Protein synthesis
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Protein Synthesis. Review What is RNA and Why is it Important? Types of RNA C odons & Anticodons Transcription Translation Amino Acids and The Codon Chart. Review. Review. Remember how the bases bond in DNA? DNA: A TGCT T AG RNA is similarly complimentary:

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Protein Synthesis

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Protein synthesis

Protein Synthesis

Review

What is RNA and Why is it Important?

Types of RNA

Codons & Anticodons

Transcription

Translation

Amino Acids and The Codon Chart


Review

Review


Review1

Review

Remember how the bases bond in DNA?

DNA: ATGCTTAG

RNA is similarly complimentary:

DNA: ATGCTTAG

RNA:

TACGAATC

UACGAAUC


Protein synthesis1

Protein Synthesis

  • Protein Synthesis is the final part of the process of making proteins from a DNA template

  • But wait a minute-

    • Where is DNA?

    • Where are proteins made?

    • How do we get proteins from DNA if the DNA can’t leave?

    • We make RNA from the DNA template!

In the nucleus

At the ribosome


Protein synthesis2

Protein Synthesis

  • Why is RNA important?

    • It uses the code from DNA in the nucleus to order (sequence) amino acids in the cytoplasm

    • Amino acids bond together (dehydration synthesis!) to make proteins


Protein synthesis

  • What is a protein?

    • Polypeptide

    • Made from amino acids linked together

      • The amino acids are held together with covalent peptide bonds

      • The long chain of amino acids is called a polypeptide

      • The polypeptide chain twists up into a complex shape called a protein.


Protein synthesis

  • Amino Acids

    • There are 20 different amino acids

    • 3 different RNA nucleotides code for 1 amino acid

      • Example:

        UAC = tyrosine (1 amino acid)

        AAU = asparginine ( 1 amino acid)

        GUU = valine (1 amino acid)

    • Linking amino acids creates a protein:

      • Example:

        tyrosine + asparginine + valine = 1 protien!


Amino acids

Amino Acids

  • The order of the amino acids determine the protein’s shape

  • The protein’s shape determines its function.

  • If the protein has the wrong shape, it won’t work right!!!!!

  • So it’s really, really important that the amino acids get put in the right order


Protein synthesis3

Protein Synthesis

  • Before we learn the process of protein synthesis, we need to learn the places:

  • Places:

    • Nucleus

      • Has the DNA template (a section of the DNA called a gene)

    • Cytoplasm

      • The fluid within the cell

      • Amino acids are floating in the cytoplasm

    • Ribosome

      • Organelle where amino acids are linked together

      • Putting together amino acids = making a protein


Protein synthesis4

Protein Synthesis

  • Before we learn the process of protein synthesis, we need to learn the parts:

  • Parts:

    • rRNA = ribosomal RNA

      • Helps make up the ribosome (rRNA and protein make up the ribosome)

      • aids in bonding mRNA to tRNA

    • mRNA = messanger RNA

      • Created in the nucleus, travels through the cytoplasm to the ribosome

      • Carries “the message”

      • Codon(more on this later)

    • tRNA = transfer RNA

      • Moves amino acids from the cytoplasm to the ribosome

      • Anticodon (more on this later)


Protein synthesis

Nucleus

DNA

mRNA

E

Cytoplasm

New Protein

tRNA

E

E

Ribosome

Amino Acids

E

The Cell


Protein synthesis5

Protein Synthesis

  • Two step process

    • Transcription- mRNA synthesis

      • Happens in the nucleus with mRNA

      • DNA  mRNA

    • Translation- protein synthesis

      • Happens in the cytoplasm at the ribosome with the mRNA, tRNA and amino acids


Protein synthesis6

Protein Synthesis

  • Part One: Transcription

    • Segments of DNA are separated by RNA polymerase

    • One of the detached strands is used as the template to make mRNA

    • RNA polymerase adds mRNA nucleotides to the exposed DNA strand

      • This creates mRNA


Protein synthesis7

Protein Synthesis

Transcription- Let’s Practice!

(remember, in RNA there are no T’s; use U’s!)

DNA = AGCTTA

mRNA =

(codon)

*Codon: every three nitrogen bases (also called “bases”, “RNA nucleotides”, “nucleotides” or just the “letters”)

(3 nucleotides = 1 codon = 1 amino acid)

How many codons are above?

UCGAAU

Codon

Codon

2


Codon question

Codon Question

  • A piece of mRNA is made of 15 nucleotides (bases)

    • How many codons does it have?

  • A piece of mRNA is made of 30 nucleotides (bases)

    • How many codons does it have?

  • A piece of mRNA is made of 60 nucleotides (bases)

    • How many codons does it have?


Protein synthesis8

Protein Synthesis

  • Part Two: Translation

    • When something is translated, it is converted from one language to another. In this case, we are converting from the “language” of nucleotides to the “language” of amino acids”


Protein synthesis9

Protein Synthesis

Translation con’t

  • The newly formed mRNA leaves the nucleus and attaches to a ribosome

  • The mRNA “translates” the DNA code to the tRNA that is in the cytoplasm.

    • Each mRNA codon is paired with a complementary tRNA that is in the cytoplasm

    • The tRNA has a specific amino acid attached to it

    • The tRNAanticodon carrying the amino acid attaches to the mRNA codon


Protein synthesis10

Protein Synthesis

  • Part Two: Translation continued…

    • The tRNA has a specific amino acid attached to it

    • The tRNAanticodon carrying the amino acid attaches to the mRNA codon

      Practice:

      DNA: ATGCAT

      mRNA:

      (codon)

      tRNA:

      (anticodon)

UACGUA

AUGCAU

AntiCodon

AntiCodon


Protein synthesis

Translation Continued

  • Once two amino acids are present at the ribosome, a peptide bond forms that hold the amino acids together

  • Multiple amino acids bonded together = a protein (a polypeptide)


Protein synthesis

The process of matching tRNA to mRNA continues until all mRNA codons are matched to their anticodons and a “STOP” codon is read.

- The end result is a polypeptide (a protein)


Amino acids1

Amino Acids

  • If I were to give you a strand of DNA, you should be able to tell me:

    • The complimentary mRNA strand (codon)

    • The amino acid the mRNA is coding for

    • The tRNA strand (anticodon) that brings the amino acid to the ribosome

  • To determine the amino acid the mRNA is coding for, you can use an mRNA codon table


Protein synthesis

If mRNA is

UCG

Find U for the first base

C for the second base

And G for the third base

-UCG codes for the amino acid Serine

- The anticodon AGC is on the tRNA that brings serine to the ribosome


Practice

Practice!

DNA: GACTTA

mRNA:

(codon)

What amino acid are the mRNA codons code for?

CUGAAU


Protein synthesis

CUG=

AAU =


Protein synthesis

What is the mRNA strand?

CUGAAU

DNA: GACTTA

mRNA:

(codon)

Amino Acids:

What must the tRNAanticodons be to attach those amino acids?

tRNA:

(anticodon)

What amino acids does the mRNA code for?

Leucine

Asparagine

GACUUA


Codon practice

Codon Practice!

  • A piece of mRNA is made of 15 nucleotides (bases)

    • How many codons does it have?

    • How many amino acids will the protein have?

  • A piece of mRNA is made of 30 nucleotides (bases)

    • How many codons does it have?

    • How many amino acids will the protein have?

  • A piece of mRNA is made of 60 nucleotides (bases)

    • How many codons does it have?

    • How many amino acids will the protein have?


Review2

Review

  • The DNA code AAA-CTG-CAA is the gene read in the nucleus

  • During transcription, the mRNA strand UUU-GAC-GUU is made

  • The mRNA strand leaves the nucleus and attaches to the ribosome

  • tRNA molecules in the cytoplasm bond to the amino acids indicated by the anticodon on that tRNA

  • During translation, the tRNAanticodons bond to the complementary mRNA codons

    • In this example would result in the amino acids phenylalanine, aspartic acid and valine out in the cytoplasm

  • The amino acids phenylalanine, aspartic acid and valine join together by peptide bonds to create a polypeptide (protein)


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