Term
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Definition
| formed from all loci on a chromosome |
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Term
| Morgan's Experiment with fruit flies |
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Definition
Hypothesis: alleles for different characteristics always assort independently
Method:Female, wild type, gray body, normal winds mate with male, black body,vestigial wings.
Results: Actual results were inconsistent with Mendel's 2nd law of segregation.
Conclusion:hypothesis rejected. The 2 genes don't assort independently but are linked on the same chromosome |
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Term
| Review: What's Mendel's 2nd law of segregation? |
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Definition
| Alleles of different genes assort independently of one another during gamete formation. |
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Term
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Definition
Genes that don't assort completely independently (50%) are linked
These genes travel together on a chromosome |
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Term
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Definition
is rare
genes at different loci on the same chromosome do sometimes separate
Genes may recombine during prophase I of meiosis by crossing over.
Chromosomes exchange corresponding segments. The exchange involves 2 chromatids in tetrad
Both chromatids become recombinant. |
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Term
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Definition
= # of recombinant offspring/ total # of offspring
recombinant offspring phenotypes appear in recombinant frequencies
is greater for loci that are farther apart
Can be used to make genetic maps |
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Term
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Definition
| shows arrangement of genes along a chromosome |
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Term
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Definition
distance between genes
=recombinant frequency of 0.01
Also called centimorgan (cM) |
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Term
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Definition
= a character is governed by loci on the sex chromosomes
In animals, sex determined by 1 or a pair of sex chromosomes
sex of offspring depends on which chromosome fertilizes the egg.
Genes on sex chromosomes don't follow Mendelian patterns.
Y chromosome carries few genes
X chromosome carries many |
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Term
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Definition
| both sexes have 2 copies of all other chromosomes |
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Term
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Definition
| Males have only one copy of these genes |
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Term
| X-linked recessive phenotypes |
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Definition
Appear much more often in males than females.
Carriers
Mutant phenotype can skip a generation if it passes from a male to his daughter. |
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Term
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Definition
| Daughters who are heterozygous |
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