What are genes?
Fundamental units of heredity located on chromosomes.
What are alleles?
Alternate forms of a gene on partner chromosomes.
What does homozygous mean?
Both alleles are the same (AA or aa).
What does heterozygous mean?
Alleles are different (Aa).
What is a dominant gene?
An allele that expresses itself and masks its recessive partner.
What is a recessive gene?
An allele whose expression is masked in the presence of a dominant allele.
What is a phenotype?
The physical expression of a trait.
What is a genotype?
The genetic makeup for a trait (allele combination).
What is diploid (2N)?
A full set of paired chromosomes (46 in humans).
What is haploid (1N)?
A single set of chromosomes in gametes (23 in humans)
What process produces diploid cells?
Mitosis.
What process produces haploid cells?
Meiosis.
Which parent determines the sex of a child?
The father (because sperm carry either X or Y).
What is dominance/recessive inheritance?
The phenotype of a heterozygote is determined by the dominant allele.
What is the genotype and phenotype of someone with “Mm” for skin pigmentation?
Normal pigmentation, heterozygous (carrier).
What is cystic fibrosis caused by?
A recessive gene that produces an abnormal chloride channel protein, leading to thick mucus.
What are sex-linked traits?
Traits carried on the X chromosome.
Why are sex-linked recessive traits more common in males?
Males have only one X chromosome, so the trait is expressed if present.
Example: Which sex can be carriers for colorblindness?
Females (heterozygous).
What is codominance?
When both alleles are equally expressed (e.g., AB blood type).
Which alleles are codominant in ABO blood types?
A and B.
Which allele is recessive in blood types?
O.
