Genetics & Heredity What is genetics? The scientific study of heredity

Predicting Inherited Characteristics Gregor Mendel Studied heredity using pea plants His work is the foundation of modern Genetics

 Born in 1822 in Czechoslovakia.  Became a monk at a monastery in  Taught biology and had interests in statistics.  Also studied at the University of Vienna

Mendel continued  After returning to the monastery he continued to teach and worked in the garden.  Between 1856 and 1863 he grew and tested over 28,000 pea plants

Peas were used because: 1. Many traits in peas exist in 2 forms *Tall or Short *Wrinkled or Non Wrinkled *Green or Yellow 2. Many offspring are produced in one generation. 3. They Self-Pollinate: this ensured pure breeding.

Mendel’s Conclusions: 1. Individual Factors (later known as genes) control inherited characteristics. 2. These factors are inherited from parents. 3. These Factors exist in pairs 4. One Factor can mask or hide another (known as dominance).

Gene A segment of a DNA molecule Contains information about a specific trait

Asexual reproduction One parent Parent divides to produce a copy of itself Offspring is genetically the same as parent

Sexual reproduction Two parents Offspring has genes from both parents Offspring is genetically DIFFERENT from parents

Alleles Different forms of a gene An organism gets one allele from each parent for a gene **It takes two alleles to make a complete gene for a trait**

Dominant allele This is the allele for a trait that always shows up in the organism Shown with a capital letter when working genetics problems DD – would be a pure form of this dominant trait Dd – would be a hybrid form of this dominant trait

Recessive allele Hidden when a dominant allele is present Only shows when offspring has two alleles for the recessive trait Shown with a lower case letter when working genetics problems dd – would be how this pure recessive trait is shown

Homozygous This means the trait is pure DD or dd The organism has two dominant or two recessive alleles for this trait

Heterozygous This means the trait is hybrid The organism has one dominant and one recessive allele for this trait Dd – is how this is shown ** the dominant trait will always show in this case **

Genotype This is the GENETIC makeup of a trait You can’t see the genotype

Phenotype This is the PHYSICAL EXPRESSION of a trait You CAN see the phenotype The dominant allele will ALWAYS show in a phenotype

Punnett Square r/view/assetGuid/7570E857-9BAE F-CF79EACA9201

Monohybrid Punnet Squares (Only one characteristic) Tall plant-TT or Tt Short plant- tt Mother plant-(Tt) heterozygous tall Father plant-(Tt) heterozygous tall Tt t T Example: Garden Pea Plant- height

Monohybrid Punnet Squares (Only one characteristic) Tt t T Example: Garden Pea Plant- height TTtTt TtTtt Mother plant- heterozygous tall Father plant- heterozygous tall Tall plant-TT or Tt Short plant- tt Match the letters: Red- across Blue- down

TTTtTt TtTttt Mother plant- heterozygous tall Father plant- heterozygous tall Tall plant-TT or Tt Short plant- tt The result is: 2 of the offspring will be heterozygous tall 1 Will be homozygous tall 1 Will be homozygous short Monohybrid Punnet Squares (Only one characteristic)

The sex of an animal is determined by chromosomes… Female – XX Male – XY What are the chances of an offspring being male? (hint – do the cross on a Punnett square)

Let’s try some more… Long fur (L) is dominant over short fur (l) in cats. Cross a heterozygous dominant male with a short furred female. Your cross should be between the male (Ll) with the female (ll)