lec 6- cytoplasmic membrane systems

Question 1

what are the 2 membranes of the nucleus?

Answer 1

the inner membrane and the outer membrane (connects with the ER)

Question 2

where does everything enter and exit from in the nucleus?

Answer 2

nuclear pores

Question 3

what is the nucleus?

Answer 3

an organelle that stores genetic information and acts as the control center

Question 4

what is the golgi apparatus?

Answer 4

it is the organelle that processes proteins after they have been synthesized by the ER

Question 5

what is the mitochondria?

Answer 5

creates ATP for the cell, multiple cells have different amounts of mitochondria

Question 6

what do peroxisomes do?

Answer 6

contains oxidase that creates hydrogen peroxide which is then used to oxidize other reactive oxygen species that are toxic. take part in redox reactions

Question 7

what do lysosomes do?

Answer 7

contain 40 types of hydrolytic enzymes which are acid hydrolases these help digest extracellular or intracellular molecules which are not needed

Question 8

what are the parts of the endomembrane system?

Answer 8

rough ER, smooth ER, golgi complex, transport vesicles (endosomes, secretory vesicles, transition vesicles), and lysosomes

Question 9

what tells proteins that are synthesized in the ER, where to go?

Answer 9

The signal sequence

Question 10

do all proteins get n-linked glycosylated?

Answer 10

yes

Question 11

why do proteins get n-linked glycosylated?

Answer 11

helps improve protein stability and folding

Question 12

what maintains the structure of the ER and golgi?

Answer 12

motor proteins

Question 13

are the rough and smooth ER seperated?

Answer 13

no, the rough and smooth ER have luminal spaces that are continuous, they are not seperate organelles

Question 14

what is a biosynthetic pathway?

Answer 14

proteins are synthesized in the ER and then modified at the golgi and then transported to various destinations

Question 15

what is the secretory pathway?

Answer 15

proteins synthesized in the ER are secreted from the cell

Question 16

what is constitutive secretion and regulated secretion?

Answer 16

-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

Question 17

what is the steps to subcellular fractionation?

Answer 17

homogenization and centrifugation

Question 18

what is homogenization?

Answer 18

disrupting (homogenizing) a quantity of cells and the plasma membrane)

Question 19

what is differential centrifugation and what are the steps?

Answer 19

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

Question 20

what is density gradient centrifugation?

Answer 20

a sample from differential centrifugation is further separated by layering the sample on top of a gradient (like sucrose)

Question 21

what are endosomes and exosomes?

Answer 21

-endosomes are vesicles inside the cell which are together
-exosomes are extracellular vesicles secreted by the cell

Question 22

what does a microscope do?

Answer 22

magnifies small objects

Question 23

what is resolution?

Answer 23

the minimum distance needed to distinguish two points

Question 24

how does wavelength affect resolution?

Answer 24

decreasing wavelength increases resolution of small objects like cells

Question 25

how do longer wavelengths make large objects visible?

Answer 25

the large objects interfere with the large wavelengths making it visible, small objects wont interfere with the large wavelengths hence why not visible

Question 26

explain the light microscope?

Answer 26

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

Question 27

what is bright field microscopy?

Answer 27

the staining of samples which are used in light microscopy to add detail to the images, important to get information

Question 28

what is fixation of cells?

Answer 28

preserves cells and prevents degradation and decay

Question 29

what is staining of cells?

Answer 29

adding a simple stain to add contrast between colors

Question 30

what is angular aperture and what does it do?

Answer 30

angular aperture is the angle of the cone of light entering objective lens from the specimen, increasing angle increases resolution

Question 31

what is refractive index and what does it do?

Answer 31

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

Question 32

what is needed for the best resolution?

Answer 32

small wavelength, high angular aperture, and high refractive index

Question 33

what equation is used to get the best resolution?

Answer 33

abbe equation, r = wavelength/ (refractive index sin angular aperture)

Question 34

what is fluorescence?

Answer 34

The ability of certain chemicals to give off light after absorbing radiation like UV light

Question 35

what fluorescence dye is used most commonly and why?

Answer 35

DAPI because it binds to DNA and stains nucleus

Question 36

are photos using different dyes put together?

Answer 36

yes because each one is at a different wavelength

Question 37

what does a fluorescent dye do?

Answer 37

it absorbs at one wavelength and emits at a longer wavelength

Question 38

what does a dichroic mirror do?

Answer 38

it transmits certain wavelengths and reflects longer wavelengths usually used by dyes

Question 39

how are fluorescent dyes used to label proteins?

Answer 39

by direct method, or 2 indirect methods

Question 40

what are the methods to label proteins with dye?

Answer 40

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

Question 41

what is GFP?

Answer 41

it is a green fluorescent protein from jellyfish used as dye, contains chromophore made from ser65-tyr66-gly67