7th Grade Cells and Heredity (Mod A) Unit 2 Lesson 4 - Heredity https://www.youtube.com/watch?v=FwJgR4ldD0s – Heredity intro – includes some vegetative reproduction, mitosis & meiosis, dominant & recessive, genetic engineering

Give Peas a Chance What is heredity? Unit 2 Lesson 4 Heredity Give Peas a Chance What is heredity? Traits, such as hair color, result from the information stored in genetic material. Heredity is the passing of genetic material from parents to offspring. Copyright © Houghton Mifflin Harcourt Publishing Company 2

What did Gregor Mendel discover about heredity? Unit 2 Lesson 4 Heredity What did Gregor Mendel discover about heredity? Gregor Mendel was an Austrian monk. In the 1800s, Mendel performed the first major experiments in heredity. Mendel studied seven characteristics of _____ _________. A characteristic is a feature that has different forms in a population. Copyright © Houghton Mifflin Harcourt Publishing Company 3

What did Gregor Mendel discover about heredity? Unit 2 Lesson 4 Heredity What did Gregor Mendel discover about heredity? The seven different characteristics Mendel studied were ______ _______, flower and pod ________, seed _______, seed _______, _____ shape, pod color, and ______ ________. Each characteristic had two different forms. These different forms are called _______. Copyright © Houghton Mifflin Harcourt Publishing Company 4

What did Gregor Mendel discover about heredity? Unit 2 Lesson 4 Heredity What did Gregor Mendel discover about heredity? Mendel studied each characteristic separately, always starting with plants that were ______ _________. True-breeding plants always produce offspring with the ______ trait if allowed to self-pollinate naturally. Copyright © Houghton Mifflin Harcourt Publishing Company 5

What did Gregor Mendel discover about heredity? Unit 2 Lesson 4 Heredity What did Gregor Mendel discover about heredity? Mendel crossed plants that were true-breeding for producing yellow seed pods with plants that were true-breeding for green seed pods. All of the plants from the first generation produced ______ seed pods. Mendel called the green seed pod the dominant trait, and the yellow seed pod the recessive trait. Copyright © Houghton Mifflin Harcourt Publishing Company 6

What did Gregor Mendel discover about heredity? Unit 2 Lesson 4 Heredity What did Gregor Mendel discover about heredity? Next, Mendel let the first generation plants ____ __________. Out of the generation that resulted, called the _________ ________, about three-fourths had green seed pods and one-fourth had yellow pods. Copyright © Houghton Mifflin Harcourt Publishing Company 7

What did Gregor Mendel discover about heredity? Unit 2 Lesson 4 Heredity What did Gregor Mendel discover about heredity? The _________ trait had seemed to disappear in the first generation, but it _________ in the second generation. Copyright © Houghton Mifflin Harcourt Publishing Company 8

What did Gregor Mendel discover about heredity? Unit 2 Lesson 4 Heredity What did Gregor Mendel discover about heredity? Mendel hypothesized that each plant must have two heritable “factors” for each trait, one from each _________. Some traits, such as yellow color, could only be observed if a plant had _____ of the same factors. A plant with two different factors would show the __________ factor but be able to pass on _____ factors to its offspring. Copyright © Houghton Mifflin Harcourt Publishing Company 9

It’s in Your Genes! How are traits inherited? Unit 2 Lesson 4 Heredity It’s in Your Genes! How are traits inherited? Mendel’s ideas can be further explained by our modern understanding of _______. What Mendel called “factors” are actually segments of DNA known as _____. Copyright © Houghton Mifflin Harcourt Publishing Company 10

How are traits inherited? Unit 2 Lesson 4 Heredity How are traits inherited? Genes are segments of DNA. They give instructions for producing a certain characteristic. Copyright © Houghton Mifflin Harcourt Publishing Company 11

How are traits inherited? Unit 2 Lesson 4 Heredity How are traits inherited? The offspring has ___ versions of the same gene for every characteristic—one from each parent. Different versions of a gene are known as alleles. Dominant alleles are shown with a ______ letter, and recessive alleles are shown with a lowercase version of the same letter. Copyright © Houghton Mifflin Harcourt Publishing Company 12

How are traits inherited? Unit 2 Lesson 4 Heredity How are traits inherited? An organism with one _________ and one ___________ allele for a gene is heterozygous for that _______. An organism with two of the same alleles for a gene is homozygous for that gene. Copyright © Houghton Mifflin Harcourt Publishing Company 13

How are traits inherited? Unit 2 Lesson 4 Heredity How are traits inherited? The _____________ of alleles that you inherited from your _________ is your genotype. Your observable traits make up your _________. The phenotypes of some traits follow patterns similar to the ones Mendel discovered. Copyright © Houghton Mifflin Harcourt Publishing Company 14

How are traits inherited? Unit 2 Lesson 4 Heredity How are traits inherited? The dominant allele contributes to the phenotype if _____ or ______copies are present in the genotype. The recessive allele contributes to the phenotype only when _____ copies of it are present. Copyright © Houghton Mifflin Harcourt Publishing Company 15

How are traits inherited? Unit 2 Lesson 4 Heredity How are traits inherited? If one chromosome in the pair contains a dominant allele and the other contains a recessive allele, the dominant allele determines the _____________. This is called __________ dominance. Copyright © Houghton Mifflin Harcourt Publishing Company 16

How are traits inherited? Unit 2 Lesson 4 Heredity How are traits inherited? Some characteristics are a result of several genes ________ _________. Sometimes, ____ gene influences more than one trait. For example, many genetic disorders, such as sickle cell anemia, are linked to a single gene but affect many _______. Copyright © Houghton Mifflin Harcourt Publishing Company 17

How are traits inherited? Unit 2 Lesson 4 Heredity How are traits inherited? Sometimes, the ____________ can influence an organism’s phenotype. Some traits are acquired only from one’s environment and are not inherited. For example, your ability to _______ and ______is an acquired trait. Copyright © Houghton Mifflin Harcourt Publishing Company 18

Bending the Rules What are the exceptions to complete dominance? Unit 2 Lesson 4 Heredity Bending the Rules What are the exceptions to complete dominance? Some traits do not follow the pattern of _________ ___________. For traits that show incomplete dominance and codominance, one trait is not completely dominant over another. Copyright © Houghton Mifflin Harcourt Publishing Company 19

What are the exceptions to complete dominance? Unit 2 Lesson 4 Heredity What are the exceptions to complete dominance? In incomplete dominance, each allele in a heterozygous individual influences the phenotype. The result of incomplete dominance is a phenotype that is a blend of the phenotypes of the parents. An example of this in humans is hair. A person with one allele for straight hair and one allele for curly hair will have wavy hair. Copyright © Houghton Mifflin Harcourt Publishing Company 20

What are the exceptions to complete dominance? Unit 2 Lesson 4 Heredity What are the exceptions to complete dominance? For a trait that shows codominance, both of the alleles in a _____________ individual contribute to the ______________. Heterozygous individuals have _____ of the traits associated with their two alleles. Copyright © Houghton Mifflin Harcourt Publishing Company 21

What are the exceptions to complete dominance? Unit 2 Lesson 4 Heredity What are the exceptions to complete dominance? ____________ __________ __________is an example of codominance. Three alleles, called A, B, and O, play a role in determining blood type. A person with an A allele and a B allele has type AB blood. Copyright © Houghton Mifflin Harcourt Publishing Company 22