Topic 1 Biological Molecules Flashcards
(18 cards)
Monomers
Small, repeating units/molecules from which larger molecules such as polymers are made
Polymers
Molecules made from many small, similar repeating monomer molecules
Name three different polymers
Polypeptides(proteins)
Polysaccharides (carbohydrates)
DNA
Structure and function of cellulose
Made of B-glucose molecules in which every other B-glucose molecule is inverted. Made of 1-4 glycosidic bonds which forms long, parallel, straight chains, joined together by many hydrogen bonds, forming microfibrils to give collective strength and support to cell walls in plants
Structure and function of glycogen
Made of a-glucose and made of 1-4 and 1-6 glycosidic bonds. A highly branched molecule to increase SA for rapid hydrolysis to release glucose molecules needed for respiration to make ATP for energy release and compact. Large, so it cannot pass through the membrane and insoluble so it will not affect water potential (no osmotic effect)
Describe two ways that a dipeptide may be similar in one way and different in another
Similarity:
Both contain NH group and carboxyl group
Difference:
Different R groups
How do enzymes catalyse reactions
Lowering the activation energy
Due to bending of hydrogen and ionic bonds
Factors that could affect rate of enzyme-controlled reaction
Concentration of substrate
Concentration of enzyme
PH, temperature
Inhibitor concentration
Why are solutions left in the water bath for 10 mins
To allow solutions to equilibrate and reach the temperature of water bath
How can rate be measured?
Measure the time taken for reaction to reach end-point e.g.concentration or colour of product
Measure concentration of product formed at regular intervals throughout reaction
Plot a graph with concentration of product in y axis and time x axis
Draw a tangent at t=0 for initial rate of reaction or any point on the curve for a specific time
Calculate rate by change in y/change in x
Describe the differences between the structure of ATP and DNA
DNA is made of only one phosphate group but ATP has 3 phosphate groups
DNA is made of deoxyribose sugar but ATP is made of ribose sugar
ATP always contains adenine nitrogenous base but DNA can have either adenine, thymine, cytosine or guanine as its nitrogenous base
Explain why nucleotides can only be added from the 5’ to 3’ direction
DNA strands are anti parallel
Shapes of 3’ and 5’ end of nucleotides are different
DNA polymerase has active sites with specific shape
DNA polymerase only complementary and binds to 3’ end of nucleotide
Name the two scientists who proposed the model for the chemical structure of DNA and DNA replication
Watson and Crick
Describe the semi-conservative model
Bacteria grown in medium containing heavy nitrogen 15N so nitrogen incorporated into DNA bases.
DNA is extracted and centrifuged and settles near bottom as all DNA molecules contain 2 heavy strands
Bacteria transferred into a medium containing light nitrogen 14N and allowed to replicate once
DNA extracted and centrifuged and settles in the middle as all DNA molecules contain 1 heavy stand and 1 light stand
Bacteria in light nitrogen 14N allowed to replicate again
DNA extracted and centrifuged and half settles in the middle as contains 1 heavy and 1 light stand and other half settles near the top as contains two light strands
Give ways in which hydrolysis of ATP is used in cells
Coupled to energy requiring reactions within cells e.g. active transport
Inorganic phosphate phosphorylates other compounds making them more reactive
Suggest how prosperities of ATP make it suitable immediate source of energy for cells
Little energy is lost as heat
Releases energy instantaneously only one bond needed to be hydrolysed to release energy
Cannot pass out of cell
Name and explain two properties of water that are important in the cytoplasm of cells
Solvent
Allows metabolic reactions to occur faster
Polar
Allows water to act as a solvent
Where are inorganic ions found in the body
Cytoplasm of cells and body fluids
