Date post: | 10-May-2015 |
Category: |
Technology |
Upload: | eruder |
View: | 1,426 times |
Download: | 0 times |
The Molecules of Life
Chapter 3
The Simplest Hydrocarbon
• Methane = Carbon + Hydrogen
Organic Molecules
• A cell is mostly water but the rest consists mainly of carbon based molecules
• Compounds that contain carbon are called organic compounds
• Carbon has the ability to form the large, complex diverse, molecules necessary for life functions
• Why are carbon atoms so versatile as molecular ingredients?
Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings
Carbon Chemistry
• Carbon a versatile atom has 4 electrons in an outer shell that holds 8- carbon can share its electrons with other atoms to form up to 4 covalent bonds
• Carbon can use its bonds to attach to other carbons
to form an endless diversity of carbon skeletons- each carbon in an organic molecule can branch off in up to 4 directions
• Carbon atoms of organic molecules can also bond with other elements (hydrogen, oxygen, nitrogen)
Variations in Carbon Skeletons
• Simplest organic compounds are hydrocarbons• Hydrocarbons consist of carbon and hydrogen• Each C atom forms 4 bonds; each H atom forms 1 bond
Fig 3.2
Larger Hydrocarbons
• Main molecules in the gasoline we burn in our cars
• Hydrocarbons of fat molecules provide energy for our bodies
Fig 3.4
Functional Groups
• Each type of organic molecule has a unique 3-dimensional shape that defines its function in an organism- the molecules of your body recognize one another based on their shapes
• The unique properties of an organic compound depend not only on its carbon skeleton but also on the atoms attached to the skeleton- these atoms are called functional groups
• Functional groups behave consistently from one organic molecule to another
4 Important Functional Groups
• Many biological molecules have 2 or more functional groups• How do cells make large molecules out of smaller organic molecules
Size of Molecules• Monomers
– Molecules used as subunits to
build larger molecules (polymers)
• Polymers– Larger molecules that are chains of
monomers– May be split and used for energy
Building Blocks
• On a molecular scale, many of life’s molecules are gigantic- biologists call them macromolecules (macro = ‘big’) such as DNA, carbohydrates, proteins
• Most macromolecules are polymers- polymers are made by stringing together many smaller molecules called monomers- cells link monomers together through a dehydration reaction (removes a molecule of water)
• Organisms break down macromolecules (digestion)- cells do this by a process called hydrolysis (hydro = ‘water’ lyse = ‘break’; to break with water)
Dehydration Reaction
Synthesis – a polymer grows in length when an incoming monomer and the monomer at the end of the existing chain contribute to the formation of a water molecule, the monomers then replace their lost covalent bonds with a bond to each other
Hydrolysis
Breaking a polymer chain – hydrolysis reverses the process by
breaking down the polymer with the addition of water molecules, which
break the bonds between monomers
Biological Molecules
There are 4 categories of large molecules in cells:
• Carbohydrates
• Lipids
• Proteins
• Nucleic Acids
Carbon-Carbon Macromolecules
• Aka: Organic Molecules
• Fall into 4 groupings:
Carbohydrates
Lipids
Proteins
Nucleic Acids
Carbohydrates
• ‘Carbs’ - from small sugar molecules in soft drinks to long starch molecules in pasta and potatoes- serve as a primary source of dietary energy
- used as building material to form the body of a plant
• Monosaccharides (mono = ‘one’, and sacchar = ‘sugar’) are simple sugars:- glucose found in sports drinks
- fructose found in fruits
• Monosaccharides glucose and fructose are isomers - they have the same molecular formula, but their atoms are arranged differently
Glucose
• Monosaccharides, particularly glucose, are the main fuel that cells use for cellular work
• Cells break down glucose molecules and extract their stored energy
- give off CO2 as waste
• Monosaccharides also provide cells with carbon skeletons that can be used as raw material
Polysaccharides
• Long repeating chains of monosaccharides
• Often used for Energy storage
• Animals form Glycogen from glucose units
• Stored in Liver and muscles
• Plants also store glucose polysaccarides
• Starch
Carbohydrate Complexity
• Monosaccharides: useable Energy
• Disaccharides: transport form
• Polysaccharides: Storage and structural forms
Lipids:Fats & Oils
• Insoluble in water, but soluble in oil• Examples include:
Oils (olive, corn…)
Waxes (bee’s, ear)
Fats• Lipids have two ends.• Hydrophilic – water loving head• Hydrophobic – water fearing tail
Other Lipids
• Phospholipids… important in cell membranes
• Steroids… testosterone, cholesterol, hormones
Proteins
• Contain C, H, O, N, sometimes P and S
• Polymers of amino acids
• Functions: Basis of Protein hormones (eg., insulin, growth hormone), structural components of muscle (actin and myosin), & skin (collagen & keratin), antibodies (immunoglobulins), transport molecules (hemoglobin), cell surface receptors and channels, enzymes, pigments
Proteins
• Make up skin and muscles.
• Used as catalysts in the form of enzymes.
• Amino acids (monomers) are linked together to form peptides.
Protein Structure
Nucleic Acids (RNA and DNA)
• Polymers of nucleotides
• A single nucleotide:
• Carry and transmit hereditary information
• Direct the synthesis of proteins
Adenine, guanine, thymine, cytosine or uracil (RNA only)
Got all that?
• Knight Starts Monday.• Check wall for room assignment.• Unit 1 test next Friday!!!! Covers
EVERYTHING since beginning of year. Review all notes and vocabulary.
• Characteristics of life.• Scientific Method• Chemistry.• Molecules of life.