BIOL 2112 Chapter Notes - Chapter 14: Punnett Square, Mendelian Inheritance, Heredity
3 May 2018
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Lecture 29 - Law of Segregation and Law of Independent Assortment
1) A. What was Medel’s odel sste? Mendel began breeding garden peas in the
abbey garden to study inheritance. B. What ere the adatages of Medel’s sstem to
study heredity? There are many varieties, they have a short generation time, they have a
large number of offspring from each mating. 2) A. What is hybridization? The mating, or
crossing of two true-breeding varieties. B. What experimental technique led to Mendel
developing the first principles of heredity? He followed traits for at least the P, F1, and F2
generations. Had Mendel stopped with the F1 generation, the basic patterns of
inheritance would have eluded him. His quantitative analysis of the F2 plants from
thousands of genetic crosses allowed him to deduce two fundamental principles of
heredity now called law of segregation and law of independent assortment. 3) The various
traits that Medel osered i pea plats ehiited a 3 dominant: 1 recessive ratio i
the F2 generatio. Medel’s odel of iheritae as deeloped i order to eplai this
ratio. List the four componets of Medel’s odel. Alternative versions of genes account
for variations in inherited characters, for each character an organism inherits two copies
of a gene (one from each parent), if the two alleles at a locus differ then one dominant
allele deteries the orgais’s appearae – the recessive allele has no noticeable
effet o the orgais’s appearae, the two alleles for a heritale harater segregate
during gamete formation and end up in different gametes. 4) A. What is an allele?
Alternative versions of a gene. B. What is a locus? Each gene is a sequence of nucleotides
at a specific place, or locus, along a particular chromosome. 5) What is meant by the
terms homozygous and heterozygous? An organism that has a pair of identical alleles for
a gene is said to be homozygous. An organism that has two different alleles for a gene is
said to be heterozygous for that gene. 6) A gene encoding orange pigment in goldfish has
two alleles. The wild type or normal allele (O) is dominant over the mutant allele (o).
Goldfish who are homozygous for the mutant allele are white. A. What is the genotype
and phenotype of an individual goldfish that is heterozygous for the gene? Oo
B. Use a Punnett Square to determine the genotypes of offspring that result from the
following cross:
(Female) Oo X Oo (male)
OO
Oo
Oo
oo
C. What is the phenotypic ratio of offspring from this cross? Phenotypic ratio
(orange:white) 3:1
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Document Summary
Lecture 29 - law of segregation and law of independent assortment: a. Mendel began breeding garden peas in the abbey garden to study inheritance. There are many varieties, they have a short generation time, they have a large number of offspring from each mating. The mating, or crossing of two true-breeding varieties. He followed traits for at least the p, f1, and f2 generations. Had mendel stopped with the f1 generation, the basic patterns of inheritance would have eluded him. His quantitative analysis of the f2 plants from thousands of genetic crosses allowed him to deduce two fundamental principles of heredity now called law of segregation and law of independent assortment. 3) the various traits that me(cid:374)del o(cid:271)ser(cid:448)ed i(cid:374) pea pla(cid:374)ts e(cid:454)hi(cid:271)ited a (cid:862)3 dominant: 1 recessive(cid:863) ratio i(cid:374) the f2 generatio(cid:374). Me(cid:374)del"s (cid:373)odel of i(cid:374)herita(cid:374)(cid:272)e (cid:449)as de(cid:448)eloped i(cid:374) order to e(cid:454)plai(cid:374) this ratio.
