Molecules

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05.10.09

Describe the structure of an amino acid.

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An amino acid consists of a molecule that has a carbolic and amino group and random group. The random group makes them into one of 22 amino acids.

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Describe how two amino acids join together and what is this reaction called?

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Amino acids join together by removing the H from one molecule and OH from another in a condensation reaction. The bond formed ina a peptide bond. Two amino acids joined together are called DIPEPTIDES and three joined together are called POLYPEPTIDES.

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How many amino acids are joined together to make haemoglobin and which stage are they linked up in?

What is a helix? How does it form? How many helices does haemoglobin contain and how is it held in shape?

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Four chains of amino acids join together to from haemoglobin and this is done during the primary stage.

An alpha helix is a secondary stucture when it twists and coils when two hydrogen bonds are the same and join. Haemoglobin has four and is held in shape by weak hydrogen bonds.

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05.10.09

Describe the following:

Primary structure.

Secondary Structure.

Tertiary Structure.

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Primary structure - the number and sequence of amino acids in a polypeptide chain. Heamoglobin is a complex protien and is made up of four polypeptide chains.

Secondary structure - This is the way the polypeptide chain twists and coils together. Different parts of the molecule are held together by weak hydrogen bonds. The two ways which the structure can fold are aplha-helix and beta-sheets.

Tertiary structure - The chains fold into 3D sheets and are held together by several types of bonds between the R groups.

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Describe the following:

Bonds in tertiary folding

Quaternary folding

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05.10.09

Bonds in tertiary folding:

Disulphide bonds - The amino acid "cysteine" contains sulphur when two cystein amino acids are near each other they form this type of bond.

Ionic bonds - bonds between R groups that carry a charge. (possitive and negative attract)

Hydrogen bonds - when postive and negative groups are found nearby they attract.

Quternary folding:

These are the joining of more than one polypeptide such as haemoglobin, At the centre of each haemoglobin molecule is a haem group containing an iron acid.

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05.10.09

Describe the role of haemoglobin,

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Haemoglobin is a globular protein, the way which they are folded means that they have hydrophillic R groups on the outside of the molecule which allows them to be soluble in water - useful when the water contains a lot of plasma. Each haemoglobin can carry four oxygen molecules.

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13.10.09

What is denaturation and how is it caused?

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13.10.09

This is when the shape of a protien molecule changes. The two ways this can happen are:

TOO HIGH TEMPERATURE - increases kinetic energy of the molecule and vibrates more causeing weak bonds to be broken and shape change.

CHANGE IN PH - changes the hydrogen ion content. H bonds and ionic bonds are reliant on the attraction between paritcles and will distrupt this.

Acidic - more H+ ions

Alkalins - more OH- ions

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13.10.09

What are the three types of diseases which can form when molecules are denatures and what is each?

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13.10.09

Sickle cell amenia - There are normal alpha chains but the beta chains have the amino acid valine present instead of acid glutanio acid. The red blood cells change shape and carry less oxygen.

Beta Thalassamemia - This is when the beta chains are much smaller and carry less oxygen around the body.

Glycolsylated Haemoglobin - when lood glucose levels are high and glucose attaches to the haemoglobin in red blood cells. Picks up oxygen easily but can not give it up due to the glucose which is attached.

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15.10.09

What is a condensation reaction?

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A condensation reaction is when the O from one molecule and the OH from another join together in a reaction and then give off water.

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Describe the structure of alphaglucose.

What is a disaccharide?

What is a polysaccharide?

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Six carbon atoms in a hexegan shape with one other carbon atom coming off the sixth carbon. A disaccharide is two monosaccharides joined together. A polysaccharide is when many monosaccharides join together.Glucose is an example. The bond which is formed between the monosaccharides (between carbons one and four) is called a glycosidic bond.

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What is a condensation reaction?

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A condensation reaction is when the O from one molecule and the OH from another join together in a reaction and then give off water.

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Give three facts about glycogen.

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Describe the structure of alphaglucose.

What is a disaccharide?

What is a polysaccharide?

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  • It's insoluble (stays in liver and won't go into the blood)
  • It's compact (takes up less space so is good for storing)
  • It's branched so there are many ends where the glucose molecules can easily be released from.
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Six carbon atoms in a hexegan shape with one other carbon atom coming off the sixth carbon. A disaccharide is two monosaccharides joined together. A polysaccharide is when many monosaccharides join together.Glucose is an example. The bond which is formed between the monosaccharides (between carbons one and four) is called a glycosidic bond.

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What is glucose and how can it be measured?

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Give three facts about glycogen.

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Glucose is a simple carbohydrate (a monosaccharide) and is a simple sugar which makes is very easy to be broken down into respiration. Glucose is very soluble so can be transported in the blood easily. The best time to test for it is after lunch and measured using a blood glucose monitor.

A carbohydrate - a molecule which contains elements of carbon and hydrogen.

How to test using a blood glucose monitor

Test strip containing enzymes is placed onto the blood and when it touches it, it is converted into gluconaactone which produces a small electrical current. This is detected by an electrode which gives a reading of blood glucose levels.

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  • It's insoluble (stays in liver and won't go into the blood)
  • It's compact (takes up less space so is good for storing)
  • It's branched so there are many ends where the glucose molecules can easily be released from.
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What is glucose and how can it be measured?

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Glucose is a simple carbohydrate (a monosaccharide) and is a simple sugar which makes is very easy to be broken down into respiration. Glucose is very soluble so can be transported in the blood easily. The best time to test for it is after lunch and measured using a blood glucose monitor.

A carbohydrate - a molecule which contains elements of carbon and hydrogen. Two glucose molecules joined together are joined with a glycosidic bond during a condensation reaction. A disaccharide of glucose is called a maltose.

How to test using a blood glucose monitor

Test strip containing enzymes is placed onto the blood and when it touches it, it is converted into gluconaactone which produces a small electrical current. This is detected by an electrode which gives a reading of blood glucose levels.

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15.10.09

Hydrolysis of disaccharides is the breaking of two bound molecules into one- when might the body want to carry this out?

What could happen is blood sugar levels went too high/too low?

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  • During respiration the body would want to break them into two as it can onlu use one at a time.
  • Too high - there would be too many and would be stored as insulin (hypo)
  • Too low - not enough for respiration (Hyper)
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19.10.09

Describe the composition of blood and what extracellular fluids are.

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55% is plasma (a straw coloured fluid)

45% celular compotnents ie. white blood cells

Red Blood cells make up the rest.

Things found in blood include: oxygen, glucose, wtaer, protiens, hormones (insulin, adreniline, testosterone, aestrogen.

Extracellular fluids are plasma, serum, tissue fluid lympth.

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19.10.09

What is osmosis and how is tissue fluid formed?

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Osmosis is the movement of water from an area of high concentration to an area of low concentration over the plasma membrane which is semi permiable.

Tissue fluid is formed in the capillaries and these are permeable to water and other small molecules. They are impermiable to blood cells and to large molecules such as proteins like albumin. Any vessels which doesn't re-enter the blood vessels is drained via lympth vessels and known as lympth and is eventually returned to the blood. (See diagram in book)

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21.10.09

Describe the properties of water and the role of electrolysis.

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21.10.09

Water molecules are polar (have a charge). The oxygen atom has a slight negative charge whilst both the hydrogen atoms have a slight positive charge. These charges attract water to each other (hydrogen bonds). Water is a good solvent. not easily compressed, good lubricant, is transparent and holds heat well. Water has a potential

Electrolysis helps to maintain the osmosic balance across two membranes. Hypotonic is when there is a high water potential, hypertonic - low water potential and an isotonic solution is when the water potential is the same across two membranes and therefore, no osmosis will take place. The three types of electrolysis found in the blood are potassium, sodium and possasium chloride.

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03.11.09

What is passive transport and name the three types?

What is active transport?

What is endocytosis and Exocytosis?

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Passive transport does not require energy and is when substances move down the concentration graident. The three examples are:

  • Osmosis - movement of water.
  • Simple Diffusion - movement of small lipid soluble materials.
  • Faciliated diffusion - required a channel protein or a carrier protein to help larger or non-lipid materials. ie. glucose.

Active transport does require energy (ATP) and is when substances move against the concentration gradient and move from low concenration to high areof concentration and always requires a carrier protein.

Endocytosis and Exocytosis is when molecules which are larger than single molcules enter or leave the cell.

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05.11.09

What is a lipid and what is it's role in the body? (DIAGRAM IN BOOK)

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Lipids are fats which are...

  • source of energy in respiration and produce more energy than carbohydrates.
  • provide insulation as we store adipose tissue under the skin.
  • protection as they surround organs.
  • store vitamins such as A (eyesight) and D (calcium for bones)

It contains a glycerol head with ester bonds which are formed in a condensation reaction. Phospolipids are formed when one of the triglicerid is replaced by a phosphate group.

Saturated fats contain a single bond whilst unsaturated contain a double bond. Saturated fats have a higher melting points because they have stronger attactions between the fatty acid chains.

The most common lipid is an triglyceride. It is insoluble in water because of the molecules long hydrocarbon tails of fatty acids. Water has a charge and lipids don't.

A fat is a solid at room temp whilst a oil is a liquid.

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09.11.09

What are enzymes, what do they do?

Name the four things that effect enzyme activity.

What is the enzyme substrate complex?

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