Cell Cycle and Chromosome Structure

Flashcards covering the cell cycle, chromosome structure, DNA packaging, and stages of mitosis.

Cell Cycle

The process where genetic material in a cell is copied (replicated) and then divided along with other cell contents into two distinct cells.

DNA

Long strands of nucleic acids that make up the genetic material.

Chromatin

The form of DNA wrapped around proteins (specifically histones) within the nucleus.

Condensed Chromatin

Chromatin that is tightly wound around proteins, forming a small, compact structure.

Decondensed Chromatin

Chromatin that is loose and unwound, resembling a loose string.

Heterochromatin

The condensed phase of chromatin when the cell is preparing to move half of its genome.

Histones

Proteins that DNA wraps around, organizing the DNA strands.

Nucleosome

One unit consisting of DNA wrapped around a histone, often described as 'beads on a string'.

Electrostatic Forces

The attraction between the negatively charged phosphate groups of DNA and the positively charged histones, holding DNA onto a histone.

Condensin Proteins

Proteins involved in winding up (condensing) or loosening DNA around histones.

Homologous Chromosomes

Chromosomes that are the same (contain the same genes) but are inherited from different parents.

Centromere

The constricted region near the center of a chromosome, joining two sister chromatids.

Kinetochore

A protein structure located at the centromere where the cell's microtubules attach during cell division, connecting replicated chromosomes.

Cohesion Proteins

Proteins that hold sister chromatids together at the centromere after DNA replication.

Sister Chromatids

Two identical copies of a chromosome produced during DNA replication, joined together at the centromere.

Microtubules

Large, hollow tubes made of tubulin protein, forming a major component of the cytoskeleton and playing a key role in the cell cycle.

Tubulin

The protein subunit that makes up microtubules.

Centrosome

A microtubule organizing center, acting as a nucleation center where microtubules grow from, typically containing two centrioles.

Centrioles

Base structures within a centrosome from which microtubules grow.

Nuclear Envelope

The double-layered membrane that encloses the nucleus, separating it from the rest of the cytoplasm.

Interphase

The longest phase of the cell cycle, occurring before mitosis, during which the cell grows, replicates its DNA, and prepares for division. It includes G1, S, and G2 phases.

G1 Phase (Growth One Phase)

The primary growth phase of the cell cycle, where the cell prepares for DNA replication by making energy and proteins.

S Phase (Synthesis Phase)

The phase of the cell cycle where the cell's entire genome is duplicated (DNA replication occurs).

G2 Phase (Growth Two Phase)

The phase where the cell prepares for mitosis by organizing microtubules, getting energy and proteins in place, and condensing chromosomes.

M Phase (Mitosis)

The phase of the cell cycle where chromosomes divide into new cells, encompassing prophase, prometaphase, metaphase, anaphase, and telophase.

Cytokinesis

The final stage of the cell cycle where the cell's cytoplasm divides to form two distinct daughter cells.

Prophase

The first stage of mitosis where chromosomes fully condense, and the nuclear membrane begins to dissolve.

Mitotic Spindle (Spindle Apparatus)

A structure formed by microtubules and centrosomes that organizes and separates chromosomes during cell division.

Prometaphase

The stage of mitosis following prophase where the nuclear envelope is completely gone, and microtubules connect to the kinetochores of the chromosomes, moving centrosomes to opposite poles.

Metaphase

The stage of mitosis where all chromosomes line up at the cell's equator, forming the metaphase plate.

Metaphase Plate

The imaginary plane at the cell's equator where chromosomes align during metaphase.

Anaphase

The stage of mitosis where cohesion proteins holding sister chromatids together break down, and sister chromatids are pulled apart towards opposite poles by shortening microtubules.

Telophase

The final stage of mitosis where separated chromosomes arrive at opposite poles, nuclear envelopes reform around them, and the DNA begins to decondense.

Homology

Shared traits between organisms due to shared ancestry or a common origin.

Descent with Modification

The concept that homologous traits can be modified over time, leading to differences in appearance or function despite a shared ancestry (e.g., vertebrate limb bones).

Emergent Property

A unique property that arises when simpler components interact and work together in a collaborative way, which cannot be predicted from the individual components alone.