Organisms only formed of one cell; like all prokaryotic organisms
what are multicellular organisms?
Organisms made of many cells, and are much more complex
In multicellular organisms, cells differentiate to become specialised cells, carrying out specific roles in the organism.
What is differentiation?
The process of becoming a specialised cell. specialised cells are the result of differentiation of stem cells.
what are stem cells?
cells that are undifferentiated. they are capable of forming many more cells of the same type by cell division, and forming certain types of specialised cell by cell division.
what is an embryo?
A very young multicellular organism, formed by fertilisation. Embryos are made of stem cells
Cell cycle
Series of stages during which cells divide to make new cells
Cell cycle
1. Cell grows larger
2. Makes more sub-cellular structures (e.g. ribosomes, mitochondria)
3. DNA is doubled by making an exact replica of the chromosomes
4. Tiny fibres pull the copies of each chromosome to opposite ends of the cell, breaking the replica chromosomes apart
5. Nucleus divides into two, each with the full set of chromosomes
6. Cytoplasm and cell membranes divide to form two genetically identical cells
What is mitosis?
The specific part of the cell cycle where cell divides to make two new cells which are identical
what is a chromosome?
a structure containing one molecule of DNA. one chromosome contains many genes. in body cells, chromosomes are found in pairs (since you inherit one copy of each chromosome from your mother and one copy from your father)
