2. Sexual Reproduction and Genetics
Section 1: Meiosis
Section 2: Mendelian Genetics
Section 3: Gene Linkage and Polyploidy

3. Chromosomes and Chromosome Number
Section 1
Sexual Reproduction and Genetics
I. Meiosis (important characteristics)
Chromosomes and Chromosome Number
Sketch a chromosome
Human body cells have 46 chromosomes
Each parent contributes 23 chromosomes
Homologous chromosomes—one of two paired chromosomes, one from each parent
Use the prefix “homo” to help!

4. Chromosomes and Chromosome Number cont.
Section 1
Sexual Reproduction and Genetics
Meiosis
Chromosomes and Chromosome Number cont.
Same length
Same centromere position
Carry genes that control the same inherited traits

5. B. Haploid and Diploid Cells
Section 1
Sexual Reproduction and Genetics
Meiosis
B. Haploid and Diploid Cells
An organism produces gametes to maintain the same number of chromosomes from generation to generation. What would happen if you received all of both parents genetic info???
Human gametes contain 23 chromosomes.
What is a gamete? Specifically what are they in humans?

6. A cell with n chromosomes is called a haploid cell.
“halved”
A cell that contains 2n chromosomes is called a diploid cell. (complete set, all the cells in your body except gametes)

7. The sexual life cycle in animals involves meiosis.
Section 1
Sexual Reproduction and Genetics
Meiosis
II. Meiosis I
The sexual life cycle in animals involves meiosis.
Meiosis produces gametes.
When gametes
combine in fertilization, the number of
chromosomes is restored.

8. Section 1
Sexual Reproduction and Genetics
Meiosis
A. Stages of Meiosis I
Reduces the chromosome number by half through the separation of homologous chromosomes
Involves two consecutive cell divisions called meiosis I and meiosis II

9. Chromosomes replicate.
Section 1
Sexual Reproduction and Genetics
Meiosis
Meiosis I
1. Interphase
Prior to prophase
Chromosomes replicate.
Chromatin condenses.
Interphase

10. Pairing of homologous chromosomes occurs. ***
Section 1
Sexual Reproduction and Genetics
Meiosis
Meiosis I
2. Prophase I
Pairing of homologous chromosomes occurs. ***
Each chromosome consists of two chromatids.
Prophase I
The nuclear envelope breaks down.
Spindles form.

11. Meiosis I 2. Prophase I (cont.)
Section 1
Sexual Reproduction and Genetics
Meiosis
Meiosis I
2. Prophase I (cont.)
**Crossing over produces exchange of genetic information. Creates variety!
Crossing over—chromosomal segments are exchanged between a pair of homologous chromosomes.

12. Chromosome centromeres attach to spindle fibers.
Section 1
Sexual Reproduction and Genetics
Meiosis
Meiosis I
3. Metaphase I
Chromosome centromeres attach to spindle fibers.
Metaphase I
Homologous chromosomes line up at the equator.

13. Homologous chromosomes separate and move
Section 1
Sexual Reproduction and Genetics
Meiosis
Meiosis I
4. Anaphase I
Homologous chromosomes separate and move
to opposite poles of the cell.
**No longer paired
Anaphase I

14. The spindles break down.
Section 1
Sexual Reproduction and Genetics
Meiosis
Meiosis I
5. Telophase I
The spindles break down.
Telophase I
Chromosomes uncoil and form two nuclei.
The cell pinches in.

15. A second set of phases begins
Section 1
Sexual Reproduction and Genetics
Meiosis
B. Stages Meiosis II
1. Prophase II
A second set of phases begins
as the spindle apparatus forms and the
chromosomes condense.
*events are very similar to mitosis
Prophase II

16. A haploid number of chromosomes
Section 1
Sexual Reproduction and Genetics
Meiosis
Meiosis II
2. Metaphase II
A haploid number of chromosomes
line up at the equator.
Metaphase II

17. The sister chromatids are
Section 1
Sexual Reproduction and Genetics
Meiosis
Meiosis II
3. Anaphase II
The sister chromatids are
pulled apart at the centromere by spindle
fibers and move toward the opposite poles
of the cell.
Anaphase II

18. The chromosomes reach the poles, and
Section 1
Sexual Reproduction and Genetics
Meiosis
Meiosis II
4. Telophase II
The chromosomes reach the poles, and
the nuclear membrane and nuclei reform.
Telophase II

19. Section 1
Sexual Reproduction and Genetics
Meiosis
Meiosis II
C. Cytokinesis results in four haploid cells, each with n number of chromosomes.
Cytokinesis

20. III. The Importance of Meiosis
Section 1
Sexual Reproduction and Genetics
Meiosis
III. The Importance of Meiosis
Meiosis consists of two sets of divisions
Produces four haploid daughter cells that are not identical
**Results in genetic variation

21. Meiosis Provides Variation
Section 1
Sexual Reproduction and Genetics
Meiosis
Meiosis Provides Variation
Depending on how the chromosomes line up at the equator, four gametes with four different combinations of chromosomes can result.
Genetic variation also is produced during crossing over and during fertilization, when gametes randomly combine.

22. Sexual Reproduction v. Asexual Reproduction
Section 1
Sexual Reproduction and Genetics
Meiosis
Sexual Reproduction v. Asexual Reproduction
Asexual reproduction
The organism inherits all of its chromosomes from a single parent.
The new individual is genetically identical to its parent.
Sexual reproduction
Beneficial genes multiply faster over time.

23. Segments of DNA that control the production
Chapter
Sexual Reproduction and Genetics
Section 1 Formative Questions
Segments of DNA that control the production
of proteins are called _______.
chromatids
chromosomes
genes
traits A B C D
FQ 1

24. What is the term for a pair of chromosomes
Chapter
Sexual Reproduction and Genetics
Section 1 Formative Questions
What is the term for a pair of chromosomes
that have the same length, same centromere
position, and carry genes that control the same
traits?
diploid
heterozygous
homozygous
homologous A B C D
FQ 2

25. Chapter
Sexual Reproduction and Genetics
Section 1 Formative Questions
How does the number of chromosomes in gametes compare with the number of chromosomes in body cells?
Gametes have 1/4 the number of chromosomes.
Gametes have 1/2 the number of chromosomes.
Gametes have the same number of chromosomes.
Gametes have twice as many chromosomes. A B C D
FQ 3

26. What type of organisms only reproduce asexually?
Chapter
Sexual Reproduction and Genetics
Section 1 Formative Questions
What type of organisms only reproduce
asexually?
bacteria
protists
plants
simple animals A B C D
FQ 4

27. I. Mendel; How Genetics Began
Section 2
Sexual Reproduction and Genetics
Mendelian Genetics
I. Mendel; How Genetics Began
The passing of traits to the next generation is called inheritance, or heredity.
Mendel performed cross-pollination in pea plants. The “father of genetics”
Mendel followed various traits in the pea plants he bred.

28. A. The parent generation is also known as the P generation.
Section 2
Sexual Reproduction and Genetics
Mendelian Genetics
A. The parent generation is also known as the P generation.

29. Section 2
Sexual Reproduction and Genetics
Mendelian Genetics
B. The offspring of this P cross are called the first filial (F1) generation.
C. The second filial (F2) generation is the offspring from the F1 cross.

30. Section 2
Sexual Reproduction and Genetics

31. Mendel studied seven different traits.
Section 2
Sexual Reproduction and Genetics
Mendelian Genetics
Mendel studied seven different traits.
Seed or pea color
Flower color
Seed pod color
Seed shape or texture
Seed pod shape
Stem length
Flower position

32. II. Genes in Pairs (language of genetics)
Section 2
Sexual Reproduction and Genetics
Mendelian Genetics
II. Genes in Pairs (language of genetics)
A. Allele
An alternative form of a single gene passed from generation to generation (2 alleles for each trait)(expressed by using letters)
B. Dominant: masks recessive; capital letter
C. Recessive: shown only if both alleles are recessive; uses a lower case letter

33. Section 2
Sexual Reproduction and Genetics
Mendelian Genetics
Dominance
D. An organism with two of the same alleles for a particular trait is homozygous.
E. An organism with two different alleles for a particular trait is heterozygous.
Practice: AA, Aa, aa

34. Genotype and Phenotype
Section 2
Sexual Reproduction and Genetics
Mendelian Genetics
Genotype and Phenotype
F. An organism’s allele pairs are called its genotype.
G. The observable characteristic or outward expression of an allele pair is called the phenotype.

35. A. Mendel’s Law of Segregation
Section 2
Sexual Reproduction and Genetics
Mendelian Genetics
III. Mendel’s laws
A. Mendel’s Law of Segregation
Two alleles for each trait separate during meiosis.
During fertilization, two alleles for that trait unite.
Heterozygous organisms are called hybrids.

36. Section 2
Sexual Reproduction and Genetics
Mendelian Genetics
Monohybrid Cross
A cross that involves hybrids for a single trait is called a monohybrid cross.

37. Dihybrids are heterozygous for both traits.
Section 2
Sexual Reproduction and Genetics
Mendelian Genetics
Dihybrid Cross
The simultaneous inheritance of two or more traits in the same plant is a dihybrid cross.
Dihybrids are heterozygous for both traits.

38. B. Law of Independent Assortment
Section 2
Sexual Reproduction and Genetics
Mendelian Genetics
B. Law of Independent Assortment
Random distribution of alleles occurs during gamete formation
Genes on separate chromosomes sort independently during meiosis.
Each allele combination is equally likely to occur.

39. Predict the possible offspring of a cross between two known genotypes
Section 2
Sexual Reproduction and Genetics
Mendelian Genetics
IV. Punnett Squares
Predict the possible offspring of a cross between two known genotypes
Punnett Squares

40. Punnett Square—Dihybrid Cross
Section 2
Sexual Reproduction and Genetics
Mendelian Genetics
Punnett Square—Dihybrid Cross
Four types of alleles from the male gametes and four types of alleles from the female gametes can be produced.
The resulting phenotypic ratio is 9:3:3:1.

41. What is the name for different forms of a
Chapter
Sexual Reproduction and Genetics
Section 2 Formative Questions
What is the name for different forms of a
single gene that are passed from generation
to generation?
alleles
genotypes
phenotypes
traits A B C D
FQ 5

42. Which pair of alleles is heterozygous?
Chapter
Sexual Reproduction and Genetics
Section 2 Formative Questions
Which pair of alleles is heterozygous? RR Rr rr yR A B C D
FQ 6

43. In rabbits, gray fur (G) is dominant to black
Chapter
Sexual Reproduction and Genetics
Section 2 Formative Questions
In rabbits, gray fur (G) is dominant to black
fur (g). If a heterozygous male is crossed with
a heterozygous female, what is the phenotypic
ratio of the possible offspring?
1:1
1:2:1
2:1
3:1 A B C D
FQ 7

44. Section 3 I. Gene Linkage
Chromosomes contain genes that code for proteins.
Genes close together on a chromosome are “linked” and travel together
*Genes that are farther apart cross over more frequently than if closer together.

45. Genetic Recombination
Section 3
Sexual Reproduction and Genetics
Gene Linkage and Polyploidy
Genetic Recombination
The new combination of genes produced by crossing over and independent assortment
Combinations of genes due to independent assortment can be calculated using the formula 2n, where n is the number of chromosome pairs.

46. Gene Linkage and Polyploidy
Section 3
Sexual Reproduction and Genetics
Gene Linkage and Polyploidy
Gene Linkage
The linkage of genes on a chromosome results in an exception to Mendel’s law of independent assortment because linked genes usually do not segregate independently.

47. Section 3
Sexual Reproduction and Genetics
Gene Linkage and Polyploidy
II. Polyploidy
Polyploidy is the occurrence of one or more extra sets of all chromosomes in an organism. (rarely occurs in animals, in humans it is always lethal!)
A triploid organism, for instance, would be designated 3n, which means that it has three complete sets of chromosomes.

48. 1 in 3 species of flowering plants is polyploid.
Increases size and vigor
Ex: strawberries, oats, wheat, sugarcane

49. Which explains how the shuffling of genes
Chapter
Sexual Reproduction and Genetics
Section 3 Formative Questions
Which explains how the shuffling of genes
during meiosis results in billions of possible
combinations?
crossing over
gene linkage
genetic recombination
independent segregation A B C D
FQ 8

50. Two genes on the same chromosome may become separated during meiosis.
Chapter
Sexual Reproduction and Genetics
Section 3 Formative Questions
Two genes on the same chromosome may
become separated during meiosis.
true
false A B
FQ 9

51. What is the term for an organism that has one
Chapter
Sexual Reproduction and Genetics
Section 3 Formative Questions
What is the term for an organism that has one
or more sets of extra chromosomes in its cells?
diploid
gamete
hybrid
polyploid A B C D
FQ 10

52. Chapter Resource Menu Chapter Diagnostic Questions
Sexual Reproduction and Genetics
Chapter Resource Menu
Chapter Diagnostic Questions
Formative Test Questions
Chapter Assessment Questions
Standardized Test Practice
connected.mcgraw-hill.com
Glencoe Biology Transparencies
Image Bank
Vocabulary
Animation
Click on a hyperlink to view the corresponding feature.

53. Which symbol is used to represent the
Chapter
Sexual Reproduction and Genetics
Chapter Diagnostic Questions
Which symbol is used to represent the
number of chromosomes in a gamete? # x r n A B C D
CDQ 1

54. Name the person known as the father of genetics.
Chapter
Sexual Reproduction and Genetics
Chapter Diagnostic Questions
Name the person known as the father of
genetics.
Felix Mendelssohn
Gregor Mendel
Dr. Reginald Punnett
Albert Einstein A B C D
CDQ 2

55. Which term refers to the outward expression of an allele pair?
Chapter
Sexual Reproduction and Genetics
Chapter Diagnostic Questions
Which term refers to the outward expression
of an allele pair?
gamete
hybrid
phenotype
genotype A B C D
CDQ 3

56. How many chromosomes would a cell have
Chapter
Sexual Reproduction and Genetics
Chapter Assessment Questions
How many chromosomes would a cell have
during metaphase I of meiosis if it has 12
chromosomes during interphase? 6 12 24 36 A B C D
CAQ 1

57. Which stage of meiosis is illustrated?
Chapter
Sexual Reproduction and Genetics
Chapter Assessment Questions
Which stage of meiosis is illustrated?
prophase I
interphase
anaphase I
anaphase II A B C D
CAQ 2

58. What is the next step for the chromosomes illustrated?
Chapter
Sexual Reproduction and Genetics
Chapter Assessment Questions
What is the next step for the chromosomes illustrated?
Chromosomes replicate.
Chromosomes move to opposite poles.
Chromosomes uncoil and form two nuclei.
Chromosomes line up at the equator. A B C D
CAQ 3

59. What is this process called?
Chapter
Sexual Reproduction and Genetics
Standardized Test Practice
What is this process called?
fertilization
gamete formation
inheritance
reproduction A B C D
STP 1

60. Standardized Test Practice
Chapter
Sexual Reproduction and Genetics
Standardized Test Practice
Before meiosis I, the sister chromatids of this chromosome were identical. What process caused a change in a section of one chromatid?
DNA replication
crossing over
synapsis
telophase A B C D
STP 2

61. At what stage is the chromosome number reduced from 2n to n?
Chapter
Sexual Reproduction and Genetics
Standardized Test Practice
At what stage is the chromosome number reduced from 2n to n?
prophase I
metaphase I
anaphase I
meiosis II A B C D
STP 3

62. To which step in this process does the law of segregation apply?
Chapter
Sexual Reproduction and Genetics
Standardized Test Practice
To which step in this process does the law of segregation apply?
grows into plant
gamete formation
fertilization
seed development A B C D
STP 4

63. 1/4 1/2 1 For human eye color, brown is dominant and
Chapter
Sexual Reproduction and Genetics
Standardized Test Practice
For human eye color, brown is dominant and
blue is recessive. If a husband is heterozygous
and his wife has blue eyes, what is the
probability that their child will have blue eyes?
1/4
1/2 1 A B C D
STP 5

64. Glencoe Biology Transparencies
Chapter
Sexual Reproduction and Genetics
Glencoe Biology Transparencies

65. Chapter
Sexual Reproduction and Genetics
Image Bank

66. Chapter
Sexual Reproduction and Genetics
Image Bank

67. Section 1 Vocabulary gene homologous chromosome gamete haploid
Sexual Reproduction and Genetics
Vocabulary
Section 1
gene
homologous chromosome
gamete
haploid
fertilization
diploid
meiosis
crossing over

68. Section 2 Vocabulary genetics allele dominant recessive homozygous
Sexual Reproduction and Genetics
Vocabulary
Section 2
genetics
allele
dominant
recessive
homozygous
heterozygous
genotype
phenotype
law of segregation
hybrid
law of independent assortment

69. Section 3 Vocabulary genetic recombination polyploidy Section 3
Sexual Reproduction and Genetics
Vocabulary
Section 3
genetic recombination
polyploidy

70. Visualizing Meiosis I and Meiosis II Generations
Chapter
Sexual Reproduction and Genetics
Animation
Visualizing Meiosis I and Meiosis II
Generations

71. Chapter
Sexual Reproduction and Genetics

72. Chapter
Sexual Reproduction and Genetics