Organic Macromolecules

1
Organic Macromolecules

• Mr. Gawles Biology Class
• September to October 2005

2
Revisit Course Big Ideas Themes
3
Essential Questions For Unit III

• Why is carbon so important to all forms of life?
  
• What do all organic compounds have in common?
  What makes them different from each other?
• What roles do the different organic compounds
  play in living things and how are their roles
  dependent upon their structure?
• Why are chemical reactions so important to the
  functioning of living things?

4
Take Home Messages

• Carbon is critical for the formation of organic
  compounds which make up living things
• The structure of the four basic groups of organic
  compounds determines their characteristics
• Carbohydrates, lipids, proteins, and nucleic
  acids
• Cells make these large molecules (polymers) from
  a set of small molecules (monomers)
• The behavior and function of organic compounds is
  often affected by their environment
• Without chemical reactions, there would be no life

5
So What Is So Special About Carbon?

• Carbon atoms have four outer electrons in a shell
  that holds eight
• Strong tendency to complete its outer shell by
  sharing electrons with other atoms in four
  covalent bonds
• Carbon is therefore unparalleled in its ability
  to form large diverse molecules of different
  shapes, sizes, and complexities
• All most all the molecules a cell makes are
  composed of carbon
• Next to water, compounds containing carbon are
  the most common substances in living things

6
Organic Molecules
Organic Compounds are defined as having
carbon-carbon or carbon-hydrogen bonds
So, is CO2 organic? C3H8? H2O?, NH3? C6H12O6?
7
Examples of Organic Molecules
Acetaminophen
Cholesterol
DDT
Vitamin C
MSG
Organic to a chemist does not mean organic to
an environmentalist!
8
Organic Molecules Often Have Functional Groups

• A functional group is a group of atoms within a
  molecule that interacts in a consistent and
  predictable way
• Give specific properties to molecules that
  contain them
• The hydroxyl group (-OH) for example, is
  hydrophillic and is attracted to water

9
Macromolecules A Polymer made of Monomers

• Cells make a huge number of large molecules
  (macromolecules) from a set of smaller units
• Proteins, for example, may consist of thousands
  of covalently connected atoms
• Cells make their macromolecules by joining
  smaller organic compounds into chains called
  polymers
• A polymer is a large molecule consisting of many
  identical or similar units strung together
• Think of how a large train consists of many
  smaller cars latched together
• The units that serve as building blocks of
  polymers are called monomers

10
How Are Polymers Made?

• There are about a trillion different kinds of
  polymers in natureall of which are made from a
  small set of about 50 monomers!
• Cells link monomers together to form polymers in
  a process called DEHYDRATION SYNTHESIS
• This same type of reaction occurs regardless of
  the specific monomers and the type of polymer
  being produced!
• I.E. ALL macromolecules are made this way!

See online activity 5.1 page 2
11
Dehydration Synthesis
12
Questions about Dehydration Synthesis?

• Why do they called it this?
• For every monomer added to a chain, a water
  molecule is removed
• What kind of bond is formed between monomers?
• A covalent bond
• What happens when monomers bond together?
• One monomer loses a hydrogen atom (-H) and the
  other monomer loses a hydroxyl (-OH) group to
  form water.
• What are your questions???
• Look at Worksheet 1 2 Bead Models

13
How Might Cells Break Down Macromolecules?

• To break a polymer apart into its constituent
  monomers a cell carries out a reaction that is in
  essence the opposite of dehydration synthesis
• This process breaks apart (lyses) the polymer by
  adding water (hydro) to it
• Known as HYDROLYSIS
• WHY DO THIS?
• Food is often in the form of macromolecules

14
Hydrolysis
15
Compare Dehydration to Hydrolysis
16
Major Groups of Organic Macromolecules

• Carbohydrates
• Sugars and starches
• Lipids
• Fats, steroids, cholesterol, waxes
• Proteins
• Includes enzymes
• Nucleic Acids
• DNA and RNA
• Genetic information carrying molecules

17
What You Need To Know About Each Group of
Macromolecules

• Monomer and Polymer names
• Examples of each
• Chemical or structural formulas
• Be able to recognize and identify pictures
• Unique chemical characteristics of the group
• Biological significance
• Why are they important? What role or function do
  they play in living things?

18
Carbohydrates I

• How can you recognize them?
• 1 carbon 2 hydrogen 1 oxygen
• Formulas are multiples of CH2O
• Often (not always!) end in ose (glucose,
  sucrose, cellulose)
• Chemical properties
• Almost all are hydrophilic due to (-OH) groups
• Most dissolve readily in water but large sugars
  do not
• cellulose does not dissolve in water or else your
  jeans would melt if they got wet

19
Carbohydrates II

• Monomers
• Called monosaccharides
• (ex. Glucose, fructose)
• Disaccharide
• Two monosaccharides joined together
• (ex. Sucrose glucose fructose)
• Polymers
• Long polymer chains made up of simple sugar
  monomers are called polysaccharides
• Starch in plants (made of glucose monomers)
• Glycogen in the liver of animals ( )
• Cellulose as a structural support material in
  plants

20
Example of a Monosaccharide
21
Example of a Disaccharide
22
Example of a Polysaccharide
23
Carbohydrate Functions

• Provide energy source
• Glucose is the main fuel for cellular work
• Cells break down glucose to extract stored energy
• RESPIRATION
• Polysaccharides serve in stockpiling or
  storing energy for cellular work
• May be broken down when energy is needed
• Starch in plants/ Glycogen in animals

• Provide building materials in plants
• Provide structure and support
• Protect and stiffen plants allowing them to
  overcome gravity
• Make up cell walls of plants
• Ex. Cellulose
• Indigestible
• Aka Fiber

24
Proteins I stop

• How can you recognize them?
• CHON Look for amino group (--NH2)
• Chemical properties
• Each protein has a unique 3D structure that
  corresponds to its unique function
• A functional protein consists of one or more
  polypeptides precisely twisted, folded, and
  coiled into a unique shape that determines its
  function
• See Closer Look after OLA 5.4
• Each protein is strongly influenced by its
  environment
• Any unfavorable change in the temperature, pH, or
  other variable can cause a protein to unravel and
  lose its normal shapethis can be the death of an
  organism!
• The protein has DENATURED
• What would this do to its functionality?

25
Proteins II

• Monomers
• Called amino acids
• 20 different types
• What makes one amino acid different from another
  is the side or R group
• Responsible for the chemical properties of each
  amino acid
• Polymers
• Called polypeptides
• Created by (SEE ONLINE ACTIVITY 5.4) linking
  hundreds to thousands of amino acids together in
  a chain that folds, twists, and coils on itself
• Incredible diversity of proteins can be made
  since there are 20 letters in the alphabet and
  each word is at least 100 letters long!

26
Amino Acids Monomers
27
Polypeptide
28
3D Structure of Protein
Myoglobin an oxygen carrying molecule
29
Protein Function

• Responsible for all the day to day functions of
  an organism
• Provide structures (fur, hair, etc)
• Long term energy storage
• Part of immune system
• Chemical messengers
• Others control rate of reactions in the body
  (called enzymes)
• Remember structure determines function!!!
• Are SOOOOOO important that this is what your DNA
  codes for!

30
Enzymes

• Are proteins that speed up specific chemical
  reactions in cells
• Provide a way for reactions to take place at the
  cells normal temperature
• Each enzyme speeds up or catalyzes a specific
  type of chemical reaction
• At any moment, the specific enzymes that are
  present and active determine which reactions
  occur
• Are NOT used up in the reactioncan be used over
  and over again.

31
Activation Energy
32
How do Enzymes work?

• Bends or distorts the reactants so their bonds
  are easier to break
• The correct functional groups are put into close
  proximity
• Holds reactants together at the right angle

33
Shape determines Function

• The reactant acted upon by the enzyme is called
  the SUBSTRATE
• The substrate fits into a particular region on
  the enzyme called the ACTIVE SITE
• The fit between active site and substrate is akin
  to a lock and key
• An enzymes shape is dependent upon its local
  environment
• Can denature if too hot or too acidic etc

34
Lipids

• Chemical Properties
• Hydrophobicdont mix with water
• Very few if any hydroxyl groups
• This property is important to some of the
  functions of lipids
• Surrounds and acts as a boundary layer for watery
  contents of cell
• Monomer of fats (not the monomers of steroids
  or Phospholipids)
• 3 carbon backbone called glycerol attached to
  three fatty acids (long hydrocarbon chains)
• Saturated fats all 3 fatty acid chains have
  single carbon bonds (often solid at room temp.)
• Unsaturated fats one of carbons in fatty acid
  chain has a double bond (often liquid at room
  temp.)

35
Saturated or Unsaturated?

• Stores energy fuel
• Insulates body tissues
• Cushions and protects organs

36
Phospholipids

• PHOSPHOLIPIDS
• Make up cell membranes
• Polar phosphate portion along with non polar
  fatty acid chain portion
• Hydrophilic polar heads interact easily with
  polar molecules
• Hydrophobic fatty acids prevents movement of
  polar molecules through it!
• See animation here

37
Phospholipids
38
Steroids

• A lipid but very different than fats in
  structure and function
• 4 fused carbon rings with functional groups
• Most famous
• Cholesterol
• Stabilizes cell membranes
• Makes bilayer less deformable
• Used in body to generate steroid hormones such as
  the sex hormones
• Used to make bile
• Helps in digestion of fats

39
Steroid Hormones
Small differences in chemistry can make a big
difference in terms of the function of the
molecule!