Lab 2 Biological Molecules Flashcards
Identify the major classes of biological molecules:carbs, proteins, lipids and nucleic acids Describe the function of the major biological molecules in the human body Evaluate the results of diagnostic tests for the presence of the major organic molecules. Use the diagnostic tests to determine which of the major organic molecules mentioned above is present in an unknown solution. Explain the use of controls and replicate in experiments.
Macromolecules
Large molecules that are made of smaller sub-unit molecules
Four most common organic molecules found in all living organisms
Carbohydrates, proteins, lipids and nucleic acid
Polymers
Some macromolecules are polymers. Polymers are made up of repeating units called monomers.
For example, proteins are made up of chains of amino acids, starch is a chain of glucose molecules, and nucleic acids are chains of nucleotides.
Lipids are not polymers. Its structure is not a repeating chain of monomers.
Control
The experimental group must always be accompanied by a control.
Ensures the effect observed in the experiment are the result of the phenomenon being test and not from another unidentified source.
Also give a baseline to which they compare their experimental results.
Negative control
Something that will get a negative result in testing.
Positive control
When you are using a solution you know contains the macromolecule you are testing for.
Should get a positive result.
Replication
Test should always be performed more than once to ensure that the initial results are repeatable.
It gives the experimenter confidence in their results.
Carbohydrates
Compounds composed of carbon, hydrogen, and oxygen with a ratio of 1:2:1.
This group includes sugars, starch, cellulose, and glycogen.
Monosaccharides
The simplest carbohydrates are monosaccharides. The most common are glucose (which often serves as an energy source in cells)
Benedict’s reagent
Is used to test for glucose in a solution.
Any colour change from blue is considered a positive test result.
Polysaccharides
Are large molecules of numerous monosaccharide components.
This is often an efficient way for cells to store energy.
Liver cells and muscle cells store glucose in the form of glycogen.
Some plant cells store glucose in the form of starch.
Iodine
Tests for starch.
It changes from yellow brown to a very dark blue black.
Protein
Proteins are polymers of amino acids.
A protein is made up of one or more polypeptide chains.
Biuret reagent
To test for proteins.
Changes from light blue to purple in presence kf protein.
Enzymes
Molecules that catalyze chemical reactions
Hormones
Chemical.messengers in the body
Denatured
A proteins exposure to extremes of temperature or oh causes the weaker hydrogen binds that are responsible for a second and tertiary structure to break. Result is unfolding and loss of biological function.
Lipids
One of the distinguishing features of these molecules is that they are insoluble in water.
Fatty acids vary in chain length and can be saturated (contain no double bonds) or unsaturated (contain one or more double bonds)
Fats serve as a long term energy source.
Adipose tissue is a form of connective tissue that is specialized in storing fats. Found beneath the skin surrounding various organs.
Sudan IV test
Based on two characteristics of lipids.
They are not polar and therefore insoluble in water.
They are less dense than water.
The reagent is also non polar and therefore does not dissolve in water or other polar substances, but will dissolve in lipids and turn bright red in colour.
Positive test would be
The top layer becomes bright red (a positive test)
The water stays at the bottom, and it may have some dark, undissolved Sudan IV particles in it.
