BioFlashcards_MidTerm2
(25 cards)
Pangenesis
Darwin’s belief that parents had tiny human organisms which accumulate in the sexual organs and when two get together, they made an offspring.
Lamarckian Inheritance of acquired characteristics
Characteristics from a parent is acquired by the offspring. However, not all characteristics are inheritable: bodybuilding, etc.
Blending Inheritance
The belief that offsprings acquire a characteristic which is a blend of both parent’s characteristics: pink snapdragons. However, generations following this presence of blending inheritance did not show blending inheritance at all.
Heredity
Study of how genetic composition of an organism and environment influences its physical appearance.
Genotype
An organism’s genetic composition made up of a pair of alleles at a locus.
Phenotype
The physical appearance of an organism, usually from the expression of its genes although not always so. (Ex: Temperature on cat fur)
Genes
The particles or factors (alleles) which is found on an organism’s DNA.
Locus
The physical location of a gene on a chromosome. (Plural = loci)
Genome
The entire combination of genes an organism has.
Homozygous
Having two of the same alleles at the same locus.
Heterozygous
Having two different alleles at the same locus.
Mendel’s First Law of Heredity
Law of Segregation: An individual produces haploid gametes (from its diploid cells) which only get one copy of a gene (one allele).
Mendel’s Second Law of Heredity
Independent Assortment: A gene passed on by a parent is independently assorted and passed on to the offspring.
Recombinant phenotypes
Phenotypic combinations that don’t match parental phenotypes.
Linkage
Some genes, whose locus is located on the same chromosome, form a linkage group and do not assort indepently.
Crossing Over and Recombination
During meiosis, genes recombine (during prophase I) by crossing over. The resulting chromatids become recombinant.
Polymorphic Loci
Loci where mutant alleles occur higher than 1% frequency.
Dominance/Recessive Genes
Genes usually have more than one allele. Some alleles are more dominant than others which result in that allele’s effect on phenotype rather than the recessive allele.
Multiple Alleles at a Locus
At a locus, there may be more than one allele which can create even more possible phenotypes.
Equation for Multiple Alleles
(n(n+1))/2 , n = number of alleles
Co-Dominance/Incomplete/Partial Dominance
When two different alleles can result in a phenotype that looks like a blend between the two genetic phenotypes. Ex: pink snapdragons
Pleiotropy
When a single allele has multiple phenotypic effects. Ex: Albino Siamese cats usually have crossed eyes
Epistasis
When the phenotypic expression of one gene is influenced by another gene. Ex: Labradors need the E (pigment disposition) gene to express the B or b gene for Black or Brown colored coat.
Environmental effects
When phenotypic expressions also depend on the environment: light, temperature, nutrition, etc. (Temp – Proteins denature, point-restricted colored furs)
