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Chapter 4: Heredity Section1- Genetics. Life Science Lesson Plan. Inheriting Traits. Create a short list of characteristics about yourself…. Heredity. Heredity is the passing of traits from parents to offspring .

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inheriting traits
Inheriting Traits
  • Create a short list of characteristics about yourself…
  • Heredityis the passing of traits from parents to offspring.
  • Inherited Traits- Traits that are passed from parents to their offspring (through fertilization)
genes are passed down but what are genes
Genes are passed down… but what are genes?
  • Genes - Sections of DNA on a chromosome.
  • Genes on chromosomes control the traits that show up in an organism.
    • There are hundreds of genes on a chromosome
Alleles are different forms of a trait that a gene may contain.
    • There are TWO alleles for every trait
  • Example: Height
    • 1 allele is tall (T)
    • 1 allele is short (t)
  • Genetics- the study of inherited traits.
  • Gregor Mendel-The Father of Genetics “The Man”
mendel s experiment
Mendel’s Experiment
  • Mendel studied the traits of Pea Plants
    • Look Page 105
  • Crossed 2 Plants with different expressions of the trait
    • Example- Tall (T)& Short (t)
    • Round (R) & Wrinkled (r)
mendel s experiment1
Mendel’s Experiment
  • When the plants were crossed he discovered that the new plant formed looked like one of the two parents.
  • Take a look…

Mendel’s Tall vs. Short Plants

Mendel used pollen from both Tall and Short Plants to pollinate by hand the flowers.
  • Cross-Pollination- the pollination of two different plants together
hybrid vs purebred
Hybrid vs. Purebred
  • 3.Purebreds- offspring that receives two of the same alleles for a trait (TT or tt)
hybrid vs purebred1
Hybrid vs. Purebred
  • 4. Hybrids- offspring that receives two different alleles for a trait (Tt)
check out these websites
Check out these websites!
2 types of alleles
2 Types of Alleles

a. Dominantallele- covers up or dominates the other trait.

Represented by a CAPITAL

b. Recessive allele- the trait seems to disappear

Represented by a lower case

homozygous vs heterozygous
Homozygous vs. Heterozygous
  • Homozygous – an organism with 2 alleles for one trait that are the same (written TT)


  • Heterozygous – an organism with 2 alleles for one trait that are different (written Tt)
phenotype vs genotype
Phenotype vs. Genotype
  • Genotype-the genetic-makeup of an organism (types of letters used)
phenotype vs genotype1
Phenotype vs. Genotype
  • Phenotype- the way an organism physically looks/behaves as a result of its genotype.
  • Types of Words used: Tall, Short, Blonde, Brown, etc.
the use of punnett squares
The Use of Punnett Squares
  • A Punnett Square can help you predict what an offspring will look like.
  • For example, Male and Female Chromosomes
  • If you crossed Purebred Red four- o’clock plants with Purebred White four-o’clock plants, what would the offspring look like?
Incomplete Dominance-when two homozygous parents combine, the offspring results in a mixed (or blended) phenotype
  • Remember the chickens?!?!
When neither allele for a trait is Dominant.
  • The phenotype produced is a blending between the two homozygous parents.
    • The combining of Purebred Red & Purebred White produced PINK plants.
Although Mendel studied peas that were controlled by two alleles, many traits can be controlled by more than two alleles…
multiple alleles
Multiple Alleles
  • A trait that is controlled by Having more than two alleles is controlled by Multiple Alleles.
  • Traits controlled by Multiple Alleles produce more than threephenotypes of that trait.
example of multiple alleles
Example of Multiple Alleles…
  • Blood Types: A, B, AB, and O.
    • The O allele is recessive to both A and B
other worksheet
Other Worksheet…
  • Phenotype A - AA or Ao Genotype
  • Phenotype B – BB or Bo Genotype
  • Phenotype AB – AB
  • Phenotype O – oo Genotype
polygenic inheritance
Polygenic Inheritance
  • Polygenic Inheritance- when a group of gene pairs acts together to produce one trait.
    • Which creates more variety in phenotypes
What would be an example?
  • Many traits such as…Eye Color, Hair Color, Skin tone, & Handspan are traits produced by a combination of genes.
human genes mutations
Human Genes & Mutations
  • What are Mutations?!?!?
  • Mutations - a permanent change in the DNA sequence
  • A mutation can be harmful, beneficial, or cause no effect.
chromosome disorder
Chromosome Disorder
  • Chromosome disorders- caused by more or fewer chromosomes than normal
    • Downs Syndrome- caused by an extra chromosome (trisomy) at Chromosome 21
recessive genetic disorders
Recessive Genetic Disorders
  • Recessive Genetic Disorders are disorders passed through the Recessive alleles.
  • Both parents contain the recessiveallele (containing the disorder) that comes together in the offspring.
When both parents are Heterozygous, they do not show any symptoms
    • (Called “carriers” for the trait.)
  • Example- Cystic Fibrosis is a homozygous recessive disorder.
sex linked disorders
Sex-Linked Disorders
  • An allele inherited on a sex chromosomes ( X or Y ) is called a sex-linked gene.
  • Inherited conditions are linked with the X and Y chromosomes.
section 3
Section 3
  • Advances in Genetics

A. Genetic Engineering- experimentations that changes the arrangement of DNA that makes up a gene.

  • Recombinant DNA
  • Inserting a useful section of DNA into a bacteria
  • Example- Creating Insulin (Page 143)
Gene Therapy-
  • When a “normal allele” is placed into a virus, the virus then delivers the normal allele when it infects a specific cell. (Figure 13 Page 144)
  • May be used to control Cystic Fibrosis and other disorders.
Genetically Engineering Plants-
  • Plants are created by genetically inserting the desired genes of one plant into another plant you want to show those genes.
  • Also genetically engineered: ANIMALS
      • “Cloning”
works cited
Works Cited