Download Organic compounds

Organic Compounds
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ORGANIC COMPOUNDS

A cell is mostly water.

The rest of the cell consists mainly of carbon-based molecules.

Carbon forms large, complex, and diverse molecules necessary
for life’s functions.

Organic compounds are carbon-based molecules.
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Carbon Chemistry

Carbon is a versatile atom.

It has four electrons in an outer shell that holds eight.

Carbon can share its electrons with other atoms to form up to four
covalent bonds.
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Form & Function of Organic Molecules

Each type of organic molecule has a unique three-dimensional
shape.

The shapes of organic molecules relate to their functions.
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Properties of Organic Compounds

The unique properties of an organic compound depend on
Its carbon skeleton
 The atoms attached to the skeleton


The groups of atoms that usually participate in chemical
reactions are called functional groups. Two common
examples are
Hydroxyl groups (-OH)
 Carboxyl groups (C=O)

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Giant Molecules from Smaller Building Blocks

Organic macromolecules are large polymers.

Three categories of macromolecules are
Carbohydrates
 Proteins
 Nucleic acids

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Polymer Formation


Polymers are made by stringing together many smaller
molecules called monomers.
A dehydration reaction
Links two monomers together
 Removes a molecule of water

Short polymer
Monomer
Dehydration
reaction
Longer polymer
a Building a polymer chain
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Breaking up Polymers

Organisms also have to break down macromolecules.

Hydrolysis
Breaks bonds between monomers
 Adds a molecule of water
 Reverses the dehydration reaction

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LARGE BIOLOGICAL MOLECULES

There are four categories of large molecules in cells:
Carbohydrates
 Lipids
 Proteins
 Nucleic acids

 Lipid is the only large molecule that isn’t also a
macromolecule
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Carbohydrates

Carbohydrates are sugars or sugar polymers. They include
Small sugar molecules in soft drinks
 Long starch molecules in pasta and potatoes

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Monosaccharides

Monosaccharides are simple sugars that cannot be broken
down by hydrolysis into smaller sugars.

Glucose and fructose are both monosaccharides

Monosaccharides are the main fuels for cellular work.
In aqueous solutions, many monosaccharides form rings.

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Disaccharides

A disaccharide is
A double sugar
 Constructed from two monosaccharides
 Formed by a dehydration reaction

Glucose
Galactose
Lactose
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Polysaccharides
Complex carbohydrates

Made of long chains of sugar units and polymers of
monosaccharides
Glucose
monomer
Starch granules
a Starch
Glycogen
granules
b Glycogen
Cellulose fibril
Cellulose
molecules
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c Cellulose
Carbohydrates (cont.)

Monosaccharides and disaccharides dissolve readily in water.

Cellulose does not dissolve readily in water.

Almost all carbohydrates are hydrophilic, or “water-loving,”
adhering water to their surface.
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Lipids

Lipids are


Neither macromolecules nor polymers, but they are large
molecules
Hydrophobic, unable to
mix with water
Oil (hydrophobic)
Vinegar (hydrophilic)
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Lipid Family
 The lipid family contains of:
1. Fatty acids
2. Triglycerides ( fats and oils )
3. Phospholipids
4. Steroids ( Cholesterol, Bile Salts, Vit. D,
Adrenocortical hormones, Sex hormones )
5. Eicosanoids ( prostaglandins and leukotrienes )
6. Others ( Carotenes, Vit. E, Vit. K, Lipoproteins )
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Fats or Triglycerides

A typical triglyceride, consists of a glycerol molecule joined
with three fatty acid molecules via a dehydration reaction.
Fatty acid
Glycerol
(a) A dehydration reaction linking a fatty acid to glycerol
(b) A fat molecule with a glycerol “head” and three
energy-rich hydrocarbon fatty acid “tails”
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Triglycerides
 Triglycerides : the most plentiful lipid in your body.
It consists of two types of building blocks:


a single three-carbon glycerol molecule and
three fatty acid molecules.
 It can be either solid (fat) or liquids (oil).
 It's functions in the human body are for protection,
insulation, and energy storage.
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Steroids
Steroids : the structure of steroids differ from triglycerides, they
have four rings of carbon atoms.
Steroids are synthesized from cholesterol.
Functions :
1. Cholesterol : minor component of cell membranes, precursor
of other steroids
2. Bile Salts : digests dietary lipid
3. Adrenocortical Hormones : regulate metabolism, resistance to
stress, have a role in salt and water balance
4. Sex hormones : stimulate reproductive functions and sexual
characteristics
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Steroids

Steroids are very different from fats in structure and
function.
The carbon skeleton is bent to form four fused rings.
 Steroids vary in the functional groups attached to this core set of
rings.

– Cholesterol is
• A key component of cell membranes
• The “base steroid” from which your body produces
other steroids, such as estrogen and testosterone
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Cholesterol
Testosterone
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A type of estrogen
Proteins
Are polymers constructed from amino acid monomers
 Perform most of the tasks the body needs to function
 Form enzymes, chemicals that change the rate of a chemical
reaction without being changed in the process

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The Monomers of Proteins: Amino Acids

All proteins are constructed
from a common set of 20
kinds of amino acids.

Each amino acid consists of
a central carbon atom
bonded to four covalent
partners in which three of
those attachment groups are
common to all amino acids.

Peptide bonds link amino
acids together to form
proteins
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Protein Structure & Function



The structure of a protein is vital to its function.
Proteins differ in their arrangement of amino acids.
The specific sequence of amino acids in a protein is its
primary structure.
A slight change in
the primary
structure of a
protein affects its
ability to function.
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Protein Structure & Function

A protein’s three-dimensional shape
Recognizes and binds to another molecule
 Enables the protein to carry out its specific function in a cell

Target
Protein
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Protein Shape

A functional protein consists of one or more polypeptide
chains, precisely folded and coiled into a molecule of unique
shape.
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Nucleic Acids

Nucleic acids
Are macromolecules that provide the directions for building
proteins
 Include DNA and RNA
 Are the genetic material that organisms inherit from their parents

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Nucleic Acids

DNA resides in cells in long
fibers called chromosomes.

A gene is a specific stretch
of DNA that programs the
amino acid sequence of a
polypeptide.

The chemical code of DNA
must be translated from
“nucleic acid language” to
“protein language.”
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Nucleotides


Nucleic acids are polymers of nucleotides.
Each nucleotide has three parts:



A five-carbon sugar
A phosphate group
A nitrogenous base
Nitrogenous base
A, G, C, or T
Thymine T
Phosphate
group
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Sugar
deoxyribose
a Atomic structure
Nucleotides

Each DNA nucleotide has one of the following bases:
Adenine (A)
 Guanine (G)
 Thymine (T)
 Cytosine (C)

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Sugar-phosphate
backbone
Base
Nucleotide
pair
Hydrogen
bond
Bases
a DNA strand
polynucleotide
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b Double helix
two polynucleotide strands
DNA Structure
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

Two strands of DNA join together to form a double helix.
Bases along one DNA strand hydrogen-bond to bases along the
other strand.
The functional groups hanging off the base determine which
bases pair up:
A only pairs with T.
 G can only pair with C.

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RNA

RNA, ribonucleic acid, is different
from DNA.
RNA is usually single-stranded but DNA
usually exists as a double helix.
 RNA uses the sugar ribose and the base
uracil (U) instead of thymine (T).

Nitrogenous base
A, G, C, or U
Uracil U
Phosphate
group
Sugar ribose
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