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Introduction to Heredity

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Introduction to Heredity. What is Heredity?. Heredity is the passing of traits from parents to offspring Genetics is the study of heredity. Gregor Mendel. Known as the “Father of Genetics ” Austrian Monk Born in 1822. Mendel’s Work.

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what is heredity
What is Heredity?
  • Heredity is the passing of traits from parents to offspring
  • Genetics is the study of heredity
gregor mendel
Gregor Mendel
  • Known as the

“Father of Genetics”

  • Austrian Monk
  • Born in 1822
mendel s work
Mendel’s Work
  • Experimented with “True Breeding” pea plants in his garden
  • True Breeding
    • Plants that produce identical offspring when allowed to self pollinate
    • AKA “Purebred”
  • Discovered how traits are passed from parent to offspring in sexual reproduction
what is a trait
What is a Trait?
  • A trait is a notable feature or quality in a person
traits inherited vs acquired
TraitsInherited vs. Acquired

Some traits can be both!

Skin Color

Received genes for skin color from both parents

Amount of time in the sun affects skin color

genes
Genes
  • A gene is a unit of heredity
  • Occupies a specific location on a chromosome
  • Codes for or determines a specific trait
    • Most traits are not coded for by just one gene
genes and chromosomes
Genes and Chromosomes
  • Genes are located on chromosomes
  • Chromosomes come in pairs
    • Each pair is called a homolog
  • On each homolog are sites where specific genes are located
alleles
Alleles
  • Alleles are various forms of the same gene.
  • Example 1:
    • Gene: Eye Color
    • Alleles: Brown, Blue, Hazel
  • Example 2:
    • Gene: Seed Color
    • Alleles: Green, white, yellow
mendel s work continued
Mendel’s Work, continued
  • Mendel also performed experiments with hybrid plants
    • Hybrids - Plants that were produced by parents with different traits
  • In these experiments, he discovered that traits are inherited by parents passing alleles to their offspring
mendel s conclusions principles of heredity
Mendel’s Conclusions(Principles of Heredity)
  • Individuals carry two alleles for each trait, but only pass down one to their offspring
  • One allele is dominant over another
heredity day 2
Heredity Day 2

Questions to ask yourself…..

+ How do alleles interact to produce traits?

+ How does my combination of traits make me unique?

+ How do my traits connect me to other people?

alleles determine traits
Alleles determine traits
  • An organism’s traits are controlled by the alleles it inherits from its parents
  • Mendel discovered that there are two types of alleles:
    • Dominant
    • Recessive
dominant alleles
Dominant Alleles
  • Dominant Allele: an allele whose trait is always shows up in the organism when the allele is present
    • Expressed if only one is present
    • Example: Brown Eye Color
recessive alleles
Recessive Alleles
  • Recessive Allele: an allele whose trait is hidden whenever the dominant one is present
    • Can only be expressed if two are present
    • Example: Blue Eye Color
alleles interact to produce traits
Alleles interact to produce traits

W

  • Each parent contributes ONE allele for a given trait
  • The combination of alleles from parents can result in varying traits in their offspring

Alleles for widows peak

chromosomes

w

genetic terminology
Genetic Terminology
  • Genotype: An organisms genetic makeup, or alleles an organism has for a trait is its genotype
    • Ww, Bb, bb, ww, etc
  • Phenotype: An organism’s physical appearance, or visible traits is its phenotype.
    • Widow’s peak, brown eyes, blue eyes, straight hairline, etc
genetic terminology1
Genetic Terminology
  • Terms used to describe an organisms genotype
    • Heterozygous – an organism that has two different alleles for a trait is said to be heterozygous
      • Example: Ww, Bb
    • Homozygous – An organism that has two identical alleles for a trait is said to be homozygous
      • Example: WW, ww, BB, bb
using genetic terminology
Using Genetic Terminology

Homozygous Recessive

Homozygous Dominant

Heterozygous

using genetic terminology1
Using Genetic Terminology

Homozygous Recessive

Homozygous Dominant

Heterozygous

using genetic terminology2
Using Genetic Terminology

Homozygous Recessive

Homozygous Dominant

Heterozygous

using genetic terminology3
Using Genetic Terminology

Homozygous Recessive

Homozygous Dominant

Heterozygous

using genetic terminology4
Using Genetic Terminology

Homozygous Recessive

Homozygous Dominant

Heterozygous

traits in a population
Traits in a population
  • Observable characteristics we inherit from our parents
  • Some traits are common in a population, while others are not
  • Every person has a different overall combination of traits that make them unique