Chap 8 part 1 Flashcards
how many membranes does the nuclear envelopes contain
2 membranes
What are Lysosomes?
they carry transport protiens and hydrolytic enzyemes that get released by proteolytic cleavage to breakdown macromolcules
What is the endo membrane system?
the
- Rough and smooth ER
- golgi appartaus
- endosomes
- lysosomes
- vacuoles
materials are passed down all along them
What is the Biosynthetic pathway
proteins are synthesized in the ER and get modified in the Golgi apparatus then transported to various destinations
Secretory pathway
proteins are synthesized in the ER and are secreted form the cell
- constitutive secretion
- regulated secretion
Constitutive secretion
the materials made by the ER are constantly discharged by secretory vesicles
regulated secretion
the materials made in the ER are stored in vesicles until stimulated to release
Subcellular fractionation
homogenization which means you want to maintain the activity of the organelles of interest then centrifugation
Differential centrigugation
separating by size/density by changing the rates of sedimentation
Density gradient centrifugation
first isolated by differential then further separated by a sucrose gradient
what needs to get out of the nucleus?
-mRNA
- mRNP
- protiens
The 3 primary characteristics of microscopy
detect - find the object
resolve - distinguish it from another
magnify - make it bigger
the relationship between wavelength and resolution
the smaller the wavelength, easier it will be able to be perturbed therefore detected by a small object
Three factors to increase resolution?
- increasing angular aperture (allows for more light)
- high refractive index (allows more light to enter objective lens)
- small wavelength
What is the effect of resolution on different wavelengths in relation to ABBE equation
shorter wavelength makes the distance between the 2 points can be resolved is smaller
What are the limitations of light miscopy
the samples must be fixed and stained in order to be visual
fixation- preserved
staining- added for colour and differentiating
The principles of fluorescence microscopy
light is absorbed at one wavelength and emitted at an longer one
What does a dichroic mirror do in fluorescence microscopy
allows light of a certain wavelength to pass through, while light of other wavelengths is reflected
Indirect labeling using antibodies
when a secondary isotope antibody with the fluorochrome will attach to primary antibody that is connected to the antigen
Direct labeling using antibodies
the primary antibody has a fluorochrome on it and is directly connected to the antigen
What is green fluorescent protein?
it comes from a oxidized chromophore of the chemiluminescent jellyfish
(oxidization occurs at 65-67 per-tyr-gly in the primary sequence)
what is a pulse chase experiment?
Placing a cell in a solution of radioactive amino acids (the pulse), allowing it to be absorbed and incorporated into the enzymes synthesized by the ribosomes of the cell. Then washing away the radioactive amnio acids and replacing it with clean ones (the chaser)
This was done with sliced pancreatic cells to determine where the secretory proteins were synthesized and the path they follow to the site of discharge
What is a cell free system?
they have been broken up and don’t contain full cell and are used to identify the roles of the proteins.
What is Translation?
when a ribosome reads the mRNA to create a protein
what is translocation?
movement of the genetic information
What is co-translational translocation?
when the secretory protein is transported into the ER lumen while being synthesized by a ribosome
what is post-translational translocation?
when the secretory protein is transported after being synthesized by a ribosome
a secretory protein to undergo co translation is detected by…?
a signal sequence of 6-15 stretch of hydrophobic amnio acid residues on the nascent polypeptide
steps of the secretory protein synthesis
- usually takes place co-translational
1) a signal recognition particle (SRP) attaches to the signal sequence of the nascent protein and the large ribosomal unit
2) then the SRP docks on the SRP receptor on the ER membrane
3) the ribosomal unit and the nascent polypeptide is handed to the translocon ( a protein channel embedded in the ER membrane
4) the signal sequence gets recognized and degraded and translation and translocation continue until the protein is released into the lumen of the ER
how is an integral membrane protein synthesized
is it the same as secretory protein except a hydrophobic stop transfer sequence somewhere along the protein will cause translocation to stop but translation will continue
what is the oligosaccharide precursor and how is it formed?
1) 2 GlcNAc and 5 mannose residues are adde to the cystolic face one at a time
2) they are flipped to the luminal side by the dolichol phosphate
3) they are added to an asparsgine residue on the nascent polypeptide in a tripeptide sequence ( Asn-X-Ser/Thr)
what is a UPR?
Unfolded protein response
- an accumulation of misfolded proteins in the ER as signal to make more chaperones and/or slow the rate of newly synthesized proteins
what is a ERAD
they are ER associated degration proteins and they remove improperly folded proteins from the Er to the cystosol to be degraded.
-This is called dislocation or reterotranslocation
