Organism whos cells have nuclei and other membrane-bound organelles. include protists, fungi, plants and animals. Transcription in nucleus and translation in cytoplasm
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Prokaryote
Cell that lacks a nucleus and other membrane-bound organelles - bacteria and archaea. Transcription and translation simultaneous
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Genes in eukaryotes have
Control region, propoter, transcription start point, introns and exons. more form nucleus to cytoplasm
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three different classes of genes, each with slightly different gene structures. These are transcribed by three different RNA polymerases
RNA polymerase I ,RNA polymerase II &
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RNA polymerase I
transcribes most ribosomal RNA (rRNA)
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RNA polymerase II
transcribes messenger RNA (mRNA).-Encode proteins. expression of these that is most important in distinguishing one cell type from another and even one organism from another.
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RNA polymerase III
transcribes transfer RNA (tRNA) and one small ribosomal RNA (rRNA)
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Discontinuous gene
A gene that is split into exons and introns
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Exon
A segment of a DNA or RNA molecule containing information coding for a protein or peptide sequence.
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Intron
A segment of a DNA or RNA molecule that does not code for proteins and interrupts the sequence of genes
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mRNA is capped in eukaryotes
to mature- able to undergo translation, enables ribosome to bind - methyl guanosine on 5'end - happens in nucleus
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mRNA is tailed in eukaryotes
Enables ribosome to bind. promotes export from the nucleus and translation, and protects the mRNA from degradation. - polyadenosine on 3' end (long sequence of adenine nucleotides) . mrNA without tail won't translate. happens in nucleus
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mRNA is spliced in eukaryotes
in which introns are removed and exons are joined. eeded for the typical eukaryotic messenger RNA before it can be used to produce a correct protein through translation. happens in nucleus
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After mRNA is capped, spliced and tailed it
Is mature so is transported from the nucleus to the cytoplasm for translation to occur
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Chemicals can be added to proteins to make them functional
Phosphorylation, methylation, glycosylation
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Phosphorylation
Addition of phosphate. Phosphorylation turns many protein enzymes on and off, thereby altering their function and activity
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Methylation
Addition of methyl chains
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Glycosylation
Addition of carbohydrate chains. some proteins dnit fold correctly unless glycosylated first. some confer stability on secreted glycoproteins. role in cell-cell adhesion via sugar-binding proteins(lectins), recognize specific carbohydrate moieties
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Post-translational proteolysis
Activates some proteins- trimming of the N or C termini or internal cleavage to yield one, or more, smaller polypeptides
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Other cards in this set
Card 2
Front
Prokaryote
Back
Cell that lacks a nucleus and other membrane-bound organelles - bacteria and archaea. Transcription and translation simultaneous
Card 3
Front
Genes in eukaryotes have
Back
Card 4
Front
three different classes of genes, each with slightly different gene structures. These are transcribed by three different RNA polymerases
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