Presentation on theme: "Mitosis & Cytokinesis. Why do Eukaryotic cells divide by Mitosis? Growth & Repair for multicelled organisms Reproduction of single celled organisms Amobea."— Presentation transcript:
Mitosis & Cytokinesis
Why do Eukaryotic cells divide by Mitosis? Growth & Repair for multicelled organisms Reproduction of single celled organisms Amobea Reproducing
Cells dividing by Mitosis……. Identical to original cell Same chromosome # Identical chromosome makeup Skin
What are chromosomes? A chromosome is an organized structure of DNA and protein that is found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences.
So where is DNA located ? In the Nucleus In the Chromosomes
Cell division requires coordinated division of chromosomes (mitosis) ….. …… and division of the cytoplasm (cytokinesis).
From Birth to Rebirth, a Cell Progresses Through Characteristic Stages That Constitute the Cell Cycle. In multicellular organisms like us, progress through the cell cycle is carefully regulated.
Stages of Mitotic Cell Division Interphase - intermission Prophase - 1st Metaphase - middle Anaphase - apart Telophase – far or seperate
Interphase “Intermission” Normal metabolic activities Major state DNA = chromatin
Late Interphase Prepares for mitosis DNA doubles = Sister chromatids Centrioles double in animals
Returns to Interphase “Intermission” Normal metabolic activities Major state DNA = chromatin
DNA and Its Faithful Replication – The Knit of Identity Because DNA stores genetic information and is faithfully replicated, information is passed largely unaltered from cell-to-cell, generation-to- generation.
Proteins and Their Production – The Primary Reason for DNA
Cell Division Demands Coordination of DNA Replication, Mitosis and Cytokinesis
DNA Replication – Simple in Principle, Complicated in Practice
DNA is Packaged into Chromosomes DNA in the cell is virtually always associated with proteins. The packaging is impressive – 2 meters of human DNA fit into a sphere about meters in diameter. chromatin duplicated chromosome
The Link Between DNA Replication and Chromosome Duplication
DNA is Condensed into Visible Chromosomes Only For Brief Periods in the Life of a Cell 95% of the time, chromosomes are like this. (chromatin) Easily visible chromosomes are apparent perhaps 5% of the time in an actively growing cell and less in a non-growing cell.
A Karyotype is an Arranged Picture of Chromosomes At Their Most Condensed State A normal human karyotype Boy or girl? Note that almost all chromosomes come in homologous pairs.
From Birth to Rebirth, a Cell Progresses Through Characteristic Stages That Constitute the Cell Cycle In multicellular organisms like us, progress through the cell cycle is carefully regulated.
The Knit of Identity - Mitosis Precisely and Evenly Divides Duplicated Chromosomes Precisely dividing the duplicated chromosomes has the consequence of providing each new cell with an identical and complete set of genetic instructions. interphase prophase metaphase
Mitosis Precisely and Evenly Divides Duplicated Chromosomes Cytokinesis is the process of cell division and it is distinct and separable from mitosis.
Mitosis in Action Blue shows DNA, green shows spindle fibers.
Cancerous cells ……... 1.Divide too many times 2.Divide into more than two cells! Masses of cells = “tumors” benign malignant
Cancer Is One Outcome of A Runaway Cell Cycle Licentious division - prostate cancer cells during division.