Protein Synthesis

DNA Review  The nucleotide bases will point to the inside of the DNA molecule while the outside (backbone) of the DNA molecule will be made of the sugar and phosphate molecules  When complete the DNA molecule forms a double helix (two spiral sides wrapped together)

CHROMOSOMES CONTAIN DNA  The nucleus contains chromatin  Chromatin is made of smaller nucleosomes  A nucleosome is formed by a DNA molecule wrapped around a protein “stick”  Looks like cotton candy wrapped around the paper cone

Protein Synthesis

Why is it important?  Cells are controlled by enzymes- enzymes are proteins  Almost every substance made by the cell is or contains a stuctural protein

Vocabulary  Gene- a portion of DNA that codes for a protein- the “recipe” for a protein  mRNA- messenger RNA  tRNA- transfer RNA- transfers amino acids  Codon- mRNA’s complementary trio of bases  Anticodon- tRNA’s complementary trio of bases  Transcription- mRNA making a template of DNA’s code  Translation- tRNA “reading” mRNA’s code and transferring the amino acids necessary to form a protein

Two Steps to Protein Synthesis  Transcription- takes place in the nucleus-mRNA makes template of DNA’s code  Translation- takes place on the ribosome in the cytoplasm- tRNA transfers amino acids

Things to Remember  DNA contains the “recipes” for proteins- called genes  DNA is made of the bases adenine, thymine, guanine and cytosine  A-T and C-G  RNA is made of the bases adenine, uracil, guanine and cytosine  A-U and C-G

Transcription  Takes place in the nucleus  DNA unzips  mRNA makes a template of the DNA code  mRNA copies the code three bases at a time- this is a codon

Transcription- mRNA forms codons

Translation- on the ribosome, tRNA transfers amino acids

Another Look

Another View

The four bases can combine in 64 different triplicate (codon) combinations  Each codon codes for a specific amino acid

Codon Chart

Another Codon Chart

Protein Structure

A Few of The Finished Products! Proteins

Think About It-  Letters→ Words→ Sentences Sam hit the ball. Sam hit the ball.  Bases→ Amino Acids→ Proteins

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Wrap Up  1. DNA message is transcribed into messenger RNA (mRNA)  2. mRNA leaves the nucleus and attaches to a ribosome  3. Each three letter codon will attract a matching three letter anti-codon of transfer RNA (tRNA)  4. Each tRNA is carrying an amino acid “on its back”  5. As the tRNA molecules line up, their amino acids also line up  6. As the amino acids are lined up, they chemically bond to form a protein

Mutations- Any error in the genetic code Can happen when:  DNA is making new copies of itself (replication)  DNA is being used to make messenger RNA (transcription)  Transfer RNA is being attracted to the messenger RNA at the ribosome (translation)

Types of Mutations  Point mutations happen when one or two bases are different than they are supposed to be  Frameshift mutations happen when extra bases are added or deleted