Cell Cycle and Cell Division Vocabulary Review

A comprehensive set of vocabulary flashcards covering the structure of chromosomes, DNA molecular components, the stages of the cell cycle (Interphase and Mitosis), and the mechanics of Meiosis and genetic variation.

Chromosomes

Highly coiled and condensed chromatin fibers that carry genetic information, visible only during active cell division.

Walther Flemming

The scientist who first studied chromosomes in the year $1882$.

Composition of human cell chromosomes

Each human cell contains $46$ ($23$ pairs) of chromosomes.

Chromatin material components

Formed of two substances: DNA ($40\%$) and Proteins ($60\%$), primarily Histones.

Nucleosome

The basic unit where DNA strands wind around a core of $8$ histone proteins (Histone Octamer), resembling a "string of beads."

DNA (Structure Proposal)

A large Double Helix macromolecule proposed by Watson & Crick in $1953$.

Nucleotides

The repeating units that compose DNA, consisting of a Phosphate group, Pentose sugar, and Nitrogenous base.

Nitrogenous Base Pairing

In DNA, Adenine (A) pairs with Thymine (T), and Cytosine (C) pairs with Guanine (G).

Chromatids

Two identical sister strands formed before cell division when chromosomes duplicate.

Centromere

The point of attachment between two sister chromatids where spindle fibers attach during division.

Spindle Fibers

Structures that attach to the centromere during cell division to pull chromatids apart.

Replacement (Cell Need)

The process of replacing old or worn-out cells, such as the $2 \times 10^6$ RBCs that die every second.

Cell Cycle

The series of events leading to a cell's division and duplication, consisting of Interphase and M-Phase.

Interphase

The non-dividing phase of the cell cycle where growth and DNA synthesis occur.

G1 Phase (First Growth)

The phase where RNA and proteins are synthesized and organelles increase in volume.

S Phase (Synthesis)

The phase where DNA is replicated and chromosomes are duplicated into two chromatids.

G2 Phase (Second Growth)

The phase involving further protein synthesis as the cell prepares for actual division.

Prophase

The first stage of Mitosis where chromosomes condense, the nuclear membrane disappears, and centrioles move to poles.

Metaphase

The stage where chromosomes line up at the center (equator) and attach to spindle fibers.

Anaphase

The stage where centromeres split and chromatids are pulled to opposite poles.

Telophase

The final stage of Karyokinesis where chromosomes reach the poles and the nuclear membrane reforms.

Karyokinesis

The process of nuclear division occurring during the M-Phase.

Cytokinesis

The division of the cytoplasm following Karyokinesis, occurring by furrowing in animal cells or cell plate formation in plant cells.

Meiosis

A reduction division that produces sex cells (gametes) where the chromosome number is halved from $2n$ to $n$.

Haploid

Cells containing a single set of chromosomes ($n$), which is essential to maintain the $2n$ number after fertilization.

Crossing Over

The exchange of genetic material between non-sister chromatids of homologous chromosomes during Meiosis, leading to genetic variation.

Chiasma

The specific points of exchange during the process of crossing over.

Diploid (2n)

The full set of chromosomes found in somatic (body) cells, which remain identical after Mitosis.