Genetic Diagrams

• Alleles are different versions of the same gene.
• An organisms genotype are their alleles.
• A chromosome is a long molecule of DNA found in the nucleus.
• A gene is a section of DNA found in a chromosome that contains the instructions needed to produced a protein.
• A dominant allele will always affect the phenotype.
• A recessive allele will only affect the phenotype if both alleles are recessive. Has no effect if one is dominant.
• Homozygous - when both alleles for a gene are the same.
• Heterozygous - when the alleles in a gene are different.
• The phenotype of an organism is the characteristic that a set of alleles produce.
• A gamete is a haploid cell used in reproduction.
• A zygote is a fertilised egg cell.
• Monohybrid inheritance is the inheritance of a single characteristic.
• Males have an X and a Y chromosome but females have 2 X chromosomes.
• All eggs have an X chromosome but sperm can have an X or a Y chromosome so the sex of the child depends on what chromosome the sperm carries.