SNAB topic 2- genes and health

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Unit 2
Genes and health
The effects of CF on the lungs:
CF= Cystic Fibrosis
Air is drawn into the lungs via the trachea due to a lower pressure in the lungs, created by
the movement of the ribs and diaphragm.
Trachea divides into 2 bronchi which carry air to and from each lung.
Within the lung there are bronchioles attached to alveoli.
Alveoli are the sites of gas exchange.
Any dust, debris or microorganisms that enter the airways become trapped in the mucus
which is then continually removed by the wavelike beating cilia that cover the epithelial
cells, lining the tubes of the gas exchange system.
People with CF have mucus drier than usual resulting in a sticky mucus layer that the cilia
find difficult to move.
The sticky mucus has 2 major effects on health: it increases the chances of lung infection
and it makes the gas exchange less efficient, particular in the later stages of the disease.
With CF the mucus layer is so sticky that cilia cannot move the mucus. The mucus
production continues, as it would in a normal lung, and the airways build up layers of
thickened mucus. There are low levels of oxygen in the mucus, partly because oxygen
diffuses slowly through it, and partly because the epithelial cells use up more oxygen in CF
patients. Harmful bacteria can thrive in these anaerobic conditions.
White blood cells fight the infections within the mucus but as they die they break down,
releasing DNA which makes the mucus even stickier. Repeated infections can eventually
weaken the body's ability to fight the pathogens, and cause damage to the structures of
the gas exchange system.
How does sticky mucus reduce the gas exchange?
Gases such as oxygen cross the walls of the alveoli into the blood system by diffusion. To supply
enough oxygen to all the body's respiring cells, gas exchange must be rapid. The fine structure of
the lungs helps maximise this.
The effect if increase in size on surface area:

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Primary structure:
Two amino acids join in a condensation reaction to form a dipeptide, with a peptide bond
forming between the two subunits.
This process can be repeated to form polypeptide chains which may contain thousands of
amino acids. A protein is made up one or more of these polypeptide chains.
The sequence of amino acids in the polypeptide chain is known as the primary structure of
a protein.…read more

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Tertiary Structure:
The final 3D structure of a protein is its Tertiary Structure, which pertains to the shaping of the
secondary structure. This may involve coiling or pleating, often with straight chains of amino
acids in between.
Tertiary Structure: The final 3D structure of a protein, entailing the shaping of a secondary
structure.…read more

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Fibrous They proteins form long fibres and mostly consist of repeated sequences of amino
acids which are insoluble in water. They usually have structural roles, such as: Collagen in bone
and cartilage, Keratin in fingernails and hair.
Quaternary Structure:
Some proteins are made up of multiple polypeptide chains, sometimes with an inorganic
component ( for example, a haem group in haemoglogin ) called a Prosthetic Group. These
proteins will only be able to function if all subunits are present.…read more

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Phospholipid bilayer:
The fluid mosaic model:…read more

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