Deoxyribose for haemoglobin. This mutation causes the haemoglobin in

Deoxyribose nucleic acid (DNA) is present in the nucleus of
all living organisms. It controls all the chemical changes within the cell and
determines the kind of organism that is produced. Each cell is identical
(unless specialised) and contains the genetic information of the living
organism. DNA consists of a double strand of nucleotides, the sugar-phosphate
chains are parallel to each other, and these chains are held together by bonds
between the bases. Nucleotides are made up of three parts; a sugar base called
ribose, a phosphate groups and an organic/nitrogenous base. The most common
organic bases are adenine, thymine, guanine and cytosine. Adenine and guanine
are purines meaning large molecule, cytosine and thymine are pyrimidines
meaning smaller molecule. A small molecule will always bond with a large
molecule. Adenine always pairs with thymine and guanine always pairs with
cytosine. REFERENCE. Sickle cell
anaemia (SCA) is the result of a point mutation, a change in just one
nucleotide in the gene for haemoglobin. This mutation causes the haemoglobin in
red blood cells to distort to a sickle shape when deoxygenated. The
sickle-shaped blood cells clog in the capillaries, cutting off circulation. REFERENCE. 


The chemical reactions inside cells are controlled by enzymes.
substance that speeds up a chemical reaction without being a reactant is called
a catalyst. The
catalysts for biochemical reactions that happen in living organisms are
called enzymes. Enzymes
are usually proteins, though some ribonucleic acid (RNA) molecules act as
enzymes too, they never ‘die’ they get recycled being used and used
again until they are denatured and no longer fit for use. REFERENCE. Enzymes perform the critical task of lowering a
reaction’s activation energy, which is the amount of energy that must be put in
for the reaction to start. Enzymes work by binding to
reactant molecules and holding them in such a way that the chemical
bond-breaking and bond-forming processes take place more readily. Long chains
of amino acids are folded to produce a special shape which is called a tertiary
structure, a tertiary structure enables other molecules to interact with the
enzymes. The ability of the enzyme to act as a catalyst depends on their
shape. On the surface of an enzyme there is a region called the active site.
The active site gets its properties from the amino acids it’s built out of.
These amino acids may have side chains that are large or small, acidic or
basic, hydrophilic or hydrophobic. The set of amino acids found in the active site
give the active site a very specific size, shape, and chemical behaviour. REFERENCE. One or more substrate
molecules fit the shape of the active site, when the substrate fits into the
active site its forms a temporary union called the enzyme-substrate complex. In
some reactions, one substrate is broken down into multiple products. In others,
two substrates come together to create one larger molecule or to swap pieces.
So the substrate enters the active site, making enzyme-substrate complex the
next stage is enzyme-products complex after this the products leave the enzyme
for the cycle to happen again. There are competitive inhibitors which are
chemicals that resemble an enzyme’s natural substrate to slow down the action
of enzymes. There is also non-competitive inhibitors that are chemically
different from the substrate and do not enter the active site, but they bind to
another part of the enzyme causing it to change shape which in turn alters the
active site. What can speed up the reaction is an enzyme concentration, the
more substrate in the solution the greater chance of the enzyme-substrate
complex will form. The opposite is a substrate concentration this also speeds
up the reaction, this is when there is a more substrate in the solution than
enzymes, and this increases the chance of a substrate molecule finding an
active site. REFERENCE. There is two
methods that scientist believe how substrates fit into active sites. The first,
is the Lock and Key theory where the enzyme’s active site is the exact shape of
the substrate to fit together exactly, which seems to be outdated and now the
new believed theory is the Induced Fit model. The Induced Fit model assumes
that the substrate plays a role in determining the final shape of the enzyme
and that the enzyme is partially flexible and will mould itself to the shape of
the substrate. REFERNCE. There are
some environmental factors that can affect an enzyme. Temperature is one of
them, the normal human body temperate (37 °) provides a good internal
environment for enzymes to work efficiently. Enzymes will work in lower
temperatures although much slower but at higher temperatures will see the
active site to break and the enzyme will become denatured at around 65 ° or
above. The pH of the body works in favours of different enzymes. Pepsin the
enzyme found in the stomach works at the optimum level between pH 1–4, salivary
amylase found in your mouth which begins the digestive process by breaking down
starch when you chew your food works at an optimum between pH 6-7 and alkaline
phosphatase (ALP) which is found in the blood (the main source found in the
liver) helps break down proteins in the body and the pH optimum for enzymatic
activity is pH 8-10. REFERNCE. 

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triphosphate (ATP) is a RNA nucleotide which bears three phosphate
chains. At the centre of the molecule lies a five-carbon sugar, ribose, which
is attached to the nitrogenous base adenine and to the chain of three
phosphates. There are four main stages of respiration, firstly glycolysis which
is the breaking down of glucose. The glucose is phosphorylated into
glucose-6-phosphate by taking a phosphate from ATP. The glucose-6-phosphate
changes to fructose via isomerisation. This is then phosphorylated for a second
time, splitting another molecule of ATP, forming fructose-1-6-bisphosphate. The
fructose-1-6-bisphosphate then splits into two molecules called triose
phosphate. They each have 3 carbon (C) and 1 phosphate. They are then converted
into pyruvic acid. This involves the removal of hydrogen and its transfer to a
hydrogen carrier molecule (NAD) to form reduced NAD. Each pyruvic acid yields 2
molecules of ATP in the process of its creation. The 2 reduced NAD made goes to
the electron transport chain and the 2 molecules of pyruvate goes into the link
reaction which is the next stage. The link reaction connects glycolysis to the
Kreb’s cycle. The pyruvate undergoes decarboxylation and dehydrogenation to produce
C02 and H+ which is used to reduce NAD. This forms acetate which taken by
coenzyme A (coA) recycled from Kreb’s cycle to form acetyl coA. No ATP is
produced or used in this stage so the net total of ATP is still 2. There is now
4 carbon. The third stage is the Kreb’s cycle, acetyl coA enters the Kreb’s cycle
by combining with a 4C acid to form a 6C compound (citrate). Citrate undergoes
decarboxylation and dehydrogenation to produce C02 and H+ which is used to
reduce NAD which creates a 5C compound (Ketoglutaric Acid). Ketoglutaric Acid
undergoes decarboxylation and dehydrogenation again producing a 4C compound.
This time enough energy was created to synthesis a molecule of ATP. 4C compound
is dehydrogenation to reduce NAD. The cycle runs twice so 2 ATP are made. The
electron transport chain is the final stage, this takes place in the inner
membrane of the mitochondria. The electrons move along and as they move from one
molecule to another, a molecule of ATP is produced. This happens 17 times, and
this happens twice so in total 34 molecules of ATP are produced. REFERENCE.