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3.1 In the beginning:

Prokaryotic cell: Bacteria and cyanobacteria (photosynthetic bacteria) They have no nuclei
or other membrane-bound cell organelles. Diameter 0.5 and 5

Eukaryotic cells: contain membrane bound organelles- nuclei, Mitochondria. Larger than a
prokaryotic cell. Diameter 20 or more.

Mitochondria: Inner of its 2 membrane is folded, form…

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SER: Like RER. Does not have any attached ribosome's. SER are make lipids are steroids. E.g.
reproductive hormones.
Golgi apparatus: stacks of flattened, membrane bound sacs formed by fusion of vesicles
from ER. Modifies proteins and packages them in vesicles for transport.
Lysosomes: Spherical sacs containing digestive enzymes and bound…

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Gamete cells are unusual:

Human cell: 46 chromosomes. 22 homologous pairs. 1 pair of sex chromosomes.

Fundemantal difference between sex cells are other cells is the no. of chromosomes they

How do gametes form: 2 types of cell divison in living organisms. MITOSIS AND MEIOSIS.

Mitosis produces new body…

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3.2: From one to many: the cell cycle.

The cell cycle can be divided into 2 distinct parts: interphase and division.

Preparation for division: Interphone:
Time of intense & organised activity during which the cell synthesizes new cell
components such as organelles and membranes, and new DNA.
Formation of new…

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Apart from usual mutation both strands are identical copies.
They are 2 chromosomes joined at 1 region called centromere.
Microtubules from the cytoplasm form a 3D structure called spindle.
The centrioles move around the nuclear envelope and position themselves at
opposite sides of the cell.
The breakdown of the…

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Potential use of human stem cells in medicine:
They may 1 day produce universal human donor cells which would provide new cell, tissues
or organs for treatment and repair by transplantation.
Their potential to develop into any cell type offers the greatest flexibility for development,
unlike adult stem cells which…


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