1. Patterns of Heredity

3. ______ all traits are simply inherited by dominant and recessive alleles (Mendelian Genetics). In some traits, neither allele is dominant or many alleles control the trait. There are different ways in which traits can be inherited from parents to offspring.
Not

4. 5 Different Modes of Inheritance

5. 1. Incomplete Dominance Definition:
Neither allele for a gene ____________.
Phenotype of the heterozygous offspring will be a ________ of the two homozygous parents.
dominates
blend

6. Incomplete Dominance homozygous
Ex. A _____________ white flower crossed with a _____________ red flower will produce all _______________ pink flowers.
homozygous
homozygous
heterozygous

7. Incomplete Dominance
NOTATION:
Alleles are all capital letters because NEITHER one ____________ the other. So one of the alleles has a ________ (‘) on it to represent an alternate expression of the gene.
dominates
prime

8. Always make a _____ to show the genotypes and the resulting phenotypes.
Still supports Mendel’s Law of Independent Assortment.
KEY

9. Ex. 1)
In a certain species of snapdragons, the combined expression of both alleles for flower color produces a new phenotype – pink. A red snapdragon is homozygous and is crossed with a homozygous white snapdragon. What are the genotypic and phenotypic ratios of this cross?

10. R R’ P cross = RR x R’R’ G: __________ 100% RR’ P: __________ RR’ RR’
Key:
Red = RR
White = R’R’
Pink = RR’
P cross = RR x R’R’
G: __________
P: __________ R R’
100% RR’
RR’
RR’
100% Pink
RR’
RR’

11. Ex. 2)
Then cross the F1 generation and what are the genotypic and phenotypic ratios of this cross?

12. P cross = RR’ x RR’ G: __________ P: _____________ R R’ RR’ RR’ RR’
Key:
Red = RR
White = R’R’
Pink = RR’
P cross = RR’ x RR’
G: __________
P: _____________ R R’
1RR:2RR’:1R’R’
RR’
RR’
1Red:2Pink:1White
RR’
R’R’

13. 2. Codominance Definition: Both __________ are expressed __________
alleles
EQUALLY

14. Codominance
Phenotypes of heterozygous offspring are showing both traits!
Ex. Red cows crossed with white will generate roan cows. _______ refers to cows that have red coats with white blotches.
Roan

15. Two ____________ alleles (capital letters) are used.
Codominance
NOTATION:
Two ____________ alleles (capital letters) are used.
Always make a _____ to show the genotypes and the resulting phenotype.
different
KEY

16. In chickens, black-feathered is not wholly dominant over white-feathered, so heterozygous chickens are black and white checkered. Cross two heterozygous chickens. What would the appearance of their offspring be?

17. P cross = BWxBW Phenotype: B W BB BW BW WW Key: Black = BB White = WW
Checkered = BW
P cross = BWxBW
Phenotype: B W
1 Black
2 Checkered
1 White BB BW BW WW

18. In shorthorn cattle, the hybrid between red and white is called a roan
In shorthorn cattle, the hybrid between red and white is called a roan. What phenotypes would result in the cross of a roan and a white?

19. P cross = RW x WW Phenotype R W RW WW RW WW Key: Red = RR White = WW
Roan = RW
P cross = RW x WW
Phenotype R W RW WW
2 Roan: 2 White RW WW

20. 3. Multiple Alleles
Definition:
More than ______________ for a single gene can control a trait.
Multiple alleles must be studies by looking at the entire population of species.
two alleles

21. Multiple Alleles
Each individual carries only two alleles for any gene (one on each homologous chromosome).
In this form of inheritance, a trait can have one gene, but ______________ for that gene.
100 alleles

22. Multiple Alleles
Ex: The human blood group can be any combination of A, B, and O.

23. Multiple Alleles
The alleles are IA, IB and i.
Alleles ___ and ___ are ________________.
Alleles ___ (“O”) is ____________. A B
CODOMINANT i
RECESSIVE

24. NOTATION: GENOTYPES PHENOTYPES Homozygous type A IAIA Type A blood
The possible genotypes/phenotypes.
GENOTYPES
PHENOTYPES
Homozygous type A
IAIA
Type A blood
Heterozygous type A
IAi
Homozygous type B
IBIB
Type B blood
Heterozygous type B
IBi
Codominant type AB
IAIB
Type AB blood
Recessive type O Ii
Type O blood

25. Multiple Alleles
NOTE: the “i” is dropped from the genotype of A and B when the ____________ is written.
(Genotype IAI is type A blood)
phenotype

26. Interesting Fact
In the US, about 45% of the population is type O, 42% type A, 10% type B and only 3% type AB.

27. The ABO Blood System

28. The positive and negative of a blood type is called the ____________, it is totally a separate _______ with RH+ (RR or Rr) and Rh- alleles (rr).
If you have the protein = Rh+
If you DO NOT have the protein = Rh-
Rh factor
gene

29. Interesting Fact
In the US, about 85% of the population is Rh+ and 15% Rh-.
Thus the chances of someone being O- (having both ii and rr) would be 45% X 15% = 6.75%.

30. The most rare blood type would be ______, about 0
The most rare blood type would be ______, about 0.45% if the population.
_____ is the universal donor.
_____ is the universal recipient.
AB- O AB

31. P cross = IAIB x ii Genotypes: Phenotypes: IA IB i IAi IBi IAi IBi
2 IAi : 2 IAIB
IAi
IBi
2 Type A: 2 Type B
IAi
IBi

32. A father is homozygous blood type A and the mother is heterozygous blood type B, what could be the possible genotypes and phenotypes of their offspring's blood types?

33. IA P cross = IAIA x IBi Genotypes: IB Phenotypes: i IAIB IAIB IAi IAi
2 IAi : 2 IAIB
IAIB
IAIB
2 Type A: 2 Type AB
IAi
IAi

34. Two Types of Chromosomes
Sex chromosomes
1. _____________________: last pair of chromosomes - 23rd pair for humans.
XX = _________
XY = _________
female
male

35. Two Types of Chromosomes
2. _________________________ or ___________
All other pairs of chromosomes – 1st – 22nd pairs in humans.
Autosomal chromosomes
Autosomes

36. 4. Sex-Linked Traits (X-Linked)
Other genes besides the alleles for sex are located on the sex chromosomes.

37. Definition:
Those traits will occur _______ frequently in males than females, such as color blindness and hemophilia.
MORE

38. Why?
Alleles on a gene may be present on the X chromosome but _________ on the Y. These are called sex-linked traits.
absent

39. This means that ________ may inherit ______ allele for a characteristic and that allele will be expressed, whether it is dominant or recessive, because it is the _______ allele present on their X chromosome.
males
one
only

40. X-Linked traits most likely will be ____________ to the normal condition and the Y chromosome lacks the gene for a trait, so males have a higher chance of having the disorder.
RECESSIVE

41. These traits generally do NOT show up in __________ since females have genes on both their X chromosomes.
females

42. Notation:
The alleles for these traits are written as ______________ on the ___ chromosome ONLY.
superscripts X

43. No
______ alleles are written on the Y chromosome!
Ex: Colorblind male = XbY
Normal male = XBY
_______________ FEMALES are known as __________
XBXb
Heterozygous
carriers

44. Ex. 1) Color blindness is a sex-linked trait that is caused by a ______________________. A colorblind man marries a woman that is homozygous for normal vision.
recessive allele

45. P cross = XNXN x XnY XN Xn Normal Y XNXn XNXn Normal XNY XNY
What possible types of vision could be found if they had boys?
__________
P cross =
XNXN x XnY
Normal XN Xn Y
What possible types of vision could be found if they had girls?
__________
XNXn
XNXn
Normal
XNY
XNY

46. Ex. 2) A girl of normal vision, whose father was colorblind, marries a colorblind man. What types of vision could be found in their children?

47. P cross = XNXn x XnY XN Xn Y XNXn XnXn XNY XnY
What types of vision could be found in their children?
P cross =
XNXn x XnY XN Xn Y
50% Normal vision and 50% colorblindness.
XNXn
XnXn
XNY
XnY

49. 5. Polygenic Inheritance
Traits are determined by ___________________.
They may or may not be found on the same chromosome.
Each gene may have more than 2 alleles.
MANY genes

50. The phenotypes may vary depending on the number of dominant and recessive alleles in the genotype.

51. Traits that show ________________ are a result of polygenic inheritance.
Ex. Eye color, skin color, height, facial features.
great variability

52. Environment & Genes
environment
The ______________ can determine whether or not a gene is fully expressed or expressed at all.

53. Environment & Genes
Internal and external environments can affect phenotypes:
Influence of ____________________:
~___________ based on sexes
(testosterone, estrogen)
Internal environment
Hormones

54. 2. Influence of _____________________:
External environment
~ temperature
~ light
~infectious agents (viruses, bacteria)
~chemicals
~nutrition

55. All of these can influence the expression of genes.
Environment & Genes
All of these can influence the expression of genes.

57. Karyotypes

58. What is a Karyotype?
___________ = a test to identify and evaluate the size, shape and number of chromosomes in a sample of body cells.
Homologous chromosomes are arranged by ______, __________ patterns and ____________ placement.
Karyotype
size
banding
centromere

59. What is a Karyotype?
Extra, missing or abnormal positions of chromosome pieces can cause problems with a person’s growth, development, and body functions.

60. Examples:
Normal Female Normal Male

61. Why is it done? abnormality defect
Determine whether the chromosomes of an adult have an _____________ that can be passed on to a child.
Determine whether a chromosome defect is preventing a woman from becoming pregnant or causing miscarriages.
Determine whether a chromosome ________ is present in a fetus.
abnormality
defect

62. Why is it done?
Determine the cause of a baby’s birth defects or disability.
Identify the _____ of a person by determining the presence of the Y chromosome.
This may be done when a newborn’s sex is not clear.
sex

63. Down syndrome
Two copies of an autosomal chromosome fail to separate during meiosis so three copies of that chromosome are made.
Trisomy 21

64. Turner Syndrome
Cause: nondisjunction of the sex chromosomes during meiosis so individuals are missing one copy of the X chromosome
Affects ONLY females
Women are usually short, sexually underdeveloped and sterile.
Women with this syndrome function well within society and are not diagnosed until they are assessed for infertility as adults.

65. Klinefelter syndrome
Cause: nondisjunction of sex chromosomes during meiosis so individuals have an extra X chromosome.
Affects ONLY males
Males are often tall, sexually underdeveloped and may have slight intellectual impairment.
Many males with this syndrome function well within society and are not diagnosed until they are assessed for infertility as adults

66. Jacobs syndrome (XYY)
Occurs when a male inherits TWO Y chromosomes from his father instead of one.
Cause: unknown.
Symptoms: learning difficulties at school and delayed emotional maturity.
Males are tall, thin, have acne, speech problems and reading problems.

67. Pedigrees

68. Pedigrees
___________ = a valuable tool for anyone working in the field of genetics.
Used to show _______________ in families, and resemble a ________ ______.
Pedigree
relationships
family
tree

69. Pedigrees A square represents a male A circle represents a female
A vertical line and a bracket connect the parents to their children.
A horizontal line connecting a male and a female represents a marriage
A circle or square that is not shaded indicates that a person does not express the trait.
A shaded circle or square indicates that a person expresses the trait.