Mitosis Flashcards
Define cellular division?
The process by which new cells are made to replace those that have died or have been damaged.
There are 2 different types of cell division. What do both involve?
- one is purely for growth, maintenance and repair of an organism
- the other is for the purpose of reproduction
Finish the sentence:
In growth division, the cells produced are ________ body cells (_________ cells) which are ____________ to the cell which _________ to produce them.
In growth division, the cells produced are NORMAL body cells (SOMATIC cells) which are PRODUCED by the cell which DIVIDED to produce them.
Explain what happens during Mitosis
The material in the nucleus of a cell first duplicates. And then the cell divides into 2, splitting the nuclear material between the two new cells. this means that after duplicating or doubling the DNA into 2, the nuclei of the 2 new cells produced are identical to the original cell and to each other.
List the 5 phases of Mitsos
1) interphase
2) prophase
3) metaphase
4) anaphase
5) telophase
IPMAT
Explain what happens during interphase.
The cell is in a resting stage, between cell divisions.
The DNA model Coles duplicate.
Explain what happens during prophase.
Nuclear material doubles = chromosomes (thread like structures)
Chromosomes are made up of an identical pair of chromatids, held together by centromere.
The membrane around the nucleus disappears.
Explain what happens during metaphase.
Chromosomes line up along the centre of the cell ready for the chromatids to seperate from each other.
Explain what happens during anaphase.
Chromatids break apart and are drawn to opposite ends/poles of the cell by small fibres called spindle fibres.
Explain what happens during telophase.
Cells star to split into 2 (cytokinesis), while a new membrane forms around each new nucleus.
What is cytokinesis?
Cytokinesis is the division of the cytoplasm of a cell following division of the nucleus.
What is another term for “sex division”
Meiosis
What is meiosis?
It is the type of division which follows the production of gametes.
This type of division is used by sexually reproducing organisms and only concurs in specialised tissues which are part of the reproductive system of the organisms.
Explain what happens during meiosis.
The material within the nucleus of a gamete duplicates once. The cell then divides into 2 and then each it the 2 new cells divides again.
This means that the nuclear material which is first doubled, then gets divided across 4 products.
How much nuclear material do the cells produced in meiosis have from the parent cell?
The cells produced have half the amount of the nuclear material that the parent cell had.
In humans, how many chromosomes does each normal cell have?
46
When meiosis occurs, how many chromosomes are there and why?
When meiosis occurs, the chromosomes duplicate to become 92. These are then divided twice to give four new cells, each with 23 chromosomes in its nucleus.
What separates mitosis and meiosis?
Major difference is that meiosis
- 2 divisions occur
- four products are formed
- each product has only half of the normal amount of nuclear material
How long does cell division take to be completed?
Several hours…
Why is cell division a continuous process?
Because the process is divided up into steps/phaseswdlifjwlkdjflkwjdf
What is gametogensis? What are the 2 types?
It is the process of gamete development, which includes meiosis.
2 types:
- spermatogensis
- oogenesis
Complete the sentence:
The process of ________ involves ___ __________ divisions, but the ___________ duplicate only once.
The process of MEIOSIS involves 2 NUCLEAR divisions, but the CHROMOSOMES duplicate only once.
Chromosomes that are identical in size and shape are referred to as what?
Homologous chromosomes
When a cell has 2 of each type of chromosome, it is said that have ________ chromosome numbers. How many are there in humans (somatic)?
Diploid. - 2n, where stands for the number of different types of chromosomes.
The diploid number for humans is 46.
What are haploid cells? Give an example.
Haploid cells are those that have half the usual number of chromosomes and are destined n. The haploid number for humans if therefore 23.
Eg. In gametes.
What is the phase during meiosis where the chromosomes shrink and thicken as the DNA becomes more tightly coiled.
Prophase.
What does term ‘crossing over’ refer to?
When the homologous chromosomes are paired, the chromatids may break and exchange segments. This is called crossing over.
