Genes & Alleles Flashcards
What is a gene?
A gene is a segment of DNA that contains the instructions for making a specific protein or set of proteins.
What are alleles?
Alleles are different versions of a gene that determine specific traits.
Define dominant allele.
A dominant allele is an allele that expresses its trait even in the presence of a recessive allele.
Define recessive allele.
A recessive allele is an allele that only expresses its trait when two copies are present.
True or False: A dominant allele can mask the presence of a recessive allele.
True
What is the genotype of an organism?
The genotype is the genetic makeup of an organism, specifically the alleles it possesses.
What is the phenotype of an organism?
The phenotype is the observable characteristics or traits of an organism.
Fill in the blank: The allele for brown eyes (B) is _____ to the allele for blue eyes (b).
dominant
If an organism has the genotype Bb, what will be the phenotype?
The phenotype will be brown eyes, as the dominant allele masks the recessive allele.
What does homozygous mean?
Homozygous means having two identical alleles for a trait.
What does heterozygous mean?
Heterozygous means having two different alleles for a trait.
Which genotype represents a recessive trait?
The genotype ‘bb’ represents a recessive trait.
True or False: An organism with genotype AA is homozygous.
True
What is a Punnett square used for?
A Punnett square is used to predict the genotypes and phenotypes of offspring from a genetic cross.
If a brown-eyed (Bb) and a blue-eyed (bb) parent breed, what is the probability of having a brown-eyed child?
50%
What is the symbol for a dominant allele?
A dominant allele is typically represented by a capital letter.
What is the symbol for a recessive allele?
A recessive allele is typically represented by a lowercase letter.
Fill in the blank: In humans, the allele for attached earlobes (e) is _____ to the allele for free earlobes (E).
recessive
What does it mean for a trait to be inherited?
It means that the trait is passed from parents to offspring through genes.
True or False: All traits are determined by a single gene.
False
What is an example of a trait that is controlled by multiple genes?
Height is an example of a trait controlled by multiple genes.
What is the term for different forms of a gene located at the same position on homologous chromosomes?
Alleles
If two parents are both heterozygous (Aa), what are the possible genotypes of their offspring?
AA, Aa, Aa, aa
True or False: A phenotype can be influenced by environmental factors.
True
