Bio Topic 2 Flashcards
1a. [3 marks]
Outline the structure of proteins.
Proteins are polymers of amino acids;
Proteins are formed by long chains of amino acids joined together by peptide bonds;
These bonds are formed by condensation reactions which allow two single amino acid molecules to join together forming a dipeptide molecule and water.
1b. [7 marks]
Cells produce a large variety of proteins with different sequences of amino acids. Explain how this is done.
A gene is a sequence of DNA that codes for a polypeptide
One gene codes for one polypeptide
The ribosome moves along the mRNA strand by one codon position.
The deacylated tRNA moves into the E site and is released, while the tRNA carrying the peptide chain moves to the P site;
Another tRNA molecules attaches to the next codon in the now unoccupied A site and the process is repeated until tRNA molecule reaches a stop codon;
These codons do not recruit a tRNA molecule, but instead recruit a release factor that signals for translation to stop
The polypeptide is released and the ribosome disassembles back into its two independent subunits
1c. [5 marks]
Outline the range of functions of proteins in cells.
Structure (spider silk, collagen)
Hormones (insulin, glucagon)
Immunity (immunoglobulins)
2a. [1 mark]
State one function of Rubisco.
Photosynthetic carbon assimilation.
2b. [1 mark]
State a role of the active site of an enzyme.
To form an enzyme-substrate complex via complementary shape bond with specific substrate.
2c. [1 mark]
State the genus of the plant where this Rubisco is found.
C3;
C4;
CAM.
2d. [2 marks]
Outline one factor that could affect the activity of Rubisco.
Light intensity;
As light intensity increases reaction rate will increase, as more chlorophyll are being photo-activated.
3a. [4 marks]
Outline four types of membrane transport, including their use of energy.
a. simple diffusion is passive movement of molecules/ions along a concentration gradient ✔
b. facilitated diffusion is passive movement of molecules/ions along a concentration gradient through a protein channel «without use of energy» ✔
c. osmosis is the passage of water through a membrane from lower solute concentration to higher ✔
d. active transport is movement of molecules/ions against the concentration gradient«through membrane pumps» with the use of ATP/energy
3b. [3 marks]
Draw the structure of a dipeptide.
k
4a. [2 marks]
Sketch a graph to show the effect of temperature on the activity of enzymes.
k
4b. [3 marks]
Explain enzyme–substrate specificity.
a. enzymes are proteins with specific 3-D geometry/shape
b. enzymes with active site that binds with the substrate/reactants
And
c. active site shape only allows it to bind with specific substrates «with complementary shapes»
5a. [1 mark]
Define metabolism.
The web of all enzyme–catalysed reactions that occur within a particular cell or organism
5b. [2 marks]
Identify the following processes as either anabolism or catabolism by placing a tick (√) in the correct box.
Photosynthesis – Anabolism
Glycolysis – Catabolism
5c. [2 marks]
Describe cell respiration in terms of metabolism.
A metabolic pathway;
Breaks down glucose and produces ATP.
