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Lecture Notes – An Overview of Plant and Animal Cells
All organisms are made of 4 classes of molecules along with the essential molecule – water
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Some of these (carbohydrates, proteins
and nucleic acids) can be combined to form polymers
Making Polymers (also known as macromolecules)
Most animal cells make macromolecules
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This provides the cells with the building blocks required to produce the
macromolecules specifically for our biosynthesis and energy (ATP)
To make polymers, or increase a polymer chain, a DEHYDRATION or CONDENSATION reaction must
occur
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This adds one molecule of water
Neither of these reactions happens spontaneously
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CARBOHYDRATES
Carbohydrates are sugars/sugar polymers made up of carbon, hydrogen and oxygen
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Carbohydrates are mainly used as storage of fuel,
structure or instant useable energy in the form of ATP
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This forms a GLYCOSIDIC BOND/LINKAGE
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G: 2 molecules of glucose produce maltose
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This can be UNBRANCHED (amylose) or BRANCHED
(amylopectin)
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In plants, carbohydrates are also stored as CELLULOSE
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The polymers
wrap themselves up to form myofibrils
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This is often
found on insects as it forms the strong outer shell that protects them
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In animals, carbohydrates are stored as GLYCOGEN, found in the muscle and the liver
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LIPID
Lipids are hydrophobic (water hating) molecules
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Their most common form is as a triglyceride
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Dehydration reactions always occur
between a molecule of glycerol and fatty acid:

+

(x3)

=

PHOSPHOLIPIDS form biological membranes
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They are formed
when glycerol is combined with two fatty acid chains and a
molecule of phosphate
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Once the chains are submerged in
solvent or water, they self-assemble into bilayer in which the
phosphate heads are exposed
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If cholesterol is in the
membrane, it lowers the fluidity of the membrane
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Cortisol is used for glucose regulation and as a stress response
PROTEIN
Proteins are made using a dehydration reaction to form a PEPTIDE BOND/LINKAGE
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The process of making proteins is called PROTEIN SYNTHESIS
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These are made on a central carbon atom
that is linked to a hydrogen atom and one other R chain
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Amino acids also have the nitrogen based amino group and the carbon based carboxylic acid group
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In proteins synthesis, amino acids are always added to the carboxyl end of the chain
There are 4 types of structure of proteins
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The SECONDARY structure is formed when the primary structure forms α-helix or a β-pleated sheet
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Finally, the
QUARTERNARY structure is made when two or more tertiary structures are placed together to form
a specific molecule, such as haemoglobin
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This includes:

ENZYMATIC – For the acceleration of reactions
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They are catalysts
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They are highly specific
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It holds all the
genetic information of a cell
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In protein synthesis, double
stranded DNA is converted into single stranded RNA, which then becomes mRNA that can be
transcribed in the cytoplasm to produce the protein
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It is known as an anti-parallel double helix
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Nitrogenous bases can
be PURINES (A and G) or PYRIMIDES (C, T and U)
In DNA, complementary bases pair up and form hydrogen bonds
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A
always pairs with T and C always pairs with G
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RNA, being single stranded, is a much more
flexible molecule and can create more variation

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