Inheritance and Gene Control in Biology

These flashcards cover key concepts related to inheritance, meiosis, gene control, and genetic mutations, aiding in exam preparation.

What is meiosis and why is it important before fertilization?

Meiosis is a type of cell division that reduces the chromosome number by half to produce haploid gametes, allowing for genetic variation and restoration of diploid number upon fertilization.

Define homologous chromosomes.

Homologous chromosomes are pairs of chromosomes that have the same length, contain the same genes at the same loci, but may have different alleles.

What are the main differences between mitosis and meiosis?

Mitosis involves one division producing 2 genetically identical diploid daughter cells, while meiosis involves two divisions producing 4 haploid genetically non-identical daughter cells.

What occurs during Prophase I of meiosis?

Chromatin condenses into chromosomes, centrioles move to poles, the nuclear envelope breaks down, and homologous chromosomes pair up to form bivalents, allowing for crossing over.

What is crossing over and why is it important?

Crossing over is the exchange of genetic material between non-sister chromatids during Prophase I of meiosis, leading to genetic variation in gametes.

Explain independent assortment.

Independent assortment refers to the random orientation of homologous chromosome pairs during metaphase I of meiosis, resulting in genetic variation in gametes.

How does meiosis contribute to genetic variation?

Meiosis contributes to genetic variation through processes like crossing over and independent assortment, which create new combinations of alleles.

What role does interphase play in meiosis?

Interphase is crucial for DNA replication and preparation of the cell for meiosis, ensuring that each daughter cell receives the correct amount of genetic material.

Define genotype and phenotype.

Genotype is the genetic makeup of an organism regarding a specific trait, while phenotype is the observable characteristics of that trait influenced by genotype and environment.

What is a test cross and why is it used?

A test cross is a cross between an individual showing a dominant phenotype but unknown genotype and a homozygous recessive individual to determine the genotype of the dominant individual.

What are sex-linked diseases and why are they more common in males?

Sex-linked diseases are genetic disorders associated with genes located on sex chromosomes, often more common in males because males have only one X chromosome and cannot be carriers.

Describe the lac operon and its role in gene regulation.

The lac operon is a cluster of genes responsible for lactose metabolism in bacteria, regulated by repressor proteins and inducers, allowing for the expression of digestive enzymes in the presence of lactose.

What is the significance of mutations in genetics?

Mutations can lead to changes in DNA sequences, resulting in new alleles and potentially affecting protein structure and function, which can cause genetic diseases.

Explain how epistasis can affect inheritance patterns.

Epistasis occurs when one gene's expression affects the expression of another gene, modifying the typical Mendelian inheritance ratios.

Define dihybrid cross and expected phenotypic ratio in F2 generation.

A dihybrid cross involves examining the inheritance of two traits simultaneously, with the expected phenotypic ratio in the F2 generation being 9:3:3:1.

What is the role of transcription factors in gene expression?

Transcription factors are proteins that regulate gene expression by binding to specific DNA sequences, either promoting or inhibiting the transcription of target genes.

How do mutations lead to genetic disorders?

Mutations can alter the function or structure of proteins, leading to diseases such as sickle cell anemia and Huntington's disease due to dysfunctional proteins.