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Topic 2: Genes & Health
Learning Objectives
Pupils should be able to:
- Know the properties of gas exchange surfaces in living organisms (large surface area to volume ratio, thickness of surface, difference in concentration).
- Understand how the rate of diffusion is dependent on these properties and can be calculated using Fick’s Law of Diffusion.
- Understand how the structure of the mammalian lung is adapted for rapid gaseous exchange.
- Know the structure and properties of cell membranes.
- Understand how models such as the fluid mosaic model of cell membranes are interpretations of data used to develop scientific explanations of the structure and properties of cell membranes.
- Understand what is meant by osmosis in terms of the movement of free water molecules through a partially permeable membrane (consideration of water potential is not required).
- Understand what is meant by passive transport (diffusion, facilitated diffusion), active transport (including the role of ATP as an immediate source of energy), endocytosis and exocytosis
- Understand the involvement of carrier and channel proteins in membrane transport.
- Know the basic structure of mononucleotides (deoxyribose or ribose linked to a phosphate and a base, including thymine, uracil, cytosine, adenine or guanine) and the structures of DNA and RNA (polynucleotides composed of mononucleotides linked through condensation reactions).
- Know how complementary base pairing and the hydrogen bonding between two complementary strands are involved in the formation of the DNA double helix.
- Understand the process of protein synthesis (transcription) including the role of RNA polymerase, translation, messenger RNA, transfer RNA, ribosomes and the role of start and stop codons.
- Understand the roles of the DNA template (antisense) strand in transcription, codons on messenger RNA and anticodons on transfer RNA.
- Understand the nature of the genetic code (triplet code, non-overlapping and degenerate).
- Know that a gene is a sequence of bases on a DNA molecule that codes for a sequence of amino acids in a polypeptide chain.
- Know the basic structure of an amino acid (structures of specific amino acids are not required).
- Understand the formation of polypeptides and proteins (as amino acid monomers linked by peptide bonds in condensation reactions).
- Understand the significance of a protein’s primary structure in determining its three-dimensional structure and properties (globular and fibrous proteins and the types of bonds involved in its three-dimensional structure).
- Know the molecular structure of a globular protein and a fibrous protein and understand how their structures relate to their functions (including haemoglobin and collagen).
- Understand the mechanism of action and the specificity of enzymes in terms of their three-dimensional structure.
- Understand that enzymes are biological catalysts that reduce activation energy.
- Know that there are intracellular enzymes catalysing reactions inside cells and extracellular enzymes produced by cells catalysing reactions outside of cells
- Understand the process of DNA replication (including the role of DNA polymerase).
- Understand how Meselson and Stahl’s classic experiment provided new data that supported the accepted theory of replication of DNA and refuted competing theories.
- Understand how errors in DNA replication can give rise to mutations.
- Understand how cystic fibrosis results from one of a number of possible gene mutations.
- Know the meaning of the terms: gene, allele, genotype, phenotype, recessive, dominant, incomplete dominance, homozygote and heterozygote.
- Understand patterns of inheritance, including the interpretation of genetic pedigree diagrams, in the context of monohybrid inheritance.
- Understand how the expression of a gene mutation in people with cystic fibrosis impairs the functioning of the gaseous exchange, digestive and reproductive systems.
- Understand the uses of genetic screening, including the identification of carriers, pre-implantation genetic diagnosis (PGD) and prenatal testing, e.g. amniocentesis and chorionic villus sampling
- Understand the implications of prenatal genetic screening.
- Be able to identify and discuss the social and ethical issues related to genetic screening from a range of ethical viewpoints.
CORE PRACTICAL 3:
- Be able to investigate membrane structure, e.g. the effect of alcohol concentration or temperature on membrane permeability.
CORE PRACTICAL 4
- Investigate the effect of enzyme and substrate concentrations on the initial rates of reactions.
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