Organic Molecules - The Building Blocks of Life

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Organic Molecules- The Building Blocks of Life
Chapter 3 Biochemistry
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I. What is an Organic Compound?

• Contains carbon atoms
• Built from carbon (C), hydrogen (H) and nitrogen
  (N)- Covalently Bonded

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Where is Carbon on the Periodic Table?
It forms 4 covalent bonds
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Carbon has 4 electrons in its outmost electron
shell.

• it forms 4 covalent bonds

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Carbon bonds Chains, Branched, RingsEach line
represents a single covalent bond
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Carbon also forms double triple bonds
A good site for more explanation
www.biologyjunction.com
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Methane - the simplest carbon compound- 1
Carbon 4 hydrogen atoms
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Other simple organic molecules

• Butane cyclohexane

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B. Functional groups
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Functional Groups - A specific group of atoms
that gives a known type of behavior to molecules
changes the characteristics of the compound-
(See page 52 in your textbook for more on
functional groups)
Hydrocarbons - C and H only Alcohols
- OH Acids - COOH Amines
- NH2
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Example -adding a hydroxyl group makes ethane
into an alcohol-

• Example - adding an amino group
• - makes methane or ethane into- an amine

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C. Sizes of Molecules

• 1. Monomers- small simple molecules
• 2. Polymers- big molecules formed when monomers
  bonded to each other

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3. Reactions to build or break down molecules

• Condensation Reaction
• 2 monomers join together- a water is released
• (an H from 1 end and an OH from the other
• end are cut loose when the monomers join.)
• Hydrolysis Reaction
• polymers are broken back down- they need a water
  added.

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Hydrolysis of sucrose
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D. Energy from ATP

• Life needs a constant supply of energy
• Chemical bonds store energy.
• One molecule that living things use to store
  energy is in the bonds of the ATP molecule
• Adenosine Triphosphate

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Adenosine Triphosphate
                                             
       
Blue ribose (a 5-carbon sugar)
Green adenine (a nitrogenous base)
Yellow phosphate groups Energy is stored in
bonds joining the phosphate groups
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ATP-ADP Cycle.
Energy is stored in ATP (ADP P) Energy is used
as needed ATP is converted back to ADP
phosphate.
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4 Classes of Organic Molecules

• Carbohydrates
• Proteins
• Lipids
• Nucleic Acids

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Monomers Polymers

• Each group has small molecules (monomers)
• linked to form larger macromolecules
• (polymers) three to millions of subunits.

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• Carbohydrates
• the most important energy source for cells
• short-term energy storage (sugar)
• intermediate-term energy storage
• starch for plants
• glycogen for animals
• as structural components in cells
• cellulose cell walls of plants
• chitin -exoskeleton of insects

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Monomers Polymers
1.   Monosaccharides - single sugar units
glucose 2.   Disaccharides - two
monosaccharides. Lactose, maltose    3.   Polysacc
harides - linking many sugar units
together Examples starch, glycogen,
cellulose
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Carbohydrates

• General formula CH2On
• where n is a number between 3 and 6.
• Ex- glucose C6H12O6

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What does it mean to be lactose intolerant?
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Got Milk?- milks sugar is lactose

• Infant mammals are fed on milk from mom
• Enzyme lactase digests
• the molecule into its two
• subunits for absorption.
• in most species, including humans,
• the production of lactase gradually
• ceases with maturity, they are
• then unable to metabolize lactose
• becoming Lactose intolerant

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A Polysaccharide
Lots of monomers linked together
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B. Proteins

• Important as control and structural elements.
• Control enzymes, hormones.
• Structural -cell membrane, muscle tissue, etc.
• Amino acids are the
• building block of proteins
• All living things (and even viruses) use various
  combinations of the same 20 amino acids.

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An Amino Acid
an amino end (NH2) a carboxyl end (COOH).
R is the variable (R-group) of each amino acid.
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Amino acids are linked together by joining the
amino end of one molecule to the carboxyl end of
another. Removal of water (condensation
reaction) links amino acids with a peptide bond.
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2. PEPTIDE BONDS
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Some examples of proteins

• Antibodies they recognize molecules of invading
  organisms.
• Receptors part of the cell membrane, they
  recognize other proteins, or chemicals, and
  inform the cell... 'The Door Bell'.
• Enzymes assemble or digest.
• Neurotransmitters and some hormones Trigger the
  receptors... (the finger on the door bell...)
• Channels, and pores holes in the cell membrane
  (with or without a gate). Usually, filter the
  flow...

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3. Enzymes

• Organic molecules that act as catalysts
• Enzymes substrates (the reactants) fit
  together like a lock key
• This fit weaken bonds so that less energy is
  needed for reaction.

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C. Lipids

• Functions
• Long-term energy storage.
• -Generally insoluble in polar substances (water)
• phospholipids are the major building block in
  cell membranes
• hormones ("messengers") play roles in
  communications within and between cells.

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Structure of Fatty Acids

• The carboxyl head is polar- therefore it is
  HYDROPHILIC water loving
• The hydrocarbon CH2 units are HYDROPHOBIC- water
  fearing
• (not water soluble).

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Fatty acids

• Can be saturated (meaning they have as many
  hydrogens bonded to their carbons as possible)
• Unsaturated (with one or more double bonds
  connecting their carbons, hence fewer hydrogens).
  
• A fat is solid at room temperature, while an oil
  is a liquid under the same conditions. The fatty
  acids in oils are mostly unsaturated, while those
  in fats are mostly saturated.

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2. Triglycerides

• Triglycerides are composed of three fatty acids
  (usually) covalently bonded to a 3-carbon
  glycerol.

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Fats and oils function in energy storage.

• Animals convert excess sugars into fats.
• Most plants store excess sugars as starch,
  although some seeds and fruits have energy stored
  as oils (e.g. corn oil, peanut oil, palm oil,
  canola oil, and sunflower oil).
• Fats yield 9.3 Kcal/gm, while carbohydrates yield
  3.79 Kcal/gm. Fats store six times as much energy
  as glycogen.

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Diets Fat Intake

• Attempts to reduce the amount of fats present in
  specialized cells known as adipose cells that
  accumulate in certain areas of the human body.
• By restricting the intakes of carbohydrates and
  fats, the body is forced to draw on its own
  stores to makeup the energy debt.
• The body responds to this by lowering its
  metabolic rate, often resulting in a drop of
  "energy level."
• Successful diets usually involve three things
  decreasing the amounts of carbohydrates and fats
  exercise and behavior modification

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3.  Phospholipids

• One fatty acid is
• replaced with a
• phosphate.
• The negative charge(s) of the phosphate makes the
  head of the phospholipid hydrophilic. The long,
  hydrocarbon tail is non-polar and, therefore,
  hydrophobic.

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•     

The water loving edge of the molecule orients
toward water- the inside and outside of the
cell. The water fearing edges of the molecule
orient toward each other to make a lipid
bilayer - the construction of the cell
membrane.
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4. Cholesterol and steroids

• Structure is a lipid with 4 carbon rings with
  various functional groups attached
• Cholesterol has many biological uses, such as its
  occurrence in the cell membranes, and its role in
  forming the sheath of some neurons. Excess
  cholesterol in the blood has been linked to
  atherosclerosis, hardening of the arteries.
• Steroids are mainly used as hormones in living
  things

• Structure of four steroids. Image from Purves et
  al., Life The Science of Biology, 4th Edition,
  by Sinauer Associates (www.sinauer.com) and WH
  Freeman (www.whfreeman.com), used with permission.

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D. Nucleic Acids

• Function - informational molecules
  heredity/genetic, protein synthesis, and energy
• A nucleotide is formed from a 5 carbon sugar, a
  phosphate and a nitrogen base.
• Polymers formed by linking together long chains
  of nucleotide monomers.

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• 3 Nucleic Acids
• DNA-deoxyribonucleic acid
• Double strand of nucleotides
• Double Helix shape
• RNA-ribonucleic acid
• Single strand nucleotides
• ATP -Adenosine Triphosphate

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Structure of DNA Structure of tRNA
-double strand of nucleotides -single
strand of nucleotides
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RNA differs from DNA in the following ways

• RNA is single stranded while DNA is double
  stranded.
• RNA has a sugar called ribose while DNA has a
  sugar called deoxyribose.
• RNA has the base uracil while DNA has the base
  thymine.

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How DNA RNA work together

• DNA(deoxyribonucleic acid) is the genetic
  material.
• It functions by storing information regarding
  the sequence of amino acids in each of the bodys
  proteins.
• This "list" of amino acid sequences is needed
  when proteins are synthesized.
• Before protein can be synthesized, the
  instructions in DNA must first be copied to
  another type of nucleic acid called messenger
  RNA.

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3 types RNA

• Messenger RNA, or mRNA.
• carries the code for building a protein from the
  nucleus to the ribosomes in the cytoplasm. It
  acts as a messenger.
• Transfer RNA or tRNA.
• picks up specific amino acids in the cytoplasm
  brings them into position on ribosome where they
  are joined together in specific order to make a
  specific protein.
• Ribosomal RNA or rRNA place for protein synthesis

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How a protein is built
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