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Mendell did what?
- created theory of inheritance
- used pea plants, controlled pollination
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Heritable Trait
A trait passed from parent to offspring
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True Breeding traits
observed trait that is the only one present throughout many generations
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Ressesive traits (lower case letter)
trait that dissapears for a generation then reappears
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Dominant Trait (capital letter)
Appears in the next generations
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reciprocal crosses
proves that each parent contributes genetic material equally
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Particulate Thoery
- Each plant has 2 genes for each character
- heritible units are discrete particles
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Genome
All genes in an organism
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Alleles
different forms of a gene
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Homozygous
individuals with 2 copies of the same allele
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Heterozygous
individuals with 2 different alleles
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phenotype
- physical apearance of an organism
- EX-spherical seeds, wrinkled seeds
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Genotype
- the genetic make up
- EX-SS, Ss, ss
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The Law of Segregation
- two copies of a geene seperate in reproduction
- EX- an Ss parent gives on S to one offspring and the s to the other
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Punnett Squares
- helps predict allele combinations
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Locus
- a site on a chromosome where the gene resides
- it encodes a particular character
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Test Crosses
- helps detirmine whether an individual is homozygous or heterozygous
- process-crossing an unknown individual with a homozygous recessive
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dihybrid cross
- crossing SsYy and SsYy
- Has 2 genes and are identical
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The law of independen assortment
- alleles of different genes assort independently during gamete formation
- *only applies to genes on different chromosomes*
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Probability
- If the event is certain probability=1
- If the event cannot happen probability=0
- All other events in between have probability between 0 and 1
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Mutation
rare, stable, inherited changes in the genetic material
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Wild type
allele present in most of population
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Polymorphic
locus with wild-type alleles present < 99% of the time
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incomplete dominance
alleles that are neither dominant or recessive
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Codominance
2 alleles at one locus producing phenotypes that are both present in the heterozygote
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Pleiotropic
a single allele that can have multiple phenotypic effects
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Epistasis
phenotypic expression of one gene being influenced by another
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Inbreeding
mating among close relatives
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heterosis
a cross between 2 different true breeding homozygotes resulting in stronger, larger phenotypes
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penetrance
proportion of individuals with a certain genotype that show the phenotype
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expressivity
degree in which genotype is expressed in an individual
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Quantitative trait loci
genes taht determine complex characters
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linkage group
formed by all of the loci in a chromosome group
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absolute linkage (rare)
genes at different loci on the same chromosome sometimes seperate
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recombinant frequencies
where recombinant offspring appear
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genetic maps
- can be made using recombinant frequencies
- shows the arrangement of genes along a chromosome
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distance between genes
Map unit (unit=centimorgan, cM)
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monoecious
- "one house"
- both male and female prodused from one
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dioecious
- "two houses"
- male and female produced by seperate individuals
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sex chromosome
- determines sex of an individual
- EX- XY, XX
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Autosomes
both sexes having 2 copies of all other chromosomes
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nondisjunction in sex chromosomes
- sister chromosomes fail to seperate in meiosis
- resullts in an abnormal amount of chromosomes
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Possible outcomes for nondisjunction in sex chromosomes
- X-turners syndrome
- XXY-klinefelter syndrome
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Primary sex determination
- Y chromosome encoded protien
- if present=male offspring
- not present=female offspring
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secondary sex determination
- results in outward characteristics of each sex (not detirmined directly by Y chromosome)
- determined by genese on autosomes and X chromosomes controlling hormones
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hemizygous
- males only have 1 copy
- -y chromosomes carry few genes
- -x chromosomes carry many genes
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sex-linked inheritance
a character is governed by loci on the sex chromosomes
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sex pilus
a projection that initiates contact between bacteria
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conjugation tube
cytoplasmic bridge that forms between cells
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plasmids
small circular chromosomes found in bacteria
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