Genetic Processes Flashcards

What is monosomy?

A chromosomal disorder where an individual has one copy of a chromosome instead of two (2n − 1).

What is trisomy?

A chromosomal disorder where an individual has three copies of a chromosome (2n + 1).

What usually causes monosomy and trisomy?

Nondisjunction during meiosis (chromosomes fail to separate).

What is a karyotype?

A picture/organization of an individual’s chromosomes arranged by size and shape.

Why are karyotypes used?

To detect chromosomal abnormalities like trisomy or monosomy.

What is the normal human chromosome number?

46 chromosomes (23 pairs).

What is amniocentesis?

A prenatal test where fluid around the fetus is sampled to detect genetic disorders.

What is chorionic villus sampling (CVS)?

A prenatal test using placental tissue to test for genetic abnormalities.

What is genetic screening?

Testing DNA or chromosomes to identify inherited disorders or risks.

What is the Law of Dominance?

Dominant alleles mask recessive alleles.

What is the Law of Segregation?

Allele pairs separate during gamete formation.

What is the Law of Independent Assortment?

Genes for different traits separate independently (if on different chromosomes).

What is a monohybrid cross?

A genetic cross involving one trait.

What is a dihybrid cross?

A genetic cross involving two traits.

What is genotype?

The genetic makeup (alleles) of an organism (AA, Aa, aa).

What is phenotype?

The observable trait (brown eyes, blue eyes).

What is a gene locus?

The specific location of a gene on a chromosome.

What is an allele?

Different versions of the same gene.

What is a test cross?

Crossing an unknown genotype with a homozygous recessive organism.

Why are test crosses used?

To determine if an organism with a dominant trait is AA or Aa.

What is incomplete dominance?

Neither allele is fully dominant, producing a blended phenotype.

What is sex-linkage?

Traits controlled by genes on the sex chromosomes, usually the X chromosome.

Why are males more affected by X-linked disorders?

Males have only one X chromosome, so recessive alleles are expressed.

What is a pedigree?

A family tree used to track inherited traits.

What is autosomal dominant inheritance?

One dominant allele causes the disorder.

Key pedigree clue for autosomal dominant?

Trait appears in every generation.

What is autosomal recessive inheritance?

Two recessive alleles are needed for expression.

Key pedigree clue for autosomal recessive?

Trait may skip generations.

What is X-linked dominant inheritance?

A dominant allele on the X chromosome causes the trait.

Father-to-son transmission?

No, fathers pass Y chromosome to sons.

What is X-linked recessive inheritance?

A recessive allele on the X chromosome causes the disorder.

What is nondisjunction?

Failure of chromosomes to separate during meiosis.

What can nondisjunction cause?

Chromosomal disorders like trisomy and monosomy.