Table of Contents. Chapter Preview. 5.1 Mendel s Work. 5.2 Probability and Heredity. 5.3 The Cell and Inheritance. 5.4 Genes, DNA, and Proteins

Transcription

1 Table of Contents Chapter Preview 5.1 Mendel s Work 5.2 Probability and Heredity 5.3 The Cell and Inheritance 5.4 Genes, DNA, and Proteins

2 Chapter 5 Preview Questions 1. What carries the instructions that cells need to carry out all the functions of life? a. amino acids b. enzymes c. nucleic acids d. proteins

3 Chapter 5 Preview Questions 1. What carries the instructions that cells need to carry out all the functions of life? a. amino acids b. enzymes c. nucleic acids d. proteins

4 Chapter 5 Preview Questions 2. Which of the following elements can be found in nucleic acids? a. carbon b. oxygen and hydrogen c. nitrogen and phosphorus d. all of the above

5 Chapter 5 Preview Questions 2. Which of the following elements can be found in nucleic acids? a. carbon b. oxygen and hydrogen c. nitrogen and phosphorus d. all of the above

6 Chapter Preview Questions 3. Which kind of nucleic acid carries information about an organism? a. RNA b. cytoplasm c. protein d. DNA

7 Chapter Preview Questions 3. Which kind of nucleic acid carries information about an organism? a. RNA b. cytoplasm c. protein d. DNA

8 Chapter Preview Questions 4. Where is most DNA found? a. in the chromatin in the nucleus of a cell b. in the cytoplasm of a cell c. in proteins d. in amino acids

9 Chapter 5 Preview Questions 4. Where is most DNA found? a. in the chromatin in the nucleus of a cell b. in the cytoplasm of a cell c. in proteins d. in amino acids This image shows the double walled nuclear envelope and rough endoplasmic reticulum with ribosomes. The chromatin inside the nucleus consists of the chromosomes, which are comprised of DNA and associated proteins.

10 How are traits passed from parents to offspring? In a litter of puppies, some of the puppies have a black and white coat, and others have a red and white coat. What can you infer about how their parents look? What can you infer about the parents DNA?

11 Use Suffixes Suffix Meaning of Suffix Example and Meaning of Example -ance, -ence state of; quality of importance State of being important

12 Use Suffixes Suffix Meaning of Suffix Example and Meaning of Example -ant, -ent inclined to; likely to dependent Likely to rely on something or someone else

13 Use Suffixes Suffix Meaning of Suffix Example and Meaning of Example -ity state of; quality of simplicity State of being simple or easy

14 Use Suffixes Suffix Meaning of Suffix Example and Meaning of Example -tion process of; state of production Process of making

15 Apply It! 1. What is the suffix in the word dominant? If the verb dominate means to have control over, what do you think dominant means? What does dominance probably mean? ant, likely to have control over, the state of having control over 2. The word probable means likely to happen. What does probability mean? the state of something that is likely to happen

16 Section 5.1: Mendel s Work What were the results of Mendel s experiments, or crosses? What controls the inheritance of traits in organisms?

17 GENETICS GENETICS =THE STUDY OF HEREDITY AND HOW TRAITS GET PASSED ALONG TO OFFSPRING FROM PARENTS. GENES= UNITS OF HEREDITY FOUND IN EVERY CELL ON THE CHROMOSOMES. GENES PROVIDE OUR TRAITS. TRAIT: A CHARACTERISTIC DENOTED BY LETTERS CAN BE DOMINANT (STRONG) T T OR RECESSIVE (WEAK) t t

18 PUREBRED ORGANISMS = ALSO SAID TO BE HOMOZYGOUS THEY HAVE THE SAME ALLELES FOR A GENE (TT OR tt ) HYBRID ORGANISMS = ALSO SAID TO BE HETEROZYGOUS THEY HAVE ALLELES THAT ARE DIFFERENT (Tt) GENOTYPE = YOUR GENES (tt, TT, Tt) PHENOTYPE= WHAT YOU LOOK LIKE

19 Gregor Johann Mendel GENETICS =THE STUDY OF HEREDITY AND HOW TRAITS GET PASSED ALONG TO OFFSPRING FROM PARENTS. GREGOR MENDEL:( ) AN AUSTRIAN MONK HIGH SCHOOL TEACHER. WORKED WITH PEA PLANTS FATHER OF GENETICS (1851)

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21 Crossing Pea Plants Gregor Mendel crossed pea plants that had different traits. The illustrations show how he did this.

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23 Mendel s Experiments In all of Mendel s crosses, only one form of the trait appeared in the F 1 generation. However, in the F 2 generation, the lost form of the trait always reappeared in about one fourth of the plants.

24 Dominant and Recessive Alleles Mendel studied several traits in pea plants.

25 End of Section: Mendel s Work

26 Section 5.2: Probability and Heredity What is probability and how does it help explain the results of genetic crosses? What is meant by genotype and phenotype? What is codominance?

27 Probability and Genetics Probability = the chance that an event will occur. The result of one event does not effect the chance of the next event. Punnett Squares= show possible combinations of crosses between organisms. Invented by Reginald C. Punnet, an English geneticist

28 Percentages One way you can express a probability is as a percentage. A percentage (%) is a number compared to 100. For example, 50% means 50 out of 100. Suppose that 3 out of 5 tossed coins landed with heads up. Here s how you can calculate what percent of the coins landed with heads up. 1. Write the comparison as a fraction. 3 out of 5 = 3/5 2. Multiply the fraction by 100% to express it as a percentage. 3/5 x 100%/1 = 60%

29 Percentages Practice Problem Suppose 3 out of 12 coins landed with tails up. How can you express this as a percent? 25%

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31 A Punnett Square The diagrams show how to make a Punnett square. In this cross, both parents are heterozygous for the trait of seed shape. R represents the dominant round allele, and r represents the recessive wrinkled allele.

32 Probability and Genetics In a genetic cross, the allele that each parent will pass on to its offspring is based on probability.

33 INCOMPLETE DOMINANCE Incomplete Dominance = when neither gene in a gene pair mask each other s Karl Correns discovered incomplete dominance in four o clock flowers.

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36 What Are the Genotypes? Mendel allowed several F 1 pea plants with yellow seeds to selfpollinate. The graph shows the approximate numbers of the F 2 offspring with yellow seeds and with green seeds.

37 What Are the Genotypes? Reading Graphs: How many F 2 offspring had yellow seeds? How many had green seeds? Yellow 6,000; green 2,000

38 What Are the Genotypes? Calculating: Use the information in the graph to calculate the total number of offspring that resulted from this cross. Then calculate the percentage of the offspring with yellow peas, and the percentage with green peas. 8,000; 75% have yellow peas and 25% have green peas.

39 What Are the Genotypes? Inferring: Use the answers to Question 2 to infer the probable genotypes of the parent plants. (Hint: Construct Punnett squares with the possible genotypes of the parents.) Both parents probably had the genotype Bb.

40 Section 5.3: The Cell and Inheritance What role do chromosomes play in inheritance? What events occur during meiosis? What is the relationship between chromosomes and genes?

41 THE CELL & INHERITANCE WALTER SUTTON (1903) DISCOVERED CHROMOSOMES IN SEX CELLS WERE HALF THE NUMBER OF CHROMOSOMES FOUND IN BODY CELLS. CHROMOSOMES :CARRY GENES ON THEM THAT ARE RESPONSIBLE FOR AN ORGANISMS TRAITS. MEIOSIS : THE PROCESS IN CELL DIVISION WHERE SEX CELLS END UP WITH HALF OF THE NUMBER OF CHROMOSOMES THAT ARE FOUND IN REGULAR BODY CELLS.

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43 Meiosis During meiosis, the chromosome pairs separate and are distributed to two different cells. The resulting sex cells have only half as many chromosomes as the other cells in the organism.

44 Punnett Square A Punnett square is actually a way to show the events that occur at meiosis.

45 A Lineup of Genes Chromosomes are made up of many genes joined together like beads on a string. The chromosomes in a pair may have different alleles for some genes and the same allele for others. CHROMOSOMES: IN HUMANS = 46 (23 PAIR) IN DOGS = 78 (39 PAIR) SILK WORM = 56 (28 PAIR)

46 Section 5.4: Genes, DNA, and Proteins What forms the genetic code? How does a cell produce proteins? How can mutations affect an organism?

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48 GENES: CONTROL THE PRODUCTION OF PROTEINS PRODUCE TRAITS. CHROMOSOMES : CARRY THE GENES ARE MADE OUT OF DNA THE ORDER OF NITROGEN BASES: IN A DNA MOLECULE DETERMINE WHAT PROTEINS WILL BE PRODUCED JUST AS THE ORDER OF LETTERS WILL DETERMINE DIFFERENT WORDS. THE NITROGEN BASES ARE: ADENINE (A), THYMINE (T), CYTOSINE (C), & GUANINE (G)

49 The DNA Code Chromosomes are made of DNA. Each chromosome contains thousands of genes. The sequence of bases in a gene forms a code that tells the cell what protein to produce.

50 PROTEIN SYNTHESIS THE DNA MOLECULE UNZIPS INSIDE THE NUCLEUS. MESSENGER RNA ENTERS THE NUCLEUS AND COPIES HALF OF THE OPENED DNA STRAND. INSTEAD OF THYMINE, MESSENGER RNA MAKES URACIL. MESSENGER RNA THEN LEAVES THE NUCLEUS AND GOES TO A RIBOSOME IN THE CYTOPLASM. THE RIBOSOME READS THE MESSENGER RNA AND BEGINS TO MAKE AMINO ACIDS OUT OF EVERY THREE BASE PAIRS. TRANSFER RNA BRINGS AMINO ACIDS TO THE GROWING PROTEIN ON THE RIBOSOME.

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52 How Cells Make Proteins During protein synthesis, the cell uses information from a gene on a chromosome to produce a specific protein.

53 Mutations Mutations can cause a cell to produce an incorrect protein during protein synthesis. As a result, the organism s trait, or phenotype, may be different from what it normally would have been.