Term
What is the genetic Code? |
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Definition
a genetic code is that specific sequence of genes as they align up on the different chromosomes in the nucleus of a cell |
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Term
How is genetic code linked to protein synthesis? |
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Definition
The genetic code determines the relationship between the three-nucleotide codon on the m RNA and the insertion of the correct amino acid into a protein during Protein Synthesis |
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Term
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Definition
A three-nucleotide sequence of DNA or mRNA that specifies a particular amino acid or termination signal; the basic unit of the genetic code. |
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Term
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Definition
A nucleotide triplet at one end of tRNA molecule that base-pairs with a particular complementary codon on an mRNA molecule |
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Term
Why is the genetic code called universal? |
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Definition
It's actually "almost" universal. This is because a codon in one organism will code for the same amino acid in another organism. This is true almost all of the time, but there may be some small differences between, say, a human and a bacteria or between other organisms |
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Term
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Definition
An enzyme that links ribonucleotides into a growing RNA chain during transcription, based on complementary binding to nucleotides on a DNA template strand |
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Term
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Definition
A specific nucleotide sequence in the DNA of a gene that binds RNA positioning it to start transcribing RNA at the appropriate place. |
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Term
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Definition
In bacteria, a sequence of nucleotides in DNA that marks the end of the gene and signals RNA polymerase to release the newly made RNA molecule and detach from the RNA. |
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Term
Define Transcription Unit? |
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Definition
A region of DNA that is transcribed into an RNA molecule |
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Term
Define Template DNA strand? |
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Definition
The DNA strand that provides the pattern, or template, for ordering, by complementary base pairing, the sequence of nucleotides in an RNA transcript. |
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Term
Define transcription factors? |
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Definition
A regulatory protein that binds to DNA and affects transcription of specific genes. |
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Term
Define transcription initiation complex? |
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Definition
The completed assembly of transcription factors and RNA polymerase bond to a promoter |
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Term
What is the first phase of transcription? |
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Definition
Initiation, Promoters signal the initiation of RNA synthesis, transcription factors mediate the bind of RNA polymerase of the initiation of transcription. The completed assembly of transcription factors and RNA polymerase II bound to a prometer is called a transcription intiation complex. The promoter called a TATA box is crucial in forming iniation complex in eukaryotes |
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Term
What is the 2nd phase of transcription? |
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Definition
As RNA polymerase moves along the DNA it, untwists the double helix, 10 to 20 bases at a time, transcription progress at a rate of 40 nucleotides per second in eukaryotes. A gene can be transcribed simultaneously. |
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Term
What is the last phase in transcription? |
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Definition
The mechanism of termination are different in bacteria and eukaryoties. In bacteria, the polymerase stops transcription at the end of the terminator. In eukaryotes, the polymerase continues transcription after the pre-mRNA is cleaved from the growing RNA chain; the polymerase eventually falls off the DNA |
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Term
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Definition
the RNA processing transcribed from a eukaryotic gene is precessed before leaving the nucleus to serve as messenger RNA (rRNA). intro are spliced out, and a cap and tail are added. |
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Term
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Definition
Transcription factors mediate the binding of RNA polymerase and the initiation of transcription |
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Term
How do we get from pre-mRNA to mRNA? |
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Definition
Each end of pre-mRNA molecule is modified in a particular way
1. The 5' end recieves a modified nucleotide 5' cap
2. The 3' end gets a poly-A tail.
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Term
The importance of the 5' cap and poly-A tail in a mRNA molecule?
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Definition
They seem to faciliate the exprt of mRNA, an protect mRNA from hydrolytic enzyme, they help ribosomes attach to the 5' ends. |
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Term
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Definition
A noncoding, intervining sequence within a primary transcrip that is remvoed from the transcript during RNA processing |
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Term
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Definition
a sequence within a primary transcript that remains in the RNA after RNA processing |
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Term
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Definition
RNA splicing removes introns and joins exons, creating an mRNA molecule with a continuous coding sequence |
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Term
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Definition
a variety of proteins and several small nuclear ribonucleoprotein that recognize the splice sites |
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Term
Sometimes RNA splicing is carried out by what? |
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Definition
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Term
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Definition
they are catalytic RNA molecules that function as enzymes and can splice RNA |
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Term
What are the three properties of RNA that enable it to function as an enzyme? |
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Definition
It can form a three-dimensional structure because of its ability to base pair with itself 2. some bases in RNA contain functional groups 3. RNA may hydrogen-bond with other nucleic acid molecules |
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Term
What is the functional and evolutionary importance of RNA introns |
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Definition
Some genes can encode more than one kind of polypeptide, depending on which segment are treated as extons during RNA splciing
Such varations are called alternative RNA splicing |
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Term
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Definition
May result in the evolution of new protiens |
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Term
What is the importance of tRNA |
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Definition
a cell translates an mRNA message into protein with the help of tRNA |
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Term
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Definition
A type of RNA, synthesized using DNA template, that attaches the ribosomes in the cytoplam and specifies the promary structure of a protien. |
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Term
What are ribosomal subunits (large and small)?
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Definition
made up of protiens and rRNA
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Term
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Definition
they faciliate specific coupling of the tRNA anticodons with mRNA codons in protein synthesis |
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Term
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Definition
the p site holds the tRNA that carries the growing polypeptide chain |
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Term
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Definition
the a site holds the tRNA that carries the amino acid to be added to the chain |
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Term
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Definition
the e sit is the exit site, where discharged tRNAs leave the ribosome |
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Term
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Definition
The start codon is the first codon of a messenger RNA (mRNA) transcript translated by a ribosome. (AUG) |
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Term
What is the termination codon? |
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Definition
In the genetic code, a stop codon (or termination codon) is a nucleotide triplet within messenger RNA that signals a termination of translation |
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Term
What are the two requirements for accurate translation? |
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Definition
First, a correct match between a tRNA and an amino acid, done by the enzyme aminoacyl tRNA synthetase. Second, a correct match between the tRNA anticodon and mRNA codon
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Term
What is the wobble effect? |
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Definition
Flexibility in the base-pairing rules in which the nucleotide at the 5' end of a tRNA anticodon can form hydrogen bonds with more than one kind of base in the third position (3' end) of a codon |
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Term
What is RNA translation elongation? |
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Definition
the amino acids are added one by one to the preceding amino acid. Each addition involves proteins called elongation factors and occurs in three steps, codon regonition, peptide bond formation, translocation |
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Term
What is termination of translation? |
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Definition
termination occurs when a stop codon in the mRNA reaches the A site of the ribosome |
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Term
What is the initiation of translation? |
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Definition
the inition stage of translation brings together mRNA, a tRNA with the first amino acid, and the two ribosomal subunits. |
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Term
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Definition
a number of ribosmes can translate a single mRNA simultaneously, forming a polyribosome.
They enable a cell to make many copies of a polypeptide very quickly
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Term
Is translation sufficient to produce a mature fully functional protien? |
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Definition
Often translation is not sufficient to make a functional protien |
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Term
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Definition
During and after synthesis, a polypeptide spontaneously coils and folds into its three dimensional shape |
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Term
The role of rough ER in protein development? |
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Definition
Bound ribosomes make proteins of the endomembrane system and protiens that secreted from the cell are marked by a single peptide |
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Term
The role of cytosol in protien development? |
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Definition
Free ribosomes mostly synthesize protien function in the cytosol. Protien synthesis always begins in the cytosol |
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Term
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Definition
are genetica material of a cell or virus |
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Term
What is a point mutations? |
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Definition
are chemical changes in just one base pair of a gene |
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Term
What are the types of point mutations? |
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Definition
Base-pair substitutions, and base-pair insertions or deletions |
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Term
What is a base-pair substitution? |
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Definition
replaces one nucleotide and its partner with another pair of nucleotides |
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Term
What is silent mutations? |
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Definition
They have no affect on the amino acid produced by a codon because of redundancy in the genetic code |
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Term
What is a missense mutation? |
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Definition
still code for an amino acid, but not nessarily the right amino acid |
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Term
What is a nonsense mutation? |
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Definition
change an amino acid codon into a stop codon, nearly always leading to a nonfunctional protein |
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Term
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Definition
Additions of the nucleotide pairs in a gene |
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Term
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Definition
losses of nucleotide pairs in a gene |
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Term
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Definition
Insertion or deletion of nucleotides may alter the reading frame |
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Term
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Definition
physical or chemical agents that can cause mutations |
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Term
How does a cell regulate gene expression? |
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Definition
RNA molecules play many roles in gene expression in eukaryotes |
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Term
What is an operon system?
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Definition
Is the entire stretch of DNA that includes the operator, the promoter and the other genes that they control |
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Term
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Definition
The regulator "switch" is a segment of DNA called an operator usually positioned within the promoter. |
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Term
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Definition
A specific nucleotide sequence in the DNA of a gene that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place |
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Term
What is a repressor protein in the operon system? |
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Definition
inhibiting expression of a particular gene |
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Term
What is the trp operon? And how does it work? |
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Definition
Trp operon is an operon - a group of genes that are used, or transcribed, together - that codes for the components for production of tryptophan. |
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Term
What is the lac operon? How does it work?
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Definition
The lac operon is an operon required for the transport and metabolism of lactose in Escherichia coli and some other enteric bacteria. |
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Term
What is differential gene expression? |
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Definition
the expression of different genes by cells with the same genome. |
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Term
What is the regulation of chromatin structure and its importance in gene regulation
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Definition
Genes within highly packed heterochromatin are usually not expressed. Chemical modifications to histones and DNA chromatin influence both chromatin structure and gene expression |
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Term
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Definition
the addition of methyl groups to certain bases in DNA, is associated with reduced transcription in some spercies. DNA methylation can cause long-term inactivation of genes in cellular differentiation |
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Term
What are control elements? |
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Definition
segments of noncoding DNA that help regulate transcription by binding certain protiens |
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Term
How do control elements work? |
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Definition
Control elements and the proteins they bind are critical to the precise regulation of gene expression in different cell types |
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Term
What is the role of transcription factors in gene expression and control? |
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Definition
To initate transcription, eukaryotic RNA polymerase requires the assistance of protien called transcription factors. |
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Term
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Definition
Distal control elements, group of which are called enhancers, may be far away from a gene or even located in an intron. |
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Term
What is the importance of gene expression in enhancers? |
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Definition
Proximal control elements are located closer to the promoter. |
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Term
How does RNA splicing and the control of gene expression? |
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Definition
in alternative RNA splicing, different mRNA molecules are produced from the same primary transcript, depending on wich RNA segments are treated as exons and wchich as introns. |
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Term
What is mRNA degradation and how it involves the control of gene expression? |
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Definition
MicroRNAs are small singlestranded RNA molecules that can bind to mRNA, these can degrade mRNA or block its translation. |
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Term
Initiation of translation and control of gene expression? |
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Definition
translation iniation factors are simultaneeously activated in an egg following fertilization |
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Term
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Definition
giant protien complexes bind protien molecules and degrade them |
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Term
Protien processing and proteasomes? |
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Definition
After translation, various types of protein processing including cleavage and the addition of chemical groups, are subject to control |
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Term
How does non-coding RNAs control gene expression? |
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Definition
A significant amount of the genome may be transcribed into noncoding RNAs. Noncoding RNAs regulate gene expression at two points: mRNA translation and chromatin configuration |
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Term
RNA interference and gene expression control? |
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Definition
The phenomenon of inhibition of gene expression by RNA molecules is called RNA interfernece (RNAi)
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Term
Cancer and genetic changes |
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Definition
Cancer can be caused by mutations to genes that regulate cell growth and division. |
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Term
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Definition
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Term
What are proto-oncogenes? |
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Definition
corresponding normal cellular genes that are responsible for normal cell growth and divison |
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Term
What are tumor suppressor genes? |
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Definition
Help prevent uncontrolled cell growth, repair damaged DNA, control cell adhesion, inhibit the cell cycle in the cell-signaling pathway |
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Term
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Definition
mutations in the ras gene can lead to production of a hyperactive ras protein and increased cell division. |
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Term
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Definition
p53 prevents a cell from passing on mutations due to DNA damage |
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Term
What is the multistep process of cancer development? |
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Definition
Multiple mutations are generally needed for full-fledged cancer; thus the incidence increases with age. At DNA level, a cancerous cell is usually characterized by at least one active oncogene and the mutation of several tumor-suppressed genes. |
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Term
Inheritance and cancer development? |
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Definition
Individuals can inherit oncogenes or mutant alleles of tumor suppressor genes. Inheritated mutations in the tumor-suppressor gene adenomatous poluposis coli are common in individuals with coloretarl cancer, mutations in the brca1 or brca2 gene are found in at least half of the inheritated breast cancer. |
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Term
What is the recombinant DNA? |
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Definition
nucleotide sequence from two different sources, often two species are combined in virtro into the same DNA molecule |
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Term
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Definition
To work directly with specific genes, scientific prepare gene-sized pieces of DNA in identical copies |
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Term
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Definition
are small circular DNA molecules that replicate separately from the bacterial chromosome |
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Term
How can plasmids be used in genetic engineering? |
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Definition
Foreign DNA is inserted into a plasmid, and recombinant plasmid is inserted into a bacteria cell. Reproduction in the bacterial cell results in cloning of the plasmid including the foreign DNA |
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Term
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Definition
gene cloning involves using bacteria to make multiple copies of a gene.
Gene inserted into plasmid, plasmid put into bacterial cell, host cell grown in culture to form a clone of cells containing the "cloned" gene of interest, |
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Term
What are restriction enzymes? |
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Definition
An endonuclease that recognizes and cuts DNA molecules foreign to bacterium. The enzyme cuts at specific nucleotide sequences. |
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Term
What is a cloning vector? |
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Definition
is a DNA molecule that can carry foreign DNA into a host cell and replicated there |
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Term
What is the genomic library? How can you make a genomic library? |
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Definition
is made by using bacteria is the collection of recombinat vector clones produced by cloning DNA fragments from an entire genome. A genomic library that is made using bacteriophages is stored as a collection of phage clones. |
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Term
What is a bacterial artificial chromosome (BAC)? Why is it important? |
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Definition
A bacterial artificaial chromosome is a large plasmid that has been trimmed down and can carry a large DNA insert.
BACs are important because another type of vector used in DNA library construction |
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Term
What is complementary DNA? How can it be made? |
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Definition
library is made by cloning DNA made in vitro by reverse transcription of all the mRNA produced by a particular cell. |
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Term
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Definition
A cDNA library represents only part of the genome-only the subset of genes transcription into mRNA in the original cells |
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Term
What is a nucleic acid probe? |
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Definition
A clone carrying the gene of interest can be indentified with a nucleic acid probe having sequence complemtary to the gene |
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Term
What is nucleic acid hybridization? |
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Definition
The process of base pairing between a gene and a complementary sequence on another nucleic acid molecule. |
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Term
What is an expression vector? |
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Definition
a cloning vector that contains a highly active prokaryotic promoter |
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Term
What is bacterial expression vectors? |
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Definition
Several technical difficulties hinder expression of cloned eukaryotic genes in bacterial host cells. To overcome differences in promoters and other DNA control sequences, scientists usually employ an expression vector. |
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Term
What is a yeast artifical chromosome (YAC)? |
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Definition
as vectors help avoid gene expression problems |
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Term
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Definition
One method of introduction recombinant DNA into eukaryotic cells is electroporation, applying a brief electrical pulse to create temporary holes in plasma membranes. |
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Term
What is polymerase chain reaction (PCR)? |
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Definition
can produce many copies of a specific targe segment of DNA. A three-step cycle- heating, cooling, and replication-brings about a chain reaction that produces an exponentially growth population of indentical DNA molecules. |
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Term
Why DNA cloning is important? |
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Definition
Compare genes and alleles between individuals, locate gene expression in a body, determine the role of a gene in an organism |
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Term
What is gel electrophoresis? How does it work? |
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Definition
One indirect method of rapid analyzing and comparing genomes is gel electrophoresis. The technique uses a gel as a molecular sieve to separate nucleic acids or protien by size. |
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Term
What is southern plotting? |
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Definition
a technique that combines gel electrophoresis of DNA fragments with nucleic acid hybridization. |
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Term
How can gene expression by studied using northern plotting? |
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Definition
Specific DNA fragments can be identified by southern blotting, using labeled probes that hybridized to the DNA immobilized on a "blot" of gel. |
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Term
What is Reverse transcriptase-polymerase chain reaction? |
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Definition
is a quicker and more sensitive, reverse transcriptase is added to mRNA to make cDNA, which serves as a template for PCR amplication of the gene of interest. |
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Term
What is situ hybridization? |
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Definition
using fluorescent dyes attached to probes to identify the location of specific mRNAs in place in the intact organism |
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Term
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Definition
compare patterns of gene expression in different tissues, at different times, or under differnet conditions? |
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Term
What is a in vitro mutagenesis? |
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Definition
mutations are introduced into a cloned gene, altering or destroying its function. When the mutated gene is returned to the cell, the normal gene's function might be determined by examing the mutant's phenotype |
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Term
What is RNAi-RNA interference? |
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Definition
Synthetic double-stranded RNA molecules matching the sequence of particular genes used to break down or block the gene's mRNA |
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Term
Why is animal cloning importance? |
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Definition
In nuclear transplantation, the nucleus of an unfertilized egg cell or zygot is replaced with the nucleus of a differentiated cell. |
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Term
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Definition
a relatively unspecialized cell that can reproduce itself indefinitely and differentiate into specialized cells of one or more types. Stem cells isolated from early embryos at the blastocyst stage are called embryonic stem cells; these are able to differentiate into all cell types |
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Term
Stem cells and medical applications? |
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Definition
One benefit of DNA technology is identical of human genes in which mutation plays a role in genetic diseases |
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Term
How can humans benefited by the DNA technology? |
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Definition
genetic reseach are important to the development new drugs to treat diseases |
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Term
Application of DNA technology? |
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Definition
DNA has medical and argricultural applications which are bing used to improve the agricultural productivity and food quality. |
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