ch 3 biological molecules (biomolecules) biochemistry review elements are substances that cannot be...
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Biochemistry Review
Elements are substances that cannot be broken down or converted into another substance
They are composed of atoms which are the smallest units of matter (recall the levels of organization)
Biochemistry Review
An atom is composed of a nucleus, an electron cloud, and 3 subatomic particles: Protons (p+) Neutrons (n0) Electrons (e-)
Protons and neutrons are located in the nucleus of an atom and electrons in the electron cloud
p+
n0
e-
Nucleus
Electron cloud
Carbon & Biomolecules
Molecules are particles composed of atoms (from elements) held together by chemical bonds Classified as organic and inorganic
Organic molecules are important because they are general types of molecules that all living organisms synthesize and use; they are essential for life
Carbon & Biomolecules
The term “organic” describes molecules that contains the element carbon (C) and some hydrogen atoms
“Inorganic” molecules are all molecules that do not contain carbon, with the exception of carbon dioxide (CO2)
Carbon & Biomolecules
Although they have a common structure and function, the tremendous variety of organic molecules contributes to the diversity of structures within an individual organism and even individual cells
The reason for this? Carbon’s structure is very versatile when it
comes to forming bonds with other atoms
Carbon & Biomolecules
Macromolecules – large molecules composed of similar repeating units
There are 4 main groups of macromolecules that compose living things:
1. Carbohydrates2. Lipids3. Proteins4. Nucleic Acids
Modular Approach
The modular approach involves building organic molecules piece by piece (like a train with individual cars): Monomer: individual subunits (car) Polymer: long chains of monomers (train)
Mono- means “one” Poly- means “many”
Biomolecules & Water
Biomolecules are joined together or broken apart by removing or adding water:Water can break apart polymers
(biomolecule), freeing up the monomers
OR…When polymers (biomolecules) are
formed, water is often produced as a by-product
Biomolecules & Water
Dehydration synthesis reactions: when monomers are joined together by removing water to make biomolecules (polymers)
A H+ is removed from one monomer and an OH- from the other…they will form water
The spaces left open allow the monomers to bond together, creating a biomolecule (polymer)
Biomolecules & Water
Hydrolysis reactions: when molecules are broken apart by water Water is added to a molecule (polymer),
causing it split back into the original monomers
Carbohydrates-Sugars
Composed of carbon, hydrogen, and oxygen (1:2:1)
Overall function: used by organisms for short term energy and structural support
Monosaccharides
1 sugar molecule (monomer) Function: mainly used to form
polymers or for cell activities Most common: glucose C6H12O6
Others: Fructosefruits Galactoselactose RiboseRNA DeoxyriboseDNA
Disaccharides
2 sugar molecules linked together Function: mainly used for short-term
energy Examples:
Sucroseglucose + fructose Lactoseglucose + galactose Maltoseglucose + glucose
Polysaccharides
Many sugar molecules linked together Function: used for long-term energy storage Examples:
Starch: found in plant seeds & roots (FYI: 1000 to ½ million glucose)
Glycogen (animals): found in animal muscles & liver (much smaller than starch)
Cellulose: found in plant cell walls Animals can’t digest it, has to be broken down by
microbes so its usually just roughage/fiber for us Chitin: found in exoskeletons and fungi cell walls
Lipids
Composed of mainly carbon and hydrogen
Have nonpolar regions that make them insoluble in water (meaning they won’t dissolve)
Types of lipids: Fats Oils Waxes Phospholipids Steroids
Oils, Fats, and Waxes
Triglyceride: the chemical name of fats and oils
Difference between fats & oils: Fats are solid, oils are liquid
Saturated Fats
Saturated fats are made of mainly hydrogen so the FA chains are “saturated” in hydrogen
Where we get them from: butter, bacon fat, steak; tends to come from animals
Unsaturated Fats
Unsaturated fats have a smaller amount of hydrogen in their FA chains
Where we get them from: the seeds of plants (they’re stored for the embryo) such as corn oil, peanut oil, etc.
FYI: Unsaturated fats
Unsaturated fats can be converted to a fat by breaking some of the double bonds and adding some hydrogens…this is known as a “hydrogenated oil” (allows margarine to be solid at room temp)
Partial hydrogenation creates trans fats which are also solid at room temperature Read Health Watch: Cholesterol-Friend or Foe
on pg. 45
Waxes
Function: used as a waterproof covering for: plant leaves and stems mammalian fur insect exoskeletons to construct beehives
FYI: Chemically similar to fats, but they aren’t a food source because we and most other animals don’t have the enzymes necessary to break them down
Phospholipids
Make up the plasma (cell) membrane
Head is hydrophilic or “water loving”
Tail is hydrophobic or “water fearing”
Steroids
Structurally different from all other lipids because it is a ring while the others were chains
Common steroid: cholesterol Component of animal cell
membranes
Amino Acids and Proteins
Monomer: amino acids (AAs); there are 20 different AAs in all
Polymer: protein (chains of AAs)
Bond between the AAs when they are making polymers is known as a peptide bond
Amino Acids and Proteins
Peptide: short chains of AAs (FYI: 2-49 AAs)
Polypeptide: long chains, aka a protein (FYI: 50 or more AAs)
Protein Structure
1. Primary structure (1o)-the chain of AAs that make up the protein
2. Secondary structure (2o)- when the protein takes on a coiled or pleated shape
Protein Structure
Tertiary structure (3o)-the 3-D shape a polypeptide becomes (like balling up a piece of paper)
Quaternary structure (4o)-when polypeptide chains link together
Types of Proteins
Can be classified as functional or structural
Functional: Enzymes: proteins that speed up almost all
chemical reactions that occur inside the cell Albumin (egg white) & Casein (milk):
provides AAs for developing young animals Some hormones such as insulin & growth
hormone Antibodies
Types of Proteins
Structural Elastin: gives skin its
elasticity Keratin: main protein
found in hair, nails, horns, scales, and feathers
Gossamer: the silk protein in spiders and silk moth cocoons
Nucleic Acids
Monomers: nucleotides
Polymers: nucleic acids (NAs)
2 types of nucleic acids: DNA-deoxyribonucleic acid RNA-ribonucleic acid
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