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35 Cards in this Set
- Front
- Back
Chromosomes
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- composed of DNA & proteins
- each chromosome consists of hundreds of structural & functional subunits called genes - A gene is a sequence of nucleotides in a DNA molecule that contains coded info for making a specific protein (usually an enzyme) - enzymes in particular determine an individual's observable physical traits of characteristics |
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Gregor Mendel
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- 1822
- father of genetics - experiments with heredity (passage of traits from one generation to the next) |
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Common Garden Pea
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- mendel used it because:
- its commercially available - easy to cultivate - grows rapidly |
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True Breeding
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- some pea plants, if allowed to self-pollinate will consistently produce the same characteristics over and over again.
- ex: if mendel allowed purple plants to self pollinate, they would produce nothing but purple plants (true breeding) |
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Chromosomes
|
- composed of DNA & proteins
- each chromosome consists of hundreds of structural & functional subunits called genes - A gene is a sequence of nucleotides in a DNA molecule that contains coded info for making a specific protein (usually an enzyme) - enzymes in particular determine an individual's observable physical traits of characteristics |
|
Gregor Mendel
|
- 1822
- father of genetics - experiments with heredity (passage of traits from one generation to the next) |
|
Common Garden Pea
|
- mendel used it because:
- its commercially available - easy to cultivate - grows rapidly |
|
True Breeding
|
- some pea plants, if allowed to self-pollinate will consistently produce the same characteristics over and over again.
- ex: if mendel allowed purple plants to self pollinate, they would produce nothing but purple plants (true breeding) |
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P Generation
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- original parent generation
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F1 Generation
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- the 1st generation of offpspring ["filial"<??(L)=son/daughter]
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Dominant Trait
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the characteristic that appears in the F1 generation
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F2 Generation
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- the 2nd generation of offspring (resulting from a cross between 2 members of the F1 generation)
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Recessive Trait
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- the trait that disappears in the F1 generation, but reappears in the F2 generation
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Alleles
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- different (alternative) molecular forms of a gene that occupy the same locus (position ) on a a pair of homologous chromosomes.
- all alleles are genes, but not all genes are alleles |
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Principle of Segregation
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- every individual carries a pair of alleles for each trait & members of the pair segregate during the formation of gametes (sex cells)
- meiosis - mendel's 1st law |
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Homozygous
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- refers to a pair of identical alleles
- both will be expressed - if 2 alleles are identical, both traits will be expressed |
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Heterozygous
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- refers to a pair of non-identical alleles
- one allele may be dominant over the other & the organism will appear as if it only had the dominant allele |
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Phenotype
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- the outward appearance of a trait; an individual's observable traits
- ex: purple flowered plant= phenotype |
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Genotype
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- the actual genetic makeup of a trait
- the genes present in an individual - each allele still exists independently & as a discrete unit, even though it may not be expressed in the phenotype |
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Punnett Square
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- predicts the possible genotypes (gene make up) and phenotypes (outward appearance) of the offspring and their expected ratios.
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Test Cross
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- a cross between 2 individuals-one with a dominant phenotype (the unknown) for a given trait, & one that is homozygous recessive for a given trait
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Monohybrid Cross
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- one that involves the transmission of only 1 trait or characteristic>through the alleles
- F2 3:1 ratio |
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Dihybrid Cross
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- one that involves the transmission of 2 traits (or characteristics) simultaneously
- F2 9:3:3:1 ratio |
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Principle of Independent Assortment
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- states that members of each pair of alleles are distributed independently when gametes (sex cells) are formed
- also known as mendel's 2nd law - a lot of exceptations |
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gene interactions- the effects of genes are influenced by:
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- their alleles (incomplete dominance & co-dominance) and their environment
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incomplete dominance
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- the heterozygous individuals (have non-identical alleles) of the F1 generation show effects of both alleles
- the F1 offspring have a phenotype different from both parents - the F2 phenotypic ratio is 1:2:1 (rather than the 3:1 as occurs in complete dominance) |
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Codominance
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- both alleles are expressed simultaneously & so are unmodified in the heterozygous individual .
- ex: ABO blood group antigens (recognition markers found on the surface of RBCs) - 3 alleles: IA, IB,i |
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multiple alleles
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-the presence of 3 or more alleles in a population for a single trait.
- ex: ABO blood groups |
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Environment
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- the phenotype (outward appearance) of any organism is the result of interaction between its genes and the environment
- ex: a seedling & the sun, temperature & the arctic fox. - the genes of the fox are the same, just the phenotype has changed - ex: seed has genetic capacity to be green in photosynthesis, but if kept in dark, won't turn green |
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Mutation
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- any relative stable, heritable change in the genetic material. at the molecular level, a mutation is a change of 1 to several bases in the nucleotide (4) sequence.
- the rate at which any one gene undergoes mutation is very low (the rate of spontaneous mutations average 1/million replications) - vast majority of mutations are deleterious (harmful) - when 2 heterozygous parents with same deleterious recessive trait mate, they have higher chance of getting child with the gene. |
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Mutant
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- any organism exhibiting changes or mutations
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Mutagen
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- any agent producing mutations. ex: something radioactive
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Lethal
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- an allele whose pheotype, when expressed results in the death of the organism
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Pleiotrophy
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- the capacity of a gene to effect a number of different phenotypic characteristics
- ex: gene for sickle cell anemia |
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Polygenic Inheritance
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- refers to the fact that a single trait is often affected by many genes
- ex: human eye color, skin color, height because your parents give you the genes they have |