Biological Molecules Flashcards
What are monomers?
Smaller repeating units in which larger molecules are made of
Give three examples of monomers
Monosaccharides
Amino acids
Nucleotides
What are polymers?
Molecules made from a large number of monomers
Give three examples of polymers
Polysaccharides
DNA
Proteins
What is a monosaccharide?
Monomers from which larger carbohydrates are made
Give three examples of monosaccharides
Glucose
Galactose
Fructose
What is a condensation reaction?
Joining of two molecules that form a chemical bond by eliminating a water molecule
What is a hydrolysis reaction?
Breaking of a chemical bond between two molecules using a water molecule
What bond is formed in a condensation reaction in monosaccharides?
Glycosidic bond
Name three disaccharides and what they are formed from
Glucose + Glucose ~> Maltose
Glucose + Galactose ~> Lactose
Glucose + Fructose ~> Sucrose
What are the two isomers of glucose
Alpha glucose
Beta glucose
What are the differences between alpha and beta glucose?
(Use diagrams)
The OH group is inverted.
On alpha glucose it is located on the bottom right carbon whereas on beta glucose it is on the top right carbon
What are glycogen and starch made out of?
Alpha glucose
What is cellulose made out of?
Beta glucose
What is the function of of glycogen in relationship to its structure?
Function- Main storage for glucose in animals
Structure- many short branches with straight adjacent chains
Relationship- easily hydrolysed to release glucose and extremely compact
What is the function of starch in relationship to its structure?
Function- main storage in plants
Structure- Amylose: 1-4 glycosidic bonds
Amylopectin: branched, spiral, 1-4 and 1-6 glycosidic bonds
Relationship- shape allows tight packing, therefore it’s an excellent storage molecule
Insoluble and easily hydrolysed
What is the function of cellulose in relationship to its structure?
Function- main constituent of plant cell wall
Structure- branched chains, 1-4 glycosidic bonds and hydrogen bonds
Relationship- hydrogen bonds form microfibrils which provide structural support in plants, cellulose chains linked by hydrogen bonds
What is the biochemical test for reducing sugars?
Add 2cm^3 of sample
Add equal amount of Benedict’s reagent
Apply heat using water bath
Positive results = red/orange ppt
Negative results= remains blue sol
What is the biochemical test for non-reducing sugars?
Add 2cm^3 of sample
Add HCL to break glycosidic bonds
Add sodium hydrogen carbonate to neutralise solution
Add Benedict’s reagent
Apply heat using water bath
Positive results= red/orange ppt
Negative results= remains blue sol
What is the biochemical test for starch?
Add iodine or potassium iodide to sample
Positive results= blue/black sol
Negative results= remains orange/brown sol
Name two lipid groups
Phospholipids
Triglycerides
Describe the structure of a triglyceride
(Use diagram)
1 glycerol
3 fatty acid groups
What is the bond formed between triglycerides and in what type of reaction?
Ester bond formed by a condensation reaction
Describe the structure of a phospholipid
(Use diagram)
1 glycerol
2 fatty acid groups
1 phosphate group
What are the differences between triglycerides and phospholipids?
Triglycerides have three fatty acid groups whereas a phospholipid has two fatty acids and one phosphate group
What is the biochemical test for lipids?
Add 2cm^3 of ethanol
Add water
Shake gently
Positive results= cloudy white sol
What is an amino acid?
(Use diagram)
Monomers from which proteins are made
What bond is formed between two amino acids?
Peptide bond
What is a dipeptide and how is it formed?
Formed by a condensation reaction between two amino acids
What is a polypeptide and now is it formed?
A condensation reaction between many amino acids
Describe the primary structure of a protein
A sequence of amino acids
Describe the secondary structure of proteins
The curling or folding of the polypeptide chains into alpha helix and beta pleated sheets, due to the formation of hydrogen bonds
Describe the tertiary structure of proteins
The overall 3D shape which is determined by the R group interactions and properties.
This contains hydrogen bonds, ionic bonds and disulphide bridges.
What is an enzyme?
A biological catalyst that speed up rates of reaction while remaining unchanged and reusable.
Explain the induced-fit model
In the presence of a substrate, the active site will undergo a change in its conformation, to allow a better fit between the active site and the enzyme.
This means that the enzymes are highly specific for the reaction that they catalyse
List the factors that affect enzyme activity
Temperature
pH
Enzyme concentrations
Substrate concentrations
Explain the effect of temperature on the rate of enzyme activity
As temperature increases the rate of enzyme activity will also increase. Optimum activity is reached at the enzymes optimum temperature. If temperature continues to increase the enzymes will begin to denature and the rate will therefore decrease.
Explain the effect of pH on the rate of enzyme activity
Enzyme activity is at its maximum value at optimum pH. If the pH value is increased above or then decreased below the optimum the rate of the reaction will decrease.
Explain the effect of substrate concentration on the rate of enzyme activity
High substrate concentration means faster rate of reaction as there are more frequent successful collisions between enzyme and substrate, this is the case until the enzyme concentration becomes the limiting factor in which all all the active sites are occupied
Explain the effect of enzyme concentration on the rate of enzyme activity
High enzyme concentration means increase in rate of reaction as more frequent succen
What are the two types of enzyme inhibitors?
Competitive
Non-competetive
Explain competitive inhibitors
Competitive inhibitors have a complementary shape to the active site and therefore compete with the substrates for the availability of the active site.
By increasing the concentration of these inhibitors the rate of reaction decreases as the active sites are being blocked which prevents enzyme-substrate complexes being formed.
Explain non- competitive inhibitors
Non-competitive inhibitors bind to the enzyme but away from he active site, this causes the active site to deform and the substrates therefore not being complementary.
By increasing the concentration of these inhibitors the rate of reaction decreases because no enzyme-substrate complexes can be formed
Describe the structure of DNA
(Use diagram)
Double helix
Two anti parallel strands
Deoxyribose sugars
Very long
Adenine, Thymine, Guanine, Cytosine bases
Stores genetic information
Describe structue of RNA
(Use diagram)
Single strand
Short
Ribose sugar
Adenine, Thymine, Guanine, Uracil bases
Transfers the genetic information
What are the four bases?
Adenine
Thymine
Guanine
Cytosine
What bond is formed between two nucleotides?
Ester bonds
What are the three steps in semi- conservative replication?
- DNA helix axe breaks hydrogen bonds between the two stands which forms a template strand
- Free floating nucleotides pair up with their complementary base on the exposed template strand
- DNA polymerase catalysed condensation reactions to join adjacent nucleotides, forming phosphodiester bonds
What is the purpose of semi- conservative replication?
Method of DNA replicating to produce a molecule of DNA that consist of one original strand and one newly synthesised DNA strand
Describe the structure of ATP
(Use diagram)
ATP consists of:
Ribose sugar
Adenine base
3 phosphate groups
What is the equation for the hydrolysis of ATP?
How is ATP resynthesised?
ADP + Pi —(ATP synthase)—> ATP
List the five properties of water
Strong cohesion
High heat capacity
Large latent heat of vaporisation
Metabolite
Solvent
Explain why water being a metabolite is useful
Water is used in hydrolysis and condensation reactions
Explain why water being a solvent is useful
Water has the ability to dissolve ionic and polar molecules, which allows them to be transported easier
Explain why water having a high heat capacity is useful
Keeps cellular environments stable
Explain why water having strong cohesion is useful
Able to be drawn up xylem in order to be transported
