GCSE Biology Week 6

7/23/2019 GCSE Biology Week 6

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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.



B2 1.6 A gene is a section

of DNA that codes for aspecific protein




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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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Protein synthesis

B2 1.23 Stages of protein synthesis,

including

transcription andtranslation

B2 1.24 Proteins

specific number and

sequence of amino

acids



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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What is the order of amino

acids?

Table showing codons and corresponding amino acids, for

the insulin molecule (:::;:;BB<<B;<B<)



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!



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



r i b o s o m a l R N A ( r R N A )

Made in nucleus.

Used in translation -

“Protein synthesis”



What is Transcription?

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What is Translation?

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Change in base

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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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GCSE Biology Week 6