A QUICK INTRODUCTION Protein Synthesis. Key Terms Gene RNA mRNA tRNA rRNA Transcription Translation...
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Transcript of A QUICK INTRODUCTION Protein Synthesis. Key Terms Gene RNA mRNA tRNA rRNA Transcription Translation...
A QUICK INTRODUCTION
Protein Synthesis
Key Terms
GeneRNAmRNAtRNArRNATranscriptionTranslationCodon AnticodonRibosomeDenatureRNA Polymerase
Protein What?
Synthesis!! The combination of parts into a whole
Protein Synthesis The process our cells go through to make proteins
Protein Synthesis Video
We will watch this twiceWrite down things YOU think are important
from this video (write at least 5)http://www.youtube.com/watch?v=D3fOXt4M
rOM&feature=related
Protein Synthesis
There are 2 steps of protein synthesis Transcription Translation
The central dogma states that information flows in one direction from DNA to RNA to proteins. DNA RNA Protein
RNA connects the 2 steps mRNA carries DNA’s instructions
replication
transcription
translation
What is a protein?
A chain of molecules called amino acidsUsed in almost every process of our cells
(replication, respiration)Provides structure (used to create cell
walls, bone and muscle)Examples:
Hemoglobin Insulin DNA polymerase major component of cartilage and hair
DNA contains the information required to make proteins
DNA must be copied before proteins can be made
Why? DNA is master blueprint of the cell – needs to be kept
safe Cell needs to make a lot of proteins
Needs to make a lot of copies of DNA
mRNA is the copy of DNA used to make proteins
RNARNA (Ribonucleic Acid) is very similar to
DNA but there are a few differences Different sugar - ribose instead of
deoxyribose Single-stranded Uses uracil instead of thyamine
Types of RNA
There are 3 types of RNA mRNA - messenger RNA, carries the message or
instructions to make a particular protein rRNA - ribosomal RNA, makes up ribosomes tRNA - transfer RNA, transport amino acids (the
building blocks of protein) to the ribosome
Step 1: Transcription
Protein Synthesis starts in the nucleus with transcription.
Transcription is very similar to replication. Transcription and replication both involve complex enzymes and complimentary base pairing. The two processes have different end results.
Replication copies all the DNA; transcription copies a gene. RNA Polymerase complex binds to DNA at the
beginning of a specific gene unzips DNA Like DNA Polymerase, RNA Polymerase matches
base pairs Remember, instead of using thymine to pair with
adenine we use uracil to pair with adenine.
After Transcription
Once the gene is completely copied DNA is zipped back up mRNA leaves the nucleus DNA is left unchanged
As many copies of RNA can be made as needed
http://www.youtube.com/watch?v=vJSmZ3DsntU&feature=related
Step 2: Translation
During translation the mRNA is used to create a polypeptide, or protein.
After the DNA has been copied mRNA leaves the nucleus and enters the cytoplasm where it binds to a ribosome.
Translation
The ribosome “reads” the mRNA strand 3 bases at a time – called a codon
Each codon codes for a specific type of amino acid One start codon, AUG Three stop codons UAA, UAG, UGA
Regardless of the organism, codons code for the same amino acid.
As the ribosome reads the mRNA codons, tRNA brings(transfers) the correct amino acid to the ribosome
An anticodon is a set of three nucleotides that are complementary to an mRNA codon. An anticodon is located on the tRNA.
The amino acid is attached to the growing chain with peptide bonds by the ribosome
Translation: Detailed View
For translation to begin, tRNA binds to a start codon and signals the ribosome to assemble. a complementary tRNA molecule binds to the exposed
codon, bringing its amino acid close to the first amino acid
the ribosome helps form a peptide bond between the amino acids
the ribosome pulls the mRNA strand length of one codon the now empty tRNA molecule exits the ribosome a complementary tRNA molecule binds to the next
exposed codon. once the stop codon is reached, the ribosome detaches
the protein and disassembles
Once the amino acid is added to the protein chain the tRNA detaches and leaves the ribosome to get another amino acid.
http://www.youtube.com/watch?v=NJxobgkPEAo
Protein Structure
Proteins are more than long strings of amino acids.
They must be folded in order to function correctly
Proteins can be damaged or “denatured”Denature is a change in shape and function
of a protein caused by forces such as temperature or pH changes
Can Proteins be Damaged?
Important! Every somatic cell in your body has the exact same DNA!!
How come the cells in your body act different if they all contain the same DNA? Some cells make hair while some digest your lunch.
It is all in the genes and proteins they express!