2. Chapter: Heredity Section 1: Genetics Section 2: Genetics Since Mendel
Table of Contents
Chapter: Heredity
Section 1: Genetics
Section 2: Genetics Since Mendel
Section 3: Biotechnology

3. Inheriting Traits 1 Traits are inherited from parents
Genetics 1
Inheriting Traits
Traits are inherited from parents
Heredity - the passing of traits from parent to offspring.

4. Genetics 1
What is genetics?
Alleles - different forms of a trait that a gene may have
Alleles for each trait separate into different sex cells during meiosis

5. What is genetics? 1 Genetics - study of how traits are inherited

6. Mendel—The Father of Genetics1
Mendel—The Father of Genetics
Mendel (1856) – studied genes of pea plants
First to:
trace one trait through several generations
use probability to explain heredity

7. Purebred - always produces the same traits generation after generation
Genetics 1
Purebred - always produces the same traits generation after generation
Hybrids – receive different alleles for a trait from each parent

8. Dominant and Recessive Factors
Genetics 1
Dominant and Recessive Factors
Cross-pollination - using pollen from one flower to pollinate others

9. Dominant and Recessive Factors
Genetics 1
Dominant and Recessive Factors
Dominant - factor expressed if there is only one allele for the trait
Recessive – factor expressed only when there are 2 alleles for the trait
Click image to view movie.

10. Studied > 30,000 pea plants over 8 yrs
Genetics 1
Punnett Squares
Studied > 30,000 pea plants over 8 yrs
Punnett square -tool used to predict results
Click image to view movie.

11. Uppercase - dominant allele
Genetics 1
Punnett Squares
Uppercase - dominant allele
Lowercase - recessive allele

12. Genotype - genetic makeup
Genetics 1
Genotype - genetic makeup
Phenotype - way an organism looks and behaves

13. Homozygous - two alleles that are the same
Genetics 1
Homozygous - two alleles that are the same
Heterozygous - two different alleles for a trait

14. Making a Punnett Square
Genetics 1
Making a Punnett Square

15. Section Check 1
Question 1
How did Gregor Mendel use his knowledge of mathematics in his study of heredity in pea plants?

16. Section Check 1
Answer
Mendel was the first person to use the mathematics of probability to explain heredity. Probability is the branch of mathematics that helps you predict the chance that something will happen.

17. Section Check 1
Question 2
According to this diagram, if meiosis proceeds correctly, how many alleles of a particular gene can a female pass on to her offspring?

18. Section Check 1
Answer
Although she has two alleles of each gene, a mother can pass only one allele to her offspring. Meiosis separates alleles so that eggs have only one allele for each gene. The new individual then gets one allele from the mother and the other from the father.

19. Section Check 1
Question 3
Mendel crossed pea plants that were pure-bred for yellow seeds with plants that were pure-bred for green seeds. All the offspring of this cross had yellow seeds. Based on these results, which form of color was recessive and which was dominant?

20. Section Check 1
Answer
Green seed color was recessive and yellow seed color was dominant. Mendel called the form that seemed to disappear (green in this case) recessive and the form that covered up (yellow in this case) dominant.

21. Incomplete dominance – results in an intermediate phenotype
Genetics Since Mendel 2
Incomplete Dominance
Incomplete dominance – results in an intermediate phenotype

22. Multiple alleles - trait that is controlled by more than two alleles
Genetics Since Mendel 2
Multiple alleles - trait that is controlled by more than two alleles
Produce more than three phenotypes

23. Alleles for blood types A, B, and O.
Genetics Since Mendel 2
Multiple Alleles
Alleles for blood types
A, B, and O.

24. Polygenic Inheritance
Genetics Since Mendel 2
Polygenic Inheritance
Polygenic inheritance - a group of gene pairs acts together to produce a trait.
Produces a wide variety of phenotypes.
Click image to view movie.

25. Polygenic Inheritance Examples: Height Eye color Skin color
Genetics Since Mendel 2
Polygenic Inheritance
Examples:
Height
Eye color
Skin color

26. Impact of the Environment
Genetics Since Mendel 2
Impact of the Environment
Environment plays a role in how some genes are expressed

27. Human Genes and Mutations Mutations – errors when DNA copies
Genetics Since Mendel 2
Human Genes and Mutations
Mutations – errors when DNA copies
Can be harmful or helpful

28. Chromosome Disorders - error in the number of chromosomes
Genetics Since Mendel 2
Chromosome Disorders - error in the number of chromosomes

29. Recessive Genetic Disorders - caused by recessive genes.
Genetics Since Mendel 2
Recessive Genetic Disorders - caused by recessive genes.

30. Sperm - 1 X or 1 Y chromosome
Genetics Since Mendel 2
Sex Determination
Egg - 1 X chromosome
Sperm - 1 X or 1 Y chromosome
Male XY
Female XX

31. Sex-linked gene - allele inherited on a sex chromosome
Genetics Since Mendel 2
Sex-Linked Disorders
Sex-linked gene - allele inherited on a sex chromosome
Color blindness is sex-linked

32. Pedigrees Trace Traits
Genetics Since Mendel 2
Pedigrees Trace Traits
Pedigree - visual tool for following a trait through generations
Males – squares
Females – circles

33. Pedigrees Trace Traits
Genetics Since Mendel 2
Pedigrees Trace Traits
Filled circle or square - shows trait
Half-colored - carriers
Empty - do not have the trait and are not carriers.

34. Section Check 2
Question 1
Why is color blindness a sex-linked trait?

35. Section Check 2
Answer
This trait is sex-linked because the alleles for this trait are carried on the X-chromosome, one of the sex chromosomes. Color-blindness is caused by a recessive allele and because males get only one X-chromosome, they are more likely to be color-blind than females.

36. Section Check 2
Question 2
In Himalayan rabbits, dark-colored fur is only found on cooler parts of the rabbits’ bodies. This is an example of _______.
A. how sex-linked conditions change coat color
B. the risk of cancer in rabbits with light fur
C. the impact of internal environment on gene
expression
D. what hybrid rabbits look like

37. Section Check 2
Answer
The correct answer is C. The alleles for dark fur color are controlled by the internal temperature of the rabbits. These alleles are expressed only at lower temperatures.

38. Section Check 2
Question 3
If an individual has three copies of chromosome 21, what condition will result?
A. color blindness
B. cystic fibrosis
C. Down’s syndrome
D. Hemophilia

39. Section Check 2
Answer
The correct answer is C. Down’s syndrome occurs when there are three copies of chromosome 21 instead of the usual two.

40. Biotechnology 3
Genetic engineering - scientists are experimenting to change the arrangement of DNA that makes up a gene.

41. Biotechnology 3
Recombinant DNA - made by inserting a useful segment of DNA from one organism into a bacterium.
Used to produce
human insulin,
human growth hormone

42. Normal allele is placed in a virus.
Biotechnology 3
Gene Therapy
Normal allele is placed in a virus.
The virus then delivers the normal allele and replaces the defective one

43. Genetically Engineered Plants
Biotechnology 3
Genetically Engineered Plants
Selective breeding - selecting plants with the most desired traits to breed

44. Genetically Engineered Plants
Biotechnology 3
Genetically Engineered Plants
Find genes that produce desired traits in one plant and then insert them into a different plant

45. Section Check 3
Question 1
What is it called when scientists use biological and chemical methods to change the arrangement of DNA in a gene?

46. Section Check 3
Answer
This is called genetic engineering. This process has been used to make large volumes of medicines and research is being conducted to find many other ways to use these techniques.

47. Section Check 3
Question 2
What does this diagram illustrate?

48. A. Bacteria cells can produce human insulin.
Section Check 3
A. Bacteria cells can produce human insulin.
B. Bacteria genes are put in human cells.

49. C. People with diabetes are given the gene for insulin.
Section Check 3
C. People with diabetes are given the gene for
insulin.
D. The insulin gene is inserted in people with
diabetes.

50. Section Check 3
Answer
The correct answer is A. Genetic engineering can be used to insert the human gene for insulin into bacterial cells. The bacterial cells then produce human insulin. This insulin can be used to treat people who have diabetes.

51. Section Check 3
Question 3
Using genetic engineering to replace defective alleles in people with genetic diseases is called _______.
A. gene therapy
B. Mendelian genetics
C. pedigree analysis
D. recombinant DNA

52. Section Check 3
Answer
The correct answer is A. Often; a virus is used to deliver the normal allele to the patient. Scientists have been conducting experiments to cure many different genetic diseases, including cystic fibrosis, in this way.

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54. End of Chapter Summary File