Heredity Unit 5, Lesson 4

What is Heredity? HEREDITY is the passing of physical characteristics from parents to offspring Brain Pop: Heredity (2:28) Brain Pop: Heredity

MENDEL’S DISCOVERY Mendel worked with Pea Plants He discovered that a characteristic is a feature that has different forms in a population (seed color, flower position…) The different forms are called Traits (green, yellow, flower low, flower high…)

Checkpoint…. Characteristic Is flower color a characteristic or a trait? Characteristic

To review…. Plant pollination… How to plants reproduce They can reproduce asexually and sexually Fruits and seeds are produced via sexually In sexual reproduction, they have gametes (sex cells) and rely on animals/insects (bee/butterfly) or wind to pollinate them /transfer the gametes

Process…

Traits depend on inherited Factors Mendel took 2 sets of plants and pollinated them to look at the outcome…. True breeding= always produces the same outcome EX: green crossed with green always gives green

What he found…. each plant has 2 heritable ‘factors’ for each trait- one from each parent Which pod color is recessive? Yellow

DOMINANT AND RECESSIVE ALLELES Individual factors, or sets of genetic information control the inheritance of TRAITS The factors that control each trait exist in PAIRS One factor comes from FEMALE parent and one factor comes from the MALE parent One factor is dominant and the other factor is recessive

How are traits inherited? Genes are passed form parents to offspring GENES are segments of DNA found in the chromosomes and give instructions for producing characteristics. ALLELES are the different versions of a gene

A dominant gene is represented by an uppercase letter and a recessive gene is represented by a lowercase letter If BOTH letters are uppercase OR if BOTH letters are lowercase, then the gene is HOMOZYGOUS If the letters are mixed (one lowercase and one uppercase) the gene is HETEROZYGOUS

Complete dominance

Genes influence Traits Genotype Combination of alleles you inherited from your parents Phenotype OBSERVABLE traits

Influences Many genes can influence a single trait (eye color, skin color, hair color) The environment can influence traits (artic fox has a gene that determines fur color, but the light effects the gene causing the fur color to change) A single trait can influence many traits (a tigers single gene effects his fur color AND eye color)

Incomplete and Complete Dominance Incomplete dominance The alleles of a gene have an influence on the trait They BLEND Snapdragon flower color Codominance The alleles of a gene have an contribute to the trait They work TOGETHER EX: Blood type

Checkpoint….

FYI…. * sex-linked characteristic