The alpha refers to the carbon atom adjacent to the carboxyl carbon atom. You need to remember how to draw amino acids linked to peptide bonds. Structures of side chains will be provided. Homologous proteins are proteins with similar amino acid sequences specified by genes derived from a common ancestral gene. A family of proteins is a group of homologous proteins, often with the same or similar functions.
Examples are haemoglobin and myoglobin, and the cytochroms c from various species.
A disulfide bond is a covalent bond formed between the sulfur atoms of two cysteine side chains. They may be interchain or intrachain. See diagram top left page 60. Globular proteins are less regular with an overall roughly spherical shape. It would be a good idea to draw simple diagrams.