1. Table of Contents Mendel’s Work Probability and Heredity
The Cell and Inheritance
The DNA Connection

2. Outlining - Mendel’s Work
As you read, make an outline about Mendel’s work. Use the red headings for the main ideas and the blue headings for the supporting ideas.
Mendel’s Experiments
Crossing Pea Plants
The F1 Offspring
The F2 Offspring
Experiments With Other Traits
Dominant and Recessive Alleles
Genes and Alleles
Alleles in Mendel’s Crosses
Symbols for Alleles
Significance of Mendel’s Contribution

3. Mendel’s Work
Introduction Pg. 218
Gregor Mendel experimented with hundreds of pea plants to understand the process of ______.
heredity
Heredity
C- is the passing of traits from parents to offspring
3. Genetics
A- is the scientific study of heredity.
Traits
B- are physical characteristics.

4. Crossing Pea Plants - Mendel’s Work
Gregor Mendel crossed pea plants that had different traits. The illustrations show how he did this.

5. Mendel’s Experiments - Mendel’s Work
In all of Mendel’s crosses, only one form of the trait appeared in the F1 generation. However, in the F2 generation, the “lost” form of the trait always reappeared in about one fourth of the plants.

6. Mendel’s Work
Mendel’s Experiments Pg
In a flower, the female sex cells, or eggs, are produced by the ____. Pollen, which contains the male sex cells, is produced by the _____.
pistil
stamens
What are purebred organisms?
They are the offspring of many generations that have the same trait.

7. Mendel’s Work Complete the flowchart:
Purebred tall plants are crossed with purebred ____plants.
short
F1 offspring are all ____.
tall
F1 offspring are allowed to self pollinate.
F2 offspring are ___and ____.
tall and short
Traits in garden peas that Mendel studied:
pod, color, seed shape, and flower position.

8. Dominant and Recessive Alleles
- Mendel’s Work
Dominant and Recessive Alleles
Mendel studied several traits in pea plants.

9. Mendel’s Work
Two forms of the trait of seed shape in pea plants are ___ and ____.
round and wrinkled
Dominate and Recessive Alleles Pg
Sentences that are true about alleles.
Alleles are different forms of a gene.
Dominant alleles always show up in the organism when the allele is present.
11. Only pea plants that have two recessive alleles for short stems will be short.
True

10. Mendel’s Work Purebred short C- two alleles for short stems
13. Purebred tall
A- two alleles for tall stems
14. Hybrid tall
B- one allele for tall stems and one allele for short stems
A dominant allele is represented by a(n) _____.
capital letter

11. Mendel’s Work A recessive allele is represented by a(n) _____.
lowercase letter
17. How would a geneticist write the alleles to show that a tall pea plant has one allele for tall stems and one allele for short stems? Tt
Some scientists during Mendel’s time thought Mendel should be called the Father of Genetics.
False

12. End of Section: Mendel’s Work

13. Building Vocabulary - Probability and Heredity
After you read the section, reread the paragraphs that contain definitions of Key Terms. Use all the information you have learned to write a definition of each Key Term in your own words.
Key Terms:
Examples:
homozygous
heterozygous
codominance
Key Terms:
Examples:
probability
An organisms that has two identical alleles for a trait is said to be homozygous.
Probability is a number that describes how likely it is that an event will occur.
Punnett square
An organisms that has two different alleles for a trait is heterozygous for that trait.
A Punnett square is a chart that shows all the possible combinations of alleles that can result from a genetic cross.
In codominance, the alleles are neither dominant nor recessive.
phenotype
An organism’s phenotype is its physical appearance, or visible traits.
genotype
An organism’s genotype is its genetic makeup, or allele combinations.

14. Probability and Heredity
Principles of Probability Pg
A number that describes how likely it is that an event will occur is called _____.
probability
Circle the following that equals the probability that a tossed coin will land heads up.
one in two
50 Percent
3. When you toss a coin 20 times, you will always get 10 heads and 10 tails.
False

15. Probability and Heredity
If you toss a coin five times and it lands heads up each time, can you expect the coin to land heads up on the sixth toss?
No, the results of the first five tosses do not affect the results of the sixth toss.
Probability and Genetics Pg
5. When Mendel crossed two hybrid plants for stem height (Tt), what results did he always get?
He always found that about three fourths of the plants had tall stems and one fourth of the plants had short stems.

16. Probability and Heredity
Mendel realized that the principles of probability could be used to _____ the results of genetic crosses.
predict
A chart that shows all the possible combinations of alleles that can result from a genetic cross is called a(n) _____.
Punnett Square
8. Work on your own using a combination of alleles Tt and Tt.

17. Probability and Heredity
Results of the cross Tt
T t T t TT Tt tt

18. A Punnett Square - Probability and Heredity
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.

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

20. Phenotypes and Genotypes
- Probability and Heredity
Phenotypes and Genotypes
An organism’s phenotype is its physical appearance, or visible traits, and an organism’s genotype is its genetic makeup, or allele combinations.

21. Probability and Heredity
Phenotypes and Genotypes Pg. 230
Phenotype
B- an organism’s physical appearance or visible traits
10. Genotype
C- an organism’s genetic makeup or allele combinations
11. Homozygous
A- describes an organism with two identical alleles for a trait

22. Probability and Heredity
Heterozygous
D- Describes an organism that has two different alleles for a trait
13. Mendel used the term ____ to describe heterozygous pea plants.
hybrid
Codominance Pg. 231
In codominance, the alleles are neither dominant nor recessive.
True

23. Probability and Heredity
In cattle, red hair and white hair are codominant. Cattle with both white hair and red hair are _____.
heterozygous

24. Codominance - Probability and Heredity
In codominance, the alleles are neither dominant nor recessive. As a result, both alleles are expressed in the offspring.

25. What Are the Genotypes? - Probability and Heredity
Mendel allowed several F1 pea plants with yellow seeds to self-pollinate. The graph shows the approximate numbers of the F2 offspring with yellow seeds and with green seeds.

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

27. Percentages - Probability and Heredity
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.
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%

28. What Are the Genotypes? - Probability and Heredity Reading Graphs:
How many F2 offspring had yellow seeds? How many had green seeds?
Yellow–6,000; green–2,000

29. What Are the Genotypes? - Probability and Heredity 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.

30. What Are the Genotypes? - Probability and Heredity 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.

31. End of Section: Probability and Heredity

32. Identifying Supporting Evidence
- The Cell and Inheritance
Identifying Supporting Evidence
As you read, identify the evidence that supports the hypothesis that genes are found on chromosomes. Write
the evidence in a graphic organizer.
Grasshoppers:
24 chromosomes in body cells, 12 in sex cells.
Chromosomes are important in inheritance.
Fertilized egg has 24 chromosomes.
Alleles exist in pairs in organisms.

33. The Cell and Inheritance
Chromosomes and Inheritance Pg. 235
Sentences that are true about what Sutton observed about chromosome number.
Grasshopper sex cells have half the number of chromosomes as body cells.
When grasshopper sex cells join, the fertilized egg has the
same number of chromosomes as the body cells of the
parents.
What is the chromosomes theory of inheritance?
Genes are carried from parents to their offspring on chromosomes.

34. Meiosis - The Cell and Inheritance
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.

35. The Cell and Inheritance
Meiosis Pg
What is Meiosis?
It is the process by which the number of chromosomes is reduced by half to form sex cells--sperm and eggs.
4. Complete the cycle diagram:
Parent cell has four chromosomes arranged in ____ pairs.
two
Chromosome pairs ______and are distributed to sex cells, Each sex cell has ____ chromosomes.
separate
Four

36. The Cell and Inheritance
The cycle continued:
Sex cells combine to produce offspring. Each offspring has ____ chromosomes, one pair from each parent.
two
5. A Punnett square is a shorthand way to show the events that occur during _____.
meiosis
6. During meiosis, the two alleles for each gene stay together.
False- separate

37. Punnett Square - The Cell and Inheritance
A Punnett square is actually a way to show the events that occur at meiosis.

38. The Cell and Inheritance
If the male parent cell is heterozygous for a trait, Tt, what alleles could the sperm cells possible have?
Half the sperm cells will have the T allele and the other half will have the t allele.
A Lineup of Genes Pg. 238
How many pairs of chromosomes do human body cells contain?
23 pairs of chromosomes
9. How are the genes lined up in a pair of chromosomes?
Genes are lined up in the same order on both chromosomes.

39. A Lineup of Genes - The Cell and Inheritance
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.

40. End of Section: The Cell and Inheritance

41. Sequencing - The DNA Connection
Sequence is the order in which the steps in a process occur. As you read, make a flowchart that shows protein synthesis. Put each step in the flowchart in the order in which it occurs.
Protein Synthesis
DNA provides code to form messenger RNA.
Messenger RNA attaches to ribosome.
Transfer RNA “reads” the messenger RNA.
Amino acids are added to the growing protein.

42. The DNA Connection
The Genetic Code Pg. 240
Sentences that are true about genes, chromosomes, and proteins.
Genes control the production of proteins in an organism’s cells.
Proteins help determine the size, shape, and other traits of an organism.
A DNA molecule is made up of four nitrogen bases:
a. Adenine (A)
Thymine (T)
Guanine (G)
Cytosine (C)

43. The DNA Connection What is the genetic code?
The genetic code is the order of nitrogen bases along a gene that specifies what type of protein will be produced.
One group of three nitrogen codes for one _____.
amino acid

44. The DNA Code - The DNA Connection
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.

45. How Cells Make Proteins
- The DNA Connection
How Cells Make Proteins
During protein synthesis, the cell uses information from a gene on a chromosome to produce a specific protein.

46. The DNA Connection
How cells Make Protein Pg
During protein synthesis, the cell uses information from a ____ on a chromosome to produce a specific _____.
gene
protein
Proteins are made on _____ in the cytoplasm of the cell.
ribosomes

47. The DNA Connection Complete the Venn Diagram: In DNA:
Thymine stays inside the nucleus.
In RNA:
Uracil goes out into the cytoplasm.
In both DNA and RNA:
Cytosine, adenine, and guanine.
8. List two kinds of RNA and tell their jobs.
a. Messenger RNA copies the coded message from the DNA in the nucleus and carries the message to the ribosomes in the cytoplasm.

48. The DNA Connection
b. Transfer RNA carries amino acids to the ribosome and adds them to the growing protein.
Circle the letter of the first step in the protein synthesis.
DNA “unzips” to direct the production of a strand of messenger RNA.
10. Circle the letter of the last step in protein synthesis.
The protein chain grows longer as each transfer RNA molecule adds an amino acid.

49. The DNA Connection 11. What is a mutation?
Mutations Pg
11. What is a mutation?
A mutation is any change in a gene or chromosome.
12. How can mutations affect protein synthesis in cells?
Mutations can cause a cell to produce an incorrect protein during protein synthesis.
13. Sentences that are true about mutations.
Some mutations occur when one nitrogen base is substituted for another.
Some mutations occur when chromosomes don’t separate correctly during meiosis.

50. The DNA Connection 14. Mutations can be a source of genetic _____.
variety
All mutations are harmful.
False
Mutation that are ____ improve an organism’s chances for survival and reproduction.
helpful
17. Whether a mutation is harmful or helpful depends partly on an organism’s _____.
environment

51. Mutations - The DNA Connection
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.

52. The DNA Connection Key Terms Meiosis Punnett Square Phenotype
Messenger RNA
Heterozygous
Probability
Dominant Allele
Trait
Gene
Genetics
Purebred

53. End of Section: The DNA Connection

54. Graphic Organizer RNA Messenger RNA Transfer RNA includes functions to
Copy the coded message from the DNA
Carry the message to the ribosome in the cytoplasm
Add amino acids to the growing protein
Carry amino acids

55. End of Section: Graphic Organizer