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Biology Unit 2
Biological Molecules:
The main types of biological molecules found in organisms are water, proteins,
carbohydrates, lipids and nucleic acids which make up the structure and undergo
chemical reactions known as metabolic reactions (metabolism refers to the total sum
of all the chemical reactions taking place within the…

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The amino acids are linked together on the ribosomes in a cell.

Peptide bonds are made between the amino acids when the OH from one molecule's
carboxyl group is removed with a H from the other molecule's amine group, making a
water molecule (a condensation reaction) and a CO-N bond.…

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from blue to lilac.


(Alpha glucose and beta glucose)

They are made up of sugar units (CnH2nOn).

They include sugars, starches and cellulose - sugars are soluble in water and taste
sweet, whereas starches and cellulose (polysaccharides) are insoluble in water and do
not taste sweet.

A carbohydrate with…

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shaking, which will turn from blue to yellow to brick-red (precipitate).

Non-reducing sugars can be detected by adding dilute hydrochloric acid and boiling for
a minute, before adding sodium hydrogencarbonate to neutralise the solution in which
the Benedict's solution will be added to, before boiling and shaking, which will turn…

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Lipids can be detected by adding ethanol, before shaking and adding water, which will
turn white (emulsion).

Nucleic Acids

Nucleic acid is the slightly acidic substance
found mostly in the nucleus of cells, made
up of DNA, which stands for
deoxyribonucleic acid.

Each nucleotide in a DNA molecule
contains a…

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they speed up a chemical reaction but are not used up in the process, and virtually
every metabolic reaction requires a specific one.

They can be intracellular (like hydrolases in lysosomes or ATPase in mitochondria) or
extracellular (like amylase in the alimentary canal).

They have an active site, which is…

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responsible for forming cross-links in bacteria cell walls, so the bacteria cell ceases to

When more non-competitive inhibitor is added, the initial rate of reaction is decreased
no matter what the substrate concentration is whereas when more competitive
inhibitor is added, the initial rate of reaction is increased until…

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attempted repair), which is called an atheromatous plaque. The hardening
of the walls is called atherosclerosis.
2. A reduced lumen, reducing the oxygen supply to the heart, giving the
person chest pain called angina.
3. Stress and exercise can make the plaque break, allowing platelets to come
into contact with…

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the volume of fluid in the body, and so lowering the blood pressure.

Food Sources

Selective breeding is chosing specific parents to breed together as they have the desired
characteristic and so they are most likely to produce an offspring with that
characteristic. It is generally carried out over several…

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effect on the food itself.

Microorganisms can however be used for food production, such as cheese and yoghurt.
A specific fungus can also make mycoprotein, which is rich in protein and low in fat,
and it mainly used as a meat substitute for vegetarians or for people on a diet.…


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