LESSON 1: CHROMOSOMAL STRUCTURE & MUTATION

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the largest (246 million nucleotide bp)

Answer 2

Chromosome 1

Question 3

the smallest (48 million nucleotide bp)

Answer 3

Chromosome 2

Question 4

is a trait or group of traits resulting from the transcription and translation of these genes.

Answer 4

Phenotype

Question 5

is the DNA nucleotide sequence responsible for a phenotype.

Answer 5

Genotype

Question 6

3 CATEGORIES OF DNA MUTATION

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Gene Mutations
Chromosome Mutations
Genome Mutations

Question 7

affect single genes and are often, but not always, small changes in the DNA sequence.

Answer 7

Gene Mutations

Question 8

affect the structures of entire chromosomes; the movement of large chromosomal regions either within the same chromosome or to another chromosome.

Answer 8

Chromosome Mutations

Question 9

changes in the number of chromosomes

Answer 9

Genome Mutations

Question 10

a cell or cell population with a normal complement of chromosomes.

Answer 10

Euploid

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mostly observed as increased numbers of chromosomes or when there are more than two copies of one or more chromosomes.

Answer 11

Aneuploid

Question 12

a phenomenon that a gene inserted or moved into a different chromosomal location may be expressed differently than it was in its original position

Answer 12

Position effect

Question 13

a disease resulting from aneuploidy, where there are three copies or trisomy of chromosome 21

Answer 13

Down syndrome

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eight histone proteins

Answer 14

two each of H2a, H2b, H3, and H4

Question 15

Nucleosomes are visible by:

Answer 15

electron microscopy

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is the state of compaction of the DNA double helix that affects gene activity.

Answer 16

Chromosome topology

Question 17

is less available for RNA transcription.

Answer 17

Highly compacted DNA

Question 18

closed chromatin, or ____

Answer 18

heterochromatin

Question 19

open chromatin, or euchromatin____

Answer 19

euchromatin

Question 20

is the site of attachment of the chromosome to the spindle apparatus.

Answer 20

centromere

Question 21

CLASSIFICATION OF CHROMOSOMES

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Metacentric
Submetacentric
Acrocentric & Telocentric

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arms are approximately equal in length

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Metacentric

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one arm is longer than the other

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Submetacentric

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one arm is extremely small or missing

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Acrocentric & Telocentric

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are considered acrocentric but may be classified as subtelocentric.

Answer 25

Chromosomes 13 to 15, 21, and 22

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cytological stains used to visualize chromosomes.

Answer 26

Feulgen, Wright, and hematoxylin

Question 27

region specific staining of chromosomes by the use of silver nitrate to stain specifically the constricted regions, or stalks on the acrocentric chromosomes.

Answer 27

Nucleolar organizing region (NOR) staining

Question 28

stains chromosomes to detect mycoplasmal contamination in cell cultures; binds to the surface grooves of dsDNA and fluoresces blue under ultraviolet (UV) light (353- nm wavelength); also used to visualize chromosomes as well as whole nuclei

Answer 28

4′,6-diamidino-2-phenylindole (DAPI)

Question 29

give particularly intense staining of the human Y chromosome and are used to distinguish the Y chromosome in interphase nuclei.

Answer 29

Q bands

Question 30

stained by chemical dye (Giemsa) similar to those seen in Q banding; also produced by Feulgen staining after treatment with DNase I.

Answer 30

G banding

Question 31

pattern produced by harsher treatment of chromosomes (87°C for 10 min, then cooling to 70°C) before Giemsa staining which can also be visualized after staining with acridine orange.

Answer 31

R banding

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Alkali treatment of chromosomes results in centromere staining

Answer 32

C banding

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the “quiet” or poorly transcribed sequences along the chromosomes that are also present around centromeres.

Answer 33

heterochromatin

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which is relatively rich in gene activity, may not be stained as much as heterochromatin in C banding.

Answer 34

euchromatin

Question 35

Genetic Mapping: ‘CARBS’

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Chromosome Number, Chromosome Arm, Region, Band, Sub-band

Question 36

complete set of chromosomes in a cell.

Answer 36

karyotype

Question 37

is the direct observation of metaphase chromosome structure by arranging metaphase chromosomes according to size.

Answer 37

Karyotyping

Question 38

translocation results in no gain nor loss of chromosomal material, therefore, without phenotypic effects.

Answer 38

Balanced translocations

Question 39

occur when chromosomes are not properly assorted during meiosis affecting the phenotype of offspring

Answer 39

Unbalanced translocations

Question 40

involves the movement of the long arm of an acrocentric chromosome to the centromere of another acrocentric chromosome. (e.g. t(9;22) translocation known as Philadelphia chromosome)

Answer 40

Robertsonian translocation

Question 41

translocation in Chronic Myelogenous Leukemia 2

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t(8;21)

Question 42

translocation in Follicular Lymphoma

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t(14;18)

Question 43

translocation in Acute Promyelocytic Leukemia.

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t(15;17)

Question 44

is a gain of chromosomal material. The inserted sequences arise from duplication of particular regions within the affected chromosome or from fragments of other chromosomes

Answer 44

Insertion

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result from excision, flipping, and reconnecting chromosomal material within the same chromosome.

Answer 45

Inversions

Question 46

include the centromere in the inverted region,

Answer 46

Pericentric inversions

Question 47

involve sequences within one arm of the chromosome.

Answer 47

paracentric inversions

Question 48

is a metacentric chromosome that results from the transverse splitting of the centromere during cell division.

Answer 48

Isochromosome

Question 49

causes two long arms or two short arms to separate into daughter cells instead of normal chromosomes with one long arm and one short arm.

Answer 49

Transverse splitting

Question 50

results from the deletion of genetic regions from the ends of the chromosome and a joining of the ends to form a ring.

Answer 50

Ring chromosome

Question 51

consists of translocated or otherwise rearranged parts from two or more unidentified chromosomes joined to a normal chromosome.

Answer 51

Derivative chromosome

Question 52

normal karyotype is ____ in a female

Answer 52

46,XX

Question 53

normal karyotype is ____ in a male

Answer 53

46,XY

Question 54

karyotype showing 46,XX,del(7)(q13) denotes a ___ in the long arm (q) of chromosome 7 at region 1, band 3.

Answer 54

deletion

Question 55

karyotype showing 46,XY,t(5;17)(p13.3;p13) denotes a___ between the short arms p of chromosomes 5 and 17 and region 1, band 3, sub-band 3, and region 1, band 3, respectively.

Answer 55

translocation

Question 56

karyotype showing 47,XX + 21 is the karyotype of a female with ___ resulting from an extra chromosome

Answer 56

Down syndrome

Question 57

is caused by an extra X chromosome in males, for example, 47,XXY.

Answer 57

Klinefelter syndrome

Question 58

+

Answer 58

Gain

Question 59

-

Answer 59

Loss

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del

Answer 60

Deletion

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der

Answer 61

Derivative of Chromosomes

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dup

Answer 62

Duplication

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ins

Answer 63

Insertion

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inv

Answer 64

Inversion

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i,iso

Answer 65

isochromosome

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mat

Answer 66

Maternal Origin

Question 67

pat

Answer 67

Paternal Origin

Question 68

r

Answer 68

Ring Chromosome

Question 69

t

Answer 69

Translocation

Question 70

tel

Answer 70

Telomere (end of chromosome arm)