Summary AQA biology topic 8 - DNA , Genes and protein synthesis

Can you de ne genome ?
A genome is the complete set of genes in a cell
Each genome contains all the information to build, grow and
DNA, GENES AND PROTEIN
develop that organism

Can you explain what a proteome is ?
SYNTHESIS
The proteome is the entire set of proteins that is, or can
be, expressed by a genome, cell, tissue, or organism at a
certain time
Can you describe the structure of transfer RNA
In eukaryotic , transcription results in pre-mRNA which ( tRNA )
needs to be sliced to form mRNA. • clover like structure
In prokaryotic , transcription results directly in mRNA • Unpaired bases on outside , paired bases inside
• Three anticodon loops
Can you explain transcription as the • Three bases form anticodon
production of mRNA from DNA ? Can you describe the structure of messenger
A mRNA copy of a gene is made from DNA RNA ( mRNA)
Eukaryotic =transcription takes place in the nucleus • shorter then DNA
Prokaryotic = no nucleus so takes place in cytoplasm • Single stranded
• RNA polymerase attaches to DNA at the beginning of • Contains uracil
a gene , DNA helicase ( attached to polymerase) • Length determined by DNA Template ( gene )
breaks hydrogen bonds between the two DNA Can you describe the structure of RNA
strands , exposing some of the bases
• One of the strands is used as a template to make an
( Ribonucleic acid )
mRNA copy • pentose sugar ( ribose )
• RNA polymerase lines up and joined together free • Single stranded
RNA nucleotides alongside the exposed bases on the • Shorter then DNA
template stand . The mRNA strand becomes a • Bases = adenine , cytosine , guanine , uracil .
complimentary copy of the DNA template. Can you describe the structure of DNA
• RNA polymerase moves along the strand continuing
• double stranded
this
• Each strand has a backbone of deoxyribose (sugar ) and
• DNAs hydrogen bonds reform once RNA polymerase
phosphate groups
has passed and coil back into a double helix.
• Each sugar is attached to one of four bases = adenine,
• When RNA meets sequence of DNA called stop
signal , it stops and detaches cytosine ,guanine or thymine
• In eukaryotic mRNA then moves out of the nucleus
through a nucleus pore and attaches to a ribosome
in the cytoplasm.
TRANSCRIPTION SUMMARY -
• RNA Polymerase separates DNA strands , DNA
helicase breaks hydrogen bonds
• One strand is used as template
• RNA polymerase joins free complimentary nucleotides
to template strand
• DNA hydrogen bonds reform and recoil
• RNA polymerase meets stop signal and detaches
• Eukaryotic = moves out nuclear pore attaches to
ribosome.


Can you explain the role of RNA polymerase in joining mRNA nucleotides ? Describe the function on Messenger RNA
What is RNA polymerase? ( mRNA) - carries copies of the genetic instructions
RNA polymerase is an enzyme that binds to DNA from DNA to ribosomes where its used to make a
during transcription and separates or unwinds the DNA strands protein in translation

What is the function of RNA polymerase in transcription?
Describe the function of Ribosomal RNA
RNA polymerase binds to DNA, separates the strands, then uses one of the strands as a template from which to (rRNA)- responsible for reading the order of amino
assemble nucleotides into a complementary RNA strand acids and linking them together

Why is RNA polymerase important?
Describe the function of transfer RNA
RNA polymerase is important because its ability to copy a single DNA sequence into RNA makes it possible for a (tRNA) - transfers each amino acid to the ribosome
single gene to produce hundreds or even thousands of RNA molecules. as it is speci ed by the coded messages in the mRNA.




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