Section 6-4

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Section 6-4Traits Genes

• Write everything that is underlined

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KEY CONCEPT Genes encode proteins that produce a
diverse range of traits
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Important Vocabulary Terms for You to Know

• Please make a chart or table at the top of your
  notes for these vocabulary terms
• Gene
• Allelle
• Homozygous
• Heterozygous
• Genome
• Genotype
• Phenotype
• Dominant
• Recessive

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A. The same gene can have many versions

• 1. A gene is a piece of DNA that tells a cell to
  make a certain protein
• Each gene has a locus,
• a specific position
• on a pair of
• homologous chromosomes

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2. An allele is an alternative form of a
gene -Each parent donates one allele for every
gene

• Pea plants have 2 alleles for shape - they
  receive one from each parent
• For shape, there is a wrinkled allele and a round
  allele

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B. Genes influence the development of traits

• All of an organisms genetic material is called
  the genome
• A genotype refers to the actual genes
• A phenotype is the physical expression of a trait

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C. Genotype

• 1. The gene combination of an organism
• It consists of 2 alleles
• For example
• Pure dominant, 2 dominant genes
• Pure recessive, 2 recessive genes
• Hybrid, 1 dominant and 1 recessive gene

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D. Phenotype

• 1. The way an organism looks
• No matter what genes are present, phenotype of a
  tall pea plant is tall and a short pea plant is
  short

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• A dominant allele is expressed as a phenotype
  when at least one allele is dominant
• A recessive allele is expressed as a phenotype
  only when two copies are present
• 2. Dominant alleles are represented by uppercase
  letters
• 3. Recessive alleles by lowercase letters

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Think fast!!!

• Determine if the following is genotype or
  phenotype.
• A horse with white stockings
• A pink rose that was bred from a white rose and
  red rose
• A pig that has super heavy muscling

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E. Mendels observed traits

1. Dominant traits covers up the other traits
2. Recessive traits traits that disappear
3. Rule of Dominance When a dominant trait is
   present the recessive trait is hidden

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Hows it related????

• You have 4 minutes and 25 seconds to draw a
  concept map to show (with words, chart, or a
  concept map) how these terms are related.
• Gene
• Genotype
• Phenotype
• Allelle
• Dominant traits
• Recessive traits

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• Most traits occur in a range and do not follow
  simple dominant-recessive patterns

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F. The Law of Independent Assortment

• Genes for different traits are inherited
  independently of each other
• When you have 2 or more different traits they are
  not stuck together

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Example (for your genetics book)

• Seed types of Parents
• Wrinkled, yellow
• Round, green
• You can get offspring with
• Wrinkled, green seeds
• Or Round, yellow seeds