Biology Exam 3

Biology Exam 3 - Biology Exam 3 Gregor Mendel-Born in...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Biology Exam 3 Gregor Mendel -Born in 1822 -Monk at the monastery of ST. Thomas in Czech Republic -In 1866 published his work “Experiments with Plant Hybrids” -Key idea was “Particulate rather than “blending” inheritance Mendel worked with edible pea plants -There was a long history of previous work on peas -Why did Mendel succeed and others fail? John Gross -English in 1824 worked with the same plants 30 years before Mendel began his work -He observed green and yellow seeds in peas followed them through a number of generations -Goss was not quantitative Today we speak of Mendelian genetics NOT Gossian genetics -Why? -Goss didn’t count Why did Mendel succeed? -He chose the right organism to work with, the edible pea plant. -The plant usually self-pollinates, ie, self fertilizes -Stigma and anthers are completely enclosed by petals until after fertilization -Therefore there is no cross contamination -He picked the “right” traits to follow. -Simple single gene inheritance -He followed the crosses for several generations -He was quantitative in his observations -he had a little help form his friends Definitions /Terminology Gene -Discrete unit of heredity information consisting of a specific sequence of DNA -Often codes fir a polypeptide chain Gene Locus -A particular position along a specific chromosome where a given gene is located Allele -Alternative form of a gene Genetics problems on MOODLE Homozygous -Having 2 identical alleles for a trait Heterozygous -Having two different alleles for a trait Genotype
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
-The genetic makeup of an individual Phenotype -The physical manifestation of a trait -How it happens -Determined by the genotype Dominant Allele -Allele that is fully expressed in the phenotype of a heterozygote -Only a single copy is required to express the trait -Represented with a capital letter Recessive allele -In a heterozygous individual the allele that is completely masked (not expressed) in the phenotype Why is it not expressed? -Inactive or defective enzyme Generations -P is parental -F1 is filial one- offspring of the parental generation-hybrids -F2 is a filial two- offspring of cross between F1 (hybrid) individuals Mendel’s First Law -The two numbers of a gene pair segregate (separate) from each other into the gametes -Each gamete carries one member When does Mendelian segregation occur? -When do homologous chromosome separate? -Anaphase I of meiosis Genotype-Phenotype -Individual displaying a dominant trait may be homozygous or heterozygous -PP or Pp -Individual displaying a recessive trait must be homozygous for the recessive allele -pp Test Cross -How do you determine whether an individual is a homozygous dominant, or heterozygous? -Phenotype is P -Genotype is P- -Could be PP or Pp -Cross the individual with an unknown genotype with a homozygous recessive individual Test Cross Outcomes -If the individual with the unknown genotype is homozygous dominant -All offspring display the dominant trait -If the individual with the unknown genotype is heterozygous
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 11/03/2011 for the course BIO 1201 taught by Professor Sibenaller during the Fall '10 term at LSU.

Page1 / 11

Biology Exam 3 - Biology Exam 3 Gregor Mendel-Born in...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online