Download Remember, transcription copies the DNA into mRNA

Remember, transcription copies
the DNA into mRNA
Transcription
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DNA gets copied.
mRNA is the copy.
If: DNA IS:
ATGAAAAACAAGGTACACATCTAG,
what is the mRNA?
• UACUUUUUGUUCCAUGUGUAGAUC
Translation
• The mRNA gets read… tRNA brings in amino
acids…
• UACUUUUUGUUCCAUGUGUAGAUC
• AUGAAAAACAAGGUACACAUCUAG
• Each group of three on the mRNA is called a
Codon. Each corresponding group of 3 on the
tRNA is called an anticodon.
Now, number 2
• ATGAAAAACAATTGCACGTAG = DNA
• UACUUUUUGUUAACGUGCAUC =mRNA
• AUGAAAAACAAUUGCACGUAG =tRNA
Translation
Continued!
Some antibiotics block translation:
Transfer RNA
It is a strand of RNA that has a 3 base ‘anticodon’. This
anticodon corresponds to a 3 base ‘codon’ on the mRNA.
Each tRNA carries an amino acid specific to its anticodon.
Aminoacyl tRNA synthetase
This is an enzyme that attaches amino acids to
tRNAs (that is how it uses the tRNA).
Ribosome
Made of 2 subunits that sandwich the mRNA
The large subunit has a ‘p’ site (polypeptide) and
an ‘a’ site (amino acid)
Hey! The tRNA comes into the ‘A’ site,
connects the amino acid to the
polypeptide chain that is located in the
‘P’ site.
Reading frame/Codons/Anticodons
mRNA is read in groups of 3 (reading frame).
Each group of 3 is called a codon.
tRNA has an anticodon on the base that lines up
with the codon of the mRNA.
Codon Practice!
AUG! What does it code for?
How about AAA?
What happens if our genetic information gets
changed? It depends on the type of change!
Point mutation – a single nucleotide is changed;
•Substitution is a point mutation… (bases are ‘swapped’)
Frameshift mutation – nucleotides added or deleted from a
sequence, and sometimes copied.
Insertions –add a base… whole codon sequence
changes.
Deletion –take out a base
Non-sense if it no longer functions at all.
Missense if it functions, though likely improperly.
Do chromosomes mutate?
Translocations occur when two DIFFERENT chromosomes swap
pieces.
Inversions occur when different parts of the same chromosome trade
places. (This is what happened with our fruit flies in the packet!)
Causes of Mutations
Spontaneous:
Pairs break down and change to other
nucleotides by losing a H, deaminating,
or losing correct base.
Induced:
Chemical – certain chemicals cause known damages, i.e.
hydrocarbons (benzene) and oxygen (free radicals).
Radiation – UV (260-280nm), T and C are weak here; Ionizing
(i.e., x-rays)
Hotspots – Certain parts mutate more often;
this happens in bacteria
Measure Twice, Cut Once
Cells check their work a lot!
Ligase puts strands back together, if
broken.
Polymerases check base pairs
consistently throughout replication and
translation, through checkpoints.
Some cells may be euthanized
(apoptosis).