(Ch 5 & 6) linkage + Chromosome variation

Question 1

Genetic map

Answer 1

Genetic maps are base on recombinant frequencies RF and are created using mapping crosses

Question 2

Linkage rule:

Answer 2

For any pair of linked genes, PARENTAL gametes are ALWAYS more numerous than recombinant gametes

Question 3

For any pair of linked genes, PARENTAL gametes are ALWAYS

Answer 3

MORE numerous than recombinant gametes

Question 4

Rule in genetic mapping cross about parents

Answer 4

One parent is heterozygous for all loci under consideration.

The other parent is completely recessive

Question 5

Rule in genetic mapping cross about genotype of offspring

Answer 5

Phenotype of the offspring must reflect its genotype.

Question 6

Fragile sites leads to ________

Answer 6

Deletions

Question 7

Compensation loops allows ________

Present in what type of variations that would Make viable embryos: 1) & 2)

Answer 7

synapsis during meiosis –> allows meiosis to proceed

1) Duplications
2) Delitions

Question 8

Tandem duplication

Answer 8

duplication of genes within the same region to give rise to the subsequent genes.

Question 9

Unequal crossing-over may be the cause of _____________

Answer 9

some deletions / duplications

Question 10

Effect of duplications

Answer 10

For some genes, having an extra copy may not cause any detectable problem. For others though, it can upset the carefully regulated interactions inside the cell, and create a problem.

Question 11

Inversion heterozygotes

1) Definition:
2) Compensation
3) Trouble

Answer 11

1) Is when one chromosome is normal and the homologue contains an inversion.
2) Then inversion loops form when the two chromosomes synapse. (Compensation loops)
3) Trouble occurs when a crossover occurs within the inversion loop region

Question 12

Segmental duplications are likely responsible for the existence of ________

Answer 12

Gene families: groups of genes with similar sequences whose products perform related (but not identical) functions.

Question 13

Gene families

Answer 13

groups of genes with similar sequences whose products perform related (but not identical) functions.

Question 14

Inversion heterozygotes lead to _______ _________

Answer 14

Reduced fertility

Question 15

Fragile- X syndrome:

1) Repeat number increases when passed through ___________ _____________
2) Female penetrance _______ Male penetrance _______

Answer 15

CGG repeats near to the gene FMR-1 (fragile-X mental retardation)

1) Female germ-line
2) 30% 80%

Question 16

Euploidy

Answer 16

Eu “true” ploidy “set.

Having a complete balanced sets of chromosomes

Question 17

Aneuploidy

Answer 17

Refers to the condition of gaining or losing a single chromosome, so that the chromosome sets are no longer balanced. Ex Nullisomy, monosomy, disomy.

Question 18

1) Nullisomy
2) Monosomy
3) Disomy
4) Trisomy
5) Tetrasomy

Answer 18

1) no copies of a specific chromosome
2) 1 copy of A chromosome in gametes is Normal. Abnormal if it is a somatic cell
3) 2 copies of A chromosome in somatic cells is Normal. Abnormal if it is in gametes.
4) 3 copies of A Chromosomes as in Patau +13 and Edwards +18
5) 4 copies fo chromosomes

Question 19

Nondisjunction

Answer 19

An error in which homologues or sister chromatids are not segregated correctly in anaphase I or II of meiosis.

Question 20

Trisomy in humans

1) Down syndrome
2) Patau syndrome
3) Edwards Syndrome

Answer 20

1) 47, XY or XX, +21
2) 47, XY or XX, +13
3) 47, XY or XX, +18

Question 21

Nondisjunction has the most effect in ___

Answer 21

Mitosis of the cells of the early embryo

Question 22

Polyploidy

Answer 22

named base on the number of complete sets: monoploid, diploid, triploid, tetraploid, pentaploid, etc.
Common in plants; also seen in lizards, amphibians, and fish, but incompatible with life in humans.

Question 23

Odd-ploidies

Answer 23

are sterile and rarely found in nature.

Question 24

1) Autopolyploidy

2) Autopolyploidy can arise from _________

Answer 24

1) is the addition of one or more extra monoploid SETS of chromosomes, identical to the existing sets.
2) nondisjunction in mitosis or meiosis

Question 25

How to create an amphidiploid (fertile hybrid)

Answer 25

Use colchicine to duplicate the new hybrid

Question 26

1) Polyploidy:
2) Autopolyploid:
3) Allopolyploid:

Answer 26

1) Is the presence of extra chromosome sets
2) posses extra chromosome sets from the same species.
3) posses extra chromosome sets from two or more species.