PAPER 1

Stephen Taylor (i-biology)

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

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

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

PAPER 2

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