reaction or a dehydration
synthesis reaction
 As the monomers link together, a
molecule of water is released
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The breakdown of a complex molecule
or polymer occurs through a hydrolysis
reaction
 This is the reverse of a condensation
reaction
 Water must be added to separate the
monomers
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Life processes require a constant supply
of energy
 Adenosine triphosphate (ATP) has 3
phosphate groups attached to each
other by covalent bonds
 When bond that holds the last
phosphate group is broken – lots of
energy is given off
 This energy drives the chemical reactions
within each cell
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Complete carbon compounds activity
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Finish for homework if not completed in
class
Why is carbon so commonly bonded to
itself and other atoms?
 What type of reaction results in the
formation of polymers?
 What type of reaction breaks down
polymers?
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THERE ARE “FOUR” DIFFERENT CLASSES OF
ORGANIC COMPOUNDS
› Carbohydrates
› Lipids
› Proteins
› Nucleic Acids
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Organic compounds of C, H and O
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Used as energy sources in cells
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Also found in several cellular structures
such as bacterial capsules
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They are synthesized from water and
carbon dioxide during photosynthesis
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Monosaccharides are the simplest
carbohydrates
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They are the building blocks for the larger
carbohydrates (polysaccharides)
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Glucose, galactose and fructose are
examples of isomers – they have the same
chemical formula C6H12O6
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But their structures and properties are
different
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Represents the basic supply of energy in
the world
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Half of the world’s carbon exists as
glucose
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Double sugars – composed of two
monosaccharides held together by covalent
bonds
They are made from glucose molecules
through dehydration synthesis – water is
removed as the new bonds are formed
Examples are:
› maltose – found in barley and used to ferment beer
› lactose – found in milk and digested by bacteria to
form yogurt, sour cream
› Sucrose – table sugar and is the starting point in wine
fermentation and may be a cause of tooth decay
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Complex sugars
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Large compounds formed by joining
together 100’s or 1000’s of glucose
molecules
› Starch – used by bacteria as an energy
source
› Cellulose – a component of the cell walls of
plants and molds and also used as an
energy source by microorganisms
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What are the 4 classes of organic
compounds?
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What 3 elements are carbohydrates
made up of?
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What carbohydrate is considered a
universal source of energy?
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Dissolve in organic solvents, but not in water
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Like carbohydrates, they are composed of C,
H, and O, but with much less O
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The best known lipids are fats
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Fats are important long-term energy sources for
living things
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Fats are also components of cell membranes
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Fats consist of a 3 carbon glycerol molecule
and up to 3 long-chain fatty acids
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2 major types of fatty acids:
› Saturated – contain the maximum number of
H atoms
› Unsaturated – contain less than the
maximum number of H atoms
› Unsaturated fatty acids are good for us –
they lower the levels of cholesterol in the
blood
What are the facts about saturated fat?
If the carbon atoms (C's) in a fat have all the
hydrogen atoms (H's) that they can hold, the fat is
saturated.
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Other types of lipids:
› Waxes – long chains of fatty acids
 Bee’s wax
 Plant leaves
› Phospholipids – contain a phosphate group
 Cell membranes
› Steroids – composed of several rings of carbon
atoms with side chains
 Cholesterol
 Estrogen
 Testosterone
What are fats used for in your body?
 What is the difference between
saturated and unsaturated fats?
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Most abundant organic compounds of living things
They can be:
› Structural
› Enzymes – regulate the rate of chemical reactions
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They are composed of chains of amino acids
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Each amino acid contains
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Carbon atom
Amino group (NH2)
Carboxyl group (COOH)
Functional (R) group - what makes the 20 AA’s different
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Amino acids are joined together by
peptide bonds
› 2 AA’s – dipeptide
› More than 2 AA’s - polypeptide
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The sequence of amino acids is extremely
important because one mistake changes
the protein (mutations)
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Protein Structure:
› Primary – AA sequence
› Secondary – AA chain twists into a corkscrew or
sheet pattern
› Tertiary – Protein folds back upon itself
› Quaternary – Multi-unit cluster
Enzyme - protein that acts as a catalyst
 They lower the amount of activation
energy needed for a reaction to occur
 Depends on a physical fit between the
enzyme molecule and its substrate (lock
and key)
 As they link, the enzyme changes shape
and some of the substrate's chemical
bonds are weakened
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Insulin – protein that regulates the
metabolism of carbohydrates and fats
 People with diabetes don’t produce
enough insulin
 If we could understand insulin’s structure,
we could make it in the lab as a drug
 Frederick Sanger – broke insulin code;
used chromatography to identify the
kinds and amounts of amino acids
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Some of the largest molecules found in
organisms
› DNA – genetic material in the chromosomes that
carries the genetic code
› RNA – cell messenger that functions in protein
construction
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Composed of nucleotides – 3 parts
› Carbohydrate molecule (ribose or deoxyribose)
› Phosphate group
› Nitrogenous base
 DNA – adenine, guanine, cytosine, thymine
 RNA – adenine, guanine, cytosine, uracil
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DNA is located in the chromosomes of
the cell
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It passes on the genetic information and
directs protein synthesis
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DNA molecule consists of 2 single strands
of DNA in opposite directions arranged
in a double helix ladder:
› Sides of ladder – sugar and phosphate
› Rungs of ladder – paired nitrogenous bases
DNA in the nucleus carries the genetic
code
 DNA gets transcribed into messenger
RNA (mRNA) in the nucleus
 mRNA leaves the nucleus and brings the
code out into the cytoplasm of the cell
 mRNA gets translated into protein with
the help of transfer RNA (tRNA) and
ribosomes
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