Cell division

In this section (IB Topic 1.6 )

- Mitosis and cytokinesis

- Cell cycle

- Cancer and mitotic index

1.6_Vocabulaty.pdf

1.6_Cell_Division_CrossWord

Answers

Mitosis

Supercoiling: formation of chromosomes

During mitosis chromosomes condense by supercoiling of the DNA. Elastic bands can be used to illustrate supercoiling. Hold one end in a fixed position and twist the other end until supercoils are formed. Then estimate the change in length of the elastic band with supercoiling.

Supercoiled DNA: topoisomeraseEach cell's DNA is about 2 meters long, so to pack it in to the nucleus, it has to be super-coiled. How the cell deals with supercoiled DNA during replication and transcription?

Microscopy of mitosis

Observe some microscope slides containing living tissues in which some cells are undergoing mitosis. To observe the stages of mitosis, DNA is stained and the phases of the cell cycle can be identified. Identify the phases of the cell cycle in which each cell was at the time the slide was prepared. Count the total number of dividing cells and the total number of cells to calculate the mitotic index. You should be able to determine the mitotic index from a micrograph.

MITOSIS VIDEO.mp4

biology mitosis.mp4

Watch here.

Virtual lab: onion root tip

Mitosis is the sequence of events by which the nuclear material of one cell is distributed, by a process involving chromosomes, into two equal parts. Complete this virtual lab to understand mitosis in root tips. The onion root tip is responsible for the downward growth of the root and therefore, is one of the regions in the plant where cells are actively dividing and elongating. The root tip is an excellent system in which to study the process of nuclear division (mitosis) and cell division (cytokinesis). In the onion root tip the chromosomes are fairly large and distinct, and this species has a relatively small number of chromosomes.

Cytokinesis

Cytokinesis is the separation of a cell into two cells and it occurs right after mitosis. Mitosis is one part of cell division, in which the nucleus divides. Cell division also includes a distinct additional process involving the division of the cytoplasm. The cytoplasm contains all the material outside of the nucleus that is inside the plasma membrane.

Cell cycle

Interphase is a very active phase of the cell cycle with many processes occurring in the nucleus and cytoplasm. Cyclins are involved in the control of the cell cycle.

Play the game!

Click here to play the Cell Cycle game!

Cancer

Mutagens, oncogenes and metastasis are involved in the development of primary and secondary tumors. The correlation between smoking and incidence of cancers.

Carcinogens

A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis, the formation of cancer. This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes.