Honors DNA Structure, Replication, and Cell Cycle Review

Comprehensive vocabulary flashcards covering DNA structure, replication enzymes, the cell cycle phases, mitosis stages, and cell division checkpoints.

DNA (Deoxyribonucleic Acid)

A nucleic acid whose function is to store and transmit genetic material, structured as a double helix.

Double Helix

The twisted ladder shape of a double-stranded DNA molecule.

Nucleotide

The basic monomer (subunit) of DNA, consisting of three parts: a phosphate group, a deoxyribose sugar, and a nitrogen base.

DNA Backbone

The outer structural sides of the DNA double helix, composed of alternating sugar (deoxyribose) and phosphate molecules.

Nitrogen Bases

The rungs of the DNA molecule whose specific sequence determines the genetic traits of an organism.

Chargaff's Rule

The pairing rule stating that the amount of adenine equals thymine and cytosine equals guanine because complementary bases match and pair together.

Hydrogen Bonds

The chemical bonds that hold complementary nitrogen base pairs together across the two strands of DNA.

Deoxyribose

The five-carbon sugar found in the backbone of DNA nucleotides.

RNA (Ribonucleic Acid)

A single-stranded genetic nucleic acid that contains a ribose sugar and uracil instead of thymine.

DNA Replication

The synthesis process where DNA unzips and unwinds to construct two identical strands of DNA, yielding genetically identical daughter strands.

Semi-Conservative Replication

The method of DNA replication resulting in two DNA molecules where each contains one parent strand (original DNA) and one newly synthesized strand.

Helicase

An enzyme responsible for unzipping and unwinding the double-stranded DNA during replication by breaking bonds between nitrogen bases.

Primase

An enzyme that lays down an RNA primer to indicate to DNA polymerase where to begin building.

DNA Polymerase

An enzyme that synthesizes new DNA strands by building in complementary nucleotides in the $5'$ to $3'$ direction.

Ligase

An enzyme that bonds together fragments on newly synthesized DNA strands.

Interphase

The preparatory period that must occur before mitosis, consisting of cell growth and DNA replication ($G_1$, $S$, and $G_2$).

$G_1$ Phase

The initial growth phase of the cell cycle characterized by general cell growth.

$S$ Phase

The synthesis phase of the cell cycle during which DNA replication occurs.

$G_2$ Phase

The cell cycle phase involving further growth and final preparations for cell division.

Cell Cycle Phases (Diagram)

The four main sections of the circular cell cycle: A is $G_1$ (growth), B is $S$ (DNA synthesis), C is $G_2$ (growth and division preparation), and D is Cell Division (mitosis and cytokinesis).

$G_0$ Phase

A resting phase of the cell cycle where cells cease dividing; cancer cells differ by skipping this phase and continuing to divide.

Cancer

A disorder characterized by uncontrolled cell division resulting in cancerous tumors.

Mitosis

The stage of cell division during which the cell nucleus divides.

Cytokinesis

The physical splitting of the entire cell cytoplasm to complete cell division into two daughter cells.

Cell Plate

The structure formed during cytokinesis in plant cells to partition the cytoplasm, contrasting with the cleavage furrow found in animal cells.

Cleavage Furrow

The pinching groove formed during cytokinesis in animal cells to split the cell into two.

Prophase

The first phase of mitosis where chromosomes condense, spindle fibers form, and the nuclear membrane breaks down.

Metaphase

The second phase of mitosis during which chromosomes line up in the middle of the cell and attach to spindle fibers.

Anaphase

The third phase of mitosis where chromosomes/sister chromatids pull apart toward opposite ends of the cell.

Telophase

The final stage of mitosis where two new nuclei form and the cell prepares to separate.

Stages of Mitosis (Diagram)

The four mitotic stages shown in the diagram: D is Prophase, A is Metaphase, C is Anaphase, and B is Telophase.

Chromatin

The loose or uncoiled form of DNA present during interphase before chromosome condensation.

Sister Chromatids

Identical copies of a replicated chromosome joined together after DNA replication.

Centromere

The middle section of a chromosome that joins sister chromatids; chromosomes are counted by the number of centromeres rather than chromatids.

Cell Cycle Checkpoint

A critical surveillance point where the cell checks size, damage, and structure before deciding whether to advance to the next phase, repair errors, or destroy the cell.

$G_1$ Checkpoint

A checkpoint that inspects cell size, available nutrients, and genomic DNA damage, triggering a halt and correction if checks fail.

$G_2$ Checkpoint

A checkpoint that verifies replicated DNA for damage, halting progression to repair errors upon failure.

$M$ Checkpoint

A mitotic checkpoint that ensures proper spindle fiber attachment; failure leads to an attempt to reconnect or apoptosis if reconnection fails.

Apoptosis

Programmed cell death or self-destruction triggered when a cell fails critical quality checkpoints and cannot successfully repair.