Biological Molecules Chapter 1 Flashcards
What are the three types of bonding?
Covalent bonding, Ionic bonding and Hydrogen bonding
What happens in covalent bonding?
Atoms share electrons
What happens in Ionic bonding?
There is a loss or gain of electrons
- metals lose (gain positive charge)
- non metals gain (gain negative charge)
What happens in Hydrogen bonding?
There is an attraction between two molecules that already participate in other chemical bonds
What are polymers?
Long chains of monomer sub-units
When are polymers formed?
During polymerisation
What is the monomer of a polysaccharide?
Monosaccharides
What is the monomer of a polynucleotide?
Mononucleotides
What is the monomer of a polypeptide?
Peptides that have amino acids as their basic sub-unit
What is a condensation reaction?
The joining of two molecules to form a larger molecule while also releasing a smaller molecule such as water
What is a hydrolysis reaction?
The splitting of a molecule by breaking its bonds through the addition of water
What is metabolism?
All chemical processes that take place in living organisms
What is a molar solution?
A solution that contains one mole of solute in each litre of solution
What is a mole?
The molecule mass expressed as grams
What are some examples of monomers?
Monosaccharides, Amino acids, Nucleotides
What are some examples of polymers?
Carbohydrates, Proteins, Other biological molecules
What are polymers mainly made up of?
Carbon, Hydrogen, Oxygen, Nitrogen and a small number of chemical elements
What is sugar?
Sugar is a saccharide
What is a single monomer of sugar called?
A monosaccharide
What do a pair of monosaccharides form?
A disaccharide
What happens if you combine a large quantity of monosaccharides?
A polysaccharide is formed
What is the general formula of a monosaccharide?
(CH2O)n
What are some examples of monosaccharides?
Glucose, Galactose and Fructose
Are monosaccharides reducing or non reducing sugars?
Monosaccharides are reducing sugars
What are the two isomers of glucose?
Alpha and Beta glucose
What is reduction?
A chemical reaction involving the gain of electrons or hydrogen
What is a reducing sugar?
A reducing sugar is a sugar that can donate electrons to another chemical
What happens when a reducing sugar is mixed with benedict’s reagent?
It will turn an orange/brown
What is the test for a reducing sugar?
- Add 2cm cubed of the food sample to a test tube (if the sample is not already in liquid form, grind it up with water in a pestle and mortar)
- Add an equal volume of benedict’s reagent
- Heat the mixture in a gently boiling water bath for five minutes
What are some examples of disaccharides?
Maltose, Sucrose and Lactose
What type of bonds are there in disaccharides?
Glycosidic bonds
What happens when water is added (hydrolysis) to a disaccharide?
The glycosidic bond is broken
Are disaccharides reducing or non reducing sugars?
Disaccharides can be both reducing and non reducing sugars
Why do non reducing sugars not change the colour of benedict’s reagent when heated with it?
This is because they must be hydrolysed into its monosaccharide components
What is the test for non reducing sugars?
- If the test for reducing sugar is negative, add another 2cm cubed of the food sample to 2cm cubed of dilute hydrochloric acid in a test tube, and place it into a water bath for 5 mins
- Slowly add sodium hydrogen carbonate solution to the test tube to neutralise the hydrochloric acid, test with pH paper to check the solution is alkaline
- Retest the solution by heating with 2cm cubed of benedicts reagent and place it in a water bath for 5 minutes
- If the solution has turned orange-brown a non reducing sugar is present
What is a polysaccharide?
Polymers combined together by many monosaccharide molecules
Why are polysaccharides good for storage?
They are good for storage because they are large and insoluble
What happens when a polysaccharide is hydrolysed?
They are broken down into disaccharides or monosaccharides
What is starch?
Starch is a polysaccharide formed by glycosidic bonds in a series of condensation reactions
What is the test for starch?
- Place 2cm cubed of the sample being tested into a test tube
- Add two drops of iodine solution and shake or stir it
- The presence of starch is indicated by a blue-black coloration
Where is starch found?
It is found in many parts of a plant in the form of mall grains
What is starch made up of?
Chains of alpha glucose monosaccharides linked by glycosidic bonds
Where is starch not found?
Starch is NEVER found in animal cells
Is starch branched or unbranched?
The chains may be branched or unbranched
What is the structure of starch?
Insoluble, Large, Compact, Forms alpha glucose during hydrolysis and the branched form has many ends
Why is it good that starch is insoluble
It does not affect water potential and there is no osmotic effect
Why is it good that starch is Large?
It means it does not diffuse out of cells
Why is it good that starch is compact?
A lot of it can be stored in a small place
Why is it good that starch forms alpha glucose when hydrolysed?
Easily transported and readily used in respiration
Why is it good that starch in branched form has many ends?
It means they can be acted on by enzymes simultaneously meaning the glucose monomers are released rapidly
