Tuesday 9 of February.

We only had a half of the class because then we had a “charla” of the police. In this half of the class the teacher explained us again the offspring colour of yellow and green peas. He said us that it was one of Mendel’s experiments. At the end he gave us the exams, which we did last week.

Thursday 11 of February.

First we corrected the homework, they were to look for a table with the information of different reproduction of hybrid.

       YyRr YR yR Yr yr
YyRr
YR YYRR YyRR YYRr YyRr
yR YyRR yyRR YyRr yyRr
Yr YYRr YyRr YYrr Yyrr
yr YyRr yyRr Yyrr yyrr

 

Yellow 9/16

Yellow/Green 3/16

Yellow/Green 3/16

Green 1/16

Then Fernando showed us a power point with some vocabulary that it is necessary for this unit. The words are:

Heredity: passing of traits from parent to offspring.

Genetics: study of heredity.

Alleles: two forms of a gene (dominant and recessive).

Dominant: stronger of two genes expressed in the hydrid; represented by a capital letter (R).

Recessive: gene that shows up less often in a cross; represented by a lowercase letter (r).

Monohybrid cross: cross involving a single trait. E.g. flower colour.

Dihybrid cross: cross involving two traits. E.g. flower colour and plant heigh.

Genotype: gene recombination for a trait. (eg. RR, Rr, rr)

Phenotype: the physical feature resulting from a genotype. (eg. red, white)

Homozygous: when both alleles are the same, e.g. RR or rr.

Heterozygous: when both alleles are different, e.g. Tt.

Friday 12 of February.

First Fernando asked if there was any doubt about the homework, they were to search the definition the three Mendel’s Laws.

1.– Law of Dominance. It states that in a cross of parents that are pure for contrasting traits, only one of the trait will appear in the first generation and is name as Dominant character.

2. – Law of Segregation. During the formation of gametes, the two alleles responsible for a trait separate from each other. Alleles for a trait are then “recombined” at fertilization, producing the genotypes for the traits of the offsring.

3. – Law of Independent assortment. It states that traits are transmitted to offspring independently of one another.

After this, Fernando gave us a photocopy with problems to resolve, one was; The polled (hornless) trait in cattle is dominant. The horned trait is recessive. A certain polled bull is mated to three cows. Cow A, which is horned gives birth to a polled calf. Cow B, also horned, and produces a horned calf. Cow C, which is polled, produces a horned calf. Name the genotypes.

Polled (P) > Horned (p)

Bull (P)

P – ?

It could be (Pp) or (PP). We don’t know yet.

(P) – ?  [X] (pp) cow A            

Genotype: (Pp)     

(P) – ? [X] (pp) cow B

Genotype: (pp). Now we now that our “incognita” is a (p)

So the genotype of the bull is (Pp).

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