15.1 Human Biology (Mendelian Inheritance) Flashcards
Who founded Mendelian Inheritance?
Gregor Mendel (1865) was a
What are the 2 principles of inheritance?
- The various hereditary characteristics were controlled by factors (now called genes) that occurred in pairs.
- During the formation of the gametes, the pairs of genes separate. Each gamete receives only one set of genes. with the other set going to another gamete.
(Gametes unite at fertilisation, allowing different combinations of genes to come together.)
What did Mendel use to conduct his experiment?
A edible garden pea, Pisum sativum
What does pure-breeding mean?
The production of the same characteristics in each succeeding generation when individuals are bred among themselves; homozygous.
What is found when pure-breeding?
That the offspring (or progeny) resemble only one of the parents.
What is a hybrid?
An offspring that is the result of a mating between individuals of different gene constitutions.
Why is the trait presented by a hybrid considered dominant
Because that trait is the only one shown, while there are two alleles, meaning it masks the other.
What is the masked trait called?
The recessive trait.
What occurs when hybrid second generation plants self-pollinate?
When Mendel allowed the hybrid plants to self-pollinate, a second generation of plants was produced. In this generation the characteristics reappeared in the ratio of about three with the dominant trait for every one with the recessive trait (3:1).
What did the self-pollination of the second generation of hybrid plants lead Mendel to conclude?
That the hereditary factors, or genes, were unchanged as they passed from one generation to the next. He further reasoned that each pea plant had two hereditary factors for each characteristic under study.
What is the principle of segregation?
The principle that the alleles for a trait are separated during the formation of gametes.
What is a monohybrid cross?
only one pair of contrasting characteristics is studied.
What is used to differentiate alleles?
Genes for a particular characteristic are represented by two letters, one for the gene that originated from the female parent and one for the gene that originated from the male parent. If the gene is a dominant one, it is shown as a capital letter; if it is a recessive one, a lower-case letter is used.
What is the phenotype?
The physical appearance of a individual as determined by the expression of the alleles for that characteristic.
What is a gene and where is it located?
The factor that determines an inherited characteristic; located in the chromosomes.
