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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