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Protein Synthesis and Mutation (Mutation (five types of chromosomal…
Protein Synthesis and Mutation
Protein Synthesis
DNA->RNA-> Proteins
2 processes to make protein from information in DNA are transcription and translation
transcription uses DNA sequence to make an RNA molecule
RNA leaves the nucleus and goes to the cytoplasm where translation occurs on a ribososme and produces a protein
biopolymer- polymer produced by living organisms composed of linked monomers
Examples: DNA, proteins, and RNA
steps in transcription process: Initiation-> elongation-> termination
exons- region in mRNA that DO code for proteins
introns- region in mRNA that do NOT code for proteins
splicing removes introns from mRNA
retroviruses are mRNA that are duplicated in a host cell by using reverse transcriptase enzyme to produce DNA from its RNA genome
Reverse transcription- transfer of formation form RNA to DNA
mRNA may be modified before it leaves the nucleus by splicing, editing, an polyadenylation
RNA polymerase are involved in transcription
RNA leaves the nucleus and goes to the cytoplasm where translation occurs on a ribosome
Transcription
happens in nucleus, uses the DNA sequence to make an RNA molecule
steps: termination, initiation, and elongation
transcription elongation involves the further addition of RNA nucleotides to the 3' end of the growing transcript
to complete preinitiation complex contains activators and repressors, various transcription factors, RNA polymerase, and the core promoter sequence
transfer of the genetic instructions from DNA to RNA
Initiation ONLY occurs when all transcription factors are aligned along the promoter correctly
Rho-
independent
the hairpin structure is the signal for the detachment of the RNA from the DNA
RNA transcription stops when the newly synthesized RNA molecule forms a hair-pin loop followed by a run of uracils
dependent
involves a protein factor
termination of transcription involves the detachment of the RNA from the DNA template
RNA polymerase
II. synthesizes mRNA and most snRNA and microRNAs
III. synthesizes tRNAs
Genetic Code
codon- a sequence of 3 nucleotides within mRNA that encode for a specific amino acid or termination sequence
genetic info is present in DNA
UAA, UGA, and UAG are all stop codons
the reading frame is the frame of three bases in which the mRNA is read and translated
Redundancy in genetic code protects against mutation
the Wobble Hypothesis states that rules of base pairing are relaxed at the third position, so that a base can pair within more than one complementary base
the genetic code is used as a language to produce a specific polypeptide
Translation always begins with an AUG codon
the start codon establishes the reading frame of mRNA
the mRNA molecule is read one codon at a time until a stop codon is reached
is a sequence of nitrogen bases
Translation
occurs on a ribosome and produces a protein
always starts with AUG codon
AUG codes for methionine to signal for translation to begin. Write the letters of the bases in this codon
process of ordering the amino acids into a polypeptide
involves changing the language of nucleotides into the language of amino acids
ribosomes tRNA binding sites: A, E, and P site
the anticodons found on the tRNA
complete the codons on the mRNA
brings correct amino acids to the ribosome
in protein synthesis, bonds form between adjacent amino acids as they are brought one by one to the ribosome, forming a polypeptide chain.
During translation, the mRNA is read in groups of 3 bases
In eukaryotes, the ribosome scans along the mRNA for the start codon to begin translation
protein folding- process whereby a protein molecule assumes its intricate three- dimensional shape
all 3 types of RNA work together during this process
Mutation
Mutation Causes
Mutation Effects
types:
Silent mutated codon codes for the same amino acid CAA (glutamine) → CAG (glutamine) none
Missense mutated codon codes for a different amino acid CAA (glutamine) → CCA (proline) variable
Nonsense mutated codon is a premature stop codon CAA (glutamine) → UAA (stop) usually serious
five types of chromosomal alterations
Deletions are the removal of a large chromosomal region, leading to loss of the genes within that region.
Duplications (or amplifications) lead to multiple copies of a chromosomal region, increasing the number of the genes located within that region. Some genes may be duplicated in their entirety.
Insertions are the addition of material from one chromosome to a nonhomologous chromosome.
Inversions are reversing the orientation of a chromosomal segment.
Translocations are the interchange of genetic material between nonhomologous chromosomes.
Gain-of-function mutations result in the gene product or protein having a new and abnormal function
Loss-of-function mutations result in a gene product or protein having less or no function.
Alu sequences are repetitive elements that form a significant part of the human genome
germline mutations change the DNA sequence within a sperm or egg, therefore can be passed on to descendants
a silent mutation codes for the same amino acid
Haploinsufficiency results in when a
reduced dosage of a normal gene product does not produce a normal phenotype.
the frameshift mutation changes the reading frame of the mRNA.
If a mother has a mutation in her gametes,
her child will have the mutation in all of his/her cells