Mendelian Genetics Flashcards
Pure breeding line
population that breeds true for a particular trait.
Hybrid
plants/animals generated from crossing two pure breeding lines.
Phenotype
physical or measurable appearance of a trait.
Gene
unit of heredity, residing at a specific point on a chromosome; a length of DNA that specifies a product
Allele
the variant of a specific gene. An individual inherits two alleles, one from each parent, for any given genomic location where such variation exists.
Genotype
the specific allelic combination for a certain gene or set of genes
Gamete
They are also referred to as sex cells. Female gametes are called ova or egg cells, and male gametes are called sperm. Gametes are haploid cells, and each cell carries only one copy of each chromosome.
Segregation
separation of parental homologous chromosomes at meiosis and the consequent separation of alleles and their distribution to different gametes
Dominant
the allele that expresses itself at the expense of an alternate allele; the phenotype that is expressed in the F1 generation from the cross of two pure lines
an allele whose expression is suppressed in the presence of a dominant allele; the phenotype that disappears in the F1 generation from the cross of two pure lines and reappears in the F2 generation
Recessive
Homozygous
an individual which contains only one allele type at the allelic pair; for example DD is homozygous dominant and dd is homozygous recessive
Heterozygous
an individual that contains two different alleles at the allelic pair; for example Dd heterozygote rather than DD or dd homozygote.
hybrid offspring of parents differing in one character => heterozygous for a single pair of alleles. 3:1
Monohybrid
hybrid offspring of parents differing in two distinct characters => heterozygous for two pairs of alleles. 9:3:3:1
Dihybrid
The Law of Independent Assortment:
During gamete formation one pair of factors (alleles) for one trait segregates independently of the alleles for a second trait.
a descendant or the descendants of a person, animal, or plant; offspring
.progeny
use of multiplication in a question about probability
probability of y multiplied by the probability of x = total probability. use when questions contain an ‘and’
use of addition in a question regarding genetic probability.
probability of y + the probability of x = total probability when answer questions with ‘or’ in them. (example: what is the probability of flipping a coin for hads or tails= 0.5 + 0.5 = 1)
Pedigree analysis
monitoring the inheritance of genes over many generations within a family it is possible to deduce how certain genes are inherited.
Autosomal traits
are those for which genes are present on the autosomes (non sex chromosomes).
Autosomal recessive traits are characterised by:
Progeny that display the phenotype arising from parents that do not display the phenotype
Autosomal dominant traits are characterised by:
Individuals displaying the phenotype MUST have had at least one parent displaying the phenotype;
The phenotype generally appears every in every generation;
The phenotype appears in males and females equally.
Pedigree methods in plant breeding are applied when:
- Handling segregating traits from crosses in self pollinated crops, or when self-pollination can be forced;
- Improving traits that are quick and easy to measure disease resistance, plant height, time to maturity;
- Improvement in an established variety for some specific character is required.
New alleles arise via
mutation
