Cell Cycle and DNA

Cell Cycle

The process cells go through preparing for cell division, actually dividing, and producing 2 identical daughter cells

Gap 1 (G1)

Cell growth; cells increase in size, new proteins and organelles are made

Synthesis (S)

DNA replication; chromosomes are replicated, cell now has 2x the DNA

Gap 2 (G2)

Preparing for cell division; many molecules and organelles are made prior to cell division

Mitosis (M)

Cell division; 2 main stages: mitosis and cytokinesis; produces 2 identical daughter cells with the same amount of DNA as the parent cell

Prophase

genetic material condenses into chromatids, spindles form, centrioles move towards opposite ends of cell

Metaphase

chromosomes line up in the middle of the cell, spindle fibers connect chromosomes to centrioles

Anaphase

sister chromatids move away from each other, spindle fibers mostly disappear

Telophase

chromosomes begin to spread back out, nuclear membranes form

Cytokinesis

The last step in cell division in which the cytoplasm divides;

Cytokinesis in animal cells

the cell membrane furrows inward to produce 2 daughter cells

Cytokinesis in plant cells

a cell plate is formed between the 2 daughter cells that eventually creates a cell membrane

chromosome

genetic information is bundled into packages of DNA; only visible during cell division

chromatid

one of the two identical halves of a chromosome that has been replicated in preparation for cell division

centromere

links a pair of sister chromatids together during cell division

cancer

disorder in which the cell cycle is disrupted and uncontrolled/unregulated growth; cells no longer respond to checkpoints or fail to produce internal regulators that ensure orderly growth

tumor

multiple cancer cells arranged in an unorganized way

James Watson and Francis Crick

build the first 3D model of DNA as a double helix (twisted ladder)

Rosalind Franklin

used a x-ray to confirm that DNA is a double helix

DNA

made of nucleotides joined into long strands by hydrogen bonds that create a double helix

nucleotide

basic unit for nucleic acid (DNA) -> CHONP; made of phosphate group, 5-carbon sugar, and nitrogenous base

sugar-phosphate backbone

structural support for DNA; contains the phosphate group and the deoxyribose sugar

nitrogenous bases

determines our genetic code; adenine (A), thymine (T), guanine (G), and cytosine (C)

Chargaff's Rule

The amount of adenine in DNA equals the amount of thymine [A = T]; the amount of guanine in DNA equals the amount of cytosine [G = C]

hydrogen bond

a weak bond that connects the nitrogenous bases together; weak so it is easy to break during DNA replication

DNA replication

process a cell goes through to copy its DNA before dividing; occurs in S phase in the cell cycle

helicase

the "unzipping" enzyme that breaks the hydrogen bond holding the nitrogenous bases together

DNA polymerase

the "building” enzyme that replicated DNA molecules to build a new strand of DNA

DNA primase

the "primer" enzyme that makes the primer so DNA polymerase can figure out where to start replicating DNA

ligase

the "gluer" enzyme that attaches the copied pieces of DNA together

semiconservative model

2 strands of DNA; one old, one new