Cell Cycle (IPMAT)

  1. Interphase

G1: Cell growth. The cell size increases, protein synthesis occurs and organelles starts to duplicate.

S: DNA replication occurs in this phase. DNA replicates by DNA polymerase enzyme.

G2: Cell growth; Protein synthesis and organelle duplication finish.

  1. Mitosis

Prophase

Metaphase

Anaphase

Telophase

Control

Cancer

Benign

Malignant

Cell division: It occurs when the cell surface area/volume ratio increases. The cell needs to divide in order to continue its functions.

DNA (double helix shaped genetic material that carry the genetic information. It is made up of nucleotides.

Chromatin: DNA is packed into chromatin (supercoil) when the cell is not dividing. It looks wool thread.

Chromosome: When the cell is dividing chromatin becomes chromosome and histone proteins pack up the DNA.

Check points (growth factors also help check point proteins. If they get damaged then cell cycle keeps going uncontrollably.

G1: Occurs toward the end of G1. Checks if the necessary proteins are synthesized. If not the cell goes to G0 phase.

S: Occurs during S phase. Checks on whether DNA has been duplicated.

M:Occurs during mitosis phase. Checks whether mitosis is complete.

Cytokinesis (cytoplasm division)

Plants

Animals

Nucleotides: Have bases : A,T,G,C and Deoxyribose sugar (5c) and Phosphate group (H3PO4) A=T ,G makes 3 Hydrogen bonds with C. Bases have nitrogen in them.

Nucleosome: When DNA is packed with histone proteins, nucleosomes are formed before they become chromosome.

Nucleus protects the DNA and the code for the cell division is given by DNA so Nucleus and DNA presence is very important for cell division.

Cell plate is formed due to cell wall.

Normal cytoplasmic division occurs by the formation of cleavage furrow.

Nuclear membrane disappears. Chromatin becomes chromosome. Spindle fibers are formed.

Chromosomes line up at the ecuador of the cell.

Sister chromatids go to opposite poles.

Nuclear membrane is formed again and cytokinesis occur.

Cells keep dividing and form tumors but these tumors do not move to the other organs, they remain stable.

Cell division is invasive and tumors make blood vessels and join the blood stream and move to the other organs.