Chapter 8
RNA and protein synthesis
Structure of RNA
The second type of nuceic acid is ___________ _____ (______). RNA also
consists of nucleotides.
(Copy fig 8.1 below)
Differences between RNA and DNA
There are three important differences between DNA and RNA.
(Copy table 8.1)
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DNA Sequence
It is the sequence of DNA bases along a strand of DNA that is unique to an
organism. It contains the genetic instructions which control the organism’s
inherited characteristics.
(make a note to explain how the DNA base sequence affects the characteristics of
an organism. Also mention how it is possible to code so much information using only
4 base types).
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Transcription of DNA
The genetic information carried by DNA is taken out of the nucleus by messenger
RNA (mRNA). The mRNA is formed from one of the DNA strands using a free pool
of RNA nucleotides.
(On the picture below label the stages of transcription using figure 8.3 from page 52.)
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mRNA
The completed molecule of mRNA leaves the nucleus through a pore in the nuclear
membrane and enters the ____________. Each triplet of bases on mRNA is called a
__________.
tRNA
A second type of RNA is found in the cell’s cytoplasm. This is called ____________
_____ (______). Each molecule of tRNA has an exposed triplet of bases, known as
an anticodon. This anticodon corresponds to a particular amino acid. Each tRNA
molecule picks up the appropriate amino acid from the cytoplasm at its site of
attachment.
Ribosomes
Ribosomes are small, almost spherical structures found in all cells.
They can occur;
1.
2.
They are the site of the _____________ of ______ into protein. Each ribsome
contains enzymes essential for protein formation. Large numbers of ribosomes are
found in growing cells which need to produce large quantities of protein.
Translation of RNA into protein
(write a note to explain how the diagram below works)
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Re-use of RNA molecule
tRNA is re-used by –
mRNA is often re-used by –
Protein synthesised in ribosomes is for use where?
Protein made in ribosomes attached to the endoplasmic reticulum is for use where?
Endoplasmic reticulum
What is the purpose of the rough endoplasmic reticulum?
Where is the rough ER?
Label the following diagram based on fig 8.6
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Golgi Apparatus
Secretory proteins are passed on to the Golgi apparatus from the rough ER.
What does the Golgi apparatus look like?
What does the Golgi apparatus do?
Where would you find lots of Golgi bodies?
Golgi apparatus
Golgi apparatus
Cell diagram
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