2.1 1 How DNA codes for proteins

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  • Created by: Hiba
  • Created on: 18-03-15 22:10
What is a gene?
A gene is a length of DNA that codes for one or more polypeptides (including enzymes)
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What is the genetic code?
It's a sequence of 3 nucleotide bases on a gene that provides a code which is used as instructions for the construction of a polypeptide or protein
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What is a codon?
The sequence of 3 nucleotide bases that make up a genetic code and code for an amino acid (complementary to anticodon on tRNA)
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What is transcription?
It's when a DNA coding strand is copied into a strand of mRNA (using a template strand of DNA and RNA nucleotides) so that instructions from DNA (in the form of a mRNA strand) can leave nucleus & travel to the ribosome to construct polypeptide.
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Which strand of DNA is mRNA complementary to?
The template strand
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What is the coding strand of DNA?
The strand of DNA that mRNA is a copy of.
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What are the 4 steps of transcription? (generation of mRNA strand)
1. Gene unwinds + unzips. H-bonds between bases break. 2. activated RNA nucleotides free in nucleus bind to complementary bases on template strand using h-bonds. Catalysed by RNA polymerase. (cont)
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(question 7 continued)
3. two phosphoryl groups are released and the energy released is used to bond adjacent nucleotides on mRNA strand 4. mRNA generated leaves nucleus via nuclear pore to ribosome in cytoplasm
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what bases bind?
Guanine and Cytosine. Adenine and Thymine. Uracil and Adenine.
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Card 2

Front

What is the genetic code?

Back

It's a sequence of 3 nucleotide bases on a gene that provides a code which is used as instructions for the construction of a polypeptide or protein

Card 3

Front

What is a codon?

Back

Preview of the front of card 3

Card 4

Front

What is transcription?

Back

Preview of the front of card 4

Card 5

Front

Which strand of DNA is mRNA complementary to?

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