1 - Biological molecules Flashcards
What is the difference between condensation and hydrolysis reactions?
-condensation joins two molecules together with a chemical bond and the elimination of a water molecule
-hydrolysis breaks a chemical bond between two molecules using a water molecule
What are isomers? Give an example:
-2 molecules with the same chemical formula but different structural formula
-alpha and beta glucose
alpha has the -OH on the bottom
Name 3 polysaccharides and their monomers:
-starch (alpha glucose)
-glycogen (alpha glucose)
-cellulose (beta glucose)
How would you quantitatively measure the amount of reducing sugar in solution without a colorimeter?
-perform Benedict’s test
-filter and dry the precipitate
-use mass balance to get the mass
Describe the structure of starch:
-made of 2 polysaccharides (amylose + amylopectin)
-amylose has α 1-4 GS bonds and forms a straight chain (can coil into a helix)
-amylopectin has frequent α 1-6 GS bonds that make it branch off
How is starch adapted for its function in plants?
-insoluble, so it won’t affect water potential
-helical structure, so it is very compact and good for storage
-large molecule, so it can’t leave the plant cell
How is cellulose adapted for its function?
-has long straight chains which are linked together via H-bonds to form fibrils
-very strong + can resist osmotic pressure (good for making cell walls)
-can resist enzymatic action so it doesn’t get digested
Describe how the structure of glycogen is related to its function:
-helical structure, so it is compact
-insoluble, so it won’t affect water potentials
-branched, higher SA, so enzymes can hydrolyse it faster into a-glucose for it to be used in the mitochondria for AR (good energy store)
What makes a fatty acid unsaturated?
double bond between 2 carbons
How are fatty acids important to the formation of new cells?
-can be used to make phospholipids, which are used in cell membranes
-can respire fatty acids to release energy, which can be used towards forming new cells and the processes involved (eg protein synthesis)
Why are lipids good for energy storage?
-high number of carbon-hydrogen bonds compared to the number of carbons, stores lots of energy
-insoluble in water, won’t affect water potentials by osmosis
-low in mass, won’t affect movement of the organism
Describe how protein structure depends on the amino acids it contains:
-structure is always determined by the relative position of the AAs
-primary is their sequencing
-secondary due to H-bonds between different peptide bonds
-tertiary is 3D structure due to R-group interactions, which is directly linked to function
-quaternary formed with multiple PP chains
If asked about function, always mention tertiary with specific R-group interactions
Explain how a protein’s secondary structure is brought about:
-the weakly -ve charged oxygen from C=O is attracted to the weakly +ve charged hydrogen on N-H on different peptide bonds, forming hydrogen bonds
-forms α-helixes (H-bond between every 4th) or β-pleated sheets (parallel parts of the same PP chain form H-bonds)
Secondary structure only refers to these types of hydrogen bonds
What is a disulfide bridge?
covalent bond formed between 2 cysteine amino acids, found in tertiary structure
What are hydrophobic interactions?
-hydrophobic molecules tend to stay near each other to minimise contact with water
-this leads to a weak interaction being formed between different non-polar R groups on different amino acids in tertiary structures
Like how fat forms globules in water rather than spreading out
Explain the difference between the 2 lines on this graph:
-as [substrate] increases, R increases for both lines
-however, using a CI reduces the likelihood of ESCs forming, and reduces R for a given [substrate]
-as [substrate] increases for the CI curve, the likelihood that a substrate will collide with the active site compared to the CI increases, and so R increases
Why is the rate of reaction affected differently between CIs and NCIs?
-with CIs, the effect of the inhibitor can be overcome by simply increasing [substrate] to increase likelihood of ESCs forming
-with NCIs, the active site’s shape is no longer complementary to the substrate, so its effects cannot be overcome, and the rate of reaction has a lower maximum
Why does this graph suggest pectin is a non-competitive inhibitor?
increasing the substrate concentration does not overcome the inhibition, and does not affect rate of reaction after a certain point
