Cell Cycle Flashcards

Cell Cycle Overview

• The cell cycle consists of an ordered sequence of events between cell divisions, necessary for growth and reproduction.

Key Terms and Definitions

• Centromere: A constricted region where sister chromatids are joined, pivotal in chromosome alignment during cell division.
• Chromatid: Each of the two duplicated strands of DNA held together at the centromere; essential for proper chromosome segregation.
• Diploid (2n): Cells or organisms that carry two sets of chromosomes, typical in somatic cells.
• Gamete: A haploid reproductive cell (sperm or egg), containing one set of chromosomes.
• Gene: The basic unit of heredity, consisting of DNA sequences that encode proteins, influencing traits.
• Genome: The complete set of genetic material present in a cell or organism, encapsulating all chromosomes.
• Haploid (n): Refers to cells with a single set of chromosomes, characteristic of gametes.
• Histone: Basic proteins that play a critical role in the packaging of DNA into nucleosomes, aiding in DNA organization.
• Homologous Chromosomes: Chromosome pairs of the same morphology, each inherited from a different parent, holding similar genes.
• Locus: The specific physical location of a gene on a chromosome.
• Nucleosome: The fundamental unit of chromatin, formed by DNA wrapped around histones, facilitating compaction of genetic material.

Chromosome Characteristics

• A diploid cell carries twice the number of chromosomes compared to a haploid cell, emphasizing genetic diversity through sexual reproduction.
• Traits in an organism are influenced by the inherited genes from both parents, as part of their DNA.
• Histones are crucial for the initial stage of DNA configuration in eukaryotic cells.

Cellular Division Phases

• Sister chromatids refer to identical copies of chromatin linked at the centromere and separated during mitosis.
• Human somatic cells harbor 46 chromosomes (22 pairs of autosomes and 2 sex chromosomes), while human gametes contain 23 chromosomes, reflecting their diploid and haploid states, respectively.

Genetic Structure Relationships

• The genome is the collective total of an organism’s chromosomes; each chromosome comprises numerous genes with coding and non-coding DNA.

Chromatin Structure and Function

• Eukaryotic chromosomes exceed typical cell length and are compacted through wrapping around histones to form nucleosomes, further organized into fibers.
• The mechanism of chromatin condensation is essential for effective chromosome segregation during division.

Summary of Genetic Concepts

• Prokaryotes possess a singular circular chromosome, while eukaryotes have multiple linear chromosomes encased within a nucleus.
• In human somatic cells, chromosomes are categorized as 22 pairs of autosomes plus 2 sex chromosomes, indicating diploid nature.
• Mitosis requires chromosomes to be highly condensed for accurate segregation, achieved through various proteins aiding in DNA organization.

Mitosis Stage

• Anaphase: A critical phase in mitosis where sister chromatids are pulled apart, ensuring each new daughter cell receives an identical set of chromosomes.

Additional Cell Cycle Concept

• Cell Plate: A structure involved in plant cell division, forming during cytokinesis, aiding in the separation of daughter cells.