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Ch17 From Gene to Protein
BIO181 BIO 181 Obermiller
83
Biology
Undergraduate 2
06/14/2012

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Term
Proteins that assist a newly formed polypeptide in folding.
Definition
Chaparones
Term
Events that end transcription or translation.
Definition
Termination
Term
The enzyme that generates the dehydrolysis reaction needed to link amino acids together during translation.
Definition
Peptidyltranferase
Term
Events that elongate either the RNA or polypeptide chain.
Definition
Elongation
Term
Term used for multiple ribosomes on the same mRNA transcript.
Definition
Polyribosomes
Term
Type of RNA that carries the amino acid to the correct site on the ribosome.
Definition
Transfer
Term
Start of transcription of translation.
Definition
Initiation
Term
Three nucleotide sequence found on tRNA that is complimentary to the codon on mRNA.
Definition
Anticodon
Term
Subunit of the ribosome that holds the tRNA in place.
Definition
Large
Term
The term used for the 5' modification of an mRNA.
Definition
Cap
Term
Events that end transcription or translation.
Definition
Termination
Term
Three nucleotide sequence found for a specific amino acid.
Definition
Codon
Term
A box of DNA sequence located in the promoter of most genes where transcription factors bind.
Definition
TATA
Term
Often proteins must be _____________ in the golgi or ER before they become functional.
Definition
Modified
Term
Term used for removal of introns.
Definition
Splicing
Term
Coding region of a primary transcript.
Definition
Exon
Term
Subunit of the ribosome that holds the mRNA.
Definition
Small
Term
Converting the code of DNA into RNA by RNA polymerase.
Definition
Transcription
Term
The number of different amino acids.
Definition
Twenty
Term
The energy used for translation elogation is ___________.
Definition
GTP
Term
The term for the tail modification of an mRNA transcript.
Definition
Polya
Term
Converting the code of RNA into protein by ribosomes.
Definition
Translation
Term
Post-translational modifications help prevent ____________ by enzymes.
Definition
Degredation
Term
Enzyme that removes the introns from the primary transcript.
Definition
Spliceosome
Term
How many different combinations are possible using the three nucleotide codon system?
Definition
Sixty-Four
Term
The first codon is always this sequence.
Definition
AUG
Term
The frame where codons are read in groups of three is called the _________ frame.
Definition
Reading
Term
Region of a gene that is recognized by RNA polymerase. Where initiation begins.
Definition
Promoter
Term
Small nuclear ribonuclear particles that make up a splicosome.
Definition
SNRNP
Term
Non-coding region in a primary transcript.
Definition
Intron
Term
What is transcription?
Definition
Converting the DNA code into a RNA code by RNA polymerase (single stranded)
Term
What is translation?
Definition
Converting the RNA code into a protein code made up of amino acids by ribosomes
Term
What are the three parts of a gene?
Definition
Promoter
Coding region
Terminator
Term
How are the parts of a gene different in prokaryotes versus eukaryotes?
Definition
Eukaryotes: transcription takes place in the nucleus and translation takes place in the cytoplasm

Prokaryotes: transcription is coupled to translation (since there is no defined nucleus)
Term
What is a promoter?
Definition
The region of a gene that is required for the initiation of transcription.

Recognized by RNA polymerase (+ accessory proteins called transcription factors)
Term
What enzymes bind to the promoter for initiation of transcription?
Definition
RNA polymerase
Term
What are the four recognition sequences in a promoter?
Definition
TATA Box
Octamer Motif
CAAT Box
GC Box
Term
What class of enzymes recognizes these sequences? (promoter)
Definition
Transcription factors
Term
What is a transcription terminator?
Definition
A sequence of DNA in the gene that causes the end of transcription
Term
What is contained in the transcription initiation complex?
Definition
Transcription factors and RNA polymerase
Term
What is the function of RNA polymerase?
Definition
Start transcription, moves along the DNA, untwisting the double helix (10-20 bases at a time) as it adds nucleotides to the 3' end of the growing strand
Term
What is the function of transcription factors?
Definition
Proteins that recognize the promotor region, especially a TATA box, and bind to the promotor
Term
What post-transcriptional modifications are done to the mRNA after transcription?
Definition
5'-cap modificaiton
3'-tail modification
RNA splicing
Term
What is the purpose of each post-transcriptional modifications?
Definition
5'-cap: by covalently adding a modified GTP (with a methyl group)to the 5'-end of the mRNA to protect the RNA from degredation by enzymes; it also helps the ribosome recognize the attachment site

3'-tail: addition of a poly A tail (30-200 A's); may inhibit degradation, help attachment to ribosome, regulate protein synthesis by helping move mRNA through the nuclear pores

RNA splicing: removing introns (non-coding sections in the DNA)
Term
What is RNA splicing?
Definition
Splicing is accomplished by an enzyme called the spliceosome

The reaction cuts out the introns, leaving only the exons spliced together

Exons can be put together in different orders
Term
What is an intron?
Definition
Non-coding sections in the DNA of a gene that are initially transcribed but not translated because they are removed first
Term
What is an exon?
Definition
Coding sections of a gene that are transcribed and translated into a protein
Term
What is a spliceosome?
Definition
Enzyme responsible for splicing

formed by lots of snRNP (small nuclear ribonuclear protein particles) and other proteins

Reaction cuts out the introns, leaving only the exons spliced together
Term
What makes up a spliceosome?
Definition
A lot of snRNP (small nuclear ribonuclear protein particles) and other proteins
Term
What is the purpose of RNA splicing?
Definition
Cut out the non-coding introns before the RNA goes into translation
Term
What is a domain?
Definition
Proteins often have a modular architecture with discrete structural and functional regions called domains
Term
What is a codon?
Definition
Three nucleotide sequence in mRNA that ccodes for a specific amino acid
Term
How many different amino acids are there?
Definition
20
Term
How many possible codons?
Definition
64
Term
What is a reading frame?
Definition
Just like the words in a book, the reading frame is important for the translation

THE FAT RED CAT

Starting at H: T HEF ATR EDC AT
Starting at E: TH EFA TRE DCA T

Different frames make very different proteins
Term
What happens if the reading frame is shifted one nucleotide?
Definition
It will produce a different protein such as T HEF ATR EDC AT
Term
What happens if the reading frame is shifted two nucleotide?
Definition
It will produce a different protein such as TH EFA TRE DCA
Term
What happens if the reading frame is shifted three nucleotide?
Definition
The message makes since but part of the message was never read such as FAT RED CAT (THE was overlooked)
Term
What is tRNA?
Definition
Transfer RNA: transfers amino acids from the cytoplasm's pool to a ribosome
Term
What is an anti-codon?
Definition
Each tRNA has a complimentary 3 nucleotide sequence (anti-codon) that base pairs with the codon
Term
What is a ribosome?
Definition
Large complex of RNA and protein which catalyzes protein translation
Term
How many different subunits make up a ribosome?
Definition
Small sub-unit and large sub-unit
Term
What is the function of the small sub-unit?
Definition
binds to the mRNA and directs it along the ribosome
Term
What is the function of the large sub-unit?
Definition
The large sub-unit contains three sites: A site, P site, and E site.
Term
What enzyme links an animo acid to a tRNA?
Definition
Aminoacyl-tRNA synthetase
Term
Are these enzymes different for each amino acid?
Definition
Yes
Term
What is an A site?
Definition
The site where the next tRNA carrying its amino acid waits to add it to the peptide chain
Term
What is a P site?
Definition
This is where the reaction adding the amino acid to the growing polypeptide chain occurs
Term
What is an E site?
Definition
Exit site that releases the tRNA to go and pick up another amino acid
Term
What is the start codon always?
Definition
AUG
Term
What is the start amino acid always?
Definition
Methionine (Met)
Term
What makes up the translation initiation complex?
Definition
Small ribosomal subunit, mRNA, initiator tRNA, and large ribosomal subunit
Term
What is the function of GTP in initiation and elongation respectively?
Definition
Initiation: GTP stabilizes the binding of initiation factors, brings in the large ribosomal subunit, and provides the energy for elongation

Elongation: energy released from the removal of a phosphate in GTP (making GDP) allows the second tRNA to occup the A site of the large ribosomal subunit
Term
What enzymes links the amino acids together during translation?
Definition
Peptidyl transferase
Term
What is this type of reaction called?
Definition
Dehydration reaction
Term
What happens at translational termination?
Definition
The ribosome reaches a stop codon, translation ends
Term
What are the stop codons?
Definition
UAG, UAA, or UGA
Term
What is the function of a release factor?
Definition
Breaks the bond between the polypeptide and the P site tRNA
Term
What is a polyribosome?
Definition
Cluster of ribosomes simultaneously translating an mRNA
Term
What enzymes help proteins fold into their correct 3D shape?
Definition
During and after translation, the protein folds into its secondary and tertiary structures; which is aided by folding assistant proteins called chaparones
Term
What are the three types of chemical post-translational modifications?
Definition
Sugar added (glycoproteins)

Lipids added (such as Low Density Lipoproteins or LDL)

Phosphates added
Term
What are the three chain length modifications?
Definition
Remove amino acids from the leading end

Divide the polypeptide into two or more proteins

Link two or more proteins together
Term
What is difference for translation between prokaryotes and eukaryotes?
Definition
Since prokaryotes do not have a nucleus, transcription is coupled to translation (occur simultaneously)

Multiple ribosomes bind to the RNA as it is being transcribed

*Prokaryote ribosomes are different from eukaryote ribosomes in size and function
**Termination is different
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