Protein SynthesisProtein Synthesis

Chapter 13Chapter 13

Protein Protein SynthesisSynthesis How does your DNA eventually lead to How does your DNA eventually lead to

your different phenotypes (hair color, eye your different phenotypes (hair color, eye color, etc)color, etc)

RNARNA RNA is a nucleic acid (like DNA) which is RNA is a nucleic acid (like DNA) which is

made up of nucleotides EXCEPT its sugar made up of nucleotides EXCEPT its sugar is is riboseribose instead of deoxyribose and it instead of deoxyribose and it has has UracilUracil instead of Thymine. instead of Thymine.

Bases:Bases:

Adenine (A), Guanine (G), Cytosine (C), & Adenine (A), Guanine (G), Cytosine (C), & Uracil (U)Uracil (U) that bonds with A in RNA that bonds with A in RNA

RNARNA

RNA is also only RNA is also only single-stranded, while single-stranded, while DNA is double-DNA is double-stranded.stranded.

Three types of RNAThree types of RNA 1. Messenger RNA (mRNA) – carries 1. Messenger RNA (mRNA) – carries

genetic information from DNA in the genetic information from DNA in the nucleus out to the ribosomes in the nucleus out to the ribosomes in the cytoplasm.cytoplasm.

Three types of RNAThree types of RNA

2. Transfer RNA 2. Transfer RNA (tRNA) – single chain (tRNA) – single chain folded into a hairpin folded into a hairpin shape that binds to shape that binds to specific amino acidsspecific amino acids

Three Types of RNAThree Types of RNA

3. Ribosomal RNA (rRNA) – Proteins are 3. Ribosomal RNA (rRNA) – Proteins are assembled on ribosomes which are made assembled on ribosomes which are made of subunits. These subunits are made of of subunits. These subunits are made of several ribosomal RNA.several ribosomal RNA.

Protein SynthesisProtein Synthesis

Protein Synthesis = Transcription + TranslationProtein Synthesis = Transcription + Translation

Steps of TranscriptionSteps of Transcription 1. Sections of DNA unzip, exposing the 1. Sections of DNA unzip, exposing the

base pairs, by using base pairs, by using RNARNA polymerasepolymerase.. 2. Pieces of mRNA come to the DNA 2. Pieces of mRNA come to the DNA

strand and match to the proper base strand and match to the proper base starting at the promotor region.starting at the promotor region.

***Note – Uracil takes the place of Thymine ***Note – Uracil takes the place of Thymine and bonds to Adenineand bonds to Adenine

Steps of TransciptionSteps of Transciption

3. This continues until a complete strand 3. This continues until a complete strand of mRNA is madeof mRNA is made

RNA EditingRNA Editing mRNA sometimes mRNA sometimes needs a bit of editing needs a bit of editing before it is able to be before it is able to be read (kind of like the read (kind of like the rough draft of a term rough draft of a term paper!)paper!)

Introns are portions of Introns are portions of the mRNA that are the mRNA that are cut out before it cut out before it leaves the nucleus.leaves the nucleus.

Exons are the Exons are the remaining portions remaining portions that are spliced back that are spliced back together to form the together to form the final mRNA strand.final mRNA strand.

TranslationTranslation

Translation = the process by which mRNA Translation = the process by which mRNA is converted into a string of amino acids is converted into a string of amino acids (building blocks of protein)(building blocks of protein)

Translation happens in the ribosomes Translation happens in the ribosomes floating in the cytoplasmfloating in the cytoplasm

Steps of TranslationSteps of Translation 1. mRNA strand 1. mRNA strand

from transcription from transcription breaks away from breaks away from the DNA & moves the DNA & moves into a ribosome into a ribosome floating in the floating in the cytoplasm.cytoplasm.

2. Floating in the 2. Floating in the cytoplasm are loose cytoplasm are loose tRNA pieces that tRNA pieces that contain an contain an anticodonanticodon – a sequence of 3 – a sequence of 3 nucleotidesnucleotides

Steps of

Steps of

Translation

Translation

3. tRNA anticodons match up with their 3. tRNA anticodons match up with their complementary complementary codonscodons on the mRNA molecule. on the mRNA molecule. The tRNA brings along the correct amino acid The tRNA brings along the correct amino acid

4. A chain of amino acids is joined to make a 4. A chain of amino acids is joined to make a specific protein.specific protein.

Codons and AnticodonsCodons and Anticodons

A codon specifies a particular amino acidA codon specifies a particular amino acid Both codons and anicodons are Both codons and anicodons are

sequences of three base pairs.sequences of three base pairs. Example: AUG or UAG or CGAExample: AUG or UAG or CGA

AUG signifies the start of an amino acid AUG signifies the start of an amino acid sequence.sequence.

Final Product = ProteinsFinal Product = Proteins

Proteins – organic molecules made up of Proteins – organic molecules made up of amino acids.amino acids.

There are 20 amino acidsThere are 20 amino acids Proteins do such things as control Proteins do such things as control

biochemical pathways, direct the biochemical pathways, direct the production of lipids, and take responsibility production of lipids, and take responsibility for cell movement.for cell movement.

Protein Synthesis AnimationProtein Synthesis Animation

Protein Synthesis Animation