Genetics Exam 2 Flashcards
What is a dominant allele?
The allele that defines the phenotype of a heterozygous cell, e.g., brown pigment allele in an iris cell.
What is a recessive allele?
The allele that does not define the phenotype of a heterozygous cell, e.g., blue pigment allele in an iris cell.
What are telomeres?
Repetitive sequences found at the ends of a chromosome that shorten with each cell division.
What happens to telomeres over time?
They lose DNA and become shorter, leading to chromosome damage and cell senescence or apoptosis.
What is the function of centromeres?
The region where proteins bind to form a kinetochore, facilitating chromosome segregation during mitosis and meiosis.
What is telomerase?
The enzyme that extends the ends of chromosomes during replication, allowing full replication.
In which types of cells is telomerase typically active?
Stem cells and germ cells.
What is apoptosis?
A cell death process that eliminates old, unnecessary, or damaged cells.
What is a true breeding organism?
An organism that is homozygous for all the genes in its genome.
What is a monohybrid?
The offspring of a cross in which one trait is followed, e.g., height of a pea plant.
What is a dihybrid?
The offspring of a cross in which two traits are followed, e.g., color and shape of pea plant fruit.
What is a mutation?
Any heritable change in genetic material, ranging from a single nucleotide change to an entire chromosome change.
What is microevolution?
The outcome of selective pressures on a population over a relatively short period, e.g., antibiotic resistance.
What is mitosis?
The final stage of the cell cycle resulting in two genetically identical daughter cells.
What are sister chromatids?
Two chromosomes generated through the replication of a single chromosome during the Synthesis phase.
What is a loss of function mutation?
Any mutation that decreases the activity of the protein coded for by the affected gene.
What is a leaky loss of function mutation?
A mutation that decreases the activity of a protein but does not eliminate it.
What is a null loss of function mutation?
A mutation that eliminates the activity of a protein.
What is a gain of function mutation?
Any mutation that changes or increases the activity of the protein coded for by the affected gene.
What is selective pressure?
Environmental factors that favor certain traits, influencing survival and reproduction in populations.
What is negative (purifying) selective pressure?
An environmental factor that selects against a particular trait, leading to its elimination from a population.
What is positive selective pressure?
An environmental factor that selects for a particular trait, leading to its abundance in a population.
What is neutral selective pressure?
An environmental trait that does not select for or against a particular trait, maintaining its constancy.
