Genetics Definitions (Learn These!!)

Gametes                                        Sex Cells

Fertilisation                                    Joining 2 gametes together.

Zygote                                           The product of joining 2 gametes together.

Diploid                                           Contains 2 complete sets of chromosomes.

Haploid                                           Contains only one set of chromosomes.

Mitosis                                    Cell division leading to 2 identical cells used for growth.

Meiosis                                          Cell division leading to 4 non-identical cells each                                                     with haploid number of chromosomes.

Gene                                              Length of DNA coding for polypeptide.

Allele                                             Different forms of a gene.

Gene Locus                                     The position on a chromosome of a gene.

Homozygous                                   2 alleles or chromosomes which are the same.

Hetrozygous                                    2 alleles or chromosomes which are different.

Genotype                                        Alleles present in a organism e.g. Aa

Phenotype                                       Observable characteristics of an organism.

Multiple alleles                                More than 2 alleles for the same gene locus.

Dominant                                        If one allele has an effect on phenotype in                                                      heterozygote.

Recessive                                       If one allele has no effect on a phenotype in                                                      heterozygote.

Codominant                                    If both alleles have effect on phenotype in                                                      heterozygote

Sex linked                                       Present on X chromosome.

Monohybrid Cross                             Inheritance using one gene locus.

Dihybrid Cross                                  Inheritance using two gene loci.

 

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