B1 - You and Your Genes

• Haploid (1n)


  A cell that has one set of chromosomes, typically found in gametes (sperm and egg cells).
• Diploid (2n)


  A cell that has two sets of chromosomes, one from each parent.
• The genome is the entire genetic material of an organism
• A gene is a section of DNA that codes for one protein
• Alleles are alternative forms of genes which code for the same characteristic but produce slightly different versions of it.
• Genetic variation occurs when there are differences between individuals within a population due to different alleles at specific loci.
• Homozygous means having two identical alleles, while heterozygous refers to having two different alleles.
• Phenotype refers to the observable characteristics or traits of an individual, such as eye color or height.
• The genetic material is stored in the nucleus and arranged into chromosomes
• A chromosome is one very long molecule of DNA thats coiled up
• Mutations are a rare, random change in the organisms DNA
• Mutations mean that the sequence of DNA bases in the gene is changed which produced a genetic varient that can be inherited
• A punnett square is used to show all the possible allele combinations in an offspring
• A capital letter, e.g, T, shows the dominant allele. A lower case letter, e.g, t, shows the recessive allele
• If both parents have two different alleles then there will always be at least one child with the same combination as its parent (homozygous)
• In humans, most genes come in pairs so we get half our genes from mum and half from dad
• The dominant allele will appear regardless of whether there is a recessive allele present (hetrozygous) or not.
• The recessive allele is only present is both alleles are recessive (homozygous)
• Cystic fibrosis is caused by a mutation on chromosome seven which affects the production of mucus in the body
• Genetic disorders can occur when a person inherits a faulty gene from their mother or father.
• Huntington's disease is caused by a mutation on chromosome four that causes brain cells to die prematurely