Protein Synthesis And Protein Function- Exam III Flashcards
Eukaryotic translation is driven by:
Ribosomes
What type of structure are ribosomes?
Multimeric
What rRNAs are involved in eukaryotic translation? (4)
28S
18S
5.8S
5S
Ribosomal machinery is assembled within the:
Nucleolus
What is unique about the nucleolus?
Not a membrane bound structure
What serves as guide RNAs to direct specific modifications of the rRNAs?
snoRNA (small nucleolar RNAs)
In eukaryotic translations, the modification on the 2-OH position of the nucleotide ribose sugar include:
~100 methylations of the 2-OH position
In eukaryotic translation, what modification occurs on uridine nucleotides creating psuedouridine?
~100 isomerizations
Ribosomes found in the cytosol (moving anywhere) - NOT found in nucleus and other organelles
Free ribosomes
If the protein being made contains an endoplasmic reticulum targeting sequences, then the ribosomes are associated with the:
Rough ER
Ribosomes associated with the rough ER are considered what type of ribosome?
Membrane bound ribosomes
There is a very specific _____ pathways associated with proteins made in the ribosome of the RER
Secretory pathways
What is read by the ribosomal machine as a triplet of sequential nucleotides (codon)
mRNA
Where does translation start?
5’ end of the mRNA
What do tRNAs have that basepair with the codons of mRNA
Anti-codon
TRNAs are “charged” by the addition of a specific _____ that corresponds to that codon.
Amino acid
The aminoacyl-tRNA is created by the action of enzymes called:
Aminoacyl-tRNA synthetases
Protein translation uses basepairing between:
The codon (in mRNA) and the anticodon (in tRNA)
There is a ____ for each codon, anticodon pair.
TRNA
Steps of translation:
Activation, initiation , elongation, termination
Step of translation: formation of aminoacyl-tRNAs
Activation
Step of translation: binding of ribosome to 5’end of mRNA and subsequent binding of initiator Met-tNA
Initiation
Step of translation: synthesis of the peptide chain
Elongation
Step of translation: synthesis stops and peptide is released from the ribosome
Termination
The 3rd base of the anticodon triplet in the codon generates the wobble position and is generally the least important for:
Base pairing
Translation starts with AUG codon in the mRNA , which in about 90% of cases is the _____ in the mRNA
First AUG
Generally speaking how many stop codons are necessary to terminate translation?
2
A small ribosomal subunit attaches to the 5’ end of mRNA due to recognition of the:
5’cap structure
The small ribosomal subunit moves along the mRNA until it encounters the first methionine where _____ will bind.
Met-tRNA and the large ribosomal subunit
Aminoacyl tRNAs will bind the ____ site of the ribosome
A site (Aminoacyl- site)
The ribosome moves 5’ to 3’ along the mRNA. As the ribosome moves, the met-tRNA is simultaneously shifted to the ____ site.
P site (peptide site)
After the met-tRNA is shifted to the P site, the ____ is now open for the next aminoacyl-tRNA corresponding to the next codon to bind.
A- site
The process of translation largely uses what form of energy?
GTP
What type of bond is formed between the Met-tRNA and the new aminoacyl-tRNA in the A site.
Peptide bond
When peptide bond is formed between the Met-tRNA and the aminoacyl-tRNA , this forms a ____ in the A site and leaves and a ____ tRNA in the p-site
Dipeptide ; empty tRNA
Once the dipeptide is formed, leavening an empty tRNA in the p site, the ribosome then moves simultaneously discharging the empty tRNA and shifting the peptide into the:
P site
Once a stop codon is encountered, termination of the polypeptide chain involves ____ of the ester bond which release the protein.
Hydrolysis
Many antibiotics target:
Transcription or translation
Prevents RNA synthesis
Riamycin
Blocked the binding of the aminoacyl-tRNA to the A-site ( also binds newly forming mineralizing surfaces)
Tetracycline
Prevents the switch from translation initiation to elongation and can also cause protein miscoding
Streptomycin
Blocks the peptides transferase reaction so elongation is prevented
Chloramphenicol
Blocks the ribosome exit channel in the ribosome so elongation is inhibited
Erythromycin
What antibiotics have some type of mechanism dealing with elongation (translation step)
Streptomycin, chloramphenicol and erythromycin
Linear sequence of amino acids
Primary structure
Stretches in the polypeptide chain that form alpha helices and beta-pleated sheets
Secondary structure
What are the two forms of the beta-pleated sheet?
Anti-parallel
Parallel
Changes in amino acids sequence can have a profound effect on:
Protein structure and function
The full 3 dimensional structure of a protein
Tertiary structure
Designation used for proteins that have multiple polypeptide chains (subunits) and refers to teh complete structure of all subunits.
Quaternary structure
Shared sequences of amino acids that can be used to identify potential members of a protein family
Protein motifs
Share protein motifs generally equate to:
Similar functions
Structural entities that function essentially independently within a protein
Protein domains
Protein domains can be build from:
Specific motif or set of motifs
A single protein can have _____motifs and domains
Multiple
Proteolytic enzyme cleavage sites and phosphorylation sites are examples of:
Protein sequence motifs
RGD sequence and heparin binding sites are examples of:
Binding motifs
Transmembrane spanning sequences and protein secretion leader sequences are examples of:
Protein sequence motifs
Many proteins have a _____ structure which also appears in other proteins. These structural motifs are formed by the 3D arrangement of amino acids nad do not necessarily predict a biological function
Supersecondary
What can be found in both proteins and DNA and generally have biological significance
Sequence motifs
Common in transcription factors and consists of alpha helices bound by a looping stretch of amino acids (motif)
Helix-loop-helix
DNA binding motif consisting of two alpha helices joined by a short stretch of amino acids
Helix-turn-helix
DNA binding motif consisting of two beta strands
Zinc finger
Alu, DNA transposing, LINE, SINE, SSRs, and etc. are all examples of:
DNA sequence repeat elements
The odontoblasts cells form:
Dentin
What are the cells derived from the dental papilla?
Odontoblasts & undifferentiated mesenchymal cells fibroblasts
What cells are derived from the dental follicle?
Cementoblasts, fibroblasts, osteoblasts
Odontoblasts give rise to:
Dentin
Undifferentiated mesenchymal cell fibroblasts give rise to:
Pulp
Cementoblasts give rise to:
Cementum
Fibroblasts give rise to:
Periodontal ligament
Osteoblasts give rise to:
Alveolar bone
What cells are derived from the inner dental epithelium
Ameloblasts
Ameloblasts give rise to:
Enamel
Major protein of enamel: that stabilizes the amorphous calcium phosphate phase, control of apatite crystal morphology and organization, and controls enamel thickness
Amelogenin
Amelogenins have the ability toe______ into nano sphere and thereby guid HAP crystal formation and growth.
Self-assemble
Major protein of enamel: cell adhesion protein, controls cell differentiation, and maintains rod integrity
Ameloblastin
Major protein of enamel: cooperates with amelogenin to control mineral nuclear ion and elongated growth
Enamelin
Major protein of enamel: Digests enamel proteins during maturation stage facilitating the removal and hardening the final layer of enamel
Kalikrein 4
Major protein of enamel: Cleaves amelogenin, ameloblastin and enamelin at the secretory stage to produce stable intermediates with defined functions
Mmp-20
What is formed by ameloblasts and contians 90% amelogenin and 10% enamelin.
Enamel
In enamel, as appetite crystals grown, ____ is removed:
Amelogenin
____ is high in proline, leucine, histidine, and glutamine, but contians no hydroxyproline of cystine.
Amelogenin
There are two genes for amelogenin, one on the X and the other on the Y chormosome which result in minor in enamel between males and females. The gene on the X is: The gene on the Y is :
AMELX
AMELY
The self assembly of amelogenin is dependent upon:
Hydrophilic C-terminus
Occurs before the formation of enamel (reciprocal induction)
Dentin formation
Odontoblasts differentiate from cells in the:
Dental papilla
Secrete their organic matrix around the area that is directly adjacent to the inner enamel epithelium.
Odontoblasts
When odontoblasts move toward the center of the center of the tooth they form:
Odontoblasts process
Odontoblasts secrete _____ and mineralize matrix forming the mantle dentin
Hydroxy appetite crystals
What is the major component found in dentin?
Type I collagen
The small integrin-binding ligand N-linked glycoproteins
SIBLING family proteins
Immediately cleaved after secretion into DSP, DGP, and DPP
DSPP
Produced by odontoblasts and early-stage osteocytes
DMP1
Plays a role in biomineralization
Bone sialoprotein
HA binding and contains and RGD motif, mineralization inhibitor
Osteopontin
Matrix extracellular phosphoglycoprotein. Contains an RGD motif and in bone appears to be an inhibitor of mineralization
MEPE
Acellular cementum forms before ____
Cellular cementum
The periodontal ligament is formed by _____ cells of the dental follical
Fibroblast cells