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Introduction%20to%20Mendelian%20Genetics

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Introduction to Mendelian Genetics Objectives Define key terms used in Mendelian Genetics Key Terms Heredity: The passing of characters from parents to offspring. – PowerPoint PPT presentation

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Title: Introduction%20to%20Mendelian%20Genetics


1
Introduction to Mendelian Genetics
2
Objectives
  • Define key terms used in Mendelian Genetics

3
Key Terms
  • Heredity The passing of characters from parents
    to offspring.
  • Genetics The branch of biology that focuses on
    heredity.
  • Traits Specific characteristics that vary from
    one individual to another. Ex. Hair color, skin
    color
  • Gene- a specific nucleotide sequence of DNA that
    codes for a protein

4
Key Terms
  • Allele alternative forms of a gene. Ex. flower
    color purple (P) or white (p)

5
Key Terms
  • Phenotype- organisms expressed traits Ex. Brown
    coat
  • Genotype An organisms genetic makeup the
    combination of alleles in the homologous
    chromosomes. Ex. - BB, Bb, bb
  • Homozygous having identical alleles for the
    trait Ex. WW, ww
  • Heterozygous having two different alleles for
    the trait- Ex.Ww.

6
Definitions
  • Dominant- an allele that determines the phenotype
    of heterozygote. (Ex. YY-yellow plant or Yy).
  • Recessive the allele that is masked by the
    dominant allele in heterozygotes
  • not observed in the phenotype unless homozygous
    recessive (yy-green plant).

7
Purpose of Punnet Square
  • Examines the probability of getting a particular
    phenotype based on combination of gametes
  • Trait resides on the homologous chromosomes
  • Each square in a monohybrid cross (i.e. one
    trait) represents 25 chance
  • Summarize result with genotypic ratio and
    phenotypic ratio

8
Practice Problem
  • Draw a Punnett square for the following cross
  • Tt X Tt
  • Give the genotypic and phenotypic ratio.

9
Practice Punnett Square Problem
  • A plant that is heterozygous for green (G) pods
    is crossed with a plant that has yellow (g) pods.
    Green pod is dominant and yellow pod is
    recessive. What are the probable genotypic and
    phenotypic ratios in the offspring from this
    cross? What is the probability that plant will
    produce yellow pods?

10
Paraphrase
Write down two genetic terms you learned today
Write the definitions of those terms in your own
words
PROPERTY OF PIMA COUNTY JTED, 2010
11
Human Traits
12
Detached Earlobes
13
Hitchhikers Thumb
14
Tongue Rolling
15
Dimples
16
Cleft Chin
17
Widows Peak
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