DNA and Genetics

The Father of Genetics Gregor Mendel, known as the "father of modern genetics," was born in Austria in 1822. A monk, Mendel discovered the basic principles of heredity through experiments in his monastery's garden. His experiments showed that the inheritance of certain traits in pea plants follows particular patterns, subsequently becoming the foundation of modern genetics and leading to the study of heredity.

What is a Trait? A trait is a specific characteristic that varies from one individual to another. Examples: Brown hair, blue eyes, tall, curly

What is an Allele? Alleles are the different possibilities for a given trait. Every trait has at least two alleles (one from the mother and one from the father) Example: Eye color – Brown, blue, green, hazel Examples of Alleles: A = Brown Eyes a = Blue Eyes B = Green Eyes b = Hazel Eyes

What are Genes? Genes are the sequence of DNA that codes for a protein and thus determines a trait.

What is DNA? DNA deoxyribonucleic acid, present in nearly all living organisms. It is the carrier of genetic information. A double helix (twisted ladder)

What are traits? Physical Traits Acquired Traits Behavioral Traits Can be seen by others Eye color, hair color, height, left handed Acquired Traits Learned skills Playing a sport, riding a bike, playing a musical instrument Behavioral Traits Instinctual actions Nest building and migration

Review Terms Used in Modern Genetics Genotype (Example TT, Tt, or tt) The particular alleles (genes) an individual carries They are inherited from your biological parents Genes control your traits Phenotype (Example Blue, Tall, or Long) An individual’s observable traits What people can SEE when they look at you

Review Terms Used in Modern Genetics An individual with non-identical alleles of a gene is heterozygous for that gene - Hybrid Examples: Bb, Tt, Aa An individual with identical alleles of a gene is homozygous for that gene - Purebred Examples: BB or bb, TT or tt

Terms Used in Modern Genetics An allele is dominant if its effect masks the effect of a recessive allele paired with it Capital letters, for example (A), signify dominant alleles; lowercase letters, for example (a), signify recessive alleles Homozygous dominant (AA) Homozygous recessive (aa) Heterozygous (Aa)

Dominant & Recessive Practice TT - Represent offspring with straight hair Tt - Represent offspring with straight hair tt - Represents offspring with curly hair T – straight hair t - curly hair

Before we go further lets review how to set up a Punnett Square… We begin by constructing a grid of two perpendicular lines.

B B b Next, put the genotype of one parent across the top and the other along the left side. For this example lets consider a genotype of BB crossed with bb. B B Notice only one letter goes above each box It does not matter which parent’s genotype goes on either side. b

Next, fill in the boxes by copying the column and row head-letters down and across into the empty spaces. B B b B b B b b B b B b

Selective Breeding Selective breeding is a process used to produce different breeds of animals or varieties of plants that have useful characteristics Using selective breeding you can produce a specific offspring with useful characteristics of both parents

Summary The key is to identify the feature you want, and only breed from the individuals that have that feature – it is achieved by… Select parents with the desired traits (things you want) Cross the parents (breed them) Select from the offspring Repeat (over many generations)… Selective breeding is used to: - Choose characteristics of the food item required Produce a more uniform crop (size / harvest time) Extend the tolerance range of an organism