GENETICS (NOTES)

What technique did Mendel use for cross-pollination in his experiments?

Mendel used cross-pollination techniques in which pollen is transferred between flowers of two different plants.

What does Mendel's law of segregation state?

The law of segregation states that a pair of factors is segregated or separated during the formation of gametes.

What defines a dominant trait according to Mendel's findings?

The trait that masks the expression of the other trait is called the dominant trait.

What are alleles?

Alleles are alternative versions of a gene that account for variations in inherited characters.

What is the difference between homozygous and heterozygous organisms?

Homozygous organisms have two identical alleles at a gene locus, while heterozygous organisms have two different alleles.

What does the Punnett square illustrate?

The possible combinations of sperm and egg during fertilization.

What does Mendel's Law of Independent Assortment state?

Each pair of factors separates independently during gamete formation.

What is complete dominance?

Complete dominance occurs when heterozygous individuals and dominant homozygous individuals are indistinguishable in phenotype.

What is the difference between incomplete dominance and codominance?

Incomplete dominance results in a phenotype intermediate between the dominant and recessive traits, while codominance results in both alleles being expressed fully in the phenotype.

What does pleiotropy refer to in genetics?

Pleiotropy refers to a single gene influencing multiple phenotypic traits.

What is polygenic inheritance?

Polygenic inheritance occurs when a trait is governed by two or more genes, which have an additive effect on that trait.

What defines the norm of reaction in genetics?

The norm of reaction is the phenotypic range of a genotype influenced by the environment.

What is a testcross used for?

A testcross is an intentional breeding used to determine the underlying genotypes of an organism.

What is the role of sex chromosomes?

Sex chromosomes contain genes that determine an organism’s sex.

What is the SRY gene responsible for?

The SRY gene on the Y chromosome codes for a protein that directs the development of male anatomical features.

In X-linked disorders, why are they more common in males?

Males have only one copy of the X chromosome (hemizygous), so they will exhibit the trait if they carry a recessive allele.

What are the four types of chromosomal mutations?

The four types are deletion, duplication, inversion, and translocation.

What does gene imprinting involve?

Gene imprinting involves alleles functioning differently depending on whether they come from the maternal or paternal parent.

What are homoplasmy and heteroplasmy?

Homoplasmy refers to having the same mitochondrial genome in all tissues, while heteroplasmy refers to having more than one mitochondrial genome in a body.

What is the principle of segregation in meiosis?

The principle of segregation explains that alleles for each gene segregate from each other during gamete formation, leading to genetic diversity.

What is a phenotype?

A phenotype is the observable physical or biochemical characteristics of an organism, determined by both genetic makeup and environmental factors.

What are genotype and its significance?

A genotype is the genetic constitution of an individual, which determines potential traits and is crucial for understanding inheritance.

What is genetic linkage?

Genetic linkage occurs when genes that are close together on a chromosome are inherited together more often than not.

What does epistasis refer to in genetics?

Epistasis is a form of gene interaction where one gene affects the expression of another gene.

What is the difference between a monohybrid and a dihybrid cross?

A monohybrid cross involves tracking one trait, while a dihybrid cross tracks two traits simultaneously.

What is a pedigree chart used for?

A pedigree chart is used to trace the inheritance of traits through generations, often identifying carriers of genetic disorders.

How does environmental influence affect gene expression?

Environmental factors can affect gene expression by altering the phenotype without changing the genotype, showcasing the norm of reaction.

What are dominant and recessive alleles?

Dominant alleles mask the effects of recessive alleles in phenotype; recessive alleles only manifest in homozygous conditions.