1. PAPER 1

3. Stephen Taylor (i-biology)

5. Sickle Cell Anemia
Base substitution: the replacement of one (or more) DNA base(s) with another
Sickle cell anemia: substitution in gene for ß chain of hemoglobin
base substitution changes DNA sequence: CTC → CAC
altering the mRNA transcript: GAG → GUG
altering a single amino acid in beta hemoglobin: glutamic acid → valine
changing the nature of beta hemoglobin
sickle cell anemia: two mutant allele copies
with two sickle cell alleles, RBCs sickle under low oxygen conditions

7. Chromosomes in us Humans have diploid cells
Diploid (2n) = two sets of each chromosome (2n = 46, where n is 23)
Haploid (n) = one set of each chromosome
Arranged in pairs known as homologous chromosomes = chromosomes pairs that are of the same length and staining pattern and possess genes for the same characters at the same length

8. Terms – refresher Chromatid = one of two copies of DNA
Sister chromatids = two identical copies of DNA
Centromere = region on chromosome that joins sister chromatids
Spindle fiber = microtubules that move chromosomes during cell division
Centriole = microtubule organizing center

9. PAPER 2

12. 2.4.7 Vesicles
Vesicles = small organelle within a cell, consisting of fluid enclosed by a lipid bilayer membrane.
Protein synthesis: rER produces proteins which travel through the lumen of the ER
Transport in vesicles: Membranes produced by the rER flows in the form of transport vesicles to the Golgi, carrying proteins within the vesicles
Modification: Golgi apparatus modifies proteins produced in rER
Transport to membrane: Golgi pinches off vesicles that contain modified proteins and travel to plasma membrane
Exocytosis: Vesicles then fuse with plasma membrane, releasing their contents by