BIOB11H3 Lecture Notes - Theodor Boveri, Mendelian Inheritance, Gamete

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Published on 3 Jul 2012
School
Course
Professor
BIOB11
Lecture 1 & 2 + Tutorial
June 21/2012
Gregory Mendel: munk who obsessed with pea plants, and listed various traits that he followed,
then assigned traits
how many plants of a given characteristic were produced and then passed on from parent
plant to individual --> gene
Alleles/genes can randomly unite at fertilization--> Mendels law of segregation
a dominant allele over the recessive allele – dominant allele masses the effect, ex: Aa = tall
segregation of alleles: segregation of dominant and recessive alleles
homozygous alleles contribute only that type of allele to the offspring, heterozygous alleles
can contribute both
identity of parents in terms of alleles determines what percentage of offspring will have what
kind of alleles
Law of independent assortment: each allele has its own effect on the offspring, ex:
blue/brown eyes is independent of tall/short alleles
Physical basis of the units of inheritance:
Theodor Boveri: took one egg taken from organism and forced it with two sperms – three sets
of alleles
initial stages of divisions were fine, but through differentiation stages, the blastists started
to disintegrate over time
concluded that messing with the number of chromosomes will lead to inviable offspring
bivalent configuration: each pair of chromosomes associated with each other
chromosomes are genes/alleles that reside on the chromosomes. If the genes are on the same
chromosomes, should they be inherited together? -- answer: not always.
Reason: there is breakage and exchange of info between homologous chromosomes, depends
on how far apart the chromosomes are from each other
unable to be inherited together
why do breaks occur? -- there is intermingling, physical breaks and resealing and exchange of
material between chromosomes – crossing over/chiasmata
Meiosis:
two separate separation events
1. doubling of DNA and homologous chromosomes pair
2. formation of chiasmata that allows exchange of DNA
Parental gamete: no crossing over/recombination
crossover gamete: formation of different gamete which has exchange of material between
chromosomes
break between chromosomes = crossing over
the further apart two genes are, the bigger the chance that there will be a break between the two
genes, wont be inherited together (unlinked traits) – Mendel's traits
S Bacteria killed mice, got pneumonia
fractionation of cell extracts: mix components of cells (proteins, lipids, DNA, etc) with R strains,
DNA fraction when given to R strain caused virulent infection in mice
Do viruses inject DNA or protein?
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Document Summary

Gregory mendel: munk who obsessed with pea plants, and listed various traits that he followed, then assigned traits. How many plants of a given characteristic were produced and then passed on from parent plant to individual --> gene. Alleles/genes can randomly unite at fertilization--> mendel"s law of segregation. A dominant allele over the recessive allele dominant allele masses the effect, ex: aa = tall. Segregation of alleles: segregation of dominant and recessive alleles. Homozygous alleles contribute only that type of allele to the offspring, heterozygous alleles can contribute both kind of alleles. Identity of parents in terms of alleles determines what percentage of offspring will have what. Law of independent assortment: each allele has its own effect on the offspring, ex: blue/brown eyes is independent of tall/short alleles. Physical basis of the units of inheritance: Theodor boveri: took one egg taken from organism and forced it with two sperms three sets of alleles.

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