BIO 239 - midterm 1 Flashcards
(45 cards)
What is natural selection?
Individuals with certain traits are more likely to survive and reproduce, leading to those genes becoming more common in a population.
Environment chooses which genes will be passed on from generation to generation.
What is artificial selection?
Humans choose which animals or plants are bred to produce specific traits.
Example: Teosinte was artificially selected to create modern corn.
What is domestication syndrome?
Animals bred for behavioral traits exhibit similar physical characteristics.
Common traits include floppy ears, smaller tooth size, and prolonged juvenile behavior.
Who is Gregor Mendel?
An Austrian monk and plant breeder known as the father of genetics.
He used garden peas for his experiments.
Define pure-breeding lines.
Offspring have the same traits as the parents, resulting from inbreeding.
Example: Two purple flowered plants will produce only purple flowered offspring.
What is the difference between self-fertilization and cross-fertilization?
Self-fertilization uses pollen from the same flower, while cross-fertilization uses pollen from a different flower.
Both methods are used in breeding experiments.
What is a monohybrid cross?
Mating between individuals that differ in only one trait.
Example: Yellow (dominant) x Green (recessive) results in a 3:1 phenotype ratio.
What is phenotype?
Observable characteristics of an organism, largely determined by genotype.
Phenotype is often referred to as traits.
What is genotype?
The genetic makeup of an individual, describing the genetic information carried.
Genotype determines the phenotype of an organism.
Define allele.
Alternate forms of a single gene.
Alleles are discrete units of inheritance.
What is Mendel’s Law of Segregation?
During gamete formation, the two alleles for a trait separate so that each gamete carries only one allele.
This law describes how alleles of one gene behave.
What is the significance of polymorphic genes?
A gene that may have several alleles normally occurring in a population.
Example: Rabbit coat color can vary significantly.
What is a tetraploid?
An organism with four copies of every chromosome.
Example: Xenopus laevis frog.
What is a test cross?
A genetic cross used to determine the genotype of an individual showing a dominant trait by crossing it with a homozygous recessive organism.
Example: Crossing a purple flowered plant with a white flowered plant.
What is codominance?
Both alleles contribute visibly to the phenotype in a heterozygous individual.
Example: AB blood type expresses both A and B sugars.
What is incomplete dominance?
The heterozygous genotype results in a blended phenotype.
Example: RR (Red) × WW (White) results in RW (Pink).
Define pleiotropy.
One gene influences multiple, seemingly unrelated phenotypic traits in an organism.
Example: Sickle cell syndrome affects red blood cells and can lead to kidney failure.
What is a lethal allele?
A dominant or excessive allele that can kill the organism.
Example: The Agouti gene is recessive for lethality.
What is conditional lethality?
An allele is only lethal under certain conditions.
Example: An allele may allow survival in one environment but not another.
What is additive gene action?
Two or more genes that influence one trait, leading to a dominant phenotypic ratio.
Example: A dominant allele can overshadow a recessive allele.
What is complementary gene action?
Two different genes work together to produce a specific phenotype; both genes are necessary for the expression of a particular characteristic.
Typical phenotypic ratio is 9:7.
What does the ABO blood type system illustrate?
Multiple alleles exist for a single gene, with IA and IB being codominant over i.
Blood type O has antibodies against A and B, making it a universal donor.
What is a heterogenous trait?
A mutation at any one of a number of genes can give rise to the same phenotype.
What is complementation in genetics?
Mutation in two different genes.
