Review EXAM I Flashcards
What are polysomes or polyribosomes?
There are mRNAs segments that have more than one ribosome attached to it, translating.
What happens if eIF-2 is phosphorylated? What process will be inhibiting or activating?
If eIF-2 is phophorylated then it is inactive. Trancription is hindered.
What are the 5 forms of covalent attachments?
Phosphorylation
Glycosylation
Hydroxylation
Biotin and farnesyl groups.
What is glycosylation?
Many of the proteins that are destined to become part of a plasma membrane or to be secreted from a cell have carbohydrate chains added en bloc to the amide nitrogen of asparagine (N-linked) or built sequentially on the hydroxyl groups of serine, threonine, or hydroxylysine (O-linked). N-glycosylation occurs in the endoplasmic reticulum and O-glycosyation in the Golgi. Glycosylation is also used to target proteins to the matrix of lysosomes. Lysosomal acid hydrolases are modified by the phosphorylation of mannose residues at carbon 6
What facilitates protein folding?
Chaperones.
Protein degradation
What targets for it?
Proteins that are defective (for example, misfolded) or destined for rapid turnover are often marked for destruction by ubiquitination, the attachment of chains of a small, highly conserved protein, called ubiquitin. Protein marked this way are quickly degraded by Proteasomes.
What are the characteristic of the genetic code?
Specificity, universality and degeneracy.
What are Cis-acting factors on DNA sequences?
They influence the expression of genes only on the same chromosome.
What are Trans acting factors on DNA sequences?
A trans-acting factor is the regulatory molecule itself, that can transit (deffise) through the cell from its site of synthesis to its DNA binding site.
For example, a protein transcription factor (a trans-acting molecule) that regulates a gene on chromosome 6 might itself have been produced from a gene on chromosome 11. The binding of proteins to DNA is through structural motifs such as the zinc finger, leucine zipper, or helix-t
What is attenuation? and where is it used?
With attenuation, transcription is initiated but it is terminated well before completion.
trp operon, negative control includes Trp itself binding to a repressor protein and facilitating the binding of the repressor to the operator: Trp is a corepressor. Because repression by Trp is not always complete, unlike the lac operon, the trp operon is also regulated by a process known as attenuation.
At what pH are all amino acids water soluble?
All A.A. are L configuration except?
At pH 7.
•All aa are L configuration except Glycine.
Nonpolar, aliphatic AA?
Glycine, Alinine, Proline, Valine, Leucine, Isoleucine, Methionine.
God Ate Very Large Melons In Private
Polar uncharged AA?
Serine, Threonine, Cysteine (sulfur), Asparagine, Tyrosine, Glutamine.
Some Testy Cats Try A Growl.
Polar Charged, AA?
Glutamate (-, acid), Lysine, Aspartate (-, acid), Arginine, Histidine, los demas son +, basic.
Good Lawyers Always Aim High.
Aromatic AA?
Phenylalanine, Tryptophan, and Tyrosine.
PaTienT.
What is cystinuria?
An inherited amino acid substitution in the transport protein that reabsorbs Cysteine, arginine, and lysine.
What are Globular, Fibrous, Transmembrane, and DNA-binding proteins?
Globular: Soluble in aqueous medium.
Fibrous: geometrically linear and repeating in structure.
Transmembrane: regions aligned to cross the lipid membranes
DNA-binding proteins: member of globar protein family.
What is the alpha-helix?
What amino acids disrupt the a-helix region?
What can of syndrome can it cause?
The a-helix is generated by H bonds.
Are common in globular proteins.
Amino acids that disrupt the alpha-helical region of protein are proline (not present at all) large number of charged aa (glutamate, aspartate, histidine, lysine, and asparagine), Tryptophan (bulky R, Valine and isoleucine.
Marfan syndrome
What is Mafan Syndrome?
It is an autosomal dominant genetic disorder of the connective tissue. Has been linked to a defect in chromosome 15, which encodes a glycoprotein called fibrillin-1. The ration of a-helix and b sheets is disrupted.
What is Creutzfeldt-Jakob disease (CJD)?
It is a very rare and incurable degenerative neurological disorder that is ultimately fatal. Caused by prions. The CJD result from the transmission of a protinaceuos agent that is capable of atering the normal a-helix arrangement and replacing with b-pleated sheets.
What are chaperones proteins?
Chaperones“heat shock” are molecules that catalyze the rate of foldingand protect the protein to form non-productive folding
What is Charcot-Marie-Tooth disease (CMT)?
Charcot-Marie-Tooth disease:is a heterogeneous inherited disorder of nerves that is characterized by loss of muscle tissue and touch sensation, predominantly in the feet and legs but also in the hands and arms in the advanced stages of disease.
The absence of these chaperones gives rise to dysfunction either in the axon or the myelin sheathof the nerve cell.
What causes Alpha 1-antitrypsin deficiency (A1AD) and what is it?
Misfolded protein
Alpha 1-antitrypsin deficiency(A1ADor Alpha-1) is a genetic disorder caused by defective production of alpha 1-antitrypsin, deficient activity in the blood and lungs, and deposition of excessive amounts of abnormal A1AT protein in liver cells (cirrhosis, emphysema). This results by a misfolded protein that gets trapped within cell.
What is the degredation sequence for some proteases?
Some proteins are degraded in a sequence-dependent manner. In the N terminus contains proline, glutamate, serine, and threonine. This sequence is a signal to degradation by nonspecific proteases.
