Biological Molecules Flashcards
Glucose + Fructose =
Sucrose
Glucose + galactose =
Lactose
Glucose + glucose =
Maltose
Difference between alpha and beta glucose
In alpha = OH group below H
What is a condensation reaction?
Joining of two molecules with the formation of chemical bond and elimination of molecule of water
What is a hydrolysis reaction?
Breaking of a chemical bond between two molecules involving use of water molecule
How is a glycosidic bond formed?
Condensation reaction between two monosaccharides
What is starch a mixture of?
Amylose and amylopectin
Describe amylose
Poly (1-4) alpha glucose chain
Coils up into a helix held together by hydrogen bonds
Describe amylopectin
Poly (1-4) alpha glucose chain with (1-6) branches
Multiple ends so can be hydrolysed quickly by amylose enzymes
Describe glycogen
Poly (1-4) alpha glucose chain with (1-6) branches
Purpose of glycogen having multiple ends?
It can be hydrolysed very quickly by enzymes to mobilise glucose for energy
Describe cellulose
Poly (1-4) beta glucose chain
Alternate glucose molecules inverted to form straight chain
How does cellulose give strength to plant cells and young plants?
Hundreds of chains linked by hydrogen bonds to form cellulose microfibrils which are strong and rigid
What is the test for reducing sugars
Add Benedicts reagent
Shake and heat
A precipitate indicates reducing sugar
How can you decipher concentration of reducing sugar from Benedicts test
Concentration increases going down
Green
Yellow
Orange
Brick red
What is the test for non reducing sugars
Test for reducing sugars
Boil with dilute hydrochloric acid to hydrolyse glycosidic bond
Neutralise with sodium hydrogen carbonate
Test for reducing sugars again
How can two organisms have similar % of bases but be very different
- different genes
- different order
- different amino acid coded for
How can % of bases tell you an organism has single stranded DNA
A doesn’t = T
No base pairing
Describe the structure of proteins
Polymer of amino acids
Joined by peptide bond
Formed by condensation
Primary structure is order of amino acids
Secondary structure is folding due to H bonds
Tertiary structure is 3-D folding due to H bonds, disulfide bonds, ionic bonds
Quaternary is more than one polypeptide chain
How are proteins digested in the gut?
Hydrolysis of peptide bonds
Endopeptidases break polypeptides into smaller chains
Exopeptidases remove terminal amino acids
Dipeptidases hydrolyse
How is starch adapted for plant cells
Insoluble - doesn’t affect water potential
Large molecule - cannot leave cell
Helical - compact
What is the test for reducing sugars ?
Heat with Benedicts
Precipitate formed
What is the test for proteins ?
Biuret test (add NaOH and CuSO4) Purple
What is the organ that produces amylase?
Small intenstine, pancreas
Describe the role of dna polymerase
joins nucleotides
Other than being smaller, give two ways in which prokaryotic DNA is different from
eukaryotic DNA.
Circular
Not associated with proteins
No introns
How is the DNA of the virus is different from that of other organisms?
No base pairing
single stranded
Describe the structure of proteins
- Polymer of amino acids;
- Joined by peptide bonds;
- Formed by condensation;
- Primary structure is order of amino acids;
- Secondary structure is folding of polypeptide chain due to hydrogen bonding;
Accept alpha helix / pleated sheet - Tertiary structure is 3-D folding due to hydrogen bonding and ionic / disulfide
bonds; - Quaternary structure is two or more polypeptide chains.
Describe how proteins are digested in the human gut
Hydrolysis of peptide bonds;
- Endopeptidases break polypeptides into smaller peptide chains;
- Exopeptidases remove terminal amino acids;
- Dipeptidases hydrolyse / break down dipeptides into amino acids
How are cellulose molecules adapted for their function in plant cells?
Long and straight chains linked together by many hydrogen bonds
To form fibrils
To provide strength
What is the difference between starch and cellulose molecules?
Position of hydrogen and hydroxyl groups on carbon 1 are inverted
Cellulose is beta glucose, starch is alpha glucose
Give two ways in which ATP is a suitable source of energy to use in cells
Releases relatively small amount of energy /
little energy lost as heat;
Releases energy instantaneously;
Phosphorylates other compounds, making them
more reactive;
Can be rapidly re-synthesised;
Is not lost from/does not leave cells
Suggest one advantage to a bacterium of secreting an extracellular protease in its
natural environment
They are able to digest protein
So they can absorb amino acids for growth
Describe the action of membrane-bound dipeptidases and explain their
importance.
Hydrolyse (peptide bonds) to release amino
acids;
2. Amino acids can cross (cell) membrane;
