Lecture 23 Flashcards
How did Mendal ensure cross pollination of his pea plants?
He removed the stamen from one flows and transferred pollen from the stamens of another flower to the carpel of the flower with the removed stamen, this formed a pod of peas which were then planted.
What does the F1 generation all showing only one parents trait mean?
The trait must be dominant (Also the parent with this trait must be pure breeding).
What happens for the genotypes of F2 offspring of two purebreeding pea plants breed, one with the dominant trait and one with the recessive
The F2 offspring are the result of self fertilisation of the F1 generation, the F1 generation will all have genotype Bb and this means 1/4 will be homozygous dominant, 1/2 will be heterozygous and 1/4 will be homozygous recessive.
What is a gene? What is an allele? How many of the allele copies will there be in each gamete?
A gene is genetic information which codes for specific proteins, individuals will typically have two copies of each gene (known as alleles), one from the father, one from the mother (more if polyploid).
What is a locus?
The locus is a genes location on a certain chromosome, different alleles of the same gene will be found on the same location on different chromosomes.
What is a punnett square?
A square which is used to work out the relative odds of the offspring genotypes, the alleles of the parents possible gametes are on the sides and are multiplied together to give the resulting offspring genotype.
What is important about dominant alleles in regards to phenotype?
Dominant alleles will cause the expression of the phenotype regardless of the other allele, as such heterozygous dominant and homozygous dominant will have the same phenotype.
What is a test cross?
Breeding done between an individual with a known genotype (e.g a recessive individual) with that of an unknown individual, the offspring ratio can be used to determin the unknown genotype.
What is the law of segregation?
Genes segregate at meiosis so that each gamete contains only one of the two possessed by the parent (mendel’s first law).
What is the law of independent assortment?
Alleles of different genes will assort independently during gamete formation. (Mendels second law).
If i had an individual of genotype RrYy what gametes would it produce assuming independent assortment? What about RRYy?
RrYy: RY, Ry, rY, ry
RRYy: RY,Ry.
What is an atavism in regards to biology?
When a recessive trait reappears after disappearing for a generation.
What do homozygous and heterozygous mean?
Homozygous: An individual which has two of the same allele.
Heterozygous: An individual with two different alleles for the same gene.
