Term
What is the ribosome made up of?
X |
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Definition
two subunits
3 sites for binding rna a,t
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Term
| What binds small subunits of mRNA in the initiation process of translation in the ribosome? |
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Definition
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Term
| Describe the ribosome binding in eukaryotes (Translation: Initiation) |
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Definition
Binds to 5 cap and slides alond mRNA until it gets to first good start codon
can be one start site on eukaryotic mRNA
Eukaryotic mitochondria (an organelle) and viruses have different systems |
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Term
| Describe the ribosome binding in eukaryotes (Translation: Initiation) |
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Definition
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Term
| What is a polycistronic message? |
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Definition
| multiple separate coding swquences on the same RNA |
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Term
| Where does the start codon line up at? |
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Definition
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Term
| What binds to start the start codon? |
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Definition
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Term
| Where does the large subunit join? |
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Definition
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Term
| What is the binds the large subunit to the P site? |
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Definition
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Term
| What energy does the large subunit use to join the complex? |
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Definition
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Term
| What are the three steps of Elongation? |
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Definition
Codon recognition
Peptide bond formation
Translocation |
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Term
| Discibe Codon recognition |
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Definition
occurs in the Aminoacyl site- tRNA loaded into A site
tRNA anticodon base pairs with mRNA codon- correct tRNA selected by sampling
Protein factor that loads tRNA requires energy-GTP |
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Term
| What kind of energy does Codon Recognition for Protein factors that load tRNA? |
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Definition
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Term
| What occurs during peptide bond formation? |
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Definition
Peptide bond is formed between peptide (short smino acid chain) on tRNA in P-site and aminoacyl tRNA in A-site
Breifly tansfers growing peptide to the A-side
(connects amino acid coming in and releases the chain) |
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Term
| What occurs during Translocation? |
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Definition
mRNA/tRNA complex is moved within the ribosome to the next site
requires energy GTP
tRNA in A-site, with peptide, ends up in P-site
Empty tRNA in P-site ends up in E-site=free to exit |
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Term
| What happens after all three steps in elongation occur? |
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Definition
| A new codon has been lined up in A-site, ready for a new tRNA to repeat the cycle |
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Term
| Do all three steps in Elongation require energy? |
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Definition
| No peptide bond formation doesn't |
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Term
| What occurs in termination? |
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Definition
Protein release factore (RFs) bind to stop codon in A-site
Hydrolyzes bond connecting peptide to P-site tRNA- releases completed protein from ribosomes
Ribosomes dissociates, releasing mRNA- requires energy GTP |
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Term
| When does GTP hydrolysis occur in intiation? |
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Definition
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Term
| When does GTP hydrolysis occur in elongation? |
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Definition
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Term
| Describe polyribosomes (polysomes) |
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Definition
Multiple ribosomes can translate the same mRNA at once
-you don't have to wait for one to finish before then next starts- as soon as one clears the start codon, another can load on and immediately start
Allows rapid translation |
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Term
| What is only seen in bacteria? |
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Definition
| linked transcription and translation |
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Term
| In the bacteria, describe linked transcription and translation |
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Definition
They are not segregated in time and space
Multiple RNA polymerases can be transcribing the same gene at once
Polyribosomes can form on each mRNA
This results in a whole lot of protein being made from the same gene, all at once |
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Term
| The basic ideas of transcription and translation are universal. Give and example of this |
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Definition
| genes from one species can be transferred to another and still work |
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Term
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Definition
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Term
| How are mutations classified? |
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Definition
| The effect they have on the protein from the gene that has been mutated |
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Term
| What is a silent mutation? |
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Definition
where there is no effect in an aminoacid that is coded by new codon as old
one nucleotide-pair is changed but the amino acid is still the same |
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Term
| What is a missense mutation? |
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Definition
changes amino acid
Different amino acid coded by new codon
changing one nucleotide pair which changes the whole amino acid |
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Term
| What is a nonsense mutation? |
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Definition
Prematurely terminates protein
New codon is stor codon
protein product is frequently completely non-functional and the mRNA is targeted for destruction |
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Term
| What is a frameshift mutation? |
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Definition
insert or delete bases
3 diff ways to divide a swquence into codons, start establishes which will be used, take out or add bases you shift into a diff reading freame, changes all subsequent amino acids |
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Term
| What does the frameshift usually lead to? |
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Definition
Usuaully terminatess early
Tandom chance will get a stop codon 3/64 or 1/20
analogous to a nonsense mutation |
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Term
| What does the Addition or removal of a number of bases divisible by 3 - entire codon (s) do? |
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Definition
| adds or removes amino acid(s) but doesn't change remainder of protein |
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Term
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Definition
errors in DNA replicatipn
Isomerization of bases during DNA replication
Induced changes-UV light, Ionizing Radiation, Chemical mutagens |
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Term
| What is protein targeting? |
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Definition
◦ Signal sequence - targets protein to endomembrane system
Specific sequence found of first amino acids of peptide
emerging from ribosome
Recognized by signal recognition protein (SRP)
Entire ribosome dragged to rough ER
Injects growing protein into or through ER membrane
Signal peptide removed from mature protein |
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Term
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Definition
| contains DNA from multiple sources- recombined |
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Term
| What is a plasmid and what does is do? |
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Definition
Circular extra-chromosomal DNA molecules
Like the genome, they have a single origin of replication
Can be gained and lost by their host
Can carry genes for specific functions not encoded by
the genome
Can be made to carry
foreign DNA
Used for genetic
engineering cloning |
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Term
| What are 3 restriction on enzymes? |
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Definition
isolated on bacteria
cleave DNA at specific sequences
Any restriction fragments with compatible ends can be glued together by ligase to produce new combinations |
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Term
| How is being isolated from bacteria a restriction to enzymes? |
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Definition
They use them to protect
from and scavenge foreign
DNA (e.g. viruses) |
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Term
| How is cleaving DNA at specific sequences a restriction to enzymes? |
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Definition
“Restriction sites”
Leave single-stranded
“sticky ends” with unique
self-complementary
sequences |
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Term
| What is gel electrophoresis? |
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Definition
Separate nucleic acids (DNA, RNA)
or protein from each other, based
on size |
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Term
| Describe how gel electrophoresis works |
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Definition
Electrical current drives molecules
forward through a gel, (a Jello-like
block of carbohydrate or synthetic
molecular chains that form a grid,
allowing selective passage of
molecules based on size
Results in size-based separation
Shorter molecules travel fastest/farthest
Visualized using stain
Bands can then be cut out as isolated
pieces |
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Term
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Definition
Isolate individual pieces of DNA
Cut with restriction enzymes
Separate by size on gel
◦ Ligate isolated pieces together to form recombinant plasmid
◦ Transform into bacteria
◦ Grow a lot of bacteria, letting bacteria make a lot of copies
of the plasmid |
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Term
| Why make recombinant DNA? |
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Definition
Make a lot of pieces of specific DNA
For subsequent genetic manipulation or study
Have bacteria make a lot of a specific protein
To change the characteristics of the host
To study the protein
For drugs
Analogous approaches
can be used to genetically
engineer eukaryotes |
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