Exploring Genetics

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Exploring Genetics

• Unit C. Basic Principles of Agricultural/Horticult
  ural Science
• Problem Area 3. Understanding Cells, Genetics,
  and Reproduction

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Next Generation Science/Common Core Standards
Addressed!

• MS-LS2-4. Construct an argument supported by
  empirical evidence that changes to physical or
  biological components of an ecosystem affect
  populations. Clarification Statement Emphasis
  is on recognizing patterns in data and making
  warranted inferences about changes in
  populations, and on evaluating empirical evidence
  supporting arguments about changes to
  ecosystems.
• RST.6-8.1 Cite specific textual evidence to
  support analysis of science and technical texts.
  (MS-LS1-6),(MS-LS2-1),(MS-LS2-4)
• RST.6-8.2 Determine the central ideas or
  conclusions of a text provide an accurate
  summary of the text distinct from prior knowledge
  or opinions.
• 6.RP.A.3 Summarize numerical data sets in
  relation to their context. (MS-LS2-2)

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Bell Work!

• Explain how genotype and phenotype are different.
• Describe how the gender of offspring is
  determined.
• Distinguish between qualitative and quantitative
  inheritance

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Terms

• Gamete
• Zygote
• Chromosome
• Genotype
• Phenotype
• Allele
• Heterozygous
• Homozygous

• Dominant
• Recessive
• Offspring
• Trait

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What determines the gender of offspring?

• The study of genetics is concerned with the
  transfer of traits.
• Gregor Mendel discovered that these traits are
  inherited through units called genes.
• Genes were found in pairs and half of the
  inherited traits come from the father and half
  from the mother.

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Gametes

• Sex cells! Known as the sperm from the male and
  egg from the female,
• Meet in fertilization and mix genetic material
  from both.
• The resulting zygote contains genes from both
  mother and father, and displays characteristics
  from both.

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Determination of the sex

• Depends on the sex chromosomes.
• Male sex chromosomes are either X or Y.
• The male makes sex determination as all eggs from
  female receive an X chromosome.
• Female zygote will have two X chromosomes (XX)
  while a male zygote will have one X and one Y
  chromosome (XY).

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The same thing may happen with color!

• Black Bull!

• Black Cow!

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How are genotype and phenotype different?

• Genotype is the actual genetic code.
• It controls physical and performance traits.
• The genotype of an organism cannot be changed by
  environmental factors.

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Phenotype

• Is the organisms physical or outward appearance.
• This is the part of the genotype the organism
  expresses or shows.
• In some instances, phenotype may be altered by
  the organisms environment.

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Homozygous

• A homozygous organism is one having similar
  alleles or genes on the DNA molecule for a
  particular trait.

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Heterozygous

• A heterozygous organism is one having different
  alleles for a particular trait.

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What is the difference between qualitative and
quantitative traits?

• Qualitative traits are traits controlled only by
  a single pair of genes and cannot be altered by
  the environment.
• These traits most easily show how genes are
  inherited.
• An example is coat color.

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Quantitative traits

• Traits controlled by several pairs of genes.
• These traits are expressed across a range.
• These traits can also be altered by environment.
• Examples include rate of gain, growth rate,
  backfat depth, etc.

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Expression of Traits

• Not all traits contained within an organism are
  expressed.
• Dominant traits cover up or mask the alleles for
  recessive traits.

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Expression of Traits

• In some organisms there are cases of codominance
  of traits in which both dominant and recessive
  genes are expressed.
• Incomplete dominance may also occur.
• This happens when a blending of the allele pair
  is expressed.

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