Variations in Chromosome Number 39-44

Question 1

What are Euploids?

Answer 1

number of complete sets of chromosomes present

Question 2

What are Aneuploids?

Answer 2

number of individual chromosomes

Question 3

What is ploidy?

Answer 3

number of sets

Question 4

What is somy?

Answer 4

number of copies of a particular chromosome
Trisomy 21 - 2 sets but 3 copies of chromosome 21

Question 5

What is polyploidy?

Answer 5

-more than 2 sets
-40% plants 70%-80% grasses
-some invertebrates

Question 6

What is Autopolyploid?

Answer 6

same species contributes to all chromosome sets
— Homologous

Question 7

What is Allopolyploid?

Answer 7

different species contribute chromosome sets
— Homeologous (partially homologous, may not pair during meiosis)

Question 8

When can Autopolyploids form?

Answer 8

-Increase in chromosome # happens during MEIOSIS when unreduced gametes are formed
-increase in chromosome # happens during MITOSIS through endoreduplication

Question 9

What are unreduced gametes?
What is endoreduplication?

Answer 9

happens most plants, specific muatations

mitosis where chromosomes replicate but cell doesn’t divide
soon after fertilization
mosaic individual but most cells tetraploid if endoreduplication very early after fertilization

Question 10

What is Autotroploid –> 3n

Answer 10

-Bananas, seedless watermelon
-sterile –> odd numbers means no even pairs during meiosis I
-no seeds
-propagated vegetatively

Question 11

What is Autotetraploid —> 4n

Answer 11

-peanut, potato
-fertile
-larger than diploids
more sets = bigger plant

Question 12

What are Allopolyploid?

Answer 12

-hybridization between different species
-endoreduplication gives plant cells 2 copies of each chromosome

Question 13

What is Aneuploidy and what phenotypic effects?

Answer 13

-loss of chromosome due to deletion of centromere or due to small size
-nondisjunction

phenotypic effects
–> lethality due to gene dosage effects
In humans, few aneuploids survive