CHROMOSOMAL STRUCTURES

Question 1

A change in the order/sequence of nucleotide in DNA found in <1%-2% of a given population (due to errors in DNA replication, exposure to
mutagens, or other factors)

Answer 1

MUTATION

Question 2

• Agents of mutation

Answer 2

MUTAGENS

Question 3

A difference in DNA sequence found in 1%-2% or more of a given population
- Doesn’t take effect that much
- Example:
o Blood types in humans, color of hair and eyes, separation of most higher organisms into male and female sexes,
polymorphism used for human ID and paternity testing

Answer 3

POLYMORPHISM

Question 4

2 TYPES OF POLYMORPHISM

Answer 4

BALANCE & BENIGN POLYMORPHISM

Question 5

• Maintained a population through a balance of positive and
  negative phenotype
• Example:
  o Sickle cell anemia
  ▪ Abnormal RBC’s resulting into resistance to
  infection by Plasmodium species (malaria).
• Sickle cell is a hostile environment for
  plasmodium species

Answer 5

BALANCE POLYMORPHISM

Question 6

• Does not have any detectable negative effects on an organism’s health/fitness
• Typically common in populations, do not lead to disease or other adverse phenotypic outcomes
• Example:
  o Blood type (ABO blood groups), eye color, facial features,
  skin pigmentation

Answer 6

BENIGN POLYMORPHISM

Question 7

o Abnormal chromosome number
o Affect single genes and are often, but not always, small
changes in the DNA sequence

Answer 7

GENE MUTATION

Question 8

o Abnormal chromosome number
o Affect single genes and are often, but not always, small
changes in the DNA sequence

Answer 8

CHROMOSOME MUTATIONS

Question 9

• Process by which the long linear DNA molecules of eukaryotic chromosomes are organized and packaged into highly condensed structure.

Answer 9

CHROMOSOMAL COMPACT

Question 10

Protective cap
o Prevents the end from being damaged
- Regulate cell division

Answer 10

TELOMERES

Question 11

• Site of attachment for spindle fibers (anaphase/metaphase) during mitosis

Answer 11

CENTROMERE

Question 12

CLASSIFICATION OF CHROMOSOME BASED ON SIZE AND CENTROMERE POSITION

• Centromere located at the end

Answer 12

TELOCENTRIC

Question 12

CLASSIFICATION OF CHROMOSOME BASED ON SIZE AND CENTROMERE POSITION
- Centromere near the tip
- Satellite
o Contains many copies of gene encoding for RNA and
chromosomal proteins

Answer 12

ACROCENTRIC

Question 12

• Feulgen, Wright, and Hematoxylin

Answer 12

CONVENTIONAL CYTOLOGICAL STAIN

Question 13

CLASSIFICATION OF CHROMOSOME BASED ON SIZE AND CENTROMERE POSITION
- Centromere divides the chromosome into a short & long arm

Answer 13

SUBMETACENTRIC

Question 14

• Quinacrine and quinacrine mustard

Answer 14

FLUORESCENT DYES

Question 15

• Giemsa stain
• Pattern: G bands

Answer 15

CHEMICAL DYE

Question 16

• Pattern: R bands (can be visualized after staining with acridine
  orange)

Answer 16

Harsher treatment of chromosomes (87oC for 10 min, then cooling to70oC) before Giemsa staining

Question 17

Centromere staining
* Pattern: C bands

Answer 17

ALKALI TREATMENT

Question 18

• Silver nitrate
  o Stain specifically at the constricted regions, or stalks, on
  the acrocentric chromosomes

Answer 18

NUCLEAR ORGANIZING REGION (NOR) STAINING

Question 19

• Indirect method of detecting genome mutations, or aneuploidy
• Measuring DNA content of individual cells
• Aneuploidy is reflected by a change in the amount of DNA

Answer 19

FLOW CYTOMETRY

Question 19

• Binds to the surface grooves of dsDNA
• Fluorescence blue under UV light
• Chromosome & nucleus → more visualized
• Used mostly in FISH
• Microscope: Fluorescence

Answer 19

4’6-DIAMIDINO-2-PHENYLINDONE

Question 19

• Exchange of genetic material between chromosomes

Answer 19

TRANSLOCATION

Question 19

TYPES OF TRANSLOCATION :

Answer 19

RECIPROCAL & ROBERTSONIAN

Question 20

• Direct method of detecting genome mutations, an aneuploidy
  → observation of metaphase chromosome structure by
  arranging them according to size.

Answer 20

KARYOTYPING

Question 21

• Loss of chromosomal material

Answer 21

DELETION

Question 22

• Gain of chromosomal material

Answer 22

INSERTION

Question 23

• Results from deletion of genetic regions from ends of the
  chromosome and a joining of the ends to farm a ring
• Sticky ends
• Affect the kids mostly
  o Microcephaly
  ▪ Smaller brain size

Answer 23

RING CHROMOSOME

Question 24

• Metacentric chromosome resulting from transverse splitting of
  centromere during cell division

Answer 24

ISOCHROMOSOME

Question 24

• Result from excision, flipping, and reconnecting chromosomal material within the same chromosome

Answer 24

INVERSION

Question 25

• Translocated or otherwise rearranged parts from 2 or more
  unidentified chromosomes joined to a normal chromosome

Answer 25

DERIVATIVE CHROMOSOMES

Question 25

Example 1: 46, XX, del (7)(q13)

Answer 25

A female with deletion in the long arm of chromosome
7 at region 1, band 3

Question 25

Example 2: 47, XX, + 21

Answer 25

A female with trisomy 21 (Down Syndrome)

Question 25

Example 3: 46, XY, t(5:17)(p13.3:p13)

Answer 25

▪ A male with a translocation between the short arms of
chromosome 5 & 7 at region 1, band 3, sub-band 3,
and region 1, band 3, respectively.

Question 26

• Does not include centromere
• Involve sequences within 1 arm of the
  chromosome

Answer 26

PARACENTRIC INVERSION

Question 27

Include centromere in the inverted
region

Answer 27

PERICENTRIC INVERSION