Life Science: Genetics Flashcards
What are the 3 Mendel’s Laws?
- Law of Segregation
- Law of Independent Assortment
- Law of Dominance
Q: What is a Genotype?
A: A Genotype is a DNA sequence that carries an allele for a trait.
Q: What is a Phenotype?
A: A Phenotype is a physical characteristic that can be observed.
Q: What is a Dominant allele?
A: A dominant allele is the phenotype that is expressed over the recessive allele.
Q: What is a Recessive allele?
A: A Recessive allele is a phenotype that will only be expressed if both recessive alleles are on the homologous chromosomes.
Q: Describe a Homozygous Dominant chromosome.
A: A homozygous dominant contains two dominant alleles.
Ex: AA
Q: Describe a Heterozygous chromosome.
A: A heterozygous chromosome contains both a dominant & recessive allele. Ex: Aa
Q: Describe a Homozygous Recessive chromosome
A: A homozygous recessive chromosome contains two recessive alleles. Ex: aa
Name the three ways that lead to genetic variation
- Random Fertilization (random combo of sperm and egg)
- Independent assortment during Meiosis I (metaphase I; shuffles whole chromosomes)
- Crossing over during meiosis I (prophase I; shuffles segments of chromosomes)
How does random fertilization lead to genetic variation?
A zygote is a combination of the DNA of two different people.
How does independent assortment lead to genetic variation?
Each gamete contains a unique set of gene from the parent.
How does crossing over lead to genetic variation?
Homologous chromosomes swap DNA with one another, meaning that is gamete is genetically unique.
A plant has a gene for flower color where the flower can be either red or white. The red color is dominant and white is recessive. Two heterozygous plants are crossed. What percentage of offspring will have a homozygous dominant genotype?
25%
The blood groups A and B are both dominant for the same allele. Which of the non-Mendelian inheritance does this represent?
Codominance
Which mechanism of evolutions specifies that species change over time in response to their environment?
Natural selection
Under which conditions would Mendel’s law not apply?
PIGS C
- Polygenic traits
- Incomplete dominance
- Gene linkage
- Sex-linked genes
- Codominance
______ is described as changes in a population and species over time.
Evolution
When would a dihybrid cross be utilized?
Used for two individuals that differ in two traits of interest.
- Ex: AaBb x AaBb
What are polygenic traits? provide an example of polygenic traits.
Traits that are influenced by multiple genes rather than a single gene
- Ex: Skin color, Height
What is gene linkage?
Genes located close to each other on the same chromosome are inherited together during meiosis, affecting inheritance patterns
What is codominance? provide an example of codominance.
non-Mendelian genetics where two or more alleles can be dominant, and both expressed., resulting in a phenotype that shows both traits
- Ex: AB blood type
What is incomplete dominance? provide an example of incomplete dominance
non-Mendelian genetics where heterozygous genotype leads to a mixed phenotype
-> Ex: Homozygous Dominant red flower (RR) and Homozygous recessive (rr) white flower create a heterozygous flower that is pink.
what are sex-linked genes? Provide an example of sex-linked genes.
non-Mendelian genetics where genes are located on sex chromosomes that are inherited differently in males and females, leading to ex-linked traits and disorders.
When would non-mendelian inheritance patterns occur?
They would occur when there are factors other than dominant & recessive traits.
