DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still...
-
Upload
sabina-miles -
Category
Documents
-
view
216 -
download
0
Transcript of DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still...
![Page 1: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/1.jpg)
DNA Transcription & Translation
![Page 2: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/2.jpg)
*How do genes work?
We’ve seen how DNA is replicated, but still haven’t learned exactly
how genes work!
The first step in understanding how genes work is to know how to
“decode” the DNA.
![Page 3: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/3.jpg)
Decoding DNA
• The decoder: RNA (Ribonucleic acid)
• Long stranded like DNA, except:– Ribose instead of
Deoxyribose– Uracil instead of Thymine– Single stranded instead of
double stranded
![Page 4: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/4.jpg)
![Page 5: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/5.jpg)
Types of RNA• The main job of all RNA types is protein
synthesis (creation)• 3 types: (*You will learn what each does later)
Messenger RNA Transfer RNA Ribosomal RNA
mRNA tRNA rRNA
![Page 6: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/6.jpg)
Protein Creation
• DNA holds the instructions for making proteins– Proteins do the cell’s work
• Two steps required for protein synthesis (creation)
1. TRANSCRIPTION2. TRANSLATION
![Page 7: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/7.jpg)
Transcription
• TRANSCRIPTION is the process by which a DNA gene is “rewritten” into RNA
![Page 8: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/8.jpg)
Transcription• A gene is only a segment of DNA
– Only the gene is transcribed, not all of the DNA (like replication)
TranscriptionDNA
mRNA
![Page 9: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/9.jpg)
Transcription
3 phases:1. Initiation (“the beginning”)
• Enzymes recognize appropriate gene in DNA
2. Elongation (“the middle”)
• Enzymes copy gene into mRNA
3. Termination (“the end”)
• Enzymes unbind from DNA
![Page 10: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/10.jpg)
![Page 11: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/11.jpg)
![Page 12: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/12.jpg)
Why re-write the instructions?
• RNA is like an inexpensive, disposable copy of the master plan
• Used at the work site (the ribosomes)
• DNA is like the “master plan” for the construction of a house
• Too important to bring to the work site and risk being damaged or lost
![Page 13: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/13.jpg)
TranscriptionINITIATION
• RNA POLYMERASE (RP) recognizes a promoter on the DNA sequence
– PROMOTER: base sequence that signals the start of a gene
• DNA is split by RP and one strand is used as a template
![Page 14: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/14.jpg)
Animation #1
Animation #2
![Page 15: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/15.jpg)
Transcription
• ELONGATION:– RP makes an mRNA copy of the gene
![Page 16: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/16.jpg)
Transcription
TERMINATION• RP reaches TERMINATOR SEQUENCE
– Signals it to unbind and stop transcription
![Page 17: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/17.jpg)
![Page 18: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/18.jpg)
Transcription
• After transcription is done you end with one mRNA copy of a gene
• Some of the mRNA must be “spliced out” (removed) before we translate it
![Page 19: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/19.jpg)
mRNA Processing
• Pieces of the mRNA that don’t contain genes (called INTRONS) are removed by a SPLICEOSOME
![Page 20: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/20.jpg)
mRNA Processing
• Pieces of DNA that do code for genes (called EXONS) are left and pieced together
![Page 21: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/21.jpg)
The Genetic Code• The mRNA strand is then used to make
proteins in the process of TRANSLATION
![Page 22: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/22.jpg)
The Genetic Code• The “language” of
mRNA is known as the genetic code
• The 4 “letters” (A-G-C-U) are used to write “words” that correspond to different amino acids
![Page 23: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/23.jpg)
The Genetic Code
• “Words”are written using 3 letters
• Every 3 letters = 1 codon
• Every 1 codon = 1 amino acid
![Page 24: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/24.jpg)
The Genetic Code
• Because there are four different bases, there are 64 (43) different codon combinations
• Certain codons code for the same amino acid
![Page 25: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/25.jpg)
Translation
• Shortly after mRNA is transcribed, translation begins.
• The sequence of bases in mRNA serves as instructions for the order in which amino acids should be joined
![Page 26: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/26.jpg)
Translation• Translation: The
decoding of an mRNA message and creation of a polypeptide chain (protein)
• RIBOSOMES are the factories that assemble the proteins
![Page 27: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/27.jpg)
Translation
INITIATION• mRNA in the
cytoplasm attaches to a ribosome
ELONGATION• The ribosome
“reads” the codons and attaches the proper amino acids
Start codon
Stop codon
![Page 28: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/28.jpg)
Transfer RNA• Transfer RNA brings the
correct amino acids for the ribosome to use
• Has an ANTI – CODON on one end, and an amino acid on the other
• Anti-codon has a sequence complementary to an mRNA codon
![Page 29: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/29.jpg)
![Page 30: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/30.jpg)
TranslationTERMINATION
• The ribosome continues along until it reaches a stop codon
• The amino acid chain is then released and allowed to fold into a protein
• Protein then performs its job within the cell
![Page 31: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/31.jpg)
Translation
Translation can occur at many different spots along the mRNA strand, creating many proteins at one time.
![Page 32: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/32.jpg)
Let’s Try it ourselves
• Transcribe and translate the following DNA sequence:
TAC GCA TGG AAT
AUG CGU ACC UUA
![Page 33: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/33.jpg)
![Page 34: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/34.jpg)
Translation AnimationsTranslation
Transcribe and Translate a Gene
Why do fireflies glow?
![Page 35: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/35.jpg)
Let’s try it ourselves
• Transcribe and translate the following DNA sequence:
TAC GCA TGG AAT
AUG CGU ACC UUA
Met – Arg – Thr – Leu
![Page 36: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/36.jpg)
Mutations
• Every now and then cells make mistakes.– Inserting incorrect bases– Deleting bases– Adding extra bases
• Mistakes that cause a change in genetic information are called mutations.
![Page 37: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/37.jpg)
Point Mutations
• Point mutations are mutations that affect one nucleotide.
• 3 different types:– Substitution– Insertion– Deletion
![Page 38: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/38.jpg)
Substitution• Occurs when the wrong base is added to
a growing nucleotide chain
Original DNA: TAC GCA TGG AATOriginal mRNA: AUG CGU ACC UUA
Original Protein: Met – Arg – Thr - Leu
SubstitutionOriginal DNA: TAC GTA TGG AAT
Original mRNA: AUG CAU ACC UUA
Original Protein: Met – His – Thr - Leu
![Page 39: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/39.jpg)
Insertion• Occurs when an extra base is added to
a growing nucleotide chain
Original DNA: TAC GCA TGG AATOriginal mRNA: AUG CGU ACC UUA
Original Protein: Met – Arg – Thr - Leu
Insertion
Original DNA: TAT CGC ATG GAA T
Original mRNA: AUA GCG UAC CUU A
Original Protein: Ile – Ala – Tyr – Leu
![Page 40: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/40.jpg)
Deletion
• When a base is deleted from a growing nucleotide chain
THE FAT CAT ATE THE RAT
TEF ATC ATA TET HER AT
![Page 41: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/41.jpg)
Frameshift Mutations
• Mutations that cause a shift in the reading frame– Insertion– Deletion
• More than one amino acid gets changed downstream
TACGCATGGAAT
TATCGTATGGAAT
![Page 42: DNA Transcription & Translation *How do genes work? We’ve seen how DNA is replicated, but still haven’t learned exactly how genes work! The first step.](https://reader035.fdocuments.us/reader035/viewer/2022062518/56649d1f5503460f949f32a8/html5/thumbnails/42.jpg)
Silent Mutations
• DNA changes that do not cause a change in the amino acid chain
Original DNA: TAC GCA TGG AATMutated DNA: TAC GCC TGG AAT
mRNA: AUG CGG ACC UUA Protein: Met – Arg – Thr - Leu