Genetics Heredity Genes DNA Chapter Introduction

How are traits passed from parents to offspring? Chapter Introduction

Genetics Why do we look like our parents? What are inherited from our parents? How are traits inherited from our parents? Lesson 1

Mendel and His Peas Why did Mendel perform cross-pollination experiments? What did Mendel conclude about inherited traits? How do dominant and recessive factors interact? Lesson 1 Reading Guide

Lesson 1 Reading Guide - Vocab Mendel and His Peas heredity genetics dominant trait recessive trait Lesson 1 Reading Guide - Vocab

What is Genetics? Genetics is the study of genes, genetic variation , and heredity in living organisms. Heredity is the passing of traits from parents to offspring. Gregor Mendel, known as the father of genetics, studied inheritance about 150 years ago. Genetics Genes Genetic variation Heredity Traits Inheritance Lesson 1

Mendel’s Experimental Methods Mendel studied genetics by doing selective breeding experiments with pea plants. First, Mendel used self-pollination to obtain purebred (true-breeding) plants. Then he used cross-pollination of purebreds to obtain hybrid plants. Self-pollination Purebred Cross-pollination Hybrid Lesson 1

Self-Pollination Lesson 1

Cross-Pollination Lesson 1

Mendel’s Experimental Methods (cont.) Why did Mendel perform cross-pollination experiments? Lesson 1

Mendel’s Results If we crossed purple flower and white flower purebred pea plants, what kind of hybrid plant will we get? Pink flowers? Purple flowers? White flowers? Lesson 1

First-Generation Crosses Lesson 1

Mendel’s Results (cont.) All the offspring are purple, there are no white offspring. The purple trait dominated the white trait. There are no pink flowers, so heredity is not blending. Lesson 1

Mendel’s Results (cont.) If we crossed the purple flower hybrids, what kind of 2nd generation hybrids will we get? All purple flower again? Lesson 1

Second-Generation (Hybrid) Crosses Lesson 1

Mendel’s Results (cont.) In the 2nd generation hybrids, about 75% are purple and 25% are white. This is called 3:1 ratio. Lesson 1

Mendel’s Results (cont.) Mendel recorded traits of offspring from many hybrid crosses. Lesson 1

Mendel’s Conclusions Mendel concluded that two factors contributed to inherited traits, one from each parent (the sperm and the egg). Lesson 1

Mendel’s Conclusions What did Mendel conclude about inherited traits? Lesson 1

Mendel’s Conclusions (cont.) Besides two factors, he also concluded that there are two kinds of traits. A dominant trait is a genetic factor that blocks another genetic factor. A recessive trait is a genetic factor that is blocked by the presence of a dominant factor. Lesson 1

Mendel’s Conclusions (cont.) How do dominant and recessive factors interact? Lesson 1

Genetics is the study of how traits are passed from parents to offspring. Mendel studied genetics by doing cross-breeding experiments with pea plants. Lesson 1

Mendel’s experiments with pea plants showed that some traits are dominant and others are recessive. Lesson 1

What method did Mendel use to select which plants pollinated other plants? A. true breeding B. self-pollination C. cross-pollination D. bees Lesson 1

How many dominant factors does a purple-flowering pea plant have? B. 1 C. 2 D. 1 or 2 Lesson 1

What is the approximate ratio of dominant to recessive expression when both parents are hybrid? Lesson 1