(Ch 5 & 6) linkage + Chromosome variation Flashcards Preview

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Flashcards in (Ch 5 & 6) linkage + Chromosome variation Deck (26):
1

Genetic map

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

2

Linkage rule:

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

3

For any pair of linked genes, PARENTAL gametes are ALWAYS

MORE numerous than recombinant gametes

4

Rule in genetic mapping cross about parents

One parent is heterozygous for all loci under consideration.
The other parent is completely recessive

5

Rule in genetic mapping cross about genotype of offspring

Phenotype of the offspring must reflect its genotype.

6

Fragile sites leads to ________

Deletions

7

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

synapsis during meiosis --> allows meiosis to proceed

1) Duplications
2) Delitions

8

Tandem duplication

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

9

Unequal crossing-over may be the cause of _____________

some deletions / duplications

10

Effect of duplications

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.

11

Inversion heterozygotes
1) Definition:
2) Compensation
3) Trouble

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

12

Segmental duplications are likely responsible for the existence of ________

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

13

Gene families

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

14

Inversion heterozygotes lead to _______ _________

Reduced fertility

15

Fragile- X syndrome:
1) Repeat number increases when passed through ___________ _____________
2) Female penetrance _______ Male penetrance _______


CGG repeats near to the gene FMR-1 (fragile-X mental retardation)
1) Female germ-line
2) 30% 80%

16

Euploidy

Eu "true" ploidy "set.
Having a complete balanced sets of chromosomes

17

Aneuploidy

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

18

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

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

19

Nondisjunction

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

20

Trisomy in humans
1) Down syndrome
2) Patau syndrome
3) Edwards Syndrome

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

21

Nondisjunction has the most effect in ___

Mitosis of the cells of the early embryo

22

Polyploidy

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.

23

Odd-ploidies

are sterile and rarely found in nature.

24

1) Autopolyploidy

2) Autopolyploidy can arise from _________

1) is the addition of one or more extra monoploid SETS of chromosomes, identical to the existing sets.

2) nondisjunction in mitosis or meiosis

25

How to create an amphidiploid (fertile hybrid)

Use colchicine to duplicate the new hybrid

26

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

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.