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biology 0610printed 235 · PDF 235
328 pagesrevision 46933
printed 235 · PDF 235
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Protein molecules are made up of smaller molecules chained up together known as
amino acids.
The sequence of amino acids determines the shape of the protein molecule.
Code for which protein to make is present in DNA.
Protein synthesis takes place in ribosomes.
To carry information from the DNA (in the nucleus) to ribosomes, messenger RNA
(mRNA) is used.
mRNA copies the base sequence from the gene and travels towards the ribosome.
Accordingly the ribosomes link amino acids together as it was written on mRNA.
Through this way a protein molecule is formed.
Mitosis:
Is a division of the nucleus of a cell resulting in formation of 2 new nuclei containing
the same number of and type of chromosomes.
The parent cell and daughter cells are genetically identical.
Used in growth repair of damaged tissues and asexual reproduction.
Meiosis:
Diploid cells divide to produce haploid cells.
Is a reduction division.
They are genetically different from their parents.
Used in the production of gametes
Stem cells:
Unspecialised cells that are able to divide by mitosis to produce different types of
specialized cells.
E.g Zygote. When zygote is forming all of our cells are unspecialised at that time, but
as it grows specialized cell are formed