Download Chemistry in Biology

Section 4
Chemistry in Biology
Organic vs. Inorganic
• Compounds are classified into 2 groups:
– Inorganic: compounds that lack Carbon; not living
or derived from living things
– Organic: living or derived from living things;
composed of Carbon, and usually Hydrogen.
• CO2 is NOT an organic molecule
Section 4
Chemistry in Biology
The Building Blocks of Life
Organic Chemistry
 The element carbon
is a component of
almost all biological
molecules.
 Why?
Section 4
Chemistry in Biology
The Building Blocks of Life
 Carbon has four electrons in its outermost energy
level.
 One carbon atom can form four covalent bonds with
other atoms.
 Carbon may form single, double, or triple bonds
 Carbon compounds can be in the shape of straight
chains, branched chains, and rings.
Section 4
Chemistry in Biology
The Building Blocks of Life
• The most common elements that bond to Carbon
are:
• Carbon
• Oxygen
Nitrogen
Hydrogen
• Simplest organic compound is Methane CH4
Section 4
Chemistry in Biology
The Building Blocks of Life
• Carbon can form long chains of Carbons
– Ex: Butane C4H10
Section 4
Chemistry in Biology
The Building Blocks of Life
Macromolecules
 Carbon atoms can be joined to form carbon
molecules.
 Macromolecules are large molecules formed
by joining smaller organic molecules together.
 Polymers are molecules made from repeating
units of identical or nearly identical compounds
linked together by a series of covalent bonds.
Section 4
Chemistry in Biology
The Building Blocks of Life
• Isomers
– Compounds with the same chemical formula but with
different structural formulas.
• Therefore, they are different compounds and may have
different properties.
– Ex: Butane vs. Isobutane
• Check formula
• Compare structures
Section 4
Chemistry in Biology
The Building Blocks of Life
• The 4 Organic Compounds essential to living
things:
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic Acids
Section 4
Chemistry in Biology
The Building Blocks of Life
Carbohydrates
 Compounds composed of carbon, hydrogen, and
oxygen in a ratio of one oxygen and two hydrogen
atoms for each carbon atom—(CH2O)n
 Function: Main source of energy for the body
Section 4
Chemistry in Biology
The Building Blocks of Life
3 Classes of Carbohydrates
 Values of n ranging from three to seven are
called simple sugars, or monosaccharides.
 Two monosaccharides joined together form
a disaccharide.
 Longer carbohydrate molecules are called
polysaccharides.
Chemistry in Biology
Section 4
The Building Blocks of Life
3 Classes of Carbohydrates - Monosaccharides
• Monosaccharides, or simple sugars, with the
chemical formula C6H12O6
• 3 monosaccharides which are isomers
1. Glucose: the body’s best source of energy
•
•
•
Produced by plants during photosynthesis
Found dissolved in the blood
The brain needs a constant supply of glucose
2. Fructose: found in fruits
3. Galactose: not found free in nature
Section 4
Chemistry in Biology
The Building Blocks of Life
3 Classes of Carbohydrates - Monosaccharides
• We take in many kinds of sugars through our
diet… since our body can only use glucose
as a source of energy, the liver converts all
other sugars into glucose.
Chemistry in Biology
Section 4
The Building Blocks of Life
3 Classes of Carbohydrates - Disaccharides
• Disaccharides, double sugars, produced when
two monosaccharides chemically combine.
– Chemical Formula: C12H22O11
– Reaction Equation:
» C6H12O6 + C6H12O6  C12H22O11 + H2O
• Common Disaccharides
1. Lactose: milk sugar (glucose + galactose)
•
Lactose intolerance?
2. Maltose: malt sugar (glucose + glucose)
3. Sucrose: cane sugar (glucose + fructose)
Section 4
Chemistry in Biology
The Building Blocks of Life
3 Classes of Carbohydrates - Polysaccharides
• Polysaccharides: large molecules of many
monosaccharides bonded together.
• Common Polysaccharides –
1. Starch: many glucose molecules bonded together
• Made by plants and has a lot of energy stored in it.
2. Glycogen: similar to starch but stored in animals;
also made of many glucose molecules.
• The liver converts glycogen to glucose
3. Cellulose: also many glucose molecules. Much
larger and more complex, but cannot be digested by
humans.
Section 4
Chemistry in Biology
The Building Blocks of Life
Lipids
 Molecules made of carbon, hydrogen, and
oxygen
 Composed of 3 fatty acid molecules and one
glycerol molecule
 Structures -
Section 4
Chemistry in Biology
The Building Blocks of Life
• Function of Fats:
1.
2.
3.
4.
5.
6.
7.
Concentrated energy source
Padding for vital organs
Insulation
4 essential vitamins are fat soluble (vitamins A, D, E, K)
Healthy epithelial tissue (skin, nails, hair)
Transmission of nerve impulses
Used in the production of hormones
Section 4
Chemistry in Biology
The Building Blocks of Life
 Lipids that have tail chains with only single
bonds between the carbon atoms are called
saturated fats.
 Lipids that have at least one double bond
between carbon atoms in the tail chain are
called unsaturated fats.
 Fats with more than one double bond in the
tail are called polyunsaturated fats.
Section 4
Chemistry in Biology
The Building Blocks of Life
Section 4
Chemistry in Biology
The Building Blocks of Life
• Two types of lipids:
1. Fats – usually animal in origin and are solids at
room temperature (saturated).
2. Oils – usually plant in origin and are liquids at
room temperature (unsaturated).
Section 4
Chemistry in Biology
The Building Blocks of Life
Proteins
 Proteins form when monomers of amino acids
bond together to form a polymer chain.
 Chains can have 100’s – 1,000’s of amino acids
 Amino acids are small compounds that are
made of carbon, nitrogen, oxygen, hydrogen,
and sometimes sulfur.
Section 4
Chemistry in Biology
The Building Blocks of Life
Protein Structure
 Amino acids have a central carbon atom.
 One of the four carbon bonds is with hydrogen.
 The other three bonds are with an amino group
(–NH2), a carboxyl group (–COOH), and a variable
group (–R).
 There are 20 different amino acids
Section 4
Chemistry in Biology
The Building Blocks of Life
Protein Structure
• When amino acids bond to one another, they are
called peptides because the bond is called a
peptide bond.
– Two amino acids bonded together is called a
“dipeptide”.
– A chain of amino acids is called a “polypeptide”.
Section 4
Chemistry in Biology
The Building Blocks of Life
Function of Proteins
• There are thousands of different proteins in our
bodies with many different functions. Unlike
carbohydrates and fats, proteins do NOT provide
energy.
• Functions of Proteins:
1.
2.
3.
4.
Enzyme catalysts – help carry out chemical reactions
Transport molecules – into and out of cells
Fight disease – production of antibodies
Movement & Mechanical support – muscle, skin, and
bone
Section 4
Chemistry in Biology
The Building Blocks of Life
Types of Proteins
• A balanced diet provides all the proteins you
need. Good sources of protein:
– Meats, eggs, dairy, nuts, etc.
• The body makes 11 of the 20 amino acids
from other compounds already in the body.
– These 11 are called “non-essential amino acids”
• We need to take in the other 9 via our diet.
– These 9 are called “essential amino acids”
Section 4
Chemistry in Biology
The Building Blocks of Life
 Nucleic acids are complex macromolecules that store
and transmit genetic information.
 They are the building blocks of ALL living things.
 Nucleic acids are made of smaller repeating subunits
called nucleotides, composed of carbon, nitrogen,
oxygen, phosphorus, and hydrogen atoms.
Section 4
Chemistry in Biology
The Building Blocks of Life
Types of Nucleic Acids
• There are two common Nucleic Acids:
1. DNA – deoxyribonucleic acid
2. RNA – ribonucleic acid
• Function: creates DNA
& RNA and holds the
information for the cell
in the form of a code.
Section 4
Chemistry in Biology
The Building Blocks of Life
Structure of Nucleic Acids
• Each nucleotide consists of 3 parts:
1. Nitrogenous Base
•
•
Purines – Adenine and Guanine
Pyrimidines – Cytosine and Thyamine (DNA), Uracil
(RNA)
2. Pentose Sugar
•
5 sided ring (Ribose)
3. Phosphate Group
Section 4
Chemistry in Biology
Basic Cellular Reactions
Food Sources
•
There are two types of organisms
1. Autotrophs – organisms that can make their own
food.
•
Most use sunlight as an energy source.
– Examples: plants, bacteria, algae
2. Heterotrophs – organisms that take in food from
other sources.
•
They break down food to produce energy.
– Examples: animals, fungi
Section 4
Chemistry in Biology
Basic Cellular Reactions
Food Sources
• Either way, food must be taken into the cell
and used to provide energy. A variety of
reactions (physical and chemical) take place
on the cellular level in order for this to
happen.
• Metabolism – the total of all the ractions that
take place in the cell.
Section 4
Chemistry in Biology
Basic Cellular Reactions
Two Types of Reactions
• Anabolic Reaction – reactions that take
simple substances and join them to form
more complex substances.
– Endergonic Reaction = Require energy
– Build new molecules & stores energy
• Synthesis Reaction = Dehydration Reaction, or loss of
H2O
– Example: Protein Synthesis, Carbohydrate
Production, Anabolic Steroids  promote cell
growth
Section 4
Chemistry in Biology
Basic Cellular Reactions
Two Types of Reactions
• Catabolic Reaction – reactions that take
complex substances and break them down
to their more basic substances.
– Exergonic Reaction = Releases/Produces energy
– Breaks down molecules and gives off energy
• Hydrolysis Reaction = Condensation Reaction or gains
water, takes up H2O
– Example: Digestion, Cellular Respiration
Section 2
Chemistry in Biology
Chemical Reactions
Energy of Reactions
• Energy – the ability to do work
• Chemical reactions need energy to take
place. Energy is used to break and form
bonds.
• There are 2 types of energy:
1. Potential Energy: stored energy
•
Example: wood, ball at top of hill
2. Kinetic Energy: energy in motion
•
Example: burning wood, ball rolling
Section 2
Chemistry in Biology
Chemical Reactions
Energy of Reactions
• Energy is stored in the bonds of molecules.
When bonds are broken, energy is released.
When new molecules are created, energy is
stored in the bonds formed.
Section 2
Chemistry in Biology
Chemical Reactions
Energy of Reactions
• Activation Energy: the
minimum amount of
energy required to
start a chemical
reaction.
Section 2
Chemistry in Biology
Chemical Reactions
Enzymes
• Chemical reactions are
controlled by substances
called catalysts.
– A catalyst is a substance
that lowers the activation
energy needed to start a
chemical reaction.
• It does not increase how much product is made and it
does not get used up in the reaction.
• One type of catalyst are special proteins called
Enzymes.
Section 2
Chemistry in Biology
Chemical Reactions
Enzymes
• Lower activation energy in a reaction to reduce
damage of cells
• Substances that are acted upon by enzymes are
called substrates.
• Enzyme named after the substrate it bonds to, name
ends in –ase,
– Protase  Protein
– Maltase  Maltose
– Ribonuclease  RNA (Ribonucleic Acid)
Section 2
Chemistry in Biology
Chemical Reactions
Enzymes
• Co-enzyme – small molecules that will work
with an enzyme to control a reaction.
– These are not needed in all reactions.
Section 2
Chemistry in Biology
Chemical Reactions
Model of an Enzyme
• Enzymes are very specific in shape and
structure.
• A special region on the enzyme where the
substrate attaches is called the active site
– Lock and Key Model: the active site is VERY
specific, only a certain substrate will attach to the
active site.
• Once the substrate binds to the enzyme, this
molecule is called the Enzyme Substrate
Complex
Section 2
Chemistry in Biology
Chemical Reactions
Model of an Enzyme
• Purpose of the Enzyme Substrate Complex
(ESC) is to lower the activation energy of the
reaction allowing it to speed up.
• Once the substrate “key” bonds to the
enzyme it will split into its various products.
• The enzyme is free to take on another
substrate
Section 2
Chemistry in Biology
Chemical Reactions
Model of an Enzyme
 The reactants that bind to the enzyme are called
substrates.
 The specific location where a substrate binds on an
enzyme is called the active site.
Section 2
Chemistry in Biology
Section 2
Chemistry in Biology
Chemical Reactions
Induced Fit Model
• Induced Fit: the substrate binds to an
enzyme, the active site changes shape
slightly so it embraces the substrate
Chemistry in Biology
Section 2
Chemical Reactions
Factors Effecting Enzyme Activity
• Four factors effect enzyme activity:
1. Temperature
•
•
Enzymes are heat specific
Low temperatures will lower the rate of the reaction
–
•
Molecules move slower, lessen collisions
Heat will increase the rate of the reaction, up to a
certain point
–
At 50°C enzymes will become denatured
» Denaturation: the change in the shape of the enzyme
destroying the active site
Section 2
Chemistry in Biology
Chemical Reactions
Factors Effecting Enzyme Activity
• Temperature
reaction rate
What’s
happening
here?!
37°
temperature
Chemistry in Biology
Section 2
Chemical Reactions
Factors Effecting Enzyme Activity
• Four factors effecting enzyme activity:
2. pH
•
Enzymes are pH specific
–
–
–
•
Some enzymes work best at low pH (acidic)
Some enzymes work best at high pH (basic)
Some enzymes work best at neutral pH
Denaturation of the enzyme will occur if the pH is
changed.
Section 2
Chemistry in Biology
Chemical Reactions
Factors Effecting Enzyme Activity
• pH
intestines
trypsin
What’s
happening
here?!
reaction rate
stomach
pepsin
0
1
2
3
4
5
6
pH
7
8
9
10 11
12 13 14
Section 2
Chemistry in Biology
Chemical Reactions
Factors Effecting Enzyme Activity
• Four factors effecting
enzyme activity:
3. Concentration of the
substrate
•
As substrate concentration
increases, so will enzyme
activity, up to a certain point.
Then it will level out because
the enzyme-substrate only
occurs when the enzyme’s
active site is free.
Chemistry in Biology
Section 2
Chemical Reactions
Factors Effecting Enzyme Activity
• Four factors
effecting enzyme
activity
4. Chemicals in the
environment
•
Chemicals that
interfere with the
enzyme-substrate
complex are
called inhibitors.
Section 2
Chemistry in Biology
Chemical Reactions
Chemical Reactions in the Human Body
• Recall: The main source of energy for living
things is glucose. When glucose is broken
down by the cell energy is given off in the
form of ATP (adenosine triphosphate).
Section 2
Chemistry in Biology
Chemical Reactions
Chemical Reactions in the Human Body
• Cellular Respiration – the process in which
glucose is broken down in the cell and the
energy is used to make ATP.
• There are 2 types:
– Aerobic: respiration which requires oxygen
– Anaerobic: respiration which does not use oxygen
• Reaction Equation
C6H12O6 + 6O2  6CO2 + 6H2O + ATP
Section 2
Chemistry in Biology
Chemical Reactions
Chemical Reactions in the Human Body
• Cellular Respiration consists of 3 main
reactions:
1. Glycolysis
2. Citric Acid Cycle
3. Electron Transport Chain
Section 2
Chemistry in Biology
Chemical Reactions
Chemical Reactions in the Human Body
• Glycolysis: anaerobic reaction that occurs in the
cytoplasm of the cell.
• Citric Acid Cycle: aerobic step that occurs in the
mitochondria of the cell.
• Electron Transport Chain: aerobic step that
occurs in the mitochondria.
• One cycle of Cellular Respiration produces a
total of 36 ATP.