Chromosome Mutations

Question 1

Chromosomal aberrations

Answer 1

Change from normal chromosome structure and #
Change in gene expression pattern
Detectable through karyotyping

Question 2

Commonality of mutations

Answer 2

6/1000 live birth have some sort of mutation
Still births and miscarriages often result from mutations (embryonic lethal)
Often cause mental/developmental disorders and infertility

Question 3

Euploid

Answer 3

Number of chromosomes in individual’s cells is a multiple of the normal haploid set

Question 4

Aneuploid

Answer 4

Number of chromosomes in individual’s cells isn’t a multiple of the normal haploid set
1 or more extra or missing chromosomes

Question 5

Nullisomy

Answer 5

Both homologous chromosomes are absent

Embryonic lethal

Question 6

Monosomy

Answer 6

1 chromosome is missing

Question 7

Trisomy

Answer 7

1 extra chromosome

Question 8

Tetrasomy

Answer 8

2 extra chromosomes

Common in cancer patients

Question 9

Nondisjunction

Answer 9

Homologous chromosomes during anaphase I or sister chromatids during anaphase II don’t separate properly

Question 10

Trisomy 21 and advanced maternal age

Answer 10

As women age, Down syndrome becomes more common
Women’s eggs get older with age (women are born with all the eggs that they are going to have) and DNA damage accumulates

Question 11

Monoploidy

Answer 11

1 complete set of chromosomes

Question 12

Diploidy

Answer 12

2 complete sets of chromosomes

Question 13

Polyploidy

Answer 13

More than 2 complete sets of chromosomes

Question 14

Autopolyploidy

Answer 14

Extra set of chromosomes is identical to the normal haploid set

Question 15

Allopolyploidy

Answer 15

Chromosomes come from 2 different species to produce a hybrid

Question 16

Endopolyploidy

Answer 16

Only certain cells of an organism are polyploid

Ex- liver cells in humans

Question 17

Deletion

Answer 17

Missing part of chromosome

Question 18

Terminal deletion

Answer 18

Deletion of the end of a chromosome

Question 19

Intercalary deletion

Answer 19

Portion of chromosome forms loop and breaks off of chromosome

Question 20

Formation of deletion loop

Answer 20

Occurs during synapsis of a normal chromosome and a deleted one
During synapsis, part of chromosome that is missing in other one bows out (deletion loop)

Question 21

Consequence of deleting a recessive allele

Answer 21

Normal dominant phenotype

Question 22

Pseudodominance

Answer 22

Deletion of a dominant allele causes unmasking of a recessive allele

Question 23

Haploinsufficiency caused by deletion

Answer 23

Deletion reduces gene dosage

Question 24

Acentric chromosome caused by deletion

Answer 24

Deletion removes centromere

Nondisjunction results during meiosis

Question 25

Duplication

Answer 25

Doubling of part of chromosome

Question 26

Results of unequal crossover

Answer 26

2 normal chromatids 1 chromatid with duplication 1 chromatid with deletion

Question 27

Consequences of duplication

Answer 27

1. Synapsis between chromosome with duplication and normal chromosome: chromosome with duplication forms deletion loop, causing it to revert to normal 2. Gene amplification: more gene product

Question 28

Multigene family

Answer 28

Multiple genes with related functions near each other on the same chromosome Can be result of duplication

Question 29

Paralogs

Answer 29

2 or more genes in an organism that have similar or identical function Result of duplication

Question 30

Ortholog

Answer 30

2 or more different genes in 2 different organisms that have the same or similar function Result of speciation

Question 31

Inversion

Answer 31

Segment of chromosome is taken out and re-inserted backwards

Question 32

Paracentric inversion

Answer 32

Doesn't include centromere

Question 33

Pericentric inversion

Answer 33

Includes centromere

Question 34

How an inversion might happen

Answer 34

Deletion loop forms, breaks off from the chromosome, and then rejoins with the chromosome, resulting in an inverted sequence

Question 35

Consequences of inversions

Answer 35

1. Inversion loops during synapsis: possible deletions and duplications 2. Position effect: inversion can cause genes to be placed next to more active or less active portions of DNA, changing expression

Question 36

Translocations

Answer 36

Piece of 1 chromosome is placed onto another chromosome

Question 37

Fragile sites

Answer 37

Narrow sites of some chromosomes | Prone to breakage