lec 6- cytoplasmic membrane systems Flashcards
what are the 2 membranes of the nucleus?
the inner membrane and the outer membrane (connects with the ER)
where does everything enter and exit from in the nucleus?
nuclear pores
what is the nucleus?
an organelle that stores genetic information and acts as the control center
what is the golgi apparatus?
it is the organelle that processes proteins after they have been synthesized by the ER
what is the mitochondria?
creates ATP for the cell, multiple cells have different amounts of mitochondria
what do peroxisomes do?
contains oxidase that creates hydrogen peroxide which is then used to oxidize other reactive oxygen species that are toxic. take part in redox reactions
what do lysosomes do?
contain 40 types of hydrolytic enzymes which are acid hydrolases these help digest extracellular or intracellular molecules which are not needed
what are the parts of the endomembrane system?
rough ER, smooth ER, golgi complex, transport vesicles (endosomes, secretory vesicles, transition vesicles), and lysosomes
what tells proteins that are synthesized in the ER, where to go?
The signal sequence
do all proteins get n-linked glycosylated?
yes
why do proteins get n-linked glycosylated?
helps improve protein stability and folding
what maintains the structure of the ER and golgi?
motor proteins
are the rough and smooth ER seperated?
no, the rough and smooth ER have luminal spaces that are continuous, they are not seperate organelles
what is a biosynthetic pathway?
proteins are synthesized in the ER and then modified at the golgi and then transported to various destinations
what is the secretory pathway?
proteins synthesized in the ER are secreted from the cell
what is constitutive secretion and regulated secretion?
-constitutive secretion is when vesicles continuously form and carry proteins from the golgi to the cell surface
-regulatory secretion is when material is stored in vesicles and are transported to the cell surface in response of a specific signal
what is the steps to subcellular fractionation?
homogenization and centrifugation
what is homogenization?
disrupting (homogenizing) a quantity of cells and the plasma membrane)
what is differential centrifugation and what are the steps?
separating organelles or other particles of different size and density by their rates of sedimentation in a centrifugal field
1. spin all of the liquid for 10 min
2. take liquid portion out and spin again for 20 min
3. take liquid portion out and spin for an hour
4. receive soluble proteins
what is density gradient centrifugation?
a sample from differential centrifugation is further separated by layering the sample on top of a gradient (like sucrose)
what are endosomes and exosomes?
-endosomes are vesicles inside the cell which are together
-exosomes are extracellular vesicles secreted by the cell
what does a microscope do?
magnifies small objects
what is resolution?
the minimum distance needed to distinguish two points
how does wavelength affect resolution?
decreasing wavelength increases resolution of small objects like cells
how do longer wavelengths make large objects visible?
the large objects interfere with the large wavelengths making it visible, small objects wont interfere with the large wavelengths hence why not visible
explain the light microscope?
condenser lens gathers diffused light from the light source and illuminates the specimen with a small cone of light, some light is diffracted while some passes through specimen, light then hits the objective lens. The focus knob changes the relative distance between the specimen and the objective lens. The ocular lens magnifies the image
what is bright field microscopy?
the staining of samples which are used in light microscopy to add detail to the images, important to get information
what is fixation of cells?
preserves cells and prevents degradation and decay
what is staining of cells?
adding a simple stain to add contrast between colors
what is angular aperture and what does it do?
angular aperture is the angle of the cone of light entering objective lens from the specimen, increasing angle increases resolution
what is refractive index and what does it do?
the measure of the lights bending ability of that medium, air has refracting index of 1, high refracting index means more light enters objective lens, increasing resolution
what is needed for the best resolution?
small wavelength, high angular aperture, and high refractive index
what equation is used to get the best resolution?
abbe equation, r = wavelength/ (refractive index sin angular aperture)
what is fluorescence?
The ability of certain chemicals to give off light after absorbing radiation like UV light
what fluorescence dye is used most commonly and why?
DAPI because it binds to DNA and stains nucleus
are photos using different dyes put together?
yes because each one is at a different wavelength
what does a fluorescent dye do?
it absorbs at one wavelength and emits at a longer wavelength
what does a dichroic mirror do?
it transmits certain wavelengths and reflects longer wavelengths usually used by dyes
how are fluorescent dyes used to label proteins?
by direct method, or 2 indirect methods
what are the methods to label proteins with dye?
direct- primary antibodies with dye attach to antigen
indirect 1- primary antibodies attach to antigens, secondary antibodies with dye attached attach to primary antibodies
indirect 2- indirect method 1 with proteins attached with dyes instead of secondary antibodies
what is GFP?
it is a green fluorescent protein from jellyfish used as dye, contains chromophore made from ser65-tyr66-gly67
