Download Introduction to Genetics Handout

Rozema Biology—Spring 2010
Name: ____________________________________________
Hr: ___________
Introduction to Genetics
BIG IDEAS:
Genetics is the study of heredity, or the transmission of characteristics from parent to
offspring. Organisms closely resemble their parents; their slight variations can accumulate
over many generations and result in more obvious differences between organisms and their
ancestors.
All plants and animals (and one-celled organisms) develop and have the capacity to
reproduce. Reproduction, whether sexual or asexual, is a requirement for the survival of
species. Characteristics of organisms are influenced by heredity and environment. Genetic
differences among individuals and species are fundamentally chemical. Different organisms
are made up of somewhat different proteins. Reproduction involves passing the DNA with
instructions for making these proteins from one generation to the next with occasional
modifications.
The principle of dominance states that some alleles are dominant and others are
recessive. Allele combinations in organisms can be described by their genetics, or by their
physical expression. Each organism carries at least two alleles for each gene. However,
some alleles are neither dominant nor recessive, and many traits are controlled by multiple
alleles or multiple genes. Some traits are also specific to types of chromosomes (such as
male and female chromosomes).
Rozema Biology—Spring 2010
Probability can be used to predict the outcomes of genetic crosses (breeding). Punnett
Squares can be used to predict and compare the genetic outcomes of a “cross” or of breeding.
The principle of independent assortment states that different alleles for genes can
segregate independently during the formation of gametes (sex cells). Independent
assortment helps account for the many genetic variations in plants and animals.
Recent advances in biochemistry and cell biology have increased understanding of the
mechanisms of inheritance and enabled the detection of disease related genes. Such
knowledge is making it possible to design and produce large quantities of substances to treat
disease and, in years to come, may lead to cures.
If an error occurs in the formation of gametes (sex cells), the errors has the possibility
of being passed on to future offspring. In gene therapy, an absent or faulty gene would be
replaced by a normal-working gene. The Human Genome Project is an ongoing effort to
analyze the human DNA sequence, in order to better understand the inheritance of traits.
Humans use selective breeding, which takes advantage of naturally occurring
genetic variation in plants, animals, and other organisms, to pass desired traits on to the next
generation of organisms. Breeders can increase the genetic variation in a population by
inducing mutations, which are the ultimate source of genetic variability.
Unit Vocabulary:
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Words You Already Learned:
Alleles
Gene
Chromosome
Homologous Pairs of Chromosomes
Sex Cell / Gamete
Sex Chromosomes
Independent Assortment
Law of Segregation
Mutations
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New Words To Learn:
Gregor Mendel
Dominant Trait
Recessive Trait
Genotype
Phenotype
Punnett Square
Heterozygous Genotype
Homozygous Genotype
Sex-Linked Traits
Co-Dominant Traits
Polygenic Traits
Genetic Diversity
Genetic Recombination
Gene Therapy
Rozema Biology—Spring 2010
“Peas In A Pod: Cracking The Code” Video
1) How cool are those singing detectives?
Super Cool
Cool
Eh
Pretty Lame
2) Why did they originally think men carried the genetic information?
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3) What did Linnaeus believe? What did he think would happen when 2
individuals would “cross-breed”?
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4) Many people used to believe in “blending” during breeding. What is
“blending”?
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5) People of Darwin’s time also believed in “acquired inheritance”. What is
“acquired inheritance”?
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6) Why did Gregor Mendel choose pea plants to study?
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7) Why did Gregor Mendel call some traits “dominant” and some “recessive”?
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8) How did Gregor Mendel KNOW that genes are not “blended” when organisms
cross-breed?
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Rozema Biology—Spring 2010
9) What is the difference between “phenotype” and “genotype”?
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10)
Mendel believed that during sperm/egg production, the “gene pair”
splits up. What is this called?
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11)
What is the difference between “homozygous” and “heterozygous”
genotypes?
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12)
When Gregor Mendel studied more than one trait at a time in pea plants,
he found that the traits were inherited randomly and separately. What is this
called?
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