EXAM 1 Flashcards
True breeding strain
A group of identical individuals that always produce offspring of the same phenotype mated with each other
Homozygous
Two identical alleles
Heterozygous
Two different alleles
Mitosis
Ends with two diploid cells
Only one cell division
Meiosis
Four haploid cells
Two cell divisions
Independent assortment
Genes on different chromosomes assort independently of each other
Dihybrid cross (two traits simultaneously)
9:3:3:1 ratio (9/16, 3/16, 3/16, 1/16)
Two point cross
1:1:1:1 ratio (1/4, 1/4, 1/4, 1/4)
Meiotic recombination
Makes haploid gametes with allele combinations different from parental gametes
Interphase
Cell grows and replicates it’s DNA preparing for cell division
G1 Phase
The growth phase
S Phase
The cell replicates it’s DNA
G2 Phase
Cell prepares for cell division
Phenotype
Observable characteristics of an organism
Genotype
The specific genetic makeup of an organism
Haplosufficiency
The wild type allele is dominant over a mutant allele
Incomplete Dominance
A form of haploinsufficiency where neither allele is completely dominant
Co-Dominance
Occurs when the contributions of both alleles are visible in the phenotype
Most affected by x-linked disorders
Males
Autosomal recessive
Affected individuals have unaffected parents
Autosomal dominant
Disease appears in every generation, affected individuals always have an affected parent
X-linked recessive
More males than females show the rare phenotype
No offspring of an affected male have the trait
Skips a generation does not show in every gen
X-linked dominant
Affected males pass trust to all daughters but no sons
Affected females pass trait to half of their daughters and half of their sons
Y-linked traits
Phenotype is only passed from father to son
Mitochondrial
Affected females always pass on the trait
Affected males never pass on the trait
Discrete trait
Can only take on certain fixed values ex: color, shape
Continuous trait
Can take any conceivable value within an observed range ex:weight,height,blood pressure
Complex inheritance
Traits take on a various range of values, Mendelian ratios are not detectable
Simple Inheritance
Traits are categories ex:purple flower white flower minimal environmental affect
Epistasis
Phenotype expression is affected by another gene onto another
Polyploid
More than two chromosome sets
Aneuploid
Individual has a chromosome number that is not an exact multiple of the haploid number
Law of segregation
Occurs during meiosis and produces gametes (one allele from each parent)
Wild-type allele
Most commonly occurring allele in a wild population (normal or without mutation)
sister chromatids
Two sister chromatids happens after replication
Homologous pair
Pair of chromosomes (one half from mom one from dad)
Haploinsufficieny
Gene is not enough to maintain normal cell function Ex: recessive wild type allele
Convergent evolution
Developing similar features independently
Divergent evolution
Eventually creates two different species from one closely related species ex: from isolation (deserted on an island)
Somatic cells
46 chromosomes TOTAL
Genetic Drift
Frequency of alleles changes over time
