Cancer cells grow and divide when they should not

• Mitosis – an asexual cell division, that occurs in somatic cells– “Soma” = body

• Cell cycle – the “lifecycle” of the cell

The Cell cycle: Interphase

• Interphase has three phases:– G1: cell grows, organelles

duplicate– S: DNA is replicated– G2: cell makes proteins

needed to complete cell division

DNA replication

• Produces exact copies of the cells chromosomes

• Nucleotides are added by an enzyme called DNA Polymerase

• semiconservative replication - each newly replicated DNA molecule contains a daughter and a parental DNA strand

Following replication, the DNA sequence ACCGTA would be paired with a daughter DNA strand with the sequence:

A. ACCGTAB. TGGCATC. ATGCCAD. UGGCAT

A. B. C. D.

25% 25%25%25%

• Chromosomes are uncondensed before cell division

• Duplicated chromosomes are called sister chromatids

• They are held together at the centromere

DNA replication duplicates chromosomes

• Mitosis produces genetically-identical daughter nuclei

• Four stages:– Prophase– Metaphase– Anaphase– Telophase

• Mitosis is followed by cytokinesis, which splits the two nuclei into two daughter cells

The Cell cycle: Mitosis

Mitosis : Prophase and Metaphase

Mitosis : Anaphase and Telophase