Unit 2.2.1

1. Explain what a differential diagnosis is. 

• A differential diagnosis is a list of possible diseases and disorders.

2. What are tumors and what causes them?

• A tumor is a lump or mass of cells caused by uncontrolled growth or cell division.

3. Explain what happens in each stage of the cell cycle:

   1. Interphase - DNA replicates so that there are two copies of each chromosome.

   2. Mitosis:

      1. Prophase - Chromosomes condense and are visible under a light microscope and pair with sister chromatids.  Spindle fibers form and the nuclear envelope disappears.

      2. Metaphase - Chromosomes line up at the center of the cell.  Fibers attach to each of the sister chromatids and will pull each chromatid to opposite poles of the cell.

      3. Anaphase - Each chromosome separates and the sister chromatids are pulled to the opposite poles of the cell.

      4. Telophase - The cleavage furrow forms and is prepared to split in two.

   3. Cytokinesis - Two Identical daughter cells are formed.

4. Define homologous chromosomes.

• chromosome pairs, one from each parent, having similar gene composition, size and structure.

5. Sketch a chromosome in prophase of mitosis. Label centromere and sister chromatids.

6. Describe the steps of DNA replication (semi-conservative replication).

• DNA replication is the copying and duplicating of DNA during interphase.  AN enzyme unzips the DNA into two strands and DNA is built according to the strand using base pairing rules using a DNA polymerase enzyme.  THe New DNA consists of one old and new strand.

7. Describe each of the following:

   1. Benign tumors - a tumor that is not cancerous and is generally considered harmless.

   2. Malignant tumors - a cancerous tumor that will grow and spread to invade other tissues and parts of the body.

   3. Cancer - a disease caused when cells divide uncontrollably and spread into other tissues.

   4. Metastasis - the spread of cancerous cells to other tissues or parts of the body.

8. What is a biopsy?

• the removal of cells or tissues from a patient's body using a needle, or scalpel. or other tools to study them more closely using a microscope.

9. What is the job of a pathologist?

• a medical professional who examines bodies, tissues, and fluid samples to look for changes and signs of disease.

10. What is the job of a cytopathologist?

• a pathologist who focuses on diagnosing disease at the cellular level.

11. Complete this table that compares normal and cancer cells 

12. What is Basal Cell Carcinoma?

• a type of skin cancer that originates in the epidermis of the skin

Unit 2.2.2

13. What are proteins?

• A 3D polymer made of amino acid monomers.  A protein's form and function are determined by a cell’s nucleic acid sequence.

14. Describe the functions of proteins

    1. Drive cellular reactions - digestion, breaking down foods and cell debris; biosynthesis, building cellular components such as DNA, RNA, and cell membranes.

    2. Provide defense - Defensive proteins such as antibodies, combat foreign invaders.

    3. Build structures - support proteins build structures such as collagen and elastin, as well as keratin.

    4. Transport materials - carry essential nutrients and gases through the body and cellular waste products for disposal.

    5. Coordinate cellular activities -  help maintain homeostasis, and regulate blood glucose levels.

    6. Movement - motor and contractile proteins such as actin and myosin found in muscles are used during cell division, help cells move.

15. On which chromosome is the NF1 gene found?

• The NF1 gene is found on chromosome 17.

16. What is the function of neurofibromin?

• a protein that reulates mitosis and works to prevent cells from growing at an uncontrolled way.

17. What is a gene?

• A sequence of nucleotides that codes for a protein resulting in a specific phenotype.

18. The building blocks of DNA are nitrogenous bases (A, T, C, and G), phosphate groups, and a sugar group.

19. Complete the table below

20. What is mRNA?

• A type of RNA that is transcribed from DNA and translated by ribosomes in the cytoplasm to produce proteins.

21. What is the name of the process that copies the information from DNA to mRNA and where does it occur in the cell?

• Transcription occurs in the nucleus

22. What is the name of the process that makes proteins and where does it occur in the cell?

• Translation, occurs in the cytoplasm

23. Complete the following table about transcription.

24. Complete the following table about translation.

25. What is a codon? 

    1. Each codon specifies only 1 amino acid

    2. Is there only one codon that codes for each amino acid?

• No, multiple codons can code for the same amino acid.

26. What is an anticodon?

• determines the amino acid that tRNA carries.

27. What is the start codon and what amino acid does it code for?

• AUG, methiamine

28. Describe the reading frame.

• sets of three consecutive bases beginning at the start codon.

29. What are Stop codons?

• don’t code anything, tell the ribosomes to stop coding

30. What does the sequence of nucleotides in a DNA molecule determine?

• the sequence of amino acids in protein synthesis

31. What is a mutation?

• a rare genetic material that ultimatelyly creates genetic diversity within a species.

32. What happens to a protein when there is a change to the sequence of DNA bases that make up a gene?

• A mutation in the gene sequence can cause the protein to no longer function, have reduced function, have increased function, and have a different function.

33. How do mutations arise?

• mutations arise when there is an alteration in the DNA sequence that makes up a gene.  Mutations often occur due to an error that occurs during cell division.

34. What is a silent mutation?

• the mutated cell doesn’t do any good or harm

35. Describe the 3 common categories of gene mutations:

    1. Substitutions - point mutation, replaces one base with another.  Ex: sickle cell and cystic fibrosis

    2. Insertions - frameshift mutation, adds a base into the sequence causing all the bases to move.

    3. Deletions - frameshift mutation - removes a base from the sequence causing all bases behind it to move up.

36. What is a point mutation?

• A point mutation is a mutation that only affects one base.

37. What type of mutation causes sickle cell disease and cystic fibrosis?

• Substitution

38. What is a frameshift mutation?

• A frameshift mutation shifts the reading frame used to make a protein.

39. What type of mutation would be more likely to produce a nonfunctional protein?

• Frameshift mutations because they affect multiple bases.

40. How do you reduce your risk of mutations?

• wearing protective clothing, and sunscreen, eating healthy, saying no to drugs

41. Sickle Cell Anemia:

    1. Hemoglobin is composed of 4 subunits.

    2. The 6^th codon of the functional hemoglobin subunit (HBB) is GAG which codes for the amino acid Glutamic Acid

    3. The 6^th codon of the dysfunctional HBB subunit is GUG which codes for the amino acid Valine  

    4. The sickle gene causes the blood cells to assume a sickle or crescent shape

42. What is DNA sequencing?

• a process that determines the order of DNA bases that compose our genes

43. What does a geneticists do?

• evaluate gene health

44. What are bioinformatics tools?

45. NF1:

    1. Symptoms - headaches, attention disorder, a learning disability, bone deformities, and high blood pressure

    2. Prognosis - If there are no complications, people with NF1 enjoy full active lives without problems.  They have an average life expectancy.

    3. Treatments - Although NF1 doesn’t necessarily cause any detrimental problems to one’s health, its tumors can be removed through chemotherapy, radiation, or surgery just like tumors from cancer.

Unit 2.2.3

46. Define genotype and provide an example.

• all or part of the genetic constitution of an individual or group

• Ex: Bb

47. Define phenotype and provide an example.

• the physical and physiological traits of an organism that are determined by the organisms genetic makeup.

• Ex: Brown

48. What are alleles?

• Any of the alternative forms of a gene that may occur at the same place on a chromosome

49. Is the neurofibromin gene dominant or recessive?

• dominant

50. Explain what a “carrier” is.

• a heterozygous individual, a person that has a recessive allele for a genetic trait but doesn’t display that trait.

51. Label the following with the correct term (word bank: dominant, heterozygous, recessive, homozygous dominant, phenotype, homozygous recessive):

    1. BB - homozygous dominant

    2. bb - homozygous recessive

    3. Bb - heterozygous

    4. B - dominant

    5. b - recessive

    6. brown hair - phenotype

52. What is a pedigree?

• a diagram that shows the occurrence of phenotypes through several generationss of genetically related individuals.

53. What do the following pedigree symbols mean?

54. What are the characteristics of a dominant pedigree?

• the disease will not skip a generation, the shapes will either be fully shaded or blank, no carriers.

55. What are the characteristics of a recessive pedigree?

• the disease may skip a generation, and there are carriers.

56. What are autosomes?

• chromosomes that are not directly involved in determining sex as opposed to the sex chromosomes X and Y.

57. What are sex chromosomes?

• A pair of chromosomes that determine the sex of an individual.  Males have the chromosomes XY.  Females have the chromosomes XX.

58. Describe an autosomal dominant inheritance pattern and provide an example.

• one mutated allele is sufficient to cause symptoms in the individual.  The mutated allele is considered dominant because of the disease traits that are experienced with one dysfunctional allele.

• Ex: NF1

59. Describe an autosomal recessive pattern and provide an example.

• Two mutated alleles are requiredd for the individual to experience disease symptoms.  If a patient inherits only one mutated allele, the other dominant allele compensates and the individual does not experience any symptoms.

• Ex: Sickle Cell Anemia

60. What is the result of a genetic cross (punnett square) between a mother with brown eyes (Bb) and a father with blue eyes (bb)? 

• 50% brown eyes

• 50% blue eyes

• none are homozygous dominant

• 50% homozygous recessive

• 50% heterozygous

61. What is the result of a genetic cross (punnett square) between a mother with one NF1 mutated allele and a normal father?

Unit 2.2.4

62. What are the products of endocrine glands?

• hormones

63. What are the functions of hormones?

• induces a specific effect on the activity of cells

64. Explain the hormones that primarily play a role in childhood growth:

    1. Human growth hormone - influences height, helps build bones and muscles.

    2. Insulin-like growth factor - manages the effects of growth hormone.

65. What does a cytogeneticist do?

• harvest cells from biological samples and prepare the cells to view under a microscope.

66. What is a chromosome spread?

• a visual display of chromosomes after they are released from their cells, stained, and spread onto a slide to be viewed under a microscope.

67. Explain the steps for preparing a chromosome spread.

• 1. Add cell sample to the culture media, a sterile solution that helps the cells grow.

• 2. Culture, or grow the cells in a lab, for up to two weeks.

• 3. Arrest, or halt, cells in metaphase. To get all the cells to this specific stage, the cells are treated with a chemical that stops cell division at that point.

• 4. Swell and drop cells onto microscope slides. Cells burst spreading out the chromosomes.

• 5. Stain with Giemsa dye and observe the chromosomes under a microscope.

68. Describe how the HeLa cell line was created.

• derived from cancer cells taken from Henrietta Lacks.

69. What is a karyotype?

• An image of the chromosome pairs of a cell arranged by size and shape.

70. How is a karyotype assembled?

• a chromosome spread is prepared and the chromosomes are stained, arranged, and numbered by size, from largest to smallest.

71. Which one is the smallest chromosome?

• chromosome 21

72. How do you know if a karyotype is of a male or a female?

• Male XY

• Female XX

73. Explain “chromosomal instability.”

• gaining or loosing whole chromosomes during mitosis

Unit 2.2.5

74. What is meiosis?

• a type of cell division that forms gametes.

75. How many chromosomes do our body cells contain?

• 46 chromosomes

76. How many chromosomes do our sex cells contain?

• 23 chromosomes

77. Describe the steps of meiosis.

• Interphase - DNA forms chromosomes

• Prophase I - chromosomes pair with homologous chromosomes

• Metaphase I - homologous chromosomes line up in the middle of the cell

• Anaphase I - homologous chromosomes are pulled apart to the opposite slides of the cell

• Telophase I - cleavage furrow is formed

• Cytokinesis - two new cells are formed

• Prophase II - individual chromosomes

• Metaphase II - chromosomes line up in the middle

• Anaphase II - chromosomes are pulled apart to opposite sides

• Telophase II 

• Cytokinesis II - four new cells are formed

78. Describe the differences between mitosis and meiosis.

• Mitosis pairs with sister chromatids, has diploid cells (2n), produces genetically identical daughter cells, takes place in somatic cells and only has one stage.

• Meiosis pairs with homologous chromosomes, is haploid (n), produces genetically unique daughter cells, takes place in sex cells, has two stages, and exchanges genetic info by crossing over in Metaphase I.

79. Explain nondisjunction and what the end result would be for each scenario:

    1. Nondisjunction of homologous chromosomes: nondisjunction in meiosis I causes two of the four cells to have two of the same chromosomes and the remaining cells to have none at all.

    2. Nondisjunction of sister chromatids: nondisjunction in meiosis II causes one of the four cells to have two of the same chromosomes and one of the four to only have one type of chromosome, the remaining two are normal.

80. What is monosomy?

• only one chromosome present

81. What is trisomy?

• three chromosomes are present

82. Complete the following table:

83. What are some sources of cells that can be used for human karyotyping?

• White blood cells from the blood

• Bone marrow

• Skin cells from biopsy

• swab of the cheek cells.

Unit 2.2.6

84. Describe Familial Hypercholesterolemia (FH).

• an autosomal dominant genetic disorder that disrupts the body's ability to eliminate LDL from the blood, resulting in an increased risk of heart attack.

85. How is FH inherited?

• FH is inherited through a mutation in chromosome 19 which is responsible for removing cholesterol from the blood stream.

86. What is a direct-to-consumer (DTC) gene testing?

• gene testing to determine predisposition.  DTC gene testing is now readily available and gene testing hits can be bought online or in stores.

87. What is the purpose of PCR?

• make a lot of copies of DNA really quickly

88. What are restriction enzymes?

• recognizes gene sequences and cuts the DNA at restriction sites

89. What are RFLPs? (HINT: Definition can be found in Activity 1.1.6)

• different sizes of DNA

90. Draw a pedigree to show a man who is heterozygous for FH marries a woman who is unaffected and have 3 children, two boys and one girl. The two boys are affected and the girl is not affected. Their daughter marries a man who is unaffected and they have a daughter.`