Chapter 14
Terms
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- GTP dependent release Factors
- cleave polypeptide from tRNA
- Ribosome
- inside, hydrogen bonding of tRNA's to mRNA holds the amino acids in proximity so that a peptide bond can be formed. Has three sites A,P,E .
- Gene Expression in Eukaryotes
- Transcription occurs in the nucleus, translation in the cytoplasm
- rRNA genes
- are moderately repetitive and tandemly repeated. Provide catalytic functions (ribosome has proteins) of translation
- tRNA
- is 75-90 nucleotides long. Specific on the amino acid they can carry. Contains post transcriptionally modified bases- it is modified before it starts working.
- Proteins
- the final product of most genes, achieve a three-dimensional conformation that is based on the primary amino acid sequences of the polypeptide chains making up each protein.
- Eukaryotic Transcription
- Transcription and Translation are spatially and temporarily separated. Translation requires more factors. Ribosomes are not free floating and are associated with the ER
- Amino acid binding site
- In Holley's two dimensional cloverleaf model of tRNA; the reactive site is at the 3' end, and it has an OH group attached to it. The amino acid is attached here with the help of aminoacyl tRNA synthase. This is a condensation Rx (H2O is pulled off)
- Hgb genes
- are developmentally regulated. Different Hgb expressed at different times in development.
- Sickle cell anemia
- autosomal recessive disorder. Hbs Hbs hemoglobin allele, HbS Hbs largely unaffected.
- Translation Termination
- signaled by a stop codon in the A site.
- Anticodon CGU: Codon? Amino Acid?
- Anticodon= CGU Codon=GCA A.A.=alanine
- Studies of Hgb
- established that one gene encodes one polypeptide ex. sickle cell anemia
- Mg2+
- cofactor that activates many enzymes
- Aminoacyl tRNA synthase
- attached the tRNA with the amino acid in the amino acid binding site.
- Translation
- involves the interaction of mRNA, tRNA, ribosomes and a variety of translation factors essential for the elongation (polymerization), and termination of the polypeptide chain.
- Three steps of Translation
- Initiation, Elongation, Termination
- Polysomes
- mRNA's with several ribosomes translating at once
- Translation Elongation requires
- both ribosomal subunits assembled w/ mRNA to form the P (peptidyl site) and A (aminoacyl site).
- List the eight functions of protein.
- 1. hormones 2. immunity 3.structure 4.enzymes 5.energy 6.transportation 7.movement 8.toxins
- Translation initiation requires:
- small & large ribosomal subunits, GTP, charged initiator tRNA, Mg2+. and initiation factors.
- Ribosomes in Eukaryotes vs. Prokaryotes
- Prokaryotes is 70S, Eukaryotes is 80S
- anti-codon
- base-pairs with the codon; carried in the tRNA