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Chapter 11 - Genetics
The Essential Question
Who is Gregor Mendel and what did
he have to do with alleles,
chromosomes, traits, or this topic
called genetics?
Chromosomes
Homologous chromosomes
Two nearly identical copies of each chromosome in an
organism. One set is donated by the mother and the other set
by the father.
Sister chromatids
After a chromosome has replicated during interphase they
consist of two identical chromatids which are called sister
chromatids.
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Chromosomes
Gene
The basic unit of heredity. The sequence of DNA
nucleotides on a chromosome encodes for the
manufacturing of proteins and thus the traits of
the organism.
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Important terms and concepts
• Gene: controls one characteristic
• Alleles: alternative forms of a gene
• Dominant: an allele that is phenotypically
expressed regardless of the other allele
• Recessive: an allele that is only phenotypically
expressed when the dominant allele is not
present
• Locus: location of a gene on a chromosome
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Important terms and concepts
• Heterozygous: contains two different alleles for the
trait being studied
• Homozygous: contains identical alleles for the trait
being studied
• Genotype: the collection of alleles in an individual
• Phenotype: the physical expression of the alleles
(appearance & behaviour)
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Gregor Mendel
• He was a High School Biology teacher that
gave up teaching to become a monk.
• For his work in genetics, he earned the title of
being know as: The Father of Genetics.
Mendels first law
• the Law of Segregation
• Each organism has two hereditary
factors for each trait, which are called
___________. And during meiosis,
gamete (egg or sperm) formation, the
two factors separate (segregate) into
different gametes so that each gamete
has only one type of each factor.
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Mendel's second law
• the Law of Independent
Assortment
• Genes located on different
chromosomes assort independently of
one another.
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Punnett Squares
• Monohybrid Cross
• TT x tt