Biochemistry & molecular biology
Biological polymers & their monomers
An introduction to the structures of biological macromolecules and polymers, with an overview of the main types of such molecules found in biological systems, condensation reactions and hydrolysis reactions.
Structure of carbohydrates (monosaccharides, disaccharides & polysaccharides), including glycosidic bonding & their functional categorisation (structural vs. storage), with examples from different organisms.
Structure of monoglycerides, diglycerides & triglycerides, including the variation of physical properties of lipids with their structure and bonding and an overview of their formation through condensation reactions.
The significance of proteins in biology, and a detailed explanation of their structure in terms of their monomers (amino acids), primary, secondary, tertiary and quaternary structures and how these relate to their functions.
Characteristics of enzymes, and how their properties are determined by their structure; “lock & key” hypothesis and the induced fit model of enzyme action; factors affecting the rate of enzyme-catalysed reactions.
Structure of nucleotides and polynucleotides (DNA & RNA); bonding in polynucleotides, including Chargaff’s rules of base-pairing by H-bonding and the phosphodiester bond; 3 main types of RNA (mRNA, rRNA, tRNA).
The need for DNA replication, and the development of competing models to explain the process by which DNA replicates; Meselson-Stahl experiment; Semi-conservative mechanism of DNA replication.
Structure of adenosine triphosphate (ATP) and its function as the “energy currency” of the cell; the release of energy from ATP by hydrolysis, and the storage of energy in the formation of ATP by condensation reaction.
The importance of water due to its many essential functions in biology; the molecular structure, bonding and physical and chemical properties of water, and the roles of these properties in biological systems & processes.
An overview of the functions and sources of many inorganic ions required by plants and animals, as well as important related concepts such as deficiency & pH; includes phosphate, nitrate, potassium, iron & sodium ions.
An introduction to eukaryotic cell structure
The 3-domain classification system; comparative sizes of different cells; details of eukaryotic cell structure (vs. prokaryotes), including chromosomes, mitochondria, chloroplasts, ribosomes; examples from Euk. kingdoms.
Eukarya – animal & plant cell structure
Further details of Euk. cell structure, exemplified by plant & animal cells; including structure & function of lysosomes, centrioles, cell walls (incl. algal & fungal) & other organelles; differences between plant & animal cells.
Eukarya – animal & plant tissues & organs
Structures & functions of animal & plant tissues, epithelium, connective, skeletal, blood, muscle & nervous (animal) tissues; photosynthetic, epidermal, vascular, meristem, packing & strengthening (plant) tissues.
Structure of prokaryotic cells & viruses
Structure of prokaryotic cells (bacteria & archaea); examples of archaea, and categorisation of bacterial types by morphology; categorisation of viruses by genetic material (DNA & RNA), structure & life-cycles of viruses.
Optical & electron microscopy
Key terms and concepts in microscopy, including graticules, staining, magnification & resolution; the functional parts of optical (including confocal & fluorescence) and electron (scanning and transmission) microscopes.
Cell fractionation & ultracentrifugation
The stages of the procedure of cell fractionation, including the preparation of samples; the stages in the process of ultracentrifugation, including the procedures of differential and density-gradient ultracentrifugation.
Mitosis & the cell cycle
Significance of mitosis; the process of mitosis and the sequence of events in each phase (prophase, metaphase, anaphase, telophase & cytokinesis); the stages of the cell cycle and the events which occur at each stage.
Membranes & transport
Fluid mosaic model; membrane permeability to different types of particle; membrane transport mechanisms (simple/facilitated diffusion, osmosis, active transport, endocytosis & exocytosis); surface area to volume ratio.
A detailed explanation of non-specific immunity (physical/chemical barriers & phagocytosis) and specific immunity (production of antibodies & the cell-mediated response), including immunological memory.
An extension of the ideas from the last lesson; Antigens & antibodies; B-lymphocytes, clonal selection & clonal expansion; medical (diagnostic & therapeutic) applications of the production of monoclonal antibodies.
Examples of pathogenic viruses to illustrate and expand upon ideas about viruses covered in previous lessons of this topic; includes chickenpox, antigenic variability (antigenic shift & drift) & vaccination for influenza.
Exchange & transport systems
Introduction, protoctista & insects
Introduction to gas exchange, with basic principles illustrated through an overview of gas exchange systems in unicellular organisms (protoctistans) and insects; Fick’s law & the factors which determine rate of diffusion.
Fish & amphibians
Structure & function of gills in fish; ventilation in fish; countercurrent exchange system (vs. parallel flow); structural factors affecting the efficiency of gas exchange; gas exchange in amphibians (tadpole & adult frog).
Structural adaptations of dicotyledonous leaves for efficient gas exchange; gas exchange in leaves during hours of daylight vs. darkness; factors affecting efficiency of gas exchange; adaptations of xerophytic plants.
Structure & function of the lungs, including the anatomy of the thorax, mechanism of ventilation at rest vs. during exercise & pressure changes in lungs & pleura; factors affecting efficiency of gas exchange in lungs.
The structure & function of haemoglobin
The structure and function of haemoglobin; cooperative binding (allostery) of oxygen to haemoglobin; oxygen dissociation curves; the “Bohr shift”; different forms of haemoglobin and their oxygen dissociation curves.
Adaptations of different organisms haemoglobin
More teaching about the adaptations of haemoglobin in different organisms (mentioned in the previous lesson) given the different oxygen partial pressures of their habitats.
Circulation & exchange
Structure & function of the mammalian circulatory system; pulmonary vs. systemic circulation; relevance of surface area vs. volume ratio; capillaries & metabolic exchange; formation of tissue fluid & the lymphatic system.
Heart & cardiac cycle
Structure of the heart; morphology of cardiac muscle cells; heart valves; cardiac cycle, including pressure changes during atrial & ventricular systole & diastole; heart rate, stroke volume & cardiac output at rest vs. exercise.
Prevalence & risk factors of cardiovascular disease; pathology of coronary heart disease, including atherosclerosis, myocardial infarction & aortic aneurysm; effects of excess cholesterol; blood pressure & hypertension.
Structure & Function of the Digestive System
Structure & function of the human digestive system, to include both the major organs and accessory structures; mechanism of peristalsis; overview of digestive enzymes secreted in different parts of the digestive system.
Digestion of carbohydrates, proteins & lipids
Detailed description & explanation of the chemical digestion of carbohydrates, proteins and lipids by digestive enzymes in various parts of the alimentary canal (extending the overview given in the previous lesson).
Absorption of digestive products
Structure of the mammalian gut with reference to the absorption of digestive products, including structure of villi and the mechanisms of transport of monosaccharides, amino acids, fatty acids & glycerol across gut lining.
A lesson in which we examine the pathology of cholera to apply the concepts covered in previous lessons concerning the absorption of digestive products to explaining the symptoms of this disease in infected persons.
Phloem structure & function, sucrose sources & sinks
Structure of phloem (sieve tubes & companion cells); positive phloem sap pressure; distribution of phloem in different plants; sucrose sources & sinks; seasonal variation in sources & sinks.
Translocation – experimental evidence & theories
Experiments, their data & models of the movement of assimilates through the phloem arising from them which have led to our modern understanding of translocation in the phloem.
Xylem structure & function
Structure of xylem tissue; development & maturation of xylem vessels; apoplastic & symplastic pathways in root; models for the mechanism of transport in xylem (capillarity, root pressure & cohesion-tension theory).
Transpiration – experimental evidence & theories
Experiments, their data & models of the water movement in the xylem arising from them which have led to our modern understanding of the water transport mechanism in xylem tissue.
Genetics, variation & biodiversity
The genetic code – introns & exons
DNA in prokaryotes vs. eukaryotes (including mitochondrial & chloroplast DNA); the “central dogma” of molecular biology; introns & exons; post transcriptional modification of mRNA; the features of the genetic code.
Transcription & translation
Overview of protein synthesis; euk. & prok. ribosomes; detailed description of the processes of transcription (including post-transcriptional modification of mRNA) and translation (initiation, elongation & termination).
Role of mutation in evolution; causes of mutations; examples of gene (point) mutations and their effects, including substitutions, deletions & additions, with examples of effects on phenotype (albinism & retinoblastoma).
Significance of meiosis; the process of meiosis, and the sequence of events in each stage of meiosis (prophase, metaphase, anaphase, and telophase in the first and second meiotic divisions); non-disjunction & mutation.
An introduction to natural selection
Changes in allele frequency & evolution; genetic drift; genetic bottlenecks & extinction; the founder effect; Darwin’s theory of “survival of the fittest”; mechanism of natural selection with examples (rat warfarin resistance).
Types of natural selection
The first of two lessons on types of natural selection in this course (the second can be found in the topic “genetics, evolution & ecology”); stabilising & directional selection; antibiotic resistance & MRSA, tuberculosis.
Species, classification & taxonomy
Origin of the modern method of classification; the concept of a species; 5 kingdom & 3 domain classification systems; taxonomy and classification (including “form” & “phylogenetic” classification) with many examples.
Biochemical & genetic evidence used in classification
Traditional classification methods (comparing anatomy, embryology & behaviour) vs. modern approaches (sequencing DNA or amino acids in proteins, immunological studies).
Reproductive behaviours in animals (random external, protected & internal fertilisation); relationships between mates (monogamy, polygamy & promiscuity); examples of courtship behaviour & its role in many animals.
Biodiversity – species diversity index
Measuring species diversity; calculation of Simpson’s Diversity Index; importance & methods of random sampling; interpretation of Simpson’s Diversity Index; sampling techniques; examples of applications in fieldwork.
Biodiversity & farming
Components of biodiversity (ecosystem, genetic & species diversity); implications of intensive farming practices for biodiversity, including use of herbicides & pesticides, monoculture, ploughing, sowing, harvesting, etc.
Energy in Biological Systems
Autotrophs & heterotrophs
Distinction between heterotrophs & autotrophs; photoautotrophs & chemoautotrophs; extremophiles and the process of chemosynthesis; overview of photosynthesis; structural adaptations of photoautotrophs.
Photosynthesis – biochemistry
Photosynthetic pigments & their organisation in thylakoid membranes (antenna complexes); detailed description & explanation of the light-dependent & light independent reactions of photosynthesis; limiting factors.
Photosynthesis – experimental evidence
Experiments supporting our current understanding of the biochemical pathways involved in photosynthesis, including those of Ruben & Kamen, Blackman, Engelmann & Calvin et al; measuring rate of photosynthesis.
Respiration – glycolysis
Significance of glycolysis; role of ATP; the sequence of biochemical reactions involved in glycolysis, including phosphorylation & isomerisation of glucose, cleavage of fructose-1,6-bisphosphate & formation of pyruvate.
Respiration – forms of anaerobic respiration
Significance of anaerobic respiration; anaerobic pathways in plants, animals and fungi, including the biochemical reactions which produce lactic acid and ethanol; anaerobic respiration in muscle cells & the “oxygen debt”.
Aerobic respiration, Krebs cycle & ETC
Phases of aerobic respiration; biochemical reactions involved in the “link reaction” & Krebs Cycle (including respiratory substrates other than glucose) & the elctron transport chain; chemiosmotic theory of ATP synthesis.
Energy flow – ecosystems
Key concepts in ecological bioenergetics; biomass and energy losses at each trophic level in a food chain; pyramids of numbers, biomass & energy; calorimetry; ecological efficiency. net primary & secondary production.
Energy flow – farming & fertilisers
Intensive farming practices (hydroponics, glasshouses, fish farms, battery farming), their advantages & disadvantages, and importance of reducing energy losses; need for & use of fertilisers (organic vs. inorganic).
The nitrogen & phosphorus cycles
4 main processes of the nitrogen cycle (nitrogen fixation, ammonification, nitrification & denitrification); roles of mycorrhizae & mycorrhizal associations; impact of nitrogen fertilisers (eutrophication); the phosphorus cycle.
Sensitivity, coordination & control systems
Taxes, kineses & reflexes
Adaptive value of phototaxis & chemotaxis, orthokinesis & klinokinesis; reflex actions and the reflex arc; modulation of reflexes; examples including pupillary, knee-jerk, withdrawal, cough, shivering & blink reflexes.
Receptors – the Pacinian corpuscle & the eye
Classification of receptors (exteroceptors, enteroceptors, proprioceptors); structure & function of pacinian corpuscles and rod & cone cells of the retina (including signal transduction & production of generator potentials).
Chemical control in plants
Plant growth factors (auxins, giberellins, ethane, florigens); phototropism, hydrotropism, gravitropism & thigmatropism; experimental demonstration of tropisms, and role of plant growth factors in plant growth responses.
Control of the heart rate
Origin of heartbeat; conduction system of the heart (sino-atrial & atrio-ventricular nodes, bundle of His & Purkinje fibres; ECG; electrical properties of cardiac muscle; sympathetic & parasympathetic control of heart rate.
Neurones & impulses
Structure of sensory, motor & relay neurones; maintenance of resting membrane potential & generation of the action potential; role of sodium & potassium ion channels (voltage-gated & leak) and Na/K-ATPase pump.
Structure of synapses & neuromuscular junctions; unidirectionality, summation & inhibition of synaptic transmission; sequence of events at synapse following arrival of action potential resulting in signal transmission.
Skeletal muscle structure ; muscle fibre structure & types, myofilaments & banding pattern; contractile proteins & sliding filament mechanism; length-tension relationship; excitation-contraction coupling; energy sources.
Homeostasis & control of blood glucose
Homeostasis & negative feedback; control of blood glucose concentration by insulin or glucagon & explaining their mechanisms of action; diabetes mellitus diagnosis, pathology & treatment; glucose tolerance tests.
Hormones & osmoregulation
Nervous vs. hormonal coordination; endocrine organs & their secretions/functions; structure of the kindney & nephrons; glomerular filtration, selective tubular reabsorption, countercurrent multiplier; control by ADH.
Genetics, evolution & ecology
Introduction & monohybrid inheritance
Mendel’s experiments & conclusions leading to his Laws of Segregation & Independent Assortment; monohybrid crosses & determination of F1 and F2 genotypic & phenotypic ratios, with examples.
Mendel’s work in dihybrid inheritance; Law of Independent Assortment; independent assortment in meiosis; determination of expected genotypic & phenotypic ratios for dihybrid crosses, with examples; test crosses.
Gender & sex linkage
Genetic determination of gender in humans & other animals; sex chromosomes; autosomal linkage and modified (non-Mendelian) genetic ratios; sex linkage in humans (e.g. haemophilia & colour blindness).
Incomplete dominance, codominance & multiple alleles
Distinction between incomplete dominance & codominance; examples of incomplete dominance and codominance with two alleles or multiple alleles leading to non-Mendelian ratios.
Polygenic inheritance, epistasis & lethal genes
Interactions of genes in determining a characteristic (polygenic inheritance); Epistasis & lethal alleles; examples to illustrate the genotypic & phenotypic ratios in offspring due to these mechanisms of inheritance.
The chi squared test
Determining statistical significance of differences between expected vs. observed genotypic & phenotypic ratios (e.g. from Mendelian monohybrid & dihybrid crosses) using the chi-squared test, with examples.
Population genetics – Hardy Weinberg
Key concepts & terminology in population genetics; the gene pool; allele frequencies; the Hardy-Weinberg equation and its use in calculating allele frequencies, with examples; Hardy-Weinberg equilibrium conditions.
Speciation & evolution
Definition of a species & its limitations; isolating mechanisms (including geographical & reproductive); allopatric & sympatric mechanisms of speciation; examples of isolation & speciation mechanisms; Darwin’s finches.
Types of natural selection
The mechanisms by which disruptive, diversifying and directional selection alter the distributions of phenotypes in populations and can lead to speciation, illustrated with many examples in humans and other populations.
Introduction to ecology
Scope of ecology; key terms and concepts in ecology; biomes & ecosystems; abiotic conditions in major biomes and the adaptations of organisms found in each biome; ecological niches; predator-prey relationships.
Practical methods used by ecologists for investigating the biotic and abiotic components of ecosystems; examples include the Tullgren funnel, Pooter, kick-sampling, frame & point quadrats, belt transects.
Rocky shore fieldwork
Examples of fieldwork conducted by ecologists on rocky shores to illustrate some of the ecological techniques and concepts covered in previous lessons of this course; includes zonation studies using belt transects.
Stages in ecological succession; stages & features of primary & secondary succession, illustrated with examples of primary succession on bare rock, sand dunes, ponds & lakes and secondary succession after forest fires.
The control of gene expression
Gene & chromosomal mutations
Mutation in evolution; gene (point) vs. chromosomal mutations; examples of point mutations (substitution, deletion & addition) and chromosomal mutations (deletion, duplication, inversion; insertion vs. translocation).
Cell potency & differentiation
Significance & process of differentiation (including in plants); concept of cell potency (totipotency, pluripotency, multipotency & unipotency); embryonic & adult stem cells; sources & potential medical uses of stem cells.
Regulation of transcription & translation – 1
Description & explanation of different types of mechanisms for regulation of gene expression (transcriptional, post-transcriptional, translational & post-translational); activators & repressors; RNA interference; examples.
Regulation of transcription & translation – 2 (epigenetics)
Nucleosome structure; methylation of DNA & histones; protein acetylation & deacetylation; epigenetic control of differentiation; histone acetylation, DNA methylation & cancer.
Introduction to Cancer
Categorisation of tumours (benign vs. malignant) & their features; types of cancer; metastasis; incidence of cancer; risk factors; pathology of lung cancer & malignant melanoma; breast & cervical cancer.
Genes & cancer
Proto-oncogenes and tumour-suppressor genes, and their role in regulation of cell cycle and mitosis; consequences of mutations in proto-oncogenes & tumour suppressor genes, with examples of cancer caused by these.
Using genome projects
Genome & epigenome; genomics vs. proteomics; genetic diversity & DNA; milestones in the development of genomics; Human Genome Project; nanopore technology; next-generation sequencing technologies.
Genetic engineering – vectors, plasmids, transgenics
Recombinant DNA technology procedure, including restriction enzymes, vectors, ligase, ultracentrifugation; examples of production of transgenic plants & animals.
Genetic engineering – locating & isolating genes
The use of automated artificial gene synthesis, shotgunning & reverse transcription to locate and isolate specific genes in genetic engineering, with examples.
Gene therapy and its potential applications; somatic & germ-line therapies; vectors for gene therapy (virus & liposome-mediated gene therapies); cystic fibrosis & potential treatment by gene therapy.
Use of DNA probes for diagnosis, including DNA isolation/extraction, DNA fragmentation, separation of fragments by electrophoresis, location of specific sequences using the DNA probe & the analysis of results.