protein syntheisis 2016
TRANSCRIPT
The Players mRNA: messenger RNA - carries
protein recipe from the nucleus
tRNA: transfer RNA -brings amino acids to the
ribosome
Ribosome: the site of protein synthesis
- made of rRNA (ribosomal RNA )and Protein
Meet mRNA (ribonucleic acid)
mRNA (messenger RNA) made in nucleus serves as a template (pattern) of the DNA molecule.
Triplet or codon: grouping of 3 nitrogenous bases in DNA or RNA
molecules (each codon will code for a specific amino acid)
HOW DOES IT DIFFER FROM DNA?
1. The RNA molecule is a SINGLE nucleotide strand, not a double strand as in DNA.
2. The sugar molecule in RNA is RIBOSE -- not deoxyribose as in DNA.
3. The base URACIL (U) takes the place of thymine. (T)
There are twenty different amino acids that build proteins
There are 64 different triplets/codons Each amino acid is coded for by more than
one triplet/codon
Meet tRNA
each molecule of tRNA carries a specific type of amino acid -each tRNA molecule can only carry one type of amino acid
The tRNA has a group of 3 nucleotides at the base called the anticodon
tRNA (transfer RNA) – reads the mRNA and transfers the amino acids into the correct order to make the protein
DNA serves as a template for the synthesis of mRNA from RNA nucleotides in the nucleus.
transcription: transfer of the genetic message from DNA to mRNA
How are proteins synthesized from a DNA template? (model)
The Process of Translation
mRNA takes recipe to the ribosome in cytoplasm
ribosome attaches to the mRNA
How does tRNA know which amino acid goes where?
The anticodon a sequence of 3 nucleotides
tRNA is complementary to a mRNA codon binds to matching codon specifies the next amino acid to be
attached during protein synthesis.
Example: mRNA codon = GAC = carries only
aspartic acid tRNA anticodon = UAC carries only
methionine
Begin Translation
The ribosome moves along the mRNA until it reaches the “Start” codon
Start codon = AUG signals the start of the recipe
AUG also codes for the amino acid methionine
mRNA molecules carrying a specific code move from the nucleus to the cytoplasm and attach to a ribosomes (rRNA)
mRNA leaves through nuclear pores
Different triplets
(codons) of nitrogenous bases in tRNA molecules pick up specific amino acids in the cytoplasm and carry them to mRNA at the ribosomes.
A molecule of transfer RNA brings the amino acid called for by the mRNA to the ribosome
transfer RNA = tRNA
A second tRNA brings the second amino acid to the ribosome
The amino acids are joined together to begin the protein
The ribosome moves over 1 codon (triplet) and another tRNA molecule brings another amino acid
The process continues until the stop codon on the mRNA is reached
The stop codon = the end of the protein recipe
These proteins are what directs the activity in each cell!
Basically, RNA translates the DNA information!
Translation: The genetic code carried by mRNA is decoded to produce the specific sequence of amino acids in a protein
gene: the sequence of nucleotides in a DNA molecule necessary to synthesize a protein (polypeptide)
** One gene codes for one protein
Protein Synthesis VideoProtein Synthesis RapProtein Synthesis Interactive
DNA determines the sequence of amino acids in specific proteins.
The specific shape of the protein (ex:enzymes and hormones) determines the function of that protein
Offspring resemble their parents because they inherit: similar genes…that code for similar proteins… that have similar structure and function
Major Understandings: