Cell Division Mitosis Cell Division in Prokaryotes Prokaryotes

Cell Division & Mitosis

Cell Division in Prokaryotes • Prokaryotes are – Like bacteria are less complex – Have a single, circular DNA and ribosomes – Divide by Binary Fission

Cell Division in Prokaryotes • Asexual reproduction: One parent = 2 offspring – Division of prokaryotic cell into two identical offspring cells – Cell grows to twice its size – Cell membrane pinches off – 2 new identical cells form from one parent

Cell Division in Eukaryotes • Mitosis – Division of the nucleus – Occurs in all cells EXCEPT sex cells • Cytokinesis – Division of the entire cell

Chromosomes • A structure found in the nucleus of eukaryotic cells that contains DNA • Eukaryotic cells contain more DNA – For example fruit flies have 8 chromosomes and humans have 46 chromosomes

Chromosomes • Homologous pairs – Two sets of chromosomes that carry genes for the same trait – So humans have 23 homologous pairs of chromosomes

Cell Cycle • Interphase – Time between cell divisions • Cells spend the majority of their life in this stage – 3 phases • G 1 phase: grows and develops • S phase: DNA replicates • G 2 phase: prepares for mitosis

Mitosis: Nuclear Division 1. Prophase – Duplicated chromosomes condense to form chromatids • Metaphase – Chromatids line up in the middle of the cell • Anaphase – Chromatids separate at the centromere and slowly move to the opposite poles – When chromatids separate they are now called chromosomes • Telophase – Nuclear membrane forms around each set of chromosomes

Mitosis

Cell Division in Eukaryotes • Cytokinesis – Process of dividing cytoplasm – Cleavage of new cell membrane or a cell plate forms to create a cell wall » Algae » Plants » Fungi – Process of dividing the cell into 2 different cells • In humans, each cell will contain 23 pair of chromosomes • A total of 46 chromosomes per cell