Mutations And Karyotypes

Question 1

Point mutation

Answer 1

Point mutation

a type of genetic mutation that occurs when a cell fails to replicate a single nitrogenous base in the DNA sequence accurately during interphase of cell division

There are three types of point mutations:
1) Base pair substitution
2) insertion
2) Deletion

Question 2

Base pair substitution (type 1)

Answer 2

One nitrogenous base in the DNA sequence is replaced with a different one

Question 3

Insertion (type 2)

Answer 3

One or more nitrogenous bases are added to the DNA sequence is replaced

Question 4

Deletion (type 3)

Answer 4

One or more nitrogenous bases are deleted from the DNA sequence is replaced

Question 5

What diseases can you get from base per substitution?

Answer 5

Sickle cell anemia

Red blood cell have a sickled shape, which can lead to blood blockages in blood vessels

Question 6

What diseases can you get from insertion?

Answer 6

Beta thalassemia

The body produces less hemoglobin, which can lead to mild to severe anemia

Question 7

What diseases can you get from deletion

Answer 7

Cystic fibrosis

The build of excess mucus within the lungs and digestive tract, which can lead to death

Question 8

What is Nondisjunction Mutation? (Also known as abnormal meiosis)

Answer 8

Nonjunction is a type of mutation which occurs when a cell fails to separate homologous chromosomes during meiosis, which leads to daughter cells having either one extra or less chromosome

Question 9

How many chromosomes leads to Trisomy?

Answer 9

Trisomy:

gamete with 24 chromosome + gamete with 23 chromosomes = a zygote with 47 chromosomes (22 normal pairs + the pair that has three copies of one chromosome)

Question 10

How much chromosomes lead to monosomy

Answer 10

gamete with 22 chromosomes + gamete with 23 chromosomes = zygote with 45 chromosomes (22 normal pairs + one copy of one chromosome

Question 11

Characteristics of Trisomy 21 (Down Syndrome)

Answer 11

Down syndrome (Trisomy 21): an extra chromosome

○ Round/full face (face)
○ Almond shaped eyes (eyes)
○ Short stature (height)
○ large forehead (forehead)
○ Low muscle tone (muscle)
○ Developmental and intellectual delays (function)

Question 12

Characteristics of Turner Syndrome (Monosomy)

Answer 12

Monosomy (XO): only one X chromosome and no second sex chromosome

○ Short stature (height)
○ Broad chest (chest)
○ Low hairline (hairline)
○ Female in appearance (gender)
○ Do not mature sexually (are sterile) (reproduction)
○ Most do not make it to term (longevity)

Question 13

What are the characteristics of Klinefelter Syndrome (XXY)

Answer 13

Klinefelter Syndrome (XXY): a extra X chromosome is present, a type of trisomy

○ Effects males
○ Usually sterile
○ Delay in puberty
○ Some feminine body characteristics (often breast tissue)
○ Tall stature

Question 14

What are the characteristics of Patau Syndrome (trisomy 13)

Answer 14

Patau Syndrome (Trisomy 13): receive a extra chromosome 13 (3 copies)

○ Cleft palate or lip
○ Small head
○ Low ears on head
○ developmental issues with brain, kidneys and heart.
○ Child rarely lives more than a few months

Question 15

What are the characteristics of Edwards Syndrome (Trisomy 18)

Answer 15

Edward’s syndrome (trisomy 18): an extra chromosome 18 copy (three copies)

○ Most fetuses die before birth
○ Average life expectancy of live-born infants is less than one month.
○ Heart and lung abnormalities
○ Decreased muscle tone
○ Clubfeet
○ Overlapping fingers

Question 16

How is nondisjunction diagnosed

Answer 16

• Confirmed by karyotypes (a photograph)
• a photo of homologous chromosomes in a cell ordered from largest to smallest
• Cell are treated to stop at metaphase, which it’s then stained and photographed