Biology 17.1 Flashcards
Selective breeding
A process where people chose and breed plants and animals for particular physical features or behaviours.
True Breeding
A true breeding is a kind of breeding wherein the parents would produce offspring that would carry the same phenotype. This means that the parents are homozygous for every trait.
Aristotle proposal on Theories of Inheritance
proposed the first widely accepted theory of inheritance, called pangenesis. According to this theory, egg and sperm consist of particles, called pangenes, from all parts of the body. Upon fertilization of the egg by a sperm, the pangenes develop into the parts of the body from which they were derived.
Antony Van Leeuwenhoek proposal on the Theories of Inheritance (3)
- Discovered living sperm in semen with his exquisitely designed single-lens microscopes.
- Believed that he saw a complete miniature person called a homunculus in the head of sperm.
- Believed that homunculus came from the father but developed in the mother.
F1, F2 and Parental
The F1 (first filial) generation consists of all the offspring from the parents. The F2 (second filial) generation consists of the offspring from allowing the F1 individuals to interbreed .
Heterozygous Trait
- Dominant and recessive allele are together
- An individual with two different alleles for a trait, such as Rr
Homozygous recessive
Two recessive alleles that are the same
Ex: yy
Homozygous dominant
If the alleles are the same and dominant
ex: (YY)
Monohybrid cross
A mating event between two parents that are heterozygous in respect to a single gene. Only one trait involved but parents can have variant of the one trait
A cross between two types of plants of same species considering only the transmission of one character is called monohybrid cross. For example, a cross between tall pea plants and dwarf pea plant that is considering only the height of the parents is a monohybrid cross.
Progeny
Children as a result of cross
What did Mendel discover?
For every trait, the F1 plants showed only one of the two parental characteristics.
Ex: In the cross between plants with round seeds and plants with wrinkled seeds, all the seeds in the F1 generation were round.
Dominant trait
When a trait is dominant, only one allele is required for the trait to be observed. A dominant allele will mask a recessive allele, if present.
Recessive trait
The characteristics not expressed/ easily masked. Only expressed when the genotype is homozygous.
Complete dominance
That is, an individual with one recessive and one dominant form had the same observable physical characteristic as an individual with two dominant forms.
Mendel’s First Law: Law of Segregation (4 plus summary)
- Discrete factors determine individual traits. (Note: Mendel used the term “factors” to describe what are now called genes.)
- Each individual organism has two copies of each factor.
- When gametes (eggs and sperm)
are formed, the copies of the factors segregate so that each gamete receives one copy of each factor. - Eggs and sperm fuse randomly. The embryo that develops into a new individual has two copies of each factor—one copy from each parent.
Mendel’s First Law:
The Law of Segregation
“All individuals have two copies of each factor. These copies segregate (separate) randomly during gamete formation, and each gamete receives one copy of every factor.”
