cell cycle

Anaphase

Sister chromatids separate.

Telophase

Chromosomes begin to uncoil, spindles break down, new nuclear membrane forms.

Mitosis

Cell division in which the nucleus divides into nuclei containing the same number of chromosomes.

DNA

Deoxyribonucleic Acid.

DNA Polymerase

An enzyme that assembles DNA nucleotides into polynucleotides using a preexisting strand of DNA as a template.

Double Helix

The form of DNA, referring to its two adjacent polynucleotide strands wound into a spiral shape.

Helicase

An enzyme that unwinds a DNA molecule during the process of DNA replication.

Replication Fork

The location in a parent DNA molecule where replication is actively occurring.

Leading Strand

A strand of DNA being replicated continuously.

Lagging Strand

A strand of DNA being replicated in smaller fragments.

Nucleotide

The monomer of nucleic acids, consisting of a sugar, phosphate, and nitrogenous base.

Okazaki Fragments

Smaller pieces of DNA synthesized on the lagging strand.

Primase

An enzyme in DNA replication that produces an RNA primer on the parent molecule.

Ligase/DNA Ligase

An enzyme in DNA replication that forms a covalent bond between pieces of DNA.

DNA Replication Steps in Order

1. Helicase unwinds the two strands of DNA.

2. Hydrogen bonds between nucleotides of the two strands break.

3. Primase produces an RNA primer.

4. DNA polymerase places free nucleotides in complementary fashion to the parent strand.

5. Hydrogen bonds between nucleotides of the two strands form.

Interphase

G1, S, G2 phases.

Prophase

Chromosomes condense and spindle apparatus begins to form.

Metaphase

Chromosomes line up in the middle of the cell.

G2 Phase

Gap, or Growth 2 phase; when the cell is synthesizing additional organelles in preparation for cellular division.

G1 Phase

Gap or Growth 1 phase; when the cell increases in volume.

G0 Phase

The phase when cells have exited the cell cycle, so they no longer produce new cells.

Watson and Crick

Discovered the double-helix structure of DNA in 1953, explaining how genetic information is stored, replicated, and mutated.

Rosalind Franklin

Produced critical X-ray diffraction images that provided key structural insights into the DNA helix.

Chargaff

Discovered base-pairing rules in DNA, showing that adenine pairs with thymine and guanine with cytosine.

Griffith

Demonstrated the phenomenon of transformation in bacteria in 1928, showing that genetic information could be transferred between organisms.