Biology 12
Mr. Kruger
Biological Molecules
Synthesis and Hydrolysis of biochemicals
Carbon rings or chains act as the skeleton for the unit molecules, which make up the life
compound.
Example: Proteins
Carbohydrates
Fats (lipids)
Nucleic Acids
Unit molecules join together to form larger molecules called Polymers.
Proteins, carbohydrates, fats and nucleic acids are all polymers.
To join 2 unit molecules together, a molecule of water must be removed. H+ is
taken from 1 molecule and OH- from the other molecule. This process is called
Dehydration synthesis. Energy is required.
To break down a polymer, a molecule of water must be added. This process is
called Hydrolysis. Energy is released.
Biology 12
Mr. Kruger
Major Organic Compounds
I. Carbohydrates: sugars (starches, cellulose and glycogen)
-Elements: Carbon, hydrogen, and oxygen.
-Ratio of hydrogen atoms to oxygen atoms is always 2:1
-Empirical formula is CH2O
1.
Sugars: Vital fuel nutrients for cells.
a) a) Monosaccharides: 5 or 6 carbon sugars (simple sugars)
i) Pentoses: 5 carbon sugars
Example: Ribose, Deoxyribose (1 less oxygen than
ribose)
ii) Hexoses: 6 carbon sugars
Example: Glucose, Fructose, and Galactose.
GLUCOSE
b)
Disaccharides: Double sugars (two simple sugars)
Have a common formula C11H22O11
Common Disaccharides
i)
Maltose: 2 molecules of glucose
ii) Sucrose: 1 glucose and 1 fructose
iii) Lactose: 1 glucose and 1 galactose
C. Polysaccharides: Starches, Cellulose and Glycogen
-long chains of glucose molecules (simple sugars)
-basic formula (C6H10O5)n
n= dozens to thousands of glucose units
i)
ii)
Starch: -Basic storage food of plants
-Few side chains.
Glycogen: “animal starch” stored in liver and muscle tissue.
-Many side chains
-Storage form of glucose in animals
-Between meals as [glucose] in blood decreases,
the liver breaks down glycogen into glucose to
maintain [sugar] at 0.1 %.
Biology 12
Mr. Kruger
-After meals, [glucose] increases, so liver converts excess
glucose to glycogen.
iii)
Cellulose: Probably the most abundant organic compound found on Earth.
-Formed in the cell walls of plants
-Gives plants its structure
-No side chains
-Different type of linkage between sugars is
found in starch or glycogen.
Our digestive system is unable to digest this linkage. Cellulose passes through our system
as fiber or roughage. May be important for good health and prevention of colon cancer.
Functions of Carbohydrates
a.
b.
Source of short-term energy source for all organisms.
-Energy is released as the carbohydrates are broken down by hydrolysis.
Structural molecules in plants
Biology 12
Mr. Kruger
II. Lipids: Fats, oils waxes, phospholipids, soaps,
steroids
We eat lipids as part of our food. Our bodies are capable of producing them as well as
metabolizing them. Next to glucose, fats are the second most important energy
molecule for us. Unfortunately, we store them in adipose (fat) cells.
Function: Long term energy source.
Elements: Carbon, hydrogen, and oxygen but the H:O ration is greater than 2:1.
Fatty acids are non-polar chains of carbon and hydrogen with a carboxylic acid end.
A tremendous number of variations exist between fatty acids.
For example: Some are saturated (without double bonds)
Some are unsaturated (with double bonds)
Basic Structure of a Neutral Fat: 1 molecule of glycerol in combination with 1, 2 or 3
molecules of fatty acids.
Monoglyceride-one fatty acid attached to a glycerol.
Diglyceride- two fatty acids attached to a glycerol.
Triglyceride- three fatty acids attached to a glycerol.
Biology 12
Mr. Kruger
a)
Fats (saturated fats): Usually of animal origin and are solid at room
temperature. Examples : Adipose tissue, Lard, Butter
b) Oils (unsaturated fats): Usually of plant origin and are usually liquid at
room temperature because of the double bonds.
Polyunsaturated fats have many double bonds therefore few
hydrogen bonds. Examples: Vegetable oils
c) Steroids: Compounds such as the sex hormones, cholesterol, some of the
ingredients of bile.Instead of a straight chain of carbons, steroids are nonpolar
ring structures.
They are insoluble in water therefore considered a lipid.
Example: Cholesterol- important part of cell membrane and the protective
cover around nerve fibers.
Note: Cholesterol is important, but too much results in fatty deposits inside arteries.
This narrows the pathway for blood so the heart has to pump harder to push the
blood through the body. Ie. Increase blood pressure.
Cholesterol is the important part of the cell membrane and the protective cover
around nerve fibers.
Steroids are able to pass through cell membranes and combine with receptors in the
cell. The steroid receptor complex activates certain genes leading to protein
synthesis. Increase protein synthesis better for the athlete for muscle development
Biology 12
Mr. Kruger
d) Phospholipids
Phospholipids are a variation of a triglyceride where one of the fatty acids is
replaced with a phosphate and a nitrogen-containing group. This creates a polar
region and consequently phospholipds can mix with both polar (likes water) and
non-polar (dislikes water) materials. Phospholipids are very important in cells as
they form much of the cell membranes.
Because they have water-soluble heads and
insoluble tails. They tend to form a thin film on with
their tails in the air. Like above
If surrounded by water they arrange themselves
in a bubble with their tails inward. (This would be
called a Rudimentary cell membrane)
The Heads of the phospholipds are polar and are said to be water loving.
(Hydrophilic)
The Tails of the phospholipds are non polar and are said to be water hating.
(Hydrophobic)
Biology 12
Mr. Kruger
PROTEINS
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Elements: Carbon, hydrogen, oxygen, & nitrogen (often sulfur is present; sometimes iron &
phosphorous
Proteins are polymers of amino acids
Molecules composed of chains of amino acids = polypeptides
Amino acids = 20 different ones … humans can synthesize 11 a.a.’s (non-essential) and 9 a.a.’s
have to come from diet (essential
Protein enzymes guide almost every chemical reaction that occur in cells
Enzymes are very specific for certain reactions, therefore there are hundreds of different
enzymes
Some proteins are used for:
 elastin (gives skin elasticity),
 keratin (protein in hair, nails, claws),
 albumin in eggs, casein in eggs,
 hemoglobin for carrying oxygen in blood,
 actin/myosin proteins in muscles which aid in contractions,
 insulin,
 growth hormones,
 antibodies for fighting disease
 venom in snakes.
All amino acids have the same fundamental structure. A carbon atom bonded to 4 different
functional groups:
 a nitrogen containing amine group (NH2)
 a carboxyl group (COOH)
 a hydrogen
 a variable group represented by the letter ‘R’
BASIC AMINO ACID STRUCTURE
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the ‘R’ group differs among amino acids giving them each distinctive properties
some amino acids are hydrophilic (the R group is polar and soluble in water) and some are
hydrophobic and insoluble in water.
Proteins are formed by dehydration synthesis (the N of the amine group is joined to the C of the
carboxyl group COOH of another amino acid by a single covalent bond
Biology 12
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Mr. Kruger
In this way, long sequences of amino acids are built. These sequences take on specific features ,
characteristics of the individual amino acids that are bonded together.
The bond is a peptide bond and the resulting chain of 2 amino acids is called a peptide
The term ‘protein’ is usually reserved for long peptides of approx. 50 or more amino acids in
length.
Dipeptide  specific for 2 amino acids
Polypeptide  for more than 2 or numerous amino acids
Structure of Proteins
There are 4 levels of protein structure:
Primary Structure:
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This is the sequence of amino acids that make up a protein
The sequence is coded for by genes (DNA)
The bonds that form the primary structure=Peptide bonds
Primary structure is simply the sequence of amino acids. . . since there are 20 aa’s there are
literally millions of different variations of amino acids sequences  each with many (some with
hundreds of) amino acids
 Therefore there are millions of different proteins
** see diagram
Secondary Structure:
As the chains of amino acids get longer they begin to twist into a spiral. (called an alpha
helix) Hydrogen bonds form between the Hydrogen of one amino acid and an Oxygen
further down the chain. There are other secondary structures, but the alpha helix is the
most common.
(eg. Keratin in hair)
 The bonds that form the secondary structure= hydrogen bonds
****see diagram
Biology 12
Mr. Kruger
Tertiary Structure
Most proteins assume the tertiary structure
The 3rd level can be described as the bending and folding of the alpha helix. As the helix gets longer
there are some aa’s that cannot fit the configuration and therefore cause kinks.
New bonds form to hold it in a three dimensional shape… the three dimensional shape it assumes will
be associated to the protein’s function
***see diagram
The bond types that can form are hydrogen, covalent and/or ionic bonding
Quaternary structure
Occurs in some proteins, particularly enzymes, where different three dimensional configurations
(tertiary structures) are associated with and function with each other.
Example – hemoglobin (4 – 3 dimensional shapes & a central heme (iron containing) component.
Hemoglobin actually exhibits all 4 structural levels – it consists of 2 pairs of tertiary structures held
together by hydrogen bonds.
Protein Denaturation
The weaker hydrogen and ionic bonds of the tertiary structure are easily broken. If a protein’s normal
shape is destroyed because of environmental conditions, it is said to be denatured…
1. Protein loses its normal three dimensional shape
2. Bonding between R groups is disturbed or changed.
3. Protein can no longer perform its normal function
4. Alter enzyme’s activity
Biology 12
Mr. Kruger
 Protein Denaturation can be caused by:
 Change in temperature
 Change in pH
 Change in salt concentration
 Presence of Heavy metals (Mercury, Lead, etc)
Eg. Acid and milk  curdling (denaturation) pH
Acid and fish  denaturing by pH
Egg and heat  excess heat denatures egg white protein
**The normal bonding between ‘R’ groups is disrupted
Protein denaturation can be a very serious problem in enzyme catalyzed reaction (enzymes = organic
catalysts… they speed up and make very specific reactions happen at the right place and time)
If a protein enzyme is denatured a very critical reaction may stop leading to the halt of an entire
metabolic pathway.
Nucleic Acids- Polymers of nucleotides
Function:
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Directs and controls all cell activities
Contains all of the genetic information necessary to make one complete
organism of very exact specifications
They form genetic material and are involved in the functioning of
chromosomes and protein synthesis.
Types of Nucleic Acids:
 Deoxyribonucleic Acid: DNA
(DNA is the largest known molecule)
 Ribonucleic Acid: RNA
Structure
nucleic acids are composed of units called NUCLEOTIDES, which are composed of three submolecules:
Pentose sugar (either ribose or deoxyribose)
Phosphate
P
Nitrogen base: two groups (purine and pyrimidine)
a.) Purines: Adenine and Guanine
Two rings
Found in both DNA and RNA
b.)Pyrimidines: Cytosine, Thymine, and Uracil
One ring
Cytosine is in both DNA and RNA
*Thymine is in DNA only …*Uracil is in RNA only
Biology 12
Mr. Kruger
DNA vs RNA
DNA (Deoxyribonucleic Acid)
RNA (Ribonucleic Acid)
Sugar is deoxyribose (5 carbon)
Sugar is ribose (5 carbon)
Double stranded
Single stranded
Shape : double helix
Strand; no particular shape
Found only in the nucleus
Found in nucleus and cytoplasm.
Bases: A – Adenine
C– Cytosine
Bases: A, C, G, but not T Thymine is replaced
by U – Uracil
G – Guanine
T – Thymine
DNA : only one type
Types of RNA:
mRNA- Messenger RNA
tRNA –Transfer RNA
rRNA – Ribosomal RNA
ATP: Adenosine Triphosphate
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One particularly important nucleic acid is the modified nucleotide known as ATP.
ATP is quite simply a RNA nucleotide with an adenine base
(adenine + ribose = adenosine ) with three phosphate groups attached to it.
High Energy Phosphate bonds
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The phosphate – phosphate bonds are unique in that they are very energy-rich
bonds. Cells store energy in this way – as chemical energy. In order to release the
energy, an enzyme, ATPase, breaks one of the bonds, thus producing ADP (
adenosine diphosphate).
Biology 12
Mr. Kruger
In this way, ATP is often called the energy currency of a cell (because cells make and
“spend” ATP)
FAT------------GLYCOGEN ------- GLUCOSE -------- ATP
Saving bonds -------- Bank Account -------- Piggy Bank -------- Pocket cash
ATP <------> ADP + P + Energy (7 Kcal per mole)
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ATP molecules can be moved all over the body. When energy is needed, the 3rd
phosphate group is broken off. This results in Adenosine Diphospate (ADP) and the
release of heat energy. The heat energy runs metabolic reactions.