Genetics and Variation

Key Issues

Titles

Chapters

• A gene is a small section of DNA
• ADAPTATION AND COMPETITION
• Alleles
• Amino Acids
• An allele which controls the development of a characteristic when it is present on only one of the chromosomes is a dominant allele
• An allele which controls the development of characteristics only if the dominant allele is not present is a recessive allele
• Asexual reproduction - clones
• Asexual reproduction leading to clones
• Causes of mutations
• Chromosomes are made up of large molecules of DNA (deoxyribose nucleic acid)
• Chromosomes in human cells and in gametes
• Consequences of mutation
• Dependence of an individual's sex on X and Y chromosomes
• describe the nucleus of a cell contains long thread-like structures called chromosomes
• describe the principles of genetic engineering: insertion
• describe the principles of genetic engineering: isolation of genes
• describe the principles of genetic engineering: replication
• describe the principles of genetic engineering: selection of desired characteristics
• Diploid and halploid numbers in human cells
• discuss two approaches to discovery of DNA structure, eg Watson, Crick and R Franklin and Wilkins
• Distinction between genotype and phenotype, heterozygous and homozygous, dominant and recessive alleles
• DNA
• Dominant Allele
• Dominant and recessive genes (alleles)
• Each gene codes for a particular combination of amino acids which make a specific protein
• Each person (apart from identical twins) has unique DNA
• evaluate potential advantages of genetic engineering and selective breeding (improved characteristics of plants and animals)
• evaluate potential disadvantages of genetic engineering and selective breeding (escape of foreign genes; safety of food products; ethical issues)
• explain a monohybrid cross involving dominant and recessive alleles
• explain how characteristics can be passed from one generation to the next
• explain that cell division is required for the growth of an organism
• explain that in multicellular organisms, growth is a combination of cell enlargement and cell division
• explain the role of mitosis in cloning, and the scientific, moral, ethical issues of cloning human cells
• explain the way in which sex is determined in humans
• Fertilisation - fusion of gametes
• fertilization as a means of restoring the diploid number and combining different sets of chromosomes
• Function of oestrogen and progesterone in the menstrual cycle and during pregnancy
• Functions of sex hormones in promoting secondary sexual characteristics
• Fusion of male and female gametes (fertilisation)
• Gene therapy to overcome inherited diseases
• Genetic counselling and pedigree analysis
• INHERITANCE
• Inherited diseases
• know that during the growth of an organism, or when a cell is cloned, cells divide by mitosis
• know that genes are short lengths of DNA
• know that radiation can cause genetic mutation to include the role of UV light and skin cancer
• know that some diseases can be inherited, limited to cystic fibrosis and Downs syndrome
• know that to produce gametes, cells divide by meiosis
• know that variation in living organisms has both a genetic and environmental basis, eg height in humans
• Mechanism of inheritance of some genetic disorders
• Meiosis
• meoisis as reduction division (diploid to haploid) and as a process which re-assorts the chromosomes (omitting crossing over and names of phases)
• Mitosis
• Mitosis and meiosis
• mitosis; outline in terms of the exact duplication of chromosomes
• Mutation as a change in the chemical structure of a gene
• Mutation leading to genetic variation
• recall that genetic information is carried in the form of genes on chromosomes in the nucleus of cells, eg eye colour and tongue rolling
• Recessive Allele
• recognise dominant and recessive characteristics and explain that these depend on dominant and recessive alleles
• recognise ethical dilemmas concerned with genetic engineering
• recognise some potential advantages and risks of genetic engineering and selective breeding
• recognise the process of genetic engineering as the transfer of foreign genes into the cells of animals, plants or microorganisms
• Sexual reproduction - fertilisation leading to variation
• Some characteristics are controlled by a single gene. Each gene may have different forms called alleles
• state that alleles are different versions of the same gene
• state that characteristics can be passed from one generation to the next
• Symptoms of cystic fibrosis and sickle cell anaemia
• The nucleus, chromosomes, genes and DNA
• The structure of DNA
• This can be used to identify individuals in a process known as DNA fingerprinting
• understand how DNA controls protein synthesis, (limited to DNA as a double helix linked by base pairs and lengths of DNA which code for specific proteins)
• understand how genetic information is passed from cell to cell and generation to generation
• understand how proteins can be obtained from genetically engineered bacteria, eg human insulin
• understand that sexual reproduction is a source of genetic variation, while asexual reproduction produces clones
• understand the principles of a simple monohybrid cross
• understand why meiosis is required to produce gametes (which contain half the normal number of chromosomes)
• use and explain the term heterozygous
• use and explain the term homozygous
• Use of backcross to determine genotype
• Use of Punnett squares to determine genotype frequencies
• Use of sex hormones to treat infertility
• VARIATION
• Variation arising from genetic and environmental causes
• when a cell divides by mitosis, two daughter cells are produced, each with a set of chromosomes identical to parent cell