Chromosome Inheritance Session 20

Question 1

How are microtubules assembled ?

Answer 1

1, Building blocks are alpha and beta tubules monomers which assemble as heterodimers
2. These tubules heterodimers then form linear protofilaments with alpha on the - side and beta on the + side
3. Thirteen Protofilametns assemble into hollow cylinders to form microtubules .

Question 2

What are motor protein kinesis and dynein transport responsible for ?

Answer 2

• For sliding of different filaments

Question 3

What are the three different type of microtubules during cell divisions ?

Answer 3

• Astral (aster) microtubules
• Interpolar microtubules
• Kinetochore microtubules

Question 4

What are kinetochores and what do they do?

Answer 4

• They are disc shaped complexes protein structures associated with duplicated chromatids.
• They are where the spindle fibers attach during cell division to pull sister chromatids apart.

Question 5

What are the different configurations of spindle attachment to sister chromatids that may occur?

Answer 5

• Amphitelic : Both Chromatids anchored to their respective pole.
• Monotelic : Only one of the chromatids anchored to microtubules and the other isn’t
• Syntelic : Both chromatids are anchored to the same microtubule
• Merotelic : both chromatids are anchored but one of them is anchored to both sides

Question 6

What is a trisomy and a monosomy?

Answer 6

• Trisomy : One type of chromosome is present in three copies (2n+1)
• Monosomy : One type of chromosome is present in a single copy (2n-1)

Question 7

What is a barr body?

Answer 7

• It is one of the X chromosomes in females that is inactive, also known as Heterochromatin

Question 8

What is the Turner Syndrome ?

Answer 8

• it is a syndrome that occurs when only 45 chromosomes are present and the femlae only has one X chromosome (XO)
• females with the syndrome are usually short with a broad chest and underdeveloped reproductive system and do not go through puberty

Question 9

What is the Jacob Syndrome?

Answer 9

• Its when the male has an extra Y chromosome (XYY)

Question 10

What gene produces the testis determining factor that is important for development of male sex organs ?

Answer 10

• SRY gene

Question 11

What is the Klinefelter syndrome and what effect does it have ?

Answer 11

• This is when the male has two X chromosomes (XXY)
• they will require assistance to father children
• receive testosterone supplements at the beginning of puberty

Question 12

What are Poly-X females and what effect does it have?

Answer 12

• this is when females have more than two X chromosomes and extra barr body
• no appearance difference aside from being tall and thin

Question 13

What are some factors that can cause chromosome break?

Answer 13

• Radiation
• Organic chemicals
• Viruses

Question 14

What are some changes that can occur in chromosome structure?

Answer 14

• deletion : part of chromosome breaks off
• duplication : the presence of ca chromosomal segment more than once in the same chromosome
• inversions : A segment of a chromosome is inverted
• translocations : the movement of a segment from one chromosome to another nonhomologous chromosome.

Question 15

How does William syndrome occur and what are some side effects ?

Answer 15

• it occurs because of deletion , chromosome 7 loses an end piece
• Turned up nose , wide mouth , small chin and large ears.