Chapter 3 HEREDITY

1. Chapter 3HEREDITY

2. Section 1 heredity: the passing on of traits from parents to offspring

3. Gregor Mendel * born 1822 in Austria * grew up on a farm & learned lots about flowers and fruit trees * at age 21 entered a monastery – received training to be a teacher, but couldn’t pass final exams – so he focused on research = discovered the principles of heredity in the monastery garden

4. Pea Plants • grow quickly • many different kinds available • able to self-pollinate = has both male & female reproductive structures

5. true-breeding plant = self pollinates; all of its offspring will have the same traits as the parent

7. Cross pollination = pollen from one plant fertilizes the ovule of a flower on a different plant • insects can carry • carried by wind

9. characteristic = a feature that has different forms in a population trait= a specific characteristic like color

11. first generation = the first set of offspring/children of parents with different traits (1 purple & 1 white) dominant trait = the trait observed in the first generation when parents that have different traits are bred

12. second generation = the second set of offspring 2 of first generation are bred together recessive traits = a trait that reappears a in the generation after disappearing in the first generation when parents with different traits are bred

14. Gregor Mendel published his findings in 1865 It was 30 years after he died that his ideas were finally understood and recognized widely = opened the door to modern genetics. * biological warfare * cloning * genetically altered food & babies Nova genetics clip

15. Section 2 Mendel knew there must be 2 sets of instructions for each characteristic. First generation (F1) plants carried instruction for both dominant and recessive traits. gene = one set of instructions for an inherited trait Each parent gives one set of genes to the offspring.

16. Offspring has 2 forms of the same gene for every characteristic – one from each parent. alleles = different forms of a gene (hair color) dominant alleles are shown with a CAPTIAL LETTER recessive alleles are shown with a lower case letter

17. An organism’s appearance is known as phenotype (what you see) Phenotypes of humans are much more complicated than that of peas. Albinism – an inherited disorder affects a person’s phenotype in many ways

18. Both inherited traits together form an organism’s genotype(only the dominant trait will be seen, but the organism can carry a recessive trait). homozygous= 2 dominant or 2 recessive traits (DD or dd) heterozygous= 1 dominant and 1 recessive trait (Dd) AA and aa are homozygous Aa is heterozygous

19. A Punnett square is used to organize all the possible combinations of offspring from particular parents.

20. The mathematic chance that something will happen is known as probability– usually written as a fraction or percentage. What is the probability of yellow pea pods? ___ What is the probability of green pea pods? ____ Probability of purple flowers? ____ Probability of white flowers? ____

21. incomplete dominance = when one trait is not completely dominant over another = a blend. (red + white = pink) The traits do not blend together, each allele has its own degree of influence.

22. Co-dominance = when both alleles are expressed independently and are uniquely recognizable – both are apparent in the offspring • Tyoe A blood - mom • Tyoe B blood – dad • Type AB blood - child

23. Some traits, such as the color of your skin, hair and eyes, are the result of several genes acting together. Therefore, it’s difficult to tell if some traits are the result of a dominant or recessive gene. Different combinations of alleles result in different eye-color shades.

24. Genes aren’t the only influence on traits… environment plays an important role. * Hair can be cut. * Eating healthy makes it possible for you to grow taller and stronger.

25. SECTION 3 • There are 2 kinds of reproduction: asexual and sexual. Asexual reproduction results in offspring with genotypes that are exact copies of their parent’s genotype. Sexual reproduction produces offspring that share traits with their parents but are not exactly like either parent.

26. Sexual reproduction * 2 parent cells (sex cells – egg & sperm) join together Chromosomes: carry the sequences of genes

27. Sex cells are made during meiosis. Meiosis = a process in cell division where the number of chromosomes decreases by half – resulting in sex cells Example = human cells have 46 chromosomes each human egg and sperm cells contain 23 chromosomes

28. Sex chromosomes = carry genesthat determine the sex of an individual In humans females = XX males = XY

29. Sex Linked Disorders Y chromosome doesn’t carry all of the genes of an X chromosome. Females have 2 X chromosomes and have 2 copies of each gene available if 1 becomes damaged. Males have only 1 copy of each gene on their 1 X chromosome. The genes for certain disorders like colorblindness are carried on the X chromosome. Because the gene for such disorders is recessive, men are more likely to have sex-linked disorders.

30. Color Blind Test

31. Hemophilia is another sex-linked disorder. Hemophilia prevents blood from clotting.

32. Genetic counselors often make use of a diagram known as a pedigreeto trace a family tree for genetic disorders. A pedigree can often predict whether a person is a carrier of a hereditary disease.

34. For thousands of years humans have seen the benefits of the careful breeding of plants & animals. In selective breeding organisms with desirable characteristics are mated. eggs – chickens bred to produce more turkeys for Thanksgiving dogs & race horses roses