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79 Cards in this Set

  • Front
  • Back

What are the different nutrients that we require?

Carbohydrates


Proteins


Lipids


Vitamins and minerals


Nucleic acids


Water

What are the roles of carbohydrates?

Energy storage, supply and structure.

Roles of proteins?

Structure, transport enzymes, antibodies and most hormones.

Roles of lipids?

Membranes, energy supply, thermal insulation, protection, electrical insulation and some hormones.

Roles of vitamins and minerals?

Coenzymes and enzyme activators.

Roles of nucleic acids?

Information molecules, they carry the instructions for life.

Roles of water?

Takes part in many reactions, support in plants, solvent/medium for many metabolic reactions and it is involved in transport.

Define metabolism

The sum total of all the biochemical reactions taking place in the cells of an organism.

What is a covalent bond?

When two atoms form a bond by sharing electrons. These bonds are very strong.

What is a condensation reaction?

The chemical reaction that links monomers together. A water molecule is released and a covalent bond is formed. A larger molecule is formed by the bonding together of smaller molecules.

What is a hydrolysis reaction?

When larger molecules are split. The reverse of a condensation reaction. A water molecule is used, a covalent bond is broken and smaller molecules are formed by the splitting of a larger molecule.

What is the difference between alpha and beta glucose?

The OH group on carbon one changes.

What are the properties of monosaccharides?

Soluble in water.


Sweet tasting.


Form crystals.

What is a disaccharide?

Two monosaccharides joined together by a glycosidic bond.

What is the structure and role of starch?

It consists of a mixture of long, straight chain amylose molecules with branches amylopectin. It is used as glucose storage in plants as it can be broken down to produce glucose.

What is the structure and role of glycogen?

It is a long branched molecule of alpha glucose subunits. It is very compact and can be used as glucose storage in animals. Glycogen granules are formed - especially in the liver.

Describe the structure of cellulose

Cellulose chains, long chains of beta glucose, group together causing many hydrogen bonds to form. This mass of cellulose chains forms a microfibril. More hydrogen bonds join the microfibrils together forming a macrofibril.

How does the structure of cellulose relate to its function in living organisms?

The cell wall in plants is made from cellulose. The cell wall supports the whole plant and allows water to pass in and out of the plant easily. Water does not cause cells to burst but causes them to become turgid. Supporting the plant.

What are the functions of proteins?

They are structural components, membrane carriers and pores. They are all enzymes, many are hormones and all antibodies are proteins.

What is the structure of an amino acid?

An amino group at one end, an acid group at the other end, a hydrogen molecule on top and an R group on the bottom.

What is deamination?

The removal of the amino group from the amino acid.

How do we test for reducing sugars?

Benedicts test. When a reducing sugar is heated with benedicts solution (alkaline copper sulfate) the solution changes colour from blue to an orange red precipitate.

What is a dipeptide?

When two amino acids join together to form a covalent bond, forming due to a condensation reaction.

What is the primary structure of a protein?

The specific sequence of amino acids that make up a protein.

What are the roles of enzymes in breaking down proteins?

Enzymes that break down proteins are known as protease enzymes. Proteins need to be broken down so that their effects are not permanent.

Describe the secondary structure of a protein

Formed when the primary structure coils or folds forming an alpha helix or a beta pleated sheet. Hydrogen bonds are what hole the coils and folds in place.

Describe the tertiary structure of a protein

When the secondary structure coils or folds again. These are held in place through disulphide bonds, ionic bonds, hydrogen bonds, hydrophobic and hydrophilic interactions. The tertiary structure is vital to a proteins function.

Describe the quaternary structure of a protein

When one or more polypeptide subunits join together to form the final working protein e.g haemoglobin.

Describe the structure of haemoglobin

Contains 4 polypeptide subunits (2 alpha and 2 beta chains).


Each polypeptide has a subunit that allows oxygen to bind (fe2+).


It is a globular protein.

Describe the structure of collagen.

It is a fibrous protein made up of three polypeptide chains wound around each other. Hydrogen bonds form between the chains. Cross links between collagen molecules form.

What are lipids?

A diverse group of chemicals that dissolve in organic solvents.

What are some functions of lipids within living organisms?

Source of energy.


Energy storage.


Biological membranes.


Insulation.


Protection.


Some hormones.

Describe saturated fatty acids.

All bonds are used, there are no double bonds. Unhealthy.

Describe unsaturated fats.

Healthier than saturated fats. These fatty acids contain double bonds. Two or more double bonds give a polyunsaturated fatty acid.

Describe the structure of a triglyceride.

3 fatty acids form an Esther bond with a glycerol molecule. This bond is formed through a condensation reaction.

Describe the structure of a phospholipid

Two fatty acids are bound to w glycerol molecule via Esther bonds. A phosphate group is also bound to the glycerol molecule. Therefore, there is a hydrophilic head with hydrophobic tails.

How is membrane fluidity controlled?

If the membrane needs to be more fluid more unsaturated fatty acids in the phospholipids are produced.

What is the function of cholesterol?

It helps regulate fluidity in biological membranes. It forms steroid hormones such as testosterone, oestrogen and vitamin d.

Why may excess cholesterol be a problem?

Gallstones are formed by excess cholesterol. Excess cholesterol can cause atherosclerosis.

How do hydrogen bonds form between water molecules?

The hydrogen atoms in water are positively charged which attract to the negatively charged oxygen atoms of the other water molecules. Forming hydrogen bonds.

How do we test for starch?

Add iodine solution to the sample. If starch is present the solution will turn from yellow-brown to blue-black.

How do we test for non-reducing sugars?

First you must make sure that there are no reducing sugars. Then: boil the sample with hydrochloride acid, cool the solution and neutralise it, carry out the reducing sugar test again. If the sucrose is present a positive result will be received.

How do we test for the presence of proteins?

Biuret test. Put the biuret reagent onto the sample. If it turns a lilac colour then proteins are present.

How do we test for lipids?

The ethanol emulsion test. Mix the sample with ethanol, pour the solution into water and if lipids are present a cloudy white emulsion will form.

Describe the structure of DNA.

A double stranded polynucleotide in the shape of a double helix. These stands are made up of nucleotides. Nucleotides are made from a phosphate, a five carbon sugar and an organic base.

What is the difference between DNA and RNA?

DNA has deoxyribose as the 5 carbon sugar. DNA has thymine as an organic base and RNA has uracil as an organic base. RNA has ribose is the five carbon sugar.

What bases are purines and what bases are pyrimidines?

Purines - adenine and guanine.


Pyrimidines - thymine, uracil and cytosine.

Why is DNA describes as antiparallel?

The DNA strands run in opposite directions.

Why is DNA replication described as semi-conservative?

Because during replication one strand of DNA is conserved and one strand is newly built.

What are the three forms of RNA?

Messenger RNA


Ribosomal RNA


Transfer RNA

What is a gene?

A length of DNA that codes for one or more polypeptides.

What are the roles of DNA and RNA?

The role of DNA is to store information/instructions for life. mRNA = a copy of a strand of DNA.


tRNA = brings amino acids to mRNA and ribosomes.


rRNA = with proteins it forms ribosomes.

Describe the structure of enzymes

Globular proteins.


Specific tertiary structure.


Have a specific active site.

Define extracellular

Enzymes that catalyse reactions outside of the cell.

Define intracellular

Enzymes catalyse reactions inside the cell.

What are heterotrophs?

Organisms that obtain their nutrients by consuming other organisms.

What is the active site of an enzyme?

The part of the enzyme where the substrate binds. Catalysing a reaction.

Define catalyst

A molecule that speeds up a chemical reaction but does not get used up in the reaction.

Define activation energy

The amount of energy required for a reaction to proceed.

What is meant by lock and key when referring to enzymes?

Every enzyme has a specifically shaped active site. This shape is complementary to the shape of the substrate molecules used in the reaction. Therefore the substrate fits into the active site.

What is the induced fit hypothesis?

As a substrate molecule collided with an enzymes active site the enzyme molecule changes shape slightly to fit more closely around the substrate. Thus change in shape puts strain on the substrate so the reaction occurs more easily. Products are formed.

What is an enzyme-substrate complex?

The intermediate structure formed when a substrate molecule binds to an enzyme molecule.

What is an enzyme product complex?

The intermediate structure in which product molecules are bound to an enzyme molecule.

How do enzymes lower the activation energy of a reaction?

The enzyme molecules hold the substrate molecules in such a way that the reaction proceeds more easily.

What are the effects of temperature changes in enzyme activity?

Higher temperatures cause enzymes to work more quickly but if the temperature gets too high enzymes become denatured. Different enzymes have different optimum temperatures. At very low temperatures enzymes do not work, activity slows completely.

What are the effects of ph changes on enzyme activity?

At lower pH's h+ ions interfere with the binding of the substrate to the active site. This can also cause changes to the shape of the enzymes. All enzymes have different optimum pH values. Changes in pH does not cause denaturation.

What is a buffer?

A chemical solution that resists changes in pH by maintaining a constant level of h+ ions in the solution.

What are the effects of enzyme concentration on enzyme activity?

As enzyme concentration increases the rate of activity increased as more enzyme substrate complexes form. However, a point will be reached when all substrate molecules are occupying an active site so increasing the enzyme concentration further would have no effect. He

What are the effects of substrate concentration on enzyme activity?

Increasing the substrate concentration will increase the rate of reaction until a point is reached when all enzymes are forming enzyme substrate complexes, therefore increasing the concentration further would have no effect.

What are competitive inhibitors?

They are molecules with similar shapes to the substrate molecules. They bind to the active site, blocking it, forming enzyme inhibitor complexes.

What are non competitive inhibitors?

Molecules that bind to an enzyme, away from its active site, changing its shape meaning the substrate can no longer bind.

Is inhibition permanent?

Most competitive inhibitors do not bind permanently. Most non competitive inhibitors do.

Describe the effects of non competitive inhibitors on enzyme controlled reaction.

They reduce the rate of reaction, this is not cancelled out by increasing substrate concentration.

What are the effects of competitive inhibitors on enzyme controlled reactions?

Competitive inhibitors reduce the rate of reaction but this can be cancelled out by increasing the substrate concentration.

Explain why inhibition of enzyme activity is important in controlling metabolic processes.

Cells must be able to control the concentration of various molecules in the cell. Where these are products of enzyme controlled, it is important to regulate enzyme activity so they the optimum level of product is achieved and maintained.

Define inhibitor

Any substance or molecule that slows down the rate of an enzyme controlled reaction by affecting the molecule in some way.

What is a cofactor?

Any substance that must be present to ensure enzyme controlled reactions take place at an appropriate rate. Some are part of the enzyme, some are temporary.

Define risk factor

A factor that increases your chances of developing a particular disease.

Define risk factor

A factor that increases your chances of developing a particular disease.