1.1 molecules

Polar molecule

An uneven distribution of charge

Waters value as a solvent includes-

-Most of a cells reactions take place in an aqueous solution.
-It's ability to act as a transport medium in living organisms.
-The effects it has an hydrophilic and hydrophobic molecules.

What are buffers? + Examples of them and how they are used

chemicals or substances which resist changes to pH and ensures the environment maintains a certain pH. Hydrogencarbonate ions and blood proteins like albumin. They're used in practical investigations with enzymes to help regulate the pH and ensure enzymes are at their optimum pH.

Why is calcium important?

Cell wall formation as calcium pectate (acts like glue) strengthens binding of adjacent cells 
Muscle activity and contraction also strengthens bone (calcium carbonate/phosphate)

Role of Magnesium ions?

Gives chlorophyll its light absorbing properties necessary for photosynthesis, also present in the middle lamella of plant cell walls.

Why is nitrate important?

Component of amino acids, nucleic acids, and ATP

Why is Phosphate important?

As phospholipids and important component of cell membranes, and manufacture of ATP and nucleic acids.

Why is hydrogencarbonate important?

It's a natural buffer. Plasma pH regulation.

What are organic molecules?

Complex carbon-containing molecules, Carbohydrates, proteins and lipids.

What is polymerisation?

When when monomers (sub-units of organic molecules) condense to form polymers.

What are carbohydrates made of?

Carbon, hydrogen and oxygen. Hydrogen to oxygen is 2:1.

What are monosaccharides?

The basic carbohydrate monomer, they have high degree of solubility in water.

What are disaccharides?

two monosaccharide monomers and held together by glycosidic bond

What are polysaccharides?

Complex molecules consisting of many monosaccharide monomers, are insoluble.

Formula for glucose?

C6H12O6

What is a-glucose?

The basic sub-unit of complex polysaccharides like starch or glycogen.

What is an isomer?

Substances with the same molecular formula and different structural formula.

How are disaccharides formed?

Two monosaccharides (usually hexose) react together in a condensation reaction. It is reversible as the disaccharide molecule can be broken into its constituent monosaccharide monomers in a hydrolysis reaction. These reactions are important in the digestion of food.

 

What bond is formed between two hexose sugars in a disaccharide?

a-1,4 glycosidic.

Formula of a disaccharide?

C12H22O11

How is maltose formed?

Two a-glucose molecules are linked through a condensation reaction. Product of starch digestion.

How is sucrose formed?

An a-glucose molecule condenses with a fructose molecule

What is sucrose?

The form in which carbohydrate is transported through phloem in plants.

How are polysaccharides formed?

Through condensation reactions which link many monomers together to form a very long chain.

Formula of polysaccharides and examples?

(C6H10O5)n 
Starch, glycogen and cellulose.

What is starch?

A polymer of a-glucose containing a mixture of amylose and amylopectin chains.

Amylose formation?

a-glucose molecules are linked by a-1,4 glycosidic bonds which forms long unbranched chains, coiled to a spiral held by hydrogen bonds.

Why do amylose chains form a coiled configuration?

The bulky side groups cause it to lie at different angles.

Amylopectin formation?

a-glucose molecules are linked by a-1,4 and a-1,6 glycosidic bonds which form side branches to form a branched molecule.

How is starch stored and where can it be found?

Its stored as solid grains and can be seen in electron micrographs of plant chloroplasts.

What are the benefits of starch?

-The molecules of amylose and amylopectin are very compact.
-Its insoluble of doesn't affect the water relations of the cell.
-Its a large molecule so can be retained in the cell and won't easily pass through the cell membrane.
-The branching nature of amylopectin creates terminal ends which are easily hydrolysed which aids enzymatic breakdown of starch into glucose at times of high respiratory demand.

Where is glycogen found and what is it for?

A storage carbohydrate in animal and fungal cells.

Glycogen formation?

Its like amylopectin with a-1,4 and a-1,6 glycosidic bonds, but the chains are more branched and shorter, so has more terminal ends for faster hydrolysis when needed. Insoluble.

Where is glycogen found?

Stored as small granules in the liver and muscle cells of mammals.

What is cellulose?

A structural polymer of B-glucose starch.

Cellulose structure?

Two B-glucose molecules form B-1,4 glycosidic bonds, alternate molecules are rotated 180 degrees because of the structure of B-glucose.

What effects does the flipping of adjacent glucose monomers have?

-The unbranched chains are straighter as the bulky CH2OH side groups alternate between being above and below the chain.
-Hydrogen bonds can form cross linkages between adjacent chains due to hydrogen being available on both sides.

How is cellulose arranged to increase its strength?

Grouped together in microfibrils orientated into many planes in the lattice to further increase its strength.

What do lipids contain?

Carbon hydrogen and oxygen. proportion of hydrogen to oxygen is greater than 2:1 for carbohydrates.

Properties of lipids?

They form macromolecules, they're not polymers and are hydrophobic, but they're soluble inorganic solvents like ethanol.

What are the types of lipids?

Triglycerides (fats and oils), phospholipids, waxes, and steroids.

How do triglycerides form?

One glycerol molecule is joined with three fatty acids by three condensation reactions. For each condensation reaction an ester bond is formed.

What are fatty acids?

organic acids which form long hydrocarbon tails linked to a carboxyl group.

What does hydrolysis of a triglyceride include?

It uses three molecules of water and produces three fatty acids and one molecule of glycerol.

What is a saturated fatty acid?

Along the length of the hydrocarbon chain each carbon atom is linked with two hydrogen atoms, the carbons are saturated and linked by C-C single bonds.

What are Unsaturated fatty acids?

They have at least one C=C double bond in chain.

What is a monounsaturated fatty acid?

One C=C double bond.

What is a polyunsaturated fatty acid?

More than one C=C double bond.

What are fats formed from?

Saturated fatty acids.

What are oils formed from?

Triglycerides with unsaturated hydrocarbon chains.

What are the uses of triglycerides?

They're a good energy store and fats are important for insulation and protection of body organs.

What do phospholipids contain?

One molecule of glycerol, two fatty acids, and a phosphate group.

Explain the hydrophobic and hydrophilic properties of phospholipids.

The fatty acid molecules repel and are insoluble in water, forming hydrophobic tails, while the phosphate is soluble in water forming through hydrophilic head

Where is cholesterol located?

In cell membranes in the hydrocarbon chains of the phospholipid bilayer. It is found amongst hydrophobic tails

 

What do elements do proteins contain?

Carbon, hydrogen, oxygen, nitrogen, and sulphur.

What is a protein?

Large polymers formed from amino acid subunits.

How many types of amino acid are there?

20

How is the shape of a protein determined?

The sequence of amino acids in the protein

How do amino acids differ?

They have different R-groups

How are amino acids linked?

Peptide bonds involving condensation reactions with the loss of water.

How is a dipeptide formed?

Two amino acids join together

How can a peptide bond be broken?

By hydrolysis reaction (adding water)

How is a polypeptide formed?

Many amino acids are condensed together in a chain through peptide bonding.

What is the primary structure of a polypeptide?

The sequence (order) of amino acids in the polypeptide chain.

What is secondary structure?

Hydrogen bonds form between amino acids to form a-helix and B-pleated sheets.

What is the tertiary structure of a polypeptide?

This involves further folding of the secondary structure which gives the protein its 3-D shape.

 

Name the bonds present in tertiary structure.

Hydrogen bonds, ionic bonds and disulphide bonds, hydrophobic interactions

What is quaternary structure of a polypeptide?

Two or more polypeptides bonded together, largely by disulphide bonds.

What is a prosthetic group?

When quaternary proteins contain non-protein components that are integral in their function.

Explain the structure of haemoglobin.

consists of four polypeptide chains, two each of two different polypeptides. Each chain is attached to an iron-rich haem group.

What are fibrous proteins?

Consist of polypeptides arranged in fibres or sheets. parallel chains are linked by cross bridges to form strong, stable molecules. They're structural in function.

What is collagen and where is it found?

A fibrous protein found in tendons which link muscle to bone.

What are globular proteins?

They have a metabolic role and include enzymes and antibodies. Haemoglobin is globular.

What are prions and where are they found?

A type of protein found in mammals and some other animal groups. They're found in the nervous system.

What happens to the produce the disease causing form of Prions

Eating contaminated prion food (transmission)
Random change in normal prion to disease prion form (sporadically)
Inheritance of DNA mutation

What is the effect of the disease causing form of Prion

Causes the formation of a protein whose secondary structure has more B pleated sheets.

Name 3 prion diseases.

-Scrapie (affects sheep).
-Bovine spongiform encephalopathy (BSE) (affects cattle through eating contaminated food).
-Variant Creuztfeldt-Jakob disease (vCJD) (Human version is BSE through eating contaminated beef).