Gregor Mendel and Inheritance

These flashcards cover key concepts in genetics, focusing on Mendelian inheritance, genetic principles, and important experiments that shaped the field.

What did Gregor Mendel demonstrate about inheritance through his experiments with pea plants?

He demonstrated that hereditary traits follow specific laws.

What is the Law of Segregation according to Mendel?

Each organism carries two alleles for each trait, and these alleles separate during gamete formation.

What principle did Avery, McLeod, and McCarty demonstrate in 1944?

They showed that DNA is the 'transforming genetic principle' responsible for heredity.

What does Mendel's First Law state?

Mendel's First Law, or the Law of Segregation, states that allele pairs separate during gamete formation.

What is the phenotypic ratio produced by a monohybrid cross in Mendelian genetics?

The phenotypic ratio is typically 3:1 for dominant to recessive traits.

Which experiment is known for transforming non-pathogenic bacteria into pathogenic ones?

Griffith's transformation experiments.

Who proposed the chromosome theory of heredity and when?

Sutton and Boveri proposed the chromosome theory of heredity in 1902.

What does the term 'autosomal dominant' mean in genetics?

It refers to traits that are expressed in individuals who have either one or two copies of the dominant allele.

What are lethal alleles?

Lethal alleles are alleles that may cause the death of the organism when present in a homozygous state.

What is the significance of the year 1953 in genetics?

Watson and Crick proposed the double helix structure of DNA.

What is the genetic hypothesis proposed by Beadle and Tatum?

The 'one gene-one enzyme' hypothesis.

How do sex-linked traits differ between males and females?

Males have one X and one Y chromosome, while females have two X chromosomes, leading to different patterns of inheritance.

What role does X-inactivation play in females?

X-inactivation ensures that only one of the two X chromosomes in females is active, preventing gene dosage problems.

What does Mendel's Second Law, the Law of Independent Assortment, state?

It states that alleles of different genes assort independently of one another during gamete formation.

What observation led to the formulation of the concept of penetrance?

Penetrance refers to the proportion of individuals with a particular genotype that manifest the corresponding phenotype.

What genetic disorder is caused by a defect in the lamin A gene?

Hutchinson-Gilford progeria syndrome (HGPS).

What is sickle cell anemia, and what causes it?

Sickle cell anemia is a blood disorder caused by inheriting two abnormal genes that alter the shape of red blood cells.

What is the relationship between phenylketonuria (PKU) and the PAH gene?

PKU occurs due to mutations in the PAH gene that prevent the conversion of phenylalanine to tyrosine.

What is meant by genetic heterogeneity?

Genetic heterogeneity refers to the phenomenon where a single phenotype or disorder may be caused by different genetic factors.

What defines a true breeding organism?

A true breeding organism consistently passes down specific phenotypic traits to its offspring.

How many alleles does an individual possess for each autosomal trait?

An individual possesses two alleles for each autosomal trait.

What is the expected genotype ratio from a dihybrid cross?

The expected genotype ratio is 1:2:1.

What is the difference between homozygous and heterozygous?

Homozygous individuals have identical alleles for a trait, while heterozygous individuals have different alleles.

What are pedigree charts used for in genetics?

Pedigree charts are used to trace the inheritance patterns of traits through generations.

What does it mean for a trait to have expressivity?

Expressivity refers to the degree to which a genotype is expressed in a phenotype.

What is the importance of genome sequencing projects initiated in the 1990s?

These projects aim to sequence and analyze the human genome, aiding in understanding genetic diseases.