Biology - Mitosis (Lesson 4)

Mitosis

• Type of cell division that results in 2 daughter cells that are identical to each other and to the mother cell

Walter Flemming

• German Biologist 

• Pioneer of mitosis research and founder of Cytogenetics (study of cell’s hereditary materials) 

Cells

• Only allowed to complete a certain number of divisions (40 - 60 times)

• “Programmed cell death” / apoptosis 

• Different cells can be in different stages

Stages of Cell Cycle

• 2 stages 

• Interphase & Mitotic Phase

Interphase

• 3 sub-phases 

• Cell spends 90% of their time, or 18-21 hours in interphase

G1 Phase / First Gap

• Small cell is absorbing nutrients, growing, & doing its job 

S Phase / Synthesis Phase

• Cell is continuing to grow & duplicates its DNA 

• Chromosome is copied 

• Histone proteins occurs alongside DNA replication

• 2 uncoiled chromatin connected by a centromere

G2 Phase / Second Gap

• Cell keeps growing and doing its job 

• Centriole is duplicated 

Mitotic Phase

• 4 sub-phases 

• Cell spends 10% of their time, or 3-6 hours 

Prophase

• Chromatin coils into x-shaped chromosomes 

• Nuclear membrane dissolves

• Centrioles appears and migrates to opposite sides 

• Spindle fiber starts to form

Metaphase

• Chromosomes line-up on the metaphase plate 

• Centromeres are attached to spindle fibers 

Anaphase

• Sister chromatids are pulled away from each other and towards the poles 

• Spindle fibers contract 

• Centromeres divide 

Telophase

• Chromosomes reach the poles

• Nuclear membrane firm around the 2 new nuclei 

Cytokinesis

Cytoplasm is distributed equally between the 2 new cells

Animal Cell

A cleavage furrow forms from outside in

Plant Cell

• A cell plate forms from inside out 

Chromosomes

• Structure that DNA is packaged into 

• Threadlike structure that carries genetic information in the form of genes 

Nucleus

• Distinct section of DNA that is inherited and codes for 1 characteristics 

Nuclei

2 Nucleus

Histones

Main protein in chromatin

Chromatin

Material that contains DNA, RNA, and proteins which makes up the contents of a cell nucleus

Chromatid

• Each of the 2 threadlike strands into which a chromosome divides during cell division 

• Each contain a double helix of DNA 

Centrioles

• Organelle occurring in pairs and involved in the development of spindle fibers in cell division

• organelle that makes mircrotubules

Centromere

Region of chromosome to which microtubules of the spindle attach

Spindle Fibers

Form a protein structure that divides the genetic material of the cell

Cell Division

• Process by which a parent cell divides into 2 daughter cells 

Equatorial Plate

• Arrangement of the centromere of chromosomes in one plane

Apoptosis

• Form of programmed cell death / cellular suicide

• Maintains the balance of cells in the human body and important in the immune system