3. Genetics – 3.4 Inheritance Name:

Understandings, Applications and Skills (This is what you maybe assessed on)

Statement Guidance3.4.U1 Mendel discovered the principles of inheritance with

experiments in which large numbers of pea plants were crossed.

3.4.U2 Gametes are haploid so contain one allele of each gene.

3.4.U3 The two alleles of each gene separate into different haploid daughter nuclei during meiosis.

3.4.U4 Fusion of gametes results in diploid zygotes with two alleles of each gene that may be the same allele of different alleles.

3.4.U5 Dominant alleles mask the effects of recessive alleles but co-dominant alleles have joint effects.

3.4.U6 Many genetic diseases in humans are due to recessive alleles of autosomal genes.

3.4.U7 Some genetic diseases are sex-linked and some are due to dominant or co-dominant alleles.

3.4.U8 The pattern of inheritance is different with sex-linked genes due to their location on sex chromosomes.

3.4.U9 Many genetic diseases have been identified in humans but most are very rare.

3.4.U10 Radiation and mutagenic chemicals increase the mutation rate and can cause genetic disease and cancer.

3.4.S1 Construction of Punnett grids for predicting the outcomes of monohybrid genetic crosses.

3.4.S2 Comparison of predicted and actual outcomes of genetic crosses using real data.

3.4.S3 Analysis of pedigree charts to deduce the pattern of inheritance of genetic diseases.

3.4 U.1 Mendel discovered the principles of inheritance with experiments in which large numbers of pea plants were crossed.

_____________________________

Austrian monk who published results of garden __________________________ inheritance in 1865

Used artificial pollination in a series of experiments by using a small brush to place the pollen on the

reproductive parts of the flowers

Key terminology:

1. ________________________________ – symbolic representation of pair of alleles possessed by an

organism, typically represented by two letters

a. Ex: _____________________________________

2. _________________________________ – characteristics or traits of an organism

a. Ex: ____________________________________________________________________

3. ______________________________________ – an allele that has the same effect on the phenotype

whether it is paired with the same allele or a different one; always expressed in

__________________________

a. Ex: ______________________ give dominant trait A because the ____________ allele is

_____________________________; the a allele is not transcribed and translated during protein

synthesis

4. _________________________________ – an allele that has an effect on the phenotype only when

present in the _______________________________ state

a. Ex: _____________________ gives rise to the ________________________________ trait

because no dominant allele is there to mask it

5. _________________________________ – pairs of alleles that both affect the phenotype when present

in a heterozygote

a. Ex: parent with curly hair and parent with straight hair can have children with different degrees

of curliness as both alleles influence hair condition when both are present in the genotype

6. _______________________________ – particular ______________________ on homologous

chromosomes of a gene

7. _______________________________ – having two _________________________ alleles of a gene

a. Ex: AA is a genotype which is homozygous dominant whereas aa is the genotype which is

homozygous recessive

8. _______________________________ – having two _________________________ alleles of a gene

a. Ex: Aa is a heterozygous genotype

9. _____________________________________ – an individual who has a recessive allele of a gene that

does not have an effect on their phenotype

10. _____________________________________ – testing a suspected heterozygote plant or animal by

crossing it with a known homozygous recessive (aa).

a. Since a recessive allele can be masked, it is often impossible to tell if an organism is AA or Aa

until they produce offspring which have the recessive trait.

11. Mendel’s Law of Segregation

a. Four parts

i. Alternative __________________________ of genes account for

_____________________ in inherited characteristics.

ii. For each characteristic, an organism inherits __________________ alleles, one from each

parent.

iii. If the two alleles differ, then one, the allele that encodes the dominant trait, is fully

expressed in the organism's ______________________________; the other, the allele

encoding the recessive trait, has _______________ noticeable effect on the organism's

appearance.

iv. The two alleles for each characteristic ____________________________ during gamete

production

3.4 S.1 Construction of Punnett grids for predicting the outcomes of monohybrid genetic crosses.

Punnet Square:

12. Used to determine the ___________________________ of a cross between _______________

individuals. In the example we have two parents that are _________________________________ for a

trait.

3.4 U.2 Gametes are haploid so contain only one allele of each gene.

13. ______________________ are _______________________ cells.

14. Sex cells contain ______________ chromosome of each type, as an example humans have _______

types.

15. Parents pass information in the form of _________________ in gametes (sex cell).

16. These cells will _________________ together with the cell of the _____________________ sex to

create a _____________________.

3.4 U.3 The two alleles of each gene separate into different haploid daughter nuclei during meiosis.

17. Meiosis = _____________________________________

18. Cells divide ______________________.

19. Result: _____________ daughter cells, each with ______________________ as many chromosomes as

parent cell.

3.4 U.4 Fusion of gametes results in diploid zygotes with two alleles of each gene that may be the same allele or

different alleles.

20. _______________________________ : reproductive history of organism, from

_______________________ production of own ___________________.

21. ________________________ and _____________________ alternate in sexual life cycles

22. ________________________ : cell division that reduces ____________ of chromosomes

(___________________________), creates ________________________

23. Fertilization : combine ______________________ (sperm + egg)

Offspring:Genotype: 1/4 ______________1/2 ______________1/4 ______________

Phenotype: 3/4 Purple and 1/4 white

– Fertilized egg =

____________________________________

24. Zygote divides by _____________________ to make

______________________________________ .organism.

3.4 U.5 Dominant alleles mask the effects of recessive alleles but co-

dominant alleles have joint effects.

Problems with predictions

1. ____________________________

2. ____________________________

3. ____________________________

3.4 U.6 Many genetic diseases in humans are due to recessive alleles of

_________________________, although some genetic diseases are due

to dominant or co-dominant alleles

25. Inheritance characterized by ________________________ expression of ____________________

alleles in the heterozygote. Seen in:

• _______________________________

• _______________________________

• _______________________________

3.4 U.6 Many genetic diseases in humans are due to recessive alleles of autosomal genes, although some genetic

diseases are due to dominant or co-dominant alleles.

26. ______________________________________ : (example of a

________________________________________________ mutation and its consequences through

____________________________________________________)

27. The Genetics of Sickle Cell Anemia

a. HB A HB A Susceptible to ____________________________ with anemia

b. HB A HB s Increase __________________________________ to malaria with mild anemia

c. HB s HB s Sickle cell shaped cell susceptible to malaria with severe anemia

There are 4: A, B, AB and O, A & B refer to 2 genetically inherited A and B antigens on the surface of red blood cells.IA – ________________IB – ________________i - codes for no antigen

3.4 U.7 Some genetic diseases are sex-linked. The pattern of inheritance is different with sex-linked genes due

to their location on sex chromosomes. [Alleles carried on X chromosomes should be shown as superscript

letters on an upper case X, such as Xh.]

28. The _______________________________ in humans spans more than 153 million base pairs (the

building material of _________________________). It represents about 2000 out of 20,000 - 25,000

genes.

29.  The ___________________________________ containing 78 genes, out of the estimated 20,000 to

25,000 total genes in the human genome. Genetic disorders that are due to _______________________

in genes on the ______________ chromosome are described as ________________________________.

30. _____________________________________ :

a. There are __________________________________________ males in which there is only

_____________________ allele per gene and that is inherited from the

______________________________ on the X-chromosome

b. In the ____________________________________ the __________________________

inherited ___________________________ copies of an allele per gene.

31. ______________________________________ :

a. All regions of the ______________ chromosome are _______________________________.

b. There are ________________________________ alleles per gene as with all other genes on all

other chromosomes.

32. This difference in x and y chromosomes plays a large role in determining rates of genetic inherited

defects.

33. Sex Linkage alleles on the ________________________________________ of the X chromosome are

more common in ___________________________ than in males.

a. A gene with two alleles where one is ____________________ and one is

____________________.

b. Female has _____________________ possible genotypes and one is the homozygous

__________________________.

c. In a population the chance of being homozygous recessive is 33.3 %.

d. Males have __________________________ possible genotypes.

There are 4: A, B, AB and O, A & B refer to 2 genetically inherited A and B antigens on the surface of red blood cells.IA – ________________IB – ________________i - codes for no antigen

e. There is a ________________________ chance of the homozygous recessive condition in the

population.

f. In sex linked conditions the _________________________ condition is more common in males

than females.

3.4 A.2 Red-green color blindness and hemophilia as

examples of sex-linked inheritance.

34. Female carriers of sex linked alleles

a. Female heterozygote's for sex linked alleles e.g.

Hemophilia _______________________ or Color

Blindness ____________________ are carriers of the

allele.

b. They are ______________________________ by the

condition.

c. They do pass on the allele which may result in a

homozygous female or a male with the sex linked

recessive allele.

35. Sex Linkage Examples: _________________________________

a. Hemophilia is an example of a ______________________________ condition.

b. The hemophilia allele is ________________________________ to the normal allele.

c. The gene is located on the ______________________________________________ of the X

chromosome.

d. The disease is associated with an inability to produce a

________________________________________________ in blood.

e. Internal bleeding takes longer to stop.

36. The homozygous genotype (*) in females has a high

mortality.

37. The genotype ________________________ in males

has a high mortality.

38.

______________________________________________

is an example of a sex linked condition.

39. Red Green Color blindness is a

_____________________________________

condition.

40. The color blind allele is recessive to the normal allele.

41. Female homozygous recessives ____________________________ are color blind.

42. Males with the genotype __________________________________ are color blind.

43. Notice that in a population the probability of having a Red Green color blind genotype in males is

higher.

3.4 S.3 Analysis of pedigree charts to deduce the pattern of inheritance of genetic diseases.

44. Pedigree Chart: Another way to visualize a monohybrid crosses or determining a genotype is by using

a pedigree chart

45. Knowing the phenotype of individuals in a

family will sometimes allow

___________________________ to be

determined. In genetic counseling this

enables

_____________________________ to be determined for the inheritance of

____________________________________ in children.

46. White ____________________ : ________________________________ female

47. White ____________________: _________________________________ male

48. _________________________ Circle: ____________________________ female

49. _________________________ square: ____________________________ male

50. _____________ and ___________...normal parents

51. _____________ affected female

52. (4), (5), and (6) normal

1.

Phenylketonuria (PKU)

• Using the allele key provided state the genotype of parents 1 and 2?

• Give the genotype and phenotype of individual 5?

• Is it possible that the condition is sex linked?

• What is the genotype and phenotype of individuals 7 and 8?

• Which two individuals have the incorrect pedigree?

2. Muscular Dystrophy

• What type of genetic disease is muscular dystrophy?

• Give the genotype and phenotype of 1?

• Give the genotype and phenotype of 2?

• Give the genotype and phenotype of 8 ?

• Give the genotype and phenotype of 5 and 6 ?

3.4 A.3 Inheritance of cystic fibrosis and Huntington’s disease.

Cystic fibrosis (CF) – non sex-linked

_______________________ genetic

trait found on Chromosome __________

Example Cross

The couple below are heterozygous for CF.

Huntington’s disease - non sex-linked

_______________________ genetic trait.

The couple two couples below are examples

• Couple 1: 1 heterozygous (has trait)

with 1 homozygous (without the

trait)

• Couple 2: Both parents are

heterozygous with Huntington's

3.4 U.9 Radiation and mutagenic chemicals increase the mutation rate and can cause genetic diseases and

cancer.

54. A ________________________ is a physical (__________________________) or chemical agent like

________________________________, found in tobacco.

55. These mutagens change the genetic material, usually DNA, of an organism and

_________________________ the frequency of mutations above the natural background level.

56. Many mutations cause cancer, mutagens are therefore also likely to be carcinogens.

57. Radiation-induced cancers do not appear until at least _______________years after exposure (for

tumors) or 2 years after exposure (for leukemia).

58. The risk of cancer after exposure can extend beyond this latent period for the rest of a person’s life for

tumors or about 30 years for leukemia.

59. Risk is calculations are based on:

a. ___________________________________________________

b. Each type of radiation is different and affects tissues differently.

c. The ____________________________ that it leaves in the body.

d. More energy means a higher _____________________________ of an effect.

e. Where in the body the energy remains.

60. Radiation exposure to a non-sensitive area of the body (i.e., wrist) really has no actual effect. Radiation

exposure to a sensitive area of the body (i.e., blood-forming organs) can have an effect if the amount of

energy left is high enough.

61. ________________________________________________________

a. Water molecule is ionized, breaks apart, and forms OH free radical.

b. OH free radical contains an unpaired electron in the outer shell and is highly reactive: Reacts

with DNA.

c. 75 percent of radiation-caused DNA damage is due to OH free radical.

62. ________________________________________________________

a. DNA molecule is struck by radiation, ionized, resulting in damage.