Mitosis, stem cells, plant growth, percentile

What is mitosis

Mitosis is the process of nuclear division, for cell growth and repair

What are the stages of mitosis

• Interphase is where the chromosomes are copied so the daughter cells have the same amount of chromosomes.

• Prophase is where spindle fibres are formed and the membrane disappears

• Metaphase is where the spindle fibres are aligned in the middle of the cell

• Anaphase is where the spindle fibres are pulled apart

• Telophase is where the nuclei forms

• Cytokinesis is where the cell membrane forms dividing the cell

What can happen if mitosis is not regulated

If the cycle is not regulated it can lead to uncontrollable cell division, forming large masses of cells known as tumours and causing cancer.

How do stem cells divide and differentiate

Stem cells divide by mitosis/self renewal

1 daughter cell differentiates into another cell

The other cell stays as a stem cell so we do not run out of stem cells.

What is produced when a single cell divides by mitosis

• 2 daughter cells

• Genetically identical cells

• Cells that have the same number of chromosomes as the parent cell

What are stem cells after birth called?

Stem cells after birth are adult stem cells

What are stem cells before birth?

Stem cells before birth are embryonic

What are possible ethical issues with stem cells

• To get adult stem cells, consent must be given

• Embryonic stem cells shouldn't be used as it could be a life

What do mitotic inhibitors do and why?

They prevent spindle fibre formation - prevents metaphase and mitosis is then not completed.

This is used to stop cancer because the cancer cells cannot then complete mitosis or reproduce uncontrollably

What is differentiation

The process of becoming specialised

What cell can differentiate in all cells? Give name of definition

Totipotent - differentiate into all cells

Zygote is totipotent

What cell can differentiate into most cells? Give name of definition.

Stem cells are PLEURIPOTENT - differentiate into most cells

What cell can differentiate in a limited range of cells? Give definition name.

MULTIPOTENT (bone marrow) - differentiate into limited range of cells

What is it called when a cell can only differentiate into 1 other cell?

UNIPOTENT - differentiate into 1 cell

What is meristem and what zone is it called in plants?

Zone of growth - meristem is a region of stem cells performing mitosis

What do cells differentiate into in Zone of Differentiation?

• Root hair cells

• Phloem

• Xylem

What are the 3 zones in a plant?

1. Zone of growth

2. Zone of elongation

3. Zone of differentiation

What can plant growth be determined?

By the change in mass

•  As the stem cells elongate and differentiate, the plant grows and more stem cells are continuously produced increasing the mass.

How do you calculate the percentage of people under a certain percentile?

The percentile = the percentage of people below the value

If the 50th percentile of 30yr olds was 60kg, 50% of 30yr olds would have a mass below 60kg

Where should the line stay on a percentile graph

Between the 2 lines of 2 percentiles