3.4 and 10.2 Inheritance Flashcards
Allele mask
when one allele covers the phenotypic expression of another allele at the same gene locus.
Autosomal genes
chromosomes that do not determine sex.
Co-dominant alleles
two alleles at a particular locus that have different effects and are distinguishable in a heterozygous individual (e.g. AB blood groups).
Colour blindness
an abnormal condition caused by an X-linked recessive allele and characterized by the inability to clearly distinguish different colours of the visible light spectrum.
Cystic fibrosis
a mutation in a gene that changes a protein that regulates the movement of salt in and out of cells; characterized by the production of thick and sticky mucus.
Dominant alleles
the allele that is fully expressed in the phenotype of a heterozygote.
Gametes
one of two haploid reproductive cells, egg or sperm, whose union is necessary in sexual reproduction to produce a diploid zygote.
Gene
a hereditary unit consisting of a sequence of DNA that occupies a specific location on a chromosome and determines a particular characteristic in an organism.
Genotype
the genetic constitution of an organism.
Haemophilia
a sex-linked inheritable disease characterized by loss or impairment of the normal clotting ability of blood, so that a minor wound may result in fatal bleeding.
Haploid cells
have one chromosome of each pair (have one full set of the chromosomes that are found in its species).
Huntington’s disease
caused by a genetic defect on chromosome 4; the defect causes a part of DNA, called a CAG repeat, to occur many more times than it is supposed to.
Mutagen
a chemical or physical agent that interacts with DNA and causes a mutation.
Phenotype
the physical and physiological traits of an organism.
Punnett grid (or Punnett square)
a tool that helps to show all possible allelic combinations of gametes in a cross of parents with known genotypes in order to predict the probability of their offspring possessing certain sets of alleles.
Recessive allele
an allele that has an effect on the phenotype only when present in the homozygous state.
Sex-linked inheritance
traits controlled by genes located on one sex chromosome but not the other.
Zygotes
the diploid product of the fusion of haploid gametes (a fertilized egg).
chi-square test
A statistical method used to calculate whether the observed and expected genotype frequencies of a population are significantly different.
continuous variation
An assemblage of measurements of a phenotypical characteristic which forms from a continuous spectrum of values, such as body height, skin color or hair curl
dihybrid cross
A cross between two individuals, concentrating on two definable traits, for example pea color and height of pea plant
discrete variation
Inherited characteristic that have a limited number of variations, such as the ability or inability to roll one’s tongue
gene loci
specific locations of genes along the chromosome
linked genes
Genes located on the same chromosome that tend to be inherited together in genetic crosses
