Tuesday, April 8, 2008
Tues-Day 1
Bio- we discussed ARTIFICIAL SELECTION, the process by which plants or animals with specific desirable traits are SELECTIVELY BRED to each other so that the alleles that code for those traits are passed on to their offspring. After many generations, most of the offspring and parents will typically have those desired traits.
INBREEDING is a type of artificial selection by which "pure-bred" organisms/ homozygous for a given trait can be created by just breeding, for many generations, the offspring that have the same traits. The goal is to have pure-bred organisms that have particular desirable traits. Occasionally, inbreeding leads to the expression of harmful traits, which occurs when heterozygotes mate and form offspring that are homozygous for a harmful recessive allele.
HYBRIDIZATION is the mating of different purebred plants or animals to form heterozygotes that can typically have BOTH of the best traits of their parents, particularly when the alleles that combine are CODOMINANT or incompletely dominant.
We also reviewed, for ASEXUALLY reproducing plants/organisms, a way to amplify the frequency of traits/offspring that are desirable via vegetative propagation: grafting, cutting, or layering. Seedless oranges first formed as a result of a random genetic mutation in the gametes of an orange tree. All seedless oranges since then were formed via grafting branches from that original tree.
Chem 7-9: we took the written-response portion of the 3rd quarterly exam; tomorrow, we take the multiple choice portion of the lab.
INBREEDING is a type of artificial selection by which "pure-bred" organisms/ homozygous for a given trait can be created by just breeding, for many generations, the offspring that have the same traits. The goal is to have pure-bred organisms that have particular desirable traits. Occasionally, inbreeding leads to the expression of harmful traits, which occurs when heterozygotes mate and form offspring that are homozygous for a harmful recessive allele.
HYBRIDIZATION is the mating of different purebred plants or animals to form heterozygotes that can typically have BOTH of the best traits of their parents, particularly when the alleles that combine are CODOMINANT or incompletely dominant.
We also reviewed, for ASEXUALLY reproducing plants/organisms, a way to amplify the frequency of traits/offspring that are desirable via vegetative propagation: grafting, cutting, or layering. Seedless oranges first formed as a result of a random genetic mutation in the gametes of an orange tree. All seedless oranges since then were formed via grafting branches from that original tree.
Chem 7-9: we took the written-response portion of the 3rd quarterly exam; tomorrow, we take the multiple choice portion of the lab.
# posted by C @ 11:59 AM 
