Lesson 1 (1 hour)

INTRODUCTION

As you know, as a multi-cellular organism, we aren't only one organism. In fact we are a community of cells. Througout this module we are going to learn how is the cell cycle and their ways of division.

CELL CYCLE

First of all, we need to have clear what the cell cycle is: 

As almost all the organism, the life of a cell is divided into 4 stages:

- G1: The cell has just "born". During this stage the cell grows and copies organelles in order to be bigger.

- S: In this phase the cell copies all their DNA.

- G2: The cell grows more, makes proteins and organelles, and begins to reorganize its contents in preparation for mitosis. G2 phase ends when mitosis begins.

- M: During the mitotic (M) phase, the cell divides its copied DNA and cytoplasm to make two new cells. M phase involves two distinct division-related processes: mitosis and cytokinesis.

- G0: This stage is sometimes called "0". Sometimes, the cell stop its life cycle at this stage, for example the neurones. It happens because this cells lose their ability of doing mitosis as a consequence of being extremly specialised cell.

 Now, please do the exercise "Match the correct option related with Cell Cycle"  .

MITOSIS

Mitosis is a type of cell division in which one cell (the mother) divides to produce two new cells (the daughters) that are genetically identical to itself. It's important to bear in mind that the "goal" of mitosis is to make sure that each daughter cell gets a perfect, full set of chromosomes. Cells with too few or too many chromosomes usually don't function well: they may not survive, or they may even cause cancer. So, when cells undergo mitosis, they don't just divide their DNA at random and toss it into piles for the two daughter cells. Instead, they split up their duplicated chromosomes in a carefully organized series of steps.

This steps are:

- Prophase: The chromosomes become packed and visible. The centrioles go to each pole of the cell. The nuclear membrane dissapears.  

- Preprometaphase: The chromosomes are blinded to the spindle fiber at their centromere (exactly at kinetochore).

- Metaphase: As a consequence of the blinding, the chromosomes seem to be at the center of the cell. 

- Anaphase: The sister chromatides are separated, and each chromatide are pulled to opposite poles of the cell.

- Telophase: The chromosomes arrive to each pole, and are unpacked. The nuclear membrane are assembled again.

Let's move on to the video with the explanation.

Now, please do the exercise "Complete these sentences".

LESSON 2 (1 HOUR) 

MEIOSIS

As you know, we have diploid cells. It means that our cells have two copies of the same chromosome (one copy from your mother and one copy from your father). The objective of the meiosis is obtaining from one mother cell 4 differents haploid cells, which they will be the gametes for the sexual reproduction. 

The phases of the meiosis are:

- Prophase I: The chromosomes become packed and visible. The centrioles go to each pole of the cell. The nuclear membrane dissapears. Each homologous chromosomes are blinded to the spindle fiber at their centromere (exactly at kinetochore) by one side. 

- Metaphase I: As a consequence of the blinding, the pairs of homologous chromosomes seem to be at the center of the cell. 

- Anaphase I: The homologous chromosomes are separated, and each chromosome are pulled to opposite poles of the cell.

- Telophase I: The chromosomes arrive to each pole, and are unpacked. The nuclear membrane are assembled again. The cytokinesis happens.

- Prophase II: The centrioles go to each pole of the cell. The nuclear membrane dissapears. Each chromosomes are blinded to the spindle fiber at their centromere (exactly at kinetochore).  

- Metaphase II: As a consequence of the blinding, the chromosomes seem to be at the center of the cell.

- Anaphase II: The sister chromatides are separated, and each chromatide are pulled to opposite poles of the cell.

- Telophase II: The chromosomes arrive to each pole, and are unpacked. The nuclear membrane are assembled again.

Let's move on to the video with the explanation:

Now please do the "Meiosis Quiz".

CLOUSURE

Now you have study mitosis and meiosis, please test what you have learned with this virtual activities:

https://www.centreofthecell.org/learn-play/games/mitosis/

https://biomanbio.com/HTML5GamesandLabs/Genegames/snurflemeiosishtml5page.html

ASSESSMENT

I want you to prepare in groups of 4 an scheme of what you have learned here. The scheme will be done on the online whiteboard Stoodle, where the teacher will check it.

URL: Stoodle Link 

EXTRA INFORMATION

If you want some extra information, please visit the Unit "The Science of Aging"