Download Acids and Bases

Lecture 6
Acids and Bases
& Organic Chemistry
Ozgur Unal
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Remember the polarity of water that can dissolve sugar
and salt.
A substance that contain H might release a hdrogen ion
(H+) because it is attracted to the Oxygen in water.
These substances are called acids.
Example: Hydrochloric acid (HCl)
Substances that release hydroxide ion (OH-) when
dissolved in water are called bases.
Example: Sodium hydroxide (NaOH)
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The concentration of H+ or OH+
determines the strength of an acid
or a base.
The measure of concentration of
these ions in a solution is called pH.
pH values lower than 7 indicates
acids, whereas values higher than 7
indicates bases. Water has a pH of 7.
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The majority of biological processes carried out by cells
occure between pH 6.5 and 7.5.
In order to maintain homeostasis, it is important to
control this pH level.
Buffers are mixtures that can react wit acids or bases to
keep the pH within a particular range.
Your blood contains buffers that keep the pH about 7.4
http://www.mhhe.com/physsci/chemistry/essential
chemistry/flash/buffer12.swf
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Almost all biological molecules contain the element
Carbon ------- > life on Earth is carbon-based.
Organic chemistry is the study of organic compounds –
compounds that contain carbon.
Why is carbon so special?
Carbon has 4 electrons in its
outermost shell, therefore it can form
4 covalent bonds.
Carbon atoms can bond to each other.
There is a variety of important organic compounds that
can be formed thanks to carbon.
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Carbon atoms can be joined to form carbon molecules.
Cells store smaller carbon compounds to build larger
molecules.
Macromolecules are large molecules that are formed by
joining smaller organic molecules together.
Biological macromolecules are organized into four
major categories:
1) Carbohydrates
2) Lipids
3) Proteins
4) Nucleic Acids
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Lecture 7
Biological Macromolecules
Ozgur Unal
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Carbohydrates are composed of hydrogen,
oxygen and carbon in a fixed ratio.
For every carbon atom , there is one oxygen atom and
two hydrogen atoms.
The general formula for carbohydrates is written as
(CH2O)n.
If the value of n ranges from 3 to 7, the molecules are
called sugar or monosaccharides.
Monosaccharides can be linked to form larger molecules
(such as disaccharide and polysaccharide).
Check Figure 6.26!
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Glucose is a monosaccharide
Sucrose (table sugar) and
Lactose (in milk) are disaccharide
Glycogen is a polysaccharide
Carbohydrates are used as
energy stores in a living body.
Excess glucose is stored as
glycogen in the body. When
the body needs energy between
meals, glycogen is broken down
into glucose.
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A carbohydrate, called cellulose, in plants provides structural
support to the plants.
Chitin is a polysaccharide containing nitrogen. It is the main
component in the hard outer shell of shrimp, lobster etc.
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Lipids are molecules made mostly
of carbon and hydrogen that make up the fats, oils and
waxes.
The primary function of lipids is to store energy.
A lipid called triglyceride is a fat if it is solid at room
temperature, an oil if it is liquid at room temperature.
Plant leaves are coated with lipids
called waxes to prevent water loss.
A honeycomb in a beehive
is made of bees
wax.
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The basic structure of a lipid
includes fatty acid tails.
Saturated fats have only single
bonds between the carbon atoms,
therefore no hydrogen atom
can bond to the tail.
Unsaturated fats have at least
one double bond between carbon
atoms, therefore the tail can
accomodate at least one more
hydrogen.
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Phospholipids are responsible for the structure and
function of the cell membrane.
Phospholipids are hydrophobic (meaning they do not
dissolve in water). They act as barriers in biological
membranes.
Steroids are a type of lipid
that include substances such
as hormones and cholesterol
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Proteins make up 15% of your total mass and are
involved in every function in your body.
10,000 different proteins
Structural support
Transport substances
Speed up chemical reactions etc.
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A protein is a compound made of small carbon
compounds called amino acids.
Amino acids are small compounds that are made of
carbon, oxygen, hydrogen and sometimes sulfur.
All amino acids share the same
general structure.
Central carbon
Hydrogen
Amino group (H2N)
Carboxyl group (COOH)
Variable (R)
There are 20 different variable group.
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Amino acids are joined together
to form proteins by covalent
bonds called peptide bonds.
A peptide forms between
the amino group of one
amino acid and the carboxyl
group of another.
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Proteins can have up to four levels of structure.
1- Primary structure: The number
and order of aminoacids
2- Secondary structure: Sequence
of amino acids linked by a hydrogen
bond
3- Tertiary structure: Globular
structure
4- Quarternary structure:
Combining with other proteins
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Nucleic acids are complex macromolecules that store
and transmit genetic information.
Nucleid acids are made of subunits called nucleotides.
Nucleotides are composed of carbon, nitrogen, oxygen,
phosphorus and hydrogen atoms.
Three units:
Phosphate
Nitrogenous base
Ribose sugar
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Two types of nucleic acids found in living organisms.
DNA: Deoxyribonucleic aicd
RNA: Ribonucleic acid
In DNA and RNA, sugar of one nucleotide bonds to the
phosphate of another nucleotide. (Check Figure 6.31)
A nucleotide with 3 phosphate groups is adenosine
triphosphate, ATP.
ATP is used to store
chemical energy that can
be used by cells.
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