1. BIO 1A – Unit 4 Notes
Genetics

2. Genetics 11.1 Genetics - the scientific study of heredity
Gregor Mendel is considered the father of genetics.
He conducted research on pea plants in a monastery garden.

3. Mendel’s Principles of Genetics
Inheritance - Genes are passed from parents to offspring.
Dominance - One form of a gene, an allele, may be dominant over another.
Segregation - Genes segregate during gamete formation in sexually reproducing organisms.
Independent assortment - Alleles for different genes segregate independently of one another.

4. Fertilization
Fertilization – a process where sperm and egg cells join during sexual reproduction.
Fertilization produces a new cell.
Mendel studied pea plants.
Pea plants are self-pollinating.

5. Fertilization
true-breeding – organisms that will produce identical offspring through self-pollination (ex. TT, tt)
hybrids - the offspring of crosses between parents with different traits through cross-pollination (ex. Tt)

6. Fertilization

7. Generations P generation: Each original pair of parents
F1 Generation: The offspring of the P generation or “first filial,” generation
F2 Generation: The offspring of the F1 generation or “second filial” generation

8. Genes
trait - a specific characteristic that varies from one individual to another: (physical representation) genes - factors of biological inheritance that determine traits, passed through generations: (genetic sequence) allele - different forms of a gene: (variation of genetic sequence)

9. Traits / Genes / Alleles

10. Mendel’s Crosses

11. Principle of Dominance
principle of dominance - states that some alleles are dominant and others are recessive.
An organism with a dominant allele for a trait will always exhibit that form of the trait.
An organism with the recessive allele for a trait will exhibit that form only when the dominant allele for that trait is not present.

12. Principle of Dominance

13. Principle of Segregation
segregation – alleles for genes separate from each other during the formation of gametes (sex cells)
Two alleles segregate from each other so that each gamete carries only a single copy of each gene.

14. Principle of Segregation

15. Dominance / Segregation

16. Probability
probability - the likelihood that a particular event will occur
The principles of probability can be used to predict the outcomes of genetic crosses.

17. Probability
Probabilities predict the average outcome of a large number of events.
Probability cannot predict the precise outcome of an individual event.
In genetics, the larger the number of offspring, the closer the resulting numbers will get to expected values.

18. Punnett Squares
Punnett square – a diagram used to predict the gene combinations that might result from a genetic cross
Punnett squares can be used to predict and compare the genetic variations that will result from a cross.

19. Punnett Squares

20. Genotypes / Phenotypes
Genotype – genetic makeup of an organism for a particular trait
Ex. TT, Tt, tt
Phenotype – physical characteristic expressed from the organism’s genetics
Ex. tall, tall, short

21. Genotypes
homozygous - organisms that have two identical alleles for a particular trait (Ex. TT, tt)
Homozygous organisms are true-breeding for a particular trait.
heterozygous - organisms that have two different alleles for the same trait (Ex. Tt)
Heterozygous organisms are hybrid for a particular trait.

22. Genotypes / Phenotypes

24. Probability / Segregation
Because the allele for tallness (T) is dominant over the allele for shortness (t), 3/4 of the F2 plants should be tall.
The ratio of tall plants (TT or Tt) to short (tt) plants is 3:1.
The predicted ratio showed up in Mendel’s experiments indicating that segregation did occur.

25. Independent Assortment 11.3
independent assortment – genes for different traits can segregate independently during the formation of gametes.
Genes that segregate independently do not influence each other's inheritance.
Alleles for seed color and seed shape segregate independently of each other.

26. Independent Assortment
To determine if the segregation of one pair of alleles affects the segregation of another pair of alleles, Mendel performed a two-factor cross.
Mendel crossed true-breeding plants that produced round yellow peas (genotype RRYY) with true-breeding plants that produced wrinkled green peas (genotype rryy).
All of the F1 offspring produced round yellow peas (RrYy).
Mendel crossed the heterozygous F1 plants (RrYy) with each other to determine if the alleles would segregate from each other in the F2 generation.

27. Two-Factor Cross: F1 Generation

28. Mendel’s Results The F1 generation produced seeds that were…
round and yellow

29. Two-Factor Cross: F2 Generation

30. Mendel’s Results The F2 generation produced seeds that were…
round and yellow
wrinkled and green
round and green
wrinkled and yellow

31. Mendel’s Results
The alleles for seed shape segregated independently of those for seed color. This principle is known as independent assortment.
Genes that segregate independently do not influence each other's inheritance.

32. Mendel’s Principles
Inheritance - Genes are passed from parents to their offspring.
Dominance - If two or more forms (alleles) of the gene for a single trait exist, some forms of the gene may be dominant and others may be recessive.
Segregation - In most sexually reproducing organisms, each adult has two copies of each gene. These genes are segregated from each other when gametes are formed.
Independent Assortment - The alleles for different genes usually segregate independently of one another.

33. Incomplete Dominance
incomplete dominance - when one allele is not completely dominant over another
In incomplete dominance, the heterozygous phenotype is between the two homozygous phenotypes.

34. Incomplete Dominance

35. Codominance codominance - both alleles contribute to the phenotype.
In certain varieties of chicken, the allele for black feathers is codominant with the allele for white feathers.
Heterozygous chickens are speckled with both black and white feathers. The black and white colors do not blend to form a new color, but appear separately.

36. Codominance

37. Codominance

38. Codominance

39. Multiple Alleles
multiple alleles - genes that are controlled by more than two alleles
More than two possible alleles can exist in a population.
A rabbit's coat color is determined by a single gene that has at least four different alleles.

40. Multiple Alleles

41. Polygenic Traits
polygenic traits - traits controlled by two or more genes
Skin color in humans is a polygenic trait controlled by more than four different genes.

42. Polygenic Traits

43. Applying Mendel’s Principles
Mendel’s principles can be used to study inheritance of other organisms’ traits and to calculate the probability of certain traits appearing in the next generation.
Thomas Hunt Morgan – Fruit Flies
Small, easy to study in lab, reproduce quickly, simple genetics

44. Genetics and Environment
Characteristics of any organism are determined by the interaction between genes and the environment.

45. Genetics and Environment: Arctic Fox

46. Disease
disease - a condition of the living animal or plant body or of one of its parts that impairs normal functioning and is typically manifested by distinguishing signs and symptoms
Ex. infectious disease, genetic disease, heart disease, diabetes, cancer, AIDS

47. Disease
infectious disease (communicable disease) - an infectious disease transmissible (as from person to person) by direct contact with an affected individual or the individual's discharges or by indirect means (as by a vector)
Ex. AIDS, tuberculosis, malaria, common cold
non-infectious disease (non-communicable disease) – a disease that is not transmissible by direct contact.
Ex. cancer, diabetes, asthma, heart disease

48. Genetics and Disease
Genetic Disease - Some disease can be caused by mutations in chromosomes (non-disjunction) or single genes (recessive traits).
Down Syndrome – caused by duplication of 21st human chromosome (non-disjunction)
Hemophilia – caused by inheritance of 2 recessive alleles

49. Genetics and Disease
Medelian Inheritance - the manner by which genes and traits are passed from parents to their children
Ex. dominant traits
Non-mendelian Inheritance - a general term that refers to any pattern of inheritance in which traits do not segregate in accordance with Mendel's laws.
Ex. polygenic traits

50. Genes and Disease The Guardian Video
disease-video

51. Genetic Engineering vs. Disease
Time Video:

52. Activity Genetics of Disease Visual Project BIO 1A 40 pts Topic 5
Description:
Disease
Role of Genetics
Keywords: Unit 4 Vocabulary (5 minimum)
Images / Visuals (2 minimum)
Creativity
Organization

53. Introduction
Name the disorder
Definition and Description
What happens to the body
What part(s) of the body does this generally affect?
How many and what type of people are likely to have the disorder?
How prevalent is it (common or not?)?
Is one race, gender, or even geographic location more likely to have the disorder?
Cause of the Disorder
What causes this disorder to occur in the body? Is it a mutation?
How is the disorder inherited?
Is it sex-linked?
Is there a particular chromosome it is located on?
Is it dominant or recessive?
How is the disorder treated or regulated?
Medications? Therapy? Other?
How is the disorder diagnosed?
What tests are done?
Is genetic counseling an option?

54. References WHO: Enrichment Reading
NIH:
The Guardian:
Time: