Heredity and Genetics - Key Words BY5
- Created by: Sophia Dowden
- Created on: 18-06-16 11:35
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- Heredity and Genetics - key words and phrases
- Genotype
- Genetic composition of an organism (genetic make-up)
- Phenotype
- Observable characteristics of an organism e.g. brown hair
- Mutation
- A change in genotype ---> inherited
- Modification
- A change in phenotype
- Gene
- A section of DNA on a chromosome that codes for a particular polypeptide
- Allele
- Alternative form of the same gene
- Homozygous/zygote
- Possessing two identical alleles of the same gene e.g. AAaa
- Heterozygous
- Possessing two different alleles on the same gene e.g. Aa
- Recessive
- Expresses itself only in the presence of another recessive allele e.g. aa
- Dominant
- The dominant allele is expressed in either the heterozygous condition or homozygous conditions
- Self-crossed
- Involving plants from the same generation
- 1st law of inheritance: law of segregation
- The characteristic of an organism are determined by factors (alleles) which occur in pairs. Only one of each pair of factors (allelles) can be represented in a single gamete
- Monohybrid inheritance
- Involving a single characteristic determined by one gene
- Dihybrid inheritance
- Two characteristics, different gene, different locus
- Second law of inheritance: Law of independent assortment
- Either one of a pair of contrasted characters may combine with either of another pair
- Co-dominance
- Alleles express themselves equally in the phenotype, therefore niether is dominant
- Sex-linked
- Genes that are located on one or the other sex chromosome
- X-linkage
- Recessive alleles will express themselves more often in the phenotype of the male
- X Chromosome
- Carries many such sex linked genes, in human, features linked on this chromosome may arise in either sex
- Y Chromosome
- Carries very few sex-linked genes, in humans, features will only arise in males
- Carriers
- Females whom are heterozygous for a sex-linked recessive trait
- Sex linked recessive allele
- Carried on the sex/X chromosome and only expressed if both chromosomes carry allele/gene is female, always expressed in the male
- Genotype
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