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Protein Synthesis & Mutation (Protein Synthesis (Biopolymers (DNA, RNA…
Protein Synthesis & Mutation
Protein Synthesis
Transcription: process by which genetic information represented by sequence of DNA nucleotides is
copied into newly synthesized molecules of RNA,
with the DNA serving as a template
Central Dogma: deals with detailed residue-by-residue transfer of sequential information; describes fundamental process that makes us different - we all have the same genes and proteins, but have different alleles of each
Translation: process by which sequence of nucleotide triplets in messenger RNA molecule give rise to a specific sequence of amino acids during synthesis of a polypeptide or protein
Biopolymers (DNA, RNA, and protein): have as many as nine types of transfers
General: DNA > DNA (Replication), DNA > RNA (Transcription), RNA > Protein (Translation)
Special: RNA > DNA (Reverse Transcription), RNA > RNA (RNA Replication), DNA > Protein (Direct Translation)
Unknown: protein > DNA, protein > RNA, protein > protein
Reverse Transcription: transfer of information from RNA to DNA that occurs in retroviruses
Reverse Transcriptase: enzyme that produces DNA from RNA genome to duplicate RNA viruses in host cell
Retrotransposon: self-replicating segments of eukaryotic genomes that use reverse transcriptase to move from one position in genome to another via RNA intermediate
Telomere: region of repetitive non-coding nucleotide sequences at each end of chromosome
Telomerase: reverse transcriptase that uses RNA intermediate to elongate 3' end of DNA strands in telomere regions after replication cycle
RNA Replication: copying one RNA to another
RNA Silencing: expression of one/more genes downregulated/entirely suppressed by binding of antisense RNA molecule
Antisense RNA: single-stranded RNA complementary to mRNA strand transcribed within cell
Transcription
During translation, a protein is synthesized using the codons in mRNA as a guide.
Translation involves the interactions of the three types of RNA: mRNA, rRNA and tRNA.
After the protein is made, it must fold into its functional conformation.
Translation: transfer of genetic instructions in RNA to protein made of amino acids
Ribosome: site of translation
Translation proceeds in three phases: initiation, elongation, and termination.
The E, A, and P sites are the ribosomes' tRNA binding sites.
The anticodons found on the tRNA complement the codons on the mRNA.
During translation, the mRNA is read in groups of three bases.
Anticodons are found on tRNA.
Genetic Code
Genetic Code: consists of sequence of nitrogen
bases - A, C, G, and U in mRNA chain
Codon: encodes one amino acid; unless codes for
start/stop signal; combined in groups of three
Start Codon: begins translation
Reading Frame: way the letters are divided into codons
Stop Codon: reached after mRNA molecule is read, codon by codon
The genetic code is universal, unambiguous, and redundant.
The genetic code consists of the sequence of bases in DNA or RNA.
All known living organisms use the same genetic code, and they share a common evolutionary history.
The codon AUG codes for methionine to signal for translation to begin.
Mutation
A mutation is a change in a DNA or RNA sequence.
Mutations may have no effect, they may be beneficial or harmful.
Alu sequences are repetitive elements that form a significant part of the human genome.
Allele: alternate form of gene
Duplications are types of chromosomal alterations.
Alu sequences are repetitive elements that form a significant part of the human genome.
Evolution could not take place without the genetic variation that results from beneficial mutations.
Many speculate that large mutations are capable of forming new genes.
A silent mutation codes for the same amino acid.
A frameshift mutation codes for the same amino acid.
The germline mutations change the DNA sequence within a sperm or egg, therefore can be passed on to descendants.
Haploinsufficiency results in when a reduced dosage of a normal gene product does not produce a normal phenotype.
Mutation Causes
Mutagenesis is a process by mutations, stable changes in the genetic material, are created.
Mutations may be due to environmental factors (mutagens) or may occur spontaneously.
Mutations may have no effect, may be beneficial, or may be harmful.
Typical mutagens include chemicals, such as those inhaled by smoking, and radiation, like X-rays, ultraviolet light, and nuclear radiation.
Cigarette smoke, UV radiation, and nitrate preservatives are mutagens.
Mutation Effects
Mutations are essential for evolution to occur because they increase genetic variation and the potential for individuals to differ.
The majority of mutations are neutral in their effects on the organisms in which they occur.
Beneficial mutations may become more common through natural selection.
Harmful mutations may cause genetic disorders or cancer.
Most mutations in somatic cells form during mitosis and DNA replication.
Translation
The steps of transcription are initiation, elongation, and termination.
Transcription elongation involves the further addition of RNA nucleotides to the 3' end of the growing transcript.
In Rho-independent termination, the hairpin structure is the signal for the detachment of the RNA from the DNA.
Initiation of transcription only occurs when all transcription factors are aligned along the promoter correctly.
Termination of transcription involves the detachment of the RNA.
Transcription is the transfer of genetic instructions from DNA to RNA.
Termination of transcription involves the detachment of the RNA from the DNA template.
RNA polymerase II synthesizes mRNAs and most snRNA and microRNAs.
The complete preinitiation complex contains the core promoter sequence, RNA polymerase, various transcription factors, and activators and repressors.
RNA polymerase III synthesizes tRNAs.
Every nucleotide triplet, or codon, encodes for a unique amino acid.
Each gene codes for one protein.