gcse biology week 6
TRANSCRIPT
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GCSE Biology Week 6
DNA, protein synthesis andmutations.
B2 1.6 A gene is a section of DNA that codes for a specific protein
B2 1.7 DNA (structure)
B2 1.9 How the structure of DNA was discovered
B2 1.22 DNA decides the order of amino acids in protein
B2 1.23 Stages of protein synthesis, including transcription and
translationB2 1.24 Proteins specific number and sequence of amino acids
B2 1.25 Gene mutations can be harmful, beneficial or neither.
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B2 1.6 A gene is a section
of DNA that codes for aspecific protein
B2 1.7 DNA (structure)
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1953 Watson & Crickworked out thestructure of DNA…
1952 – Rosalind Franklin and MauriceWilkins used X-rays to work out thatDNA was Helical.
B2 1.9 How the structureof DNA was discovered
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Recap- DNA Structure
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B2 1.7 DNA (structure)
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Protein synthesis
B2 1.23 Stages of protein synthesis,
including
transcription andtranslation
B2 1.24 Proteins
specific number and
sequence of amino
acids
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What are Proteins?
But… How does a cell arrange theamino acids in the correct order…?
Proteins are polymers built up from amino acids.
It is the order of amino acids that determines the 3Dconformational shape and function of the protein.
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Codon Codon Codon Codon Codon
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What is the order of amino
acids?
Table showing codons and corresponding amino acids, for
the insulin molecule (:::;:;BB<<B;<B<)
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mRNA CODONS
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M e s s e n g e r R N A ( m R N A )
Single helical strands ofseveral thousand
nucleotides.
It is produced in the
nucleus by transcriptionof DNA.
It contains tripletCODONS!
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T r a n s f e r R N A ( t R N A )
Single strand foldedinto clover-leaf
shape.
Different types oftRNA: each providinga code for one amino
acid.
Used in translation
Has the Anticodon
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r i b o s o m a l R N A ( r R N A )
Made in nucleus.
Used in translation -
“Protein synthesis”
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What is Transcription?
@5&%9.5(B'(/% -! # =)(0*!! "4#" -$6(16*! "4*
'5&%9.5(4(%) E./%705'(%)> (' 7*$*"-0 -$'()5#"-($?*272 # <393@ ')(5 !"# "( 2"#2
Transcription can be thought of in 3 phases…
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Transcription can broken down into steps…
H> K%('(&'(/%L 2"# B/+,305&90 4/%$9 '/ B5/3/'05 9('09
/% !"#G
M> N+/%)&'(/%L 32"# (9 O./B(0$P 85/3 !"#
Q> @*0 )5/R(%) 32"#9'5&%$ B5/'5<$09 85/3
'*0 S'5&%9.5(B'(/%
4<44+0TG
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U> @053(%&'(/%L :" "4* *$% (' # 7*$*C # 9'/B ./$/%
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B4-! -! 0#11*% Z9: !=1-0-$7>
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K%'5/%9 #)* "4* %/%A./$(%) !*0"-($! ('
89: N 32"# 6 (%'5/%9 &50 503/70$1
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H$0* "4* -$")($!
4#6* .**$ )*5(6*%C
"4* 5Z9: *+-"! "4*$/01*/! 6-# $/01*#)
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5*5.)#$*V
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What is Translation?
@5&%9+&'(/% -! # !"*= -$ B5/'0(% 9,%'*09(9 A4*)*
"4* 7*$*"-0 0(%* 0#))-*% ., 32"# -! %*0(%*% "(=)(%/0* "4* !=*0-'-0 !*W/*$0* (' &3(%/ &.($9 -$
# B/+,B0B'($0 EJ5/'0(%> 04#-$2
@5&%9+&'(/% 3%//%?+ @5&%9.5(B'(/% ?-$ A4-04 "4* 89:!*W/*$0* -! 0(=-*% ?")#$!0)-.*%@ -$"( 5Z9:@2
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Translation can broken down into steps…
H> B4* 0(%* ($ "4* 5Z9: -! /!*% "( #!!*5.1* "4*
#5-$( #0-%! -$ "4* 0())*0" ()%*)2
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Q> 3#04 ./$/% ($ 5Z9: 0())*!=($%! "( # !=*0-'-0&%'(./$/% ($ "4* "Z9:2
M> Z-.(!(5*! .-$% "( "4* 5Z9: #$% #11(A! "Z9:! "(
#""#042
U> :5-$( #0-%! #)* ](-$*% ., B0B'($0 4/%$9V8/53(%) =(1,=*="-%*! ?B5/'0(%9@>
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W<'&'(/% R 04#$7* -$ "4* .#!* !*W/*$0* (' 89:
Change in base
of DNA
Change in base of
mRNA
Change in
mRNA CondonChange in amino acid of
protein
Change in protein
structure
Change in proteinfunction
Change in cell function !!!
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^ " "- 4 - 89: ? "
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G2 8 1*"-($
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G2 8*1*"-($
S4*$ # .#!* -! %*1*"*% ')(5 89:
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