Topic: Cell division and chromosomes (DNA and chromosomes (DNA organises…
Topic: Cell division and chromosomes
DNA and chromosomes
DNA organises amino acids which make proteins
DNA means Deoxyribo Nucleic Acid
DNA is normally found in the nucleus
Chromosomes contain DNA
A gene provides the code for a specific protein
There are two stands of DNA described as a double helix
DNA is made of many nucleotides (a polynucleotide)
A nucleotide is composed of a sugar a base and phosphate
There are four types of base, represented by the letters: A and T, and C and G
Mitosis is the production of two daughter cells that are genetically identical to the parent cell. The function of mitosis is to replace and repair cells.
Mitosis occurs in Eukaryotic cells to replace, repair or create new tissues
1 - DNA duplication
2 - Membrane of the nucleus closes in
3 - The fibres split the chromosomes
4 - The membrane fully splits
Stem cells are cells that haven't become specialised yet
Animal stem cells:
Found in the bone marrow and in the embryo.
They can't keep differentiating though-out life.
Plant stem cells:
Found in the meristem, the roots and the shoots. They can keep growing back.
In therapeutic cloning an embryo is split into individual stem cells. The nucleus of these cells is removed and replaced with the nucleus of the patient's skin cell. These stem cells are then cloned and specialised.
For: The embryonic cells shouldn't be treated as humans as they do not have emotions.
Against: The embryonic cells should be treated as human beings as they have the possibility to be.
Uses of stem cells
Growing leaves back
Making more food crops
Someone suffering from paralysis may be able to use stem cells to grow new nerve cells
A skin graft could b made from tem cells to treat a variety of problems