Textbook Day 1 Cell Cycle Note Review

Comprehensive vocabulary flashcards covering the cell cycle, cell division, chromosome architecture, signal reception, mitosis, and bacterial binary fission.

Chromosome (in a Non-Dividing Cell)

A discrete cellular structure consisting of one very long DNA molecule associated with many proteins that carry genetic information within the nucleus.

Microtubules

Cellular structures made up of subunits of tubulin along which substances are transported within the cell.

Reception

The target cell's detection of an external signaling molecule, occurring when a signaling protein binds to a surface receptor protein and induces a conformational change.

Transduction

An intracellular multistep pathway initiated by receptor activation that converts an extracellular signal into a specific form to elicit a cellular response.

Protein Phosphorylation

The covalent addition of phosphate groups to a protein, altering its shape via interactions with charged or polar amino acids and most frequently activating or changing its function.

Somatic Cells

All body cells of an organism except reproductive cells; for example, a chicken's somatic cells contain $78$ chromosomes ($39$ inherited from each parent).

Gametes

Haploid reproductive cells containing half the chromosome number found in somatic cells, carrying $39$ chromosomes in chickens.

Cell Division

The process of cellular reproduction wherein a parent cell replicates its DNA, distributes the two copies to opposite ends of the cell, and divides into two daughter cells.

Chromatin

The entire complex of DNA and proteins that serves as the building material of eukaryotic chromosomes.

Sister Chromatids

Two identical copies of an original duplicated chromosome, joined along their length by protein complexes and densely coiled and folded.

Centromere

The specialized DNA region where a chromatid is most closely attached to its sister chromatid, mediated by specific DNA-binding proteins.

Mitotic (M) Phase

The stage of the cell cycle that encompasses both mitosis and cytokinesis; it is typically the shortest segment of the cycle.

Interphase

The period representing approximately $90\%$ of the cell cycle, during which the cell grows, synthesizes proteins, and copies its chromosomes through $G_1$, $S$, and $G_2$ phases.

S Phase

The synthesis phase of interphase during which the cell continues to grow and duplicates its nuclear DNA and chromosomes.

Mitotic Spindle

An apparatus composed of microtubules and associated proteins that begins forming in the cytoplasm during prophase to orchestrate chromosome movement.

Kinetochore

A protein structure assembled on specific sections of chromosomal DNA at each centromere that functions like a coupling device linking chromatids to spindle microtubules.

Kinetochore Microtubules

Spindle fibers that attach directly to the kinetochores of sister chromatids during prometaphase to pull them during division.

Separase

An enzyme that cleaves the cohesin protein complexes holding sister chromatids together, triggering the onset of anaphase.

Gary Borisy Experiment

An experiment demonstrating that motor proteins on kinetochores 'walk' chromosomes poleward along microtubules while the microtubules depolymerize at their kinetochore ends.

Binary Fission

A form of asexual reproduction in bacteria wherein a single cell grows to double its size, replicates its circular DNA, and divides into two cells.

Origin of Replication

The specific site on a bacterial chromosome where replication begins, after which the two origins move toward opposite poles of the elongating cell.