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BIOLOGY STUDY SHEET
THE CHEMISTRY OF LIFE
Atoms – The smallest unit of matter (living/nonliving) that can take part in a
chemical reaction.
Molecule – Two or more atoms that are chemically bound to each other (can be
element or compound).
Element – A pure substance that is not made up of other, simpler substances.
Compound – A pure substance that is made up of simpler substances (elements).
Therefore, 2 or more elements that are chemically bonded.
Example: Water:
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A compound that consists of elements, Hydrogen and Oxygen.
Hydrogen and Oxygen are made up of atoms
The compound water is made of different water molecules, where each
molecule consists of 2 hydrogen atoms and one oxygen atom.
Cell – The smallest unit of life contains cell inclusions, i.e. organelles.
Tissue- A group of similarly differentiated cells that perform a common function.
(muscle tissue, connective tissue, epithelial tissue)
Organ- A group of different tissues, which each performs its own function, but also
perform a common function as a group.
System – (blood, vessels, heart etc.)
Organism- living creature.
ORGANIC COMPOUNDS
Organic Compounds vs. Inorganic Compounds:
Organic compounds – chemical compounds that contain element carbon (C) and
are produced by living organisms (Plants).
E.g. Carbohydrates, lipids, proteins, nucleic acids, vitamins.
Inorganic compounds- chemical compounds that do not contain carbon and are
not produced by living organisms.
E.g. Water, mineral salts.
EXEPTIONS: carbon dioxide (CO2), carbon monoxide (CO), and the carbonates
(-CO3), they have carbon but are considered inorganic.
1. Carbohydrates:
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Carbohydrates consist of the elements C , H and O
The ratio of H-atoms: O- atoms is 2:1 (Therefore, if there are 20 H atoms in a
carbohydrate molecule there will be 10 O atoms)
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They consist of ring shape units that are known as Saccharides.
They can be divided into 3 groups according to the number of saccharides
they contain
 Monosaccharides (single sugars)
 Disaccharides (double sugars)
 Polysaccharides (many sugars)
• Used as an energy source or structural material
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MONOSACCHARIDES:
Glucose: Found in table sugar and syrup.
Produced during photosynthesis
-Source of energy
-Most important fuel molecule. During cellular
respiration energy is released from glucose
while CO2 and H2O are formed.
Galactose: Found in Sugerbeet and dairy
products and also synthesize in body.
It is less sweet than glucose.
Fructose: Found in fruits.
DISACCHARIDES:
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Maltose: Maltose or malt sugar is the least common disaccharide in nature. It is
present in germinating grain, in a small proportion in corn syrup.
Lactose: Lactose or milk sugar occurs in the milk of mammals - 4-6% in cow's milk
and 5-8% in human milk. It is also a by-product in the manufacture of cheese.
Provides source of energy for young.
-Sugar found in the milk of mammals.
Sucrose: Is obtained from sugar cane or sugar beets.
POLYSACCHARIDES:
Polysaccharides are long chains of monosaccharaides that are bound to each other.
Monomers: The single units that make up the long chains of polysaccharides.
Polymers: Large molecules, which are made up from long chains of single units.
-The building blocks of starch, glycogen and cellulose are glucose; however the way
in which they are bound together differs.
 Starch: The form in which carbohydrates are stored in the plant.
 Glycogen: The form in which carbohydrates are stored in humans.
-Short-term energy storage.
- Especially abundant in the liver and muscles of active animals, including people.
 Cellulose: Forms a structural component of cell walls in plant cells.
-Is not actually digested. In the form of fiber it keeps food moving smoothly
through the intestine (dietary fiber).
-Cell walls of plant cells mainly consist of cellulose, which strengthens the cell wall.
CONDENSATION AND HYDROLOSIS: (how disaccharides and polysaccharides are formed)
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2. LIPIDS (fats and oils)
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Fats consist of the elements C, H and O – the same three elements as
carbohydrates.
The H:O ratio is much greater than 2:1
Fat molecules consist of two types of building blocks, i.e. GLYCEROL and
FATTY ACIDS.
One fat molecule consists of one glycerol molecule and three fatty acids.
Their Properties:
1. Insoluble in water (because the are non polar – are not attracted to – of
oxygen or + of Hydrogen)
2. Hydrophobic (water-repelling) (push away the water)
3. Soluble in alcohol and ether.
Importance of Fats in animals and plants:
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Source of Reserve energy: a large amount of energy is released when fat
molecules are broken down.
Insulating Material: poor conductor of heat. Marine animals have a layer of
blubber under the skin, which insulates their body heat from the cold
seawater.
Shock Absorption: The kidneys and eyes are surrounded by a layer of fat, to
protect them against hard blows.
Structural Component of Cell Membranes: Cell membranes consist of a
double layer of phospholipid molecules with a layer of proteins on either
side. Phospholipid: A lipid where one fatty acid molecule is replaced by a
phosphate group (PO4).
Waterproofing: A fatty substance, cutin, forms the cuticle that covers the
epidermal cells of plants. The cuticle prevents excessive loss of water. Birds
have oil glands that secrete oil to make their feathers waterproof.
Absorption of vitamins: Fat-soluble vitamins A, D, E and K can only be
absorbed if they are dissolved in fat.
Source of water: Animals that hibernate in cold weather or others that
survive in warm, dry conditions store fat that is broken down to CO2 and
H2O during respiration. The camel that lives in the desert is an example of an
animal that survives by using metabolic water.
Protects nervous system.
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• Fats
– Lipids with one, two, or three fatty acids “tails” attached to glycerol.
– Triglycerides
– Neutral fats with three fatty acids attached to glycerol
– The most abundant energy source in vertebrates
– Concentrated in adipose tissues (for insulation and cushioning)
ENERGY STORAGE: CARBS VS LIPIDS
- Carbs are more easily digested than
lipids, so the energy they store can be
released more rapidly
-Lipids contain more energy per gram
than carbs. So they are a lighter store of
energy.
-Lipids are normally used for long-term
energy storage. Starving animals tends
to use glycogen stores before using fat
storages.
3. PROTIENS
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Proteins consist of the elements C, H, O and N. In some proteins P and S also
occur.
A protein is a very large molecule (polymer) with amino acids as monomers.
There are only 20 different amino acids
The sequence and type of amino acid, determines the type of protein.
The link/bond between two amino acids is known as peptide bond.
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Dipeptide: two amino acids link together
Tripeptide: three amino acids
Polypeptide: long chain of amino acids
Protein: 50 amino acids linked together.
-Each protein has its own shape
-The shape (spherical, helix, etc) determine its function
-High temperatures and drastic changes in pH = proteins denature
-Denature: protein loses its shape and can no longer perform its function.
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Importance of Proteins in animals and plants:
-Structural component of protoplasm: ±15% of protoplasm consists of proteins.
Protoplasm: The colorless material comprising the living part of a cell, including the
cytoplasm, nucleus, and other organelles.
-Building materials:
Myosin in muscle tissue
Collagen in bone,
Chondrin in cartilage,
Keratin in skin, hair and nails.
-Structural component of cell membranes: Together with phospholipids, forms
the membrane that surrounds the cell.
-Plays a role in permeability of cell membranes: Act as carrier molecules that
carry other molecules across the cell membrane.
-Source of reserve energy: Excess amino acids are broken down to urea and
glucose during the process of deamination. Glucose is the body’s main source of
energy. E.g. albumin in eggs acts as a reserve source of nutrients for developing
chickens.
Deamination:
-Enzymes control metabolic processes in the body: Enzymes are proteins that
accelerate chemical reactions
-Hormones regulate processes in the body: Hormones are proteins that act as
chemical messengers.
-Hemoglobin transports O2 and CO2 in the blood.
-Protect the body from diseases: Antibodies are proteins that fight bacteria and
viruses.
-Chromosomes carry hereditary material: chromosomes consist of proteins and
DNA.
-Act as buffers: Proteins keep the pH of bodily fluids constant.
**ADD COMPARISON TABLE
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4. ENZYMES:
Metabolic Reactions: Chemical reactions that take place in living cells.
Metabolism: The sum of metabolic reactions
Metabolic Pathway: A single chain of biochemical reactions
Anabolic (constructive) Reaction:
- Complex molecules are built
up from simple molecules
- Energy required.
-
Catabolic (deconstructive)
Reaction:
Complex molecules are broken
down to simpler molecules
Energy released.
Catalysts: substances that accelerate chemical reactions
- Enzymes: biological catalysts- accelerates chemical reactions that occur in cells.
Activation Energy: required to start a chemical reaction.
- Enzymes: Lower activation energy that is needed for reaction…cause reaction to
accelerate.
Therefore, an enzyme is a biological catalyst that accelerates a chemical reaction
by lowering the activation energy without itself being changed by the reaction.
During digestion of food, very large molecules (macromolecules) are broken down to
smaller soluble molecules by the addition of H2O (hydrolysis). These reactions will
not take place without the help of the enzymes that catalyze the reaction.
Carbohydrates (Disaccharides)
Maltose + Water _________Maltase___________> Glucose + Glucose
Lactose + Water _________Lactase____________> Glucose + Galactose
Sucrose + Water _________Sucrase____________> Glucose + Fructose
(Polysaccharides)
Starch + water __________Salivary amylase______> Maltose
Lipid + Water _________________Lipase_____________> 3 Fatty Acids and Glycerol
Proteins + Water ____________Proteases e.g. Pepsin_____> Smaller polypeptides.
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ENZYME ACTION (lock-and-key mechanism):
1. During a chemical reaction, one substance is converted to another.
2. The substance that the enzyme acts on is known as a substrate.
3. The new substance that is formed during the reaction is known as the product.
4. Enzymes are proteins, and you have already learned that proteins have a
particular shape to be able to perform its specific functions.
5. A specific enzyme can only act on its specific substrate
6. On the enzyme there is an area known as the active site. The substrate molecule
fits into the active site of the enzyme, like a key that fits into a lock – this ensures
the specificity of the enzyme.
7. A temporary enzyme-substrate complex is formed.
8. The enzyme lowers the activation energy of the reaction.
9. The substrate changes chemically and leaves the active site.
10. The enzyme remains unchanged during the reaction and is then able to bind
with the next substrate molecule.
TEMPERATURE AND ENZYMES:
- Enzymes are very sensitive to temperature changes
- Low temperatures temporarily in active enzymes.
- The temperature at which enzymes work best, is known as the optimum
temperature (37 degrees C – the body temperature of a human)
- At high temperatures, usually above 45 degrees the substrate will no longer fit
into the active site. The enzyme denatures….
- Denatures: Denaturing is an irreversible process. Therefore, when an enzyme
has been denatured, it cannot be repaired if the temperature decreases again.
When an enzyme is inactivated due to low temperatures, it can become active
again when the temperature increases.
WHY?
- Temperature increases = enzyme reactions become faster (better chance of them
colliding with substrates), they have more energy = higher temp. Molecules vibrate
faster and break the weak bonds that hold the tertiary structure together = the
shape changes and doesn’t fit the substrate = DENATURED
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ENZYME SHAPES:
1. Primary Structure
Amino acids are
arranged in a protein
chain.
2. Secondary Structure
Some chains coil up or fold into
pleats that are held together by
weak forces of chemical
attraction (hydrogen bonds).
3. Tertiary Structure
Enzymes (and other proteins) have
a tertiary structure, where the
coiled chain of amino acids is folded
into a ball that is held together by
weak chemical bonds and stronger
chemical bonds.
Most enzymes work inside cells, but glandular tissue of digestive system produce
enzyme that are used outside cell membrane.
Glandular Tissue
Salivary Gland
Gastric Glands in
stomach wall
Pancreas
Cells in small
intestine wall
Enzyme Produced
Amylase
(carbohydrase)
Endopeptidase
(protease)
Amylase
Endopeptidases
Lipase
Maltase
Exopeptidases
Substance Digested Products of digestion
Starch
Maltose
Long protein
molecules
Starch
Short protein
molecules
Fats (lipids)
Maltose
Very short protein
molecules
Short protein molecules
Maltose
Very short protein
molecules
Fatty acids and glycerol
Glucose
Amino acids
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5. DNA AND RNA:
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6. VITAMINS: Red= Fat soluble Green=Water soluble
Vitamin
A
Function
Maintain health of epithelial cells, formation of lightabsorbing pigment, growth of bones and teeth.
D
Absorption of calcium and phosphorus in digestive tract.
E
K
Formation of DNA, RNA and red blood cells
Blood clotting
B1
B2
Niacin
B6
Sugar metabolism, synthesis of neurotransmitters
Sugar and protein metabolism in cells of eyes, skin,
intestines, blood
Energy-releasing reactions, fat metabolism
Fat metabolism
B12
Red blood cells formation, metabolism of amino acids
Pantothenic Aerobic respiration, synthesis of hormones
acid
Folic Acid
Synthesis of DNA and RNA, production of red and white
blood cells
Biotin
Aerobic respiration, fat metabolism
C
Protein metabolism, wound healing
Sources
Liver, broccoli, green
and yellow vegetables,
tomatoes, butter.
Egg yolk, shrimp, yeast,
liver, sun
Leafy veg., milk, butter
Green vegetable,
tomatoes
Ham, egg, chicken
Yeast, meats, liver
Salmon, yeast,
tomatoes, corn, spinach,
liver, yogurt, wheat
bran
Liver, milk, cheese,
eggs, meats
Milk, liver, yeast, green
veg., whole grain.
Liver, leafy green veg.
Yeast, liver, egg yolk
Citrus fruits, tomatoes,
leafy green, broccoli
Minerals (not organic)
Fluorine (F)
Calcium (Ca)
Iodine (I)
Phosphorus (P)
Dental cavity reduction
Teeth and bone formation, muscle and nerve activity,
blood clothing
Formation of thyroid hormone
Sodium (Na)
Potassium (K)
Teeth and bone formation, blood pH, muscle and nerve
activity, part of enzymes and nucleic acids.
Formation of hemoglobin (carries oxygen to body cells)
and cytochromes (ATP formation)
Development of red blood cells, formation of some
respiratory enzymes
Nerve activity, body pH regulation
Nerve and muscle activity
Magnesium
(Mg)
Sulfur (S)
Muscle and nerve activity, bone formation, enzyme
function
Builds hair, nails and skin, component of insulin
Iron (Fe)
Copper (Cu)
Fluoridated water
Milk and grain groups
Seafood, eggs, iodized
salt
Milk, grain, and
vegetable group
Liver, egg yolk, grain
and meat groups
Grain group, liver
Bacon, butter, table salt
Vegetable group,
bananas
Fruit, vegetable and
grain groups
Grain and fruit groups,
eggs, cheese