Zusammenfassung der Ressource
Chapter 11:
Introduction
to Genetics
- Gregor Mendel
- Born in 1822 in
the Czeh Republic
- Priest, scientist,
mathmaticion,
teacher, gardener
- Studied the
inheritance of traits
in garden peas
- Mendel's Work
- Fertilization - joining of
male and female
reproductive cells during
sexual reproduction
- True-breeding - offspring of
self-pollinated plants produce
offspring identical to itself
- Cross-pollinate
- Hybrid - the offspring of a
cross between parents
with different traits
- Pea flowers normally self
pollinate - sperm cells in pollen
fertilize egg cells within the
pistil of the same flower
- Traits
- Dominant - expressed
by TT or Tt
- Recessive - expressed when the
dominant allele is not present( tt )
- Given that recessive traits
re-appear in the F2 generation,
alleles must have segregated
when gametes were formed
- Terms
- Probability - the likely-hood that
a particular event will occur
- Can be used to predict the
outcome of genetic codes
- Homozygous - 2
identical alleles
- Heterozygous -
2 different alleles
- Phenotype - physical
characteristics
- Genotype -
genetic makeup
- Principle of Independent Assortment: genes for
different traits can segregate independently
during gamete formation. This accounts for
many genetic variations in organisms
- Codominance - both phenotypes are produced
- Multiple Alleles - a gene with more than
2 possible alleles in a population
- Polygenic traits - traits
controlled by 2 or more genes
- Western White Butterfly
- When adults hatch in spring, wings are darker than
those that hatch in summer. The dark wing color
helps increase their body heat in the cooler spring.
- Diploid(2N) - a cell contains both
sets of homologous chromosomes
- Haploid(N) - contains a
single set of genes;
Gametes(sex cells) are
haploid
- Homologous Chromosomes - a pair
of chromosomes that carry genes
coding for the same characteristics
- Tetrad - a pair of
homologous chromosomes;
includes 4 chromatids
- Crossing Over - alleles are exchanged
between homologous chromosomes when
they are lined up as tetrads; produces a
new combination of alleles; contributes to
genetic diversity
- Meiosis
- Process when gametes are formed;
homologous chromosomes are
separated to create haploid gamates;
1 diploid = 4 haploid
- Can't assort independently, they are linked
together because they are on the same gene. So,
their alleles tend to be inherited together. Crossing
over can be done and separate linked genes. The
loser together genes are on a chromosome the
more likely they will be inherited together.