Transcript dna-replication-recap-and-gene-expression

Pair, Share!
• Show your DNA replication diagrams to
someone else on ANOTHER TABLE.
• You will now “mark” it
Check List
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Includes ;
DNA Polymerase
Ligase,
Primer
Bases/nucleotides joining
Unwinds
• Still not clear …..
Same but different ....
• Four of the many
different types of
human cells
(a) Three muscle cells (partial)
(b) A nerve cell (partial)
(c) Sperm cells
(d) Blood cells
– They all share
the same
genome
– What makes
them different?
What things similar/different?
Why have specialised cells?
• Division of Labour
• Multicellular organisms
have millions of cells
• To ensure all process
carried out – division of
labour where cells
become differentiated
and specialised to carry
out 1 specific function
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How many chromosomes/DNA?
Big Question
Gene Expression; On and Off
Once a cell becomes differentiated –
the genes that code for only specific
proteins to the workings of that cell
are turned on.
Only 3-5% of genes expressed in a
typical human cell
Think!
• For a nerve cell neurotransmitters would be
switched on, but mucus would be off
• What genes would be turned on for ...
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Goblet cell in lining of wind pipe
Saliva cells
White blood cells
Ovary cells
Selective Gene Expression
• Once a cell becomes differentiated it only
expresses the genes that produce the
proteins characteristic for that type of cell.
• So what happens before .......
Review
• Genes are ....
• For different cells to become specialised ....