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Transcription and Translation. Protein Structure. Made up of amino acids Polypeptide - string of amino acids bonded together (peptide bonds) Enzymes are proteins 20 amino acids are arranged in different orders to make a variety of proteins Assembled on a ribosome.

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Protein structure
Protein Structure

  • Made up of amino acids

  • Polypeptide- string of amino acids bonded together (peptide bonds)

    • Enzymes are proteins

  • 20 amino acids are arranged in different orders to make a variety of proteins

  • Assembled on a ribosome

Rna vs dna


Double stranded

Deoxyribose sugar

Bases: C,G A,T


Single stranded

Ribose sugar

Bases: C,G,A,U



  • mRNA from DNA

  • mRNA’s bases are complementary to that of DNA

    • C-G

    • A-U

    • NOTICE: Uracil replaces Thymine

  • Occurs in nucleus

Major players in transcription
Major players in transcription

  • RNA polymerase-

    • Unwind DNA sequence

    • mRNA is synthesized using 1 strand of DNA (template strand)

    • Long chain of mRNA nucleotides are createdbases complementary to the DNA template







**Each group of 3 bases of mRNA (see colors above) are called a codons


  • After transcription, mRNA- now has the information to carry out protein synthesis

Transcription is done what now
Transcription is done…what now?

Now we have mRNA transcribed from the cell’s DNA.

It leaves the nucleus through a nuclear pore into the cytoplasm

Once in the cytoplasm, it finds a ribosome where translation can begin.

The mRNA code has to be read now so a protein can be “assembled”


  • Second stage of protein production

  • mRNA is on a ribosome and “read” in groups of three bases (a codon)

  • tRNA brings amino acids to the ribosome


  • Transfer RNA (tRNA) is bound to one amino acid on one end

  • tRNAanticodon complements mRNA codon.

  • If they do not complement, the tRNA’samino acid will not be a part of the protein!

Ribosome reads the dna code
Ribosome Reads the DNA code

  • Every mRNA codon of bases encode for an amino acid (see chart handout of Amino Acids)

  • There is a Start codon(AUG) telling the ribosome where to start translation and a STOP codon ending protein synthesis

After all is said and done
After All Is Said and Done….

  • The amino acid sequence forms a protein

    • Leads to a particular function and phenotype (trait) in an organism

  • Proteins can be structural (forming a part of cell materials)

  • Proteins can be functional (hormones, enzymes, biochemicals)

Protein shapes vary
Protein Shapes Vary

Amylase – an enzyme in your mouth

Hemoglobin on Red blood cells

Transcription vs translation review


Process by which genetic information encoded in DNA is copied onto messenger RNA

Occurs in the nucleus



Process by which information encoded in mRNA is used to assemble a protein at a ribosome

Occurs on a Ribosome

mRNA protein as tRNA brings in its Amino Acid

Transcription vs. Translation Review