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Biological molecules (Lecture 1), proteins, Lipids, Carbohydrates, Nucleic…
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proteins
Enzymatic proteins.
- accelerate chemical reactions.
- An example of this is hydrolysis of bonds in food by digestive enzymes
Substrate.
- binds to the enzyme, forming a enzyme-substrate complex
- binding of the substrate and enzyme places stress on the bonds,
- the bonds are broken. a product is released.
Defensive proteins.
- protection against disease.
- An example is antibodies destroying viruses and bacteria.
Antibodies.
- Y in shape, consisting of a light chain: Small polypeptide subunit**.
- A heavy chain; large polypeptide subunit.
- The FC region; constant region involved in complement activation and cell surface receptor binding.
Structural Proteins
- support. examples are collagen ( Rigid) and elastin ( Flexible x1000) in connective tissues. - Produced by fibroblasts.**
Storage proteins.
- storage of amino acids,
- an example of this is Ovalbumin
- the protein of egg white, good source of amino acid for developing chickens.
Hormonal proteins.
- coordination's of an organism activities.**
- regulates blood sugar levels.
- through the release of insulin and glucagon via the pancreas.**
- Insulin initiates the uptake of glucose from the blood, the formation of glycogen lowering** blood sugar levels.
- Glucagon stimulates the breakdown of glycogen, increasing blood sugar.
Contractile and motor proteins.
- provides movement through muscle - contraction,
- when actin and myosin interact.
Transport Proteins.
- Transports substances around the body,
- An example of this is that haemoglobin transports oxygen.
Receptor Proteins
- respond to chemical **stimuli,**
- an example is receptor of the nerve cell detecting signalling of molecules.
Proteins are long polymer chains consist of **amino acid subunit.
- 20 in total, they all have basic structures.**
- A central carbon atom with 4 of the following groups bonded:
- hydrogen atom.
amino group (-NH2)
Carboxyl group (-COOH)
- R group.
Lipids
Lipids
- Water insoluble cell component, no common structures, the
- 3 key types
- Fats,
- Phospholipids**
- steroids
Fats
- provide a major stored energy source.
- Glycogen is bulky, even more energy dense structure. Provides insulation.
- fat cells produce molecules from the immune system and hormones ( Adipokines)
Saturated fats
- are solid at room temperature.
- Consist of hydrocarbon chains
- connected by single bonds only.
unsaturated fats
- are usually liquid at room temperature.
- Consisting of hydrocarbon chains with one or more double bond.
- Each double bond may be cis ( both hydrogens are on the same side of the hydrocarbon chain)
- trans ( opposite sides of the hydrocarbon chain)
Triglycerides (fats)
- are the molecular building blocks of fat they consist of glycerol head and 3 fatty acids tails.
- assembled through a dehydration reaction.
Phospholipids
- are the major component of cell membranes.
- similar structure to fat but only have 2 and not 3 fatty acids attached to glycerol
- organised in a bilayer*
- hide their hydrophobic tail region and expose the hydrophilic regions to water containing environment.
- provides a highly impermeable barrier that only allows for the passage of water and gases.
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Steroids
- essential component in cell membranes,
- cholesterol and sex hormones, - synthesized in the liver or from diet.
hypothalamus. -
connected to the immune system via the adrenal gland.
- immune cells can produce steroids.
- immune cells can feedback to the hypothalamus.
Carbohydrates
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Formed from the building blocks or monomers of simple sugars, such as glucose
Monomers - can be linked to form larger carbohydrate polymers, known as polysaccharides and complex carbohydrates
Monosaccharides..
- simple sugars
- based around a** common formula
- ( 6 Carbon ) (12 Hydrogen ) ( 6 Oxygen )**
Glucose.
- most important biological sugar.
- highly soluble
- provides energy for the brain and half of the energy for muscles and tissues.
- Glucose is immediate energy. - Glycogen is reserved energy.
Disaccharides
- 2 monosaccharides covalently bonded,
- contain glucose.** Maltose, Dimer of glucose and makes up starch**. Lactose, glucose and galactose,
- present in milk, broken down by the enzyme lactase
Polysaccharides
- polymers formed from hundreds of simple sugars
- Structural role in chitin and cellulose.
- Energy storage** starch in plants and glycogen in animals**
Glycogen.
- 1 million glucose covalently bonded together,
- forms branches every 5-6 glucose.
- highly soluble that's stored in the liver and skeletal muscle cells
Nucleic acids
Nucleotides:
- monomers of nucleic acids. consisting of 5 carbon sugar.
- nitrogen containing a base and phosphate group.
Nucleic acids
- polymers of the nucleotide monomers, they are bonded by sugar phosphate bonds ( DNA, RNA, coenzymes, energy carriers and ,messengers.
Adenosine triphosphate:
- nucleotides that consist of an adenine base.
- five carbons ribose sugar, and three phosphate groups.
- primary function as an energy carrier.
Hydrolysis of ATP.
- water is added ATP breaks down into ADP.
P rest and energy.
- energy is then used to transport molecules or do mechanical work.
Genetic material.
- Pyrimidines: Cytosine (C) Thymine (T), DNA. Uracil (U), RNA.
- Purines: Adenine (A) Guanine (G)
- Sugars: Deoxyribose ( DNA- deoxyribonucleic acid) Ribose (RNA- ribonucleic acid)
Base pairs
- Adenine
- thymine
- cytosine
- guanine within a phosphate backbone
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How to make a protein
- Specific sequencing of amino acids
- joined together in a particular order.
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- Polypeptides
- long chains of amino acids
- bonded through peptide bonds
Sickle cell anaemia
- Glutamine is replaced by valine.
- causing changes within the B haemoglobin subunits.
- although the haemoglobin assembles normally there are to faulty B subunits present in the quaternary structure.
- consequently proteins aggregate into fibres, reducing oxygen