Lecture 1 Flashcards
What did Gregor Mendel’s work lead to?
Discovery of dominant and recessive traits.
Concept of the Gene.
Formulation of laws of inheritance.
What is a character in genetics?
Heritable feature of an individual.
What is a trait?
Variant form of the character (phenotype).
What is the definition for the law of segregation?
How did he come about with this Law?
The two forms of a gene (alleles) present in each parent segregate independently.
Studied results of monohybrid crosses.
What is a monohybrid cross?
A cross between 2 true breeding individuals differing in only one character.
What were Mendel’s observations when crossing green and yellow pea pods?
All F1 progeny resembled one of their parents.
But both original parental traits appeared in F2 generation.
Ratio in F2 = 3:1.
Same pattern of inheritance seen for all 7 characters studied.
Which pods were dominant and recessive in Mendel’s experiments?
Green = dominant. Yellow = recessive.
Had the heritable factor for the recessive trait been lost in the F1 pea pod progeny?
No, just masked by presence of the factor for the dominant trait.
Do alleles blend in Mendel’s model?
No, remain discrete.
What happens in gamete formation according to Mendel’s model?
Two alleles segregate, ending up in different gametes.
What is a method for determining the genotype of an individual with the dominant phenotype of a trait?
Testcross.
Define Mendel’s law of independent assortment.
Each pair of alleles assorts independently of each other pair of alleles during gamete formation.
What does Mendel’s law of independent assortment relate to?
Situation where the inheritance of two or more different pairs of alleles is being studied.
How did Mendel formulate law of independent assortment?
By following inheritance of two characters at the same time.
What is a dihybrid cross?
A cross involving parents differing in 2 characters.
What results were seen in F2 generation when Mendel crossed yellow-round seeds, and green wrinkled seeds (dihybrid cross)?
Two new phenotypes in addition to 2 parental phenotypes - recombinants.
9:3:3:1.
What would happen if independent assortment did not occur in dihybrid crosses?
No recombinant phenotypes in F2, with pairs of alleles inherited together.
Would still be 3:1.
How would you calculate probabilities of 3 independent allele pairs occurring on the same object?
Multiply 3 probabilities together.
What did Sutton write in his 1902 paper?
The association of paternal and maternal chromosomes in pairs and their subsequent separation during the reducing division, may constitute the physical basis of the Mendelian law of heredity.
How many haploid or diploid cells does mitosis produce?
2- Diploid.
How many haploid or diploid cells does meiosis produce?
4 - Haploid.
What type of cells does mitosis and meiosis occur in?
Mitosis - somatic cells.
Meiosis - germ line.
Does synapsis occur in mitosis or meiosis?
Meiosis.
What are the roles of mitosis and meiosis?
Mitosis - drive growth and tissue repair.
Meiosis - produce haploid gametes and introduce genetic invariability.
