What happens when pollen fertilizes an egg cell?
A seed for a new plant is born
What is genetics?
The scientific study of heredity
What does the phrase true-breeding mean?
If a plant is allowed to self-pollinate, it will produce offspring identical to itself
How did Mendel prevent plants from self-pollinating?
He cut away parts that produce pollen and dusted pollen from one plant to another
What are specific characteristics that vary from one individual to another?
Traits
What are genes?
Chemical factors that determine traits
What are the offspring crosses between parents with different traits called?
Hybrids
What are alleles?
The different forms of a gene
What does the principle of dominance mean?
Some alleles are dominant while others are recessive
True or false: In Mendel’s pea plants, tall and yellow were controlled by dominant alleles.
True
About how many of Mendel’s F2 generation showed a recessive trait?
1/4
What are gametes?
Sex cells that, when produced, cause a segregation of a dominant and recessive allele
What is probability?
The likelihood that something will occur
True or false: Alleles do not segregate randomly.
False
How do geneticists use Punnett squares?
To predict and compare the genetic variations that will result from a cross
What is the difference between genotype and phenotype?
Genotype is the genetic makeup of an organism while phenotype is the physical characteristics
What does it mean when a plant is homozygous or heterozygous?
A homozygous plant have two identical alleles for a particular trait while a heterozygous plant has two different alleles for the same trait
True or false: Homozygous organisms are true-breeding for a particular trait.
True
What was the genotype for Mendel’s true-breeding round yellow peas?
RRYY
True or false: Mendel observed that genes segregate independently in the F2 generation.
True
What was Mendel’s principle of independent assortment?
Genes for different traits can segregate independently during the formation of gametes
What happens in incomplete dominance?
One allele is not completely dominant over another
What happens during codominance?
Both alleles contribute to the phenotype of the organism.
What three criteria was Thomas Hunt Morgan looking for in a model organism for genetic studies?
Small
Easy to keep in a laboratory
Able to produce lots of offspring in little time
What two factors determine an organism’s characteristics?
Genes
Interaction with the environment
What does it mean when two sets of chromosomes are homologous?
Each chromosome from the female parent corresponds with the male parent
What does 2N stand for?
A diploid cell
Why is meiosis described as the process of reduction division?
The number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell
What are the two distinct divisions of meiosis called?
Meiosis I and Meiosis II
How many chromatids are in a tetrad?
4
What results from the process of crossing-over?
The exchange of alleles between homologous chromosomes and produces new combinations of alleles
What are the four phases of meiosis?
Prophase
Metaphase
Anaphase
Telophase
True or false: Sperm and egg gametes are diploid cells.
False (haploid)
What are polar bodies?
Cells produced in females that do not produce in reproduction
True or false: Meiosis begins with a diploid cell and produces two genetically identical diploid cells.
True
True or false: Thomas Hunt Morgan discovered that all genes follow the principle of independent assortment.
False
What two conclusions did Morgan make about genes and chromosomes?
Each chromosome is actually a group of linked genes
Mendel’s principle of independent assortment still holds true
What process sometimes separates linked genes?
Crossing-over
True or false: Crossing over limits genetic diversity
False
True or false: Genes that are closer are more likely to be separated by a crossover event in meiosis.
False
What is a gene map?
A diagram that shows the relative location of each new gene