Mcp Lecture 3

Front 1

lysosome

Back 1

low pH environment containing enzymes for cellular degradation

Front 2

endosomes

Back 2

series of compartments which sort endocytosed materials

Front 3

peroxisomes

Back 3

small compartments that contain enzymes that oxidize organic molecules; involved in the synthesis of plasmalogens which are specialized phospholipids found in the myelin sheaths of nerve cells

Front 4

how big are human body cells on average?

Back 4

5-20um

Front 5

visualizing cells:
conventional light microscopy

Back 5

-non-destructive to specimen
-typically used to study cells as a whole, limited in sub-cellular detail
~200nm resolution

Front 6

visualizing cells:
Fluorescence microscopy

Back 6

-type of light microscopy that uses fluorescent dyes to detect specific macromolecules within cells
dyes with different excitation and emission wavelengths can be used simultaneously to visualize multiple macromolecules in a single cell

Front 7

visualizing cells:
transmission electron microscopy

Back 7

2nm resolution
used to study sub-cellular structures in great detail
uses a beam or electrons rather than light as the illumination source; dark regions represent density
specimen preparation is complex and requires very dry and thin specemins (thinner than the smallest cell) which are usually stained with electron-dense heavy metals

Front 8

visualizing cells
scanning electron microscopy

Back 8

~10nm resolution
-typically used to view surfaces of whole cells and tissues rather than sub-cellular organelles
-focused beam of e- is moved across a specimen which has been coated with a thin film of heavy metal to generate an image that appears three dimensional

Front 9

visualizing cells:
immunofluorescence

Back 9

combines fluorescent dyes with antibody molecules that bind selectively to particular macromolecules; amplification of the fluorescent signal can be achieved by using unlabeled primary antibodies and fluorescently labeled secondary antibodies

Front 10

which organelle is the site of synthesis of proteins destined for secretion from the cell?

Back 10

ER

Front 11

A defect in the ER targeting signal sequience (not the ER retention signal) of an ER resident protein would result in the protein being secreted from the cell. TRue/False

Back 11

False

Front 12

What is the role of chaperone proteins in the ER?

Back 12

To prevent improperly folded proteins from exiting the ER

Front 13

The targeting of newly synthesized enzymes to mitochondria involves which transport mechanism?

Back 13

transmembrane transport

Front 14

What is the role of the SRP receptor in protein targeting to the ER?

Back 14

To release SRP from the ER targeting signal

Front 15

Which of the following is NOT a function of the rough or smooth ER
Ca2+ storage
lipid metabolism
sythesis of secreted proteins
O-linked glycosylation of proteins
folding of newly sythesized proteins

Back 15

O-linked glycosylation of proteins
(N-linked)

Front 16

to which layer of the ER membrane are newly sythesized phospholipids added?

Back 16

cytosolic side (then flippases flip them over to the other side)

Front 17

What carries newly synthesized lipids to peroxisomes and mitochondria for usage?

Back 17

phospholipid exchange proteins

Front 18

What is the sequence of amino acids for the ER retention signal?

Back 18

KDEL

Front 19

Which protein mediates the formation of disulfide bonds between cysteines

Back 19

the enzyme protein disulfide isomerase

Front 20

If the ER targeting signal is internal on the AA sequence, what will the final orientation of the protein on the membrane be?

Back 20

double-pass membrane (sequence is not cleaved)

Front 21

If ER targeting is at the N-terminus, what is the confirmation of the molecule in the ER membrane?

Back 21

single-pass
(signal will be cleaved by signal peptidase)

Front 22

The ER-retention signal is found at the (N/C) terminus of the AA?

Back 22

C terminus

Front 23

Give an example of an ER resident protein

Back 23

BiP (chaperone), protein disulfide isomerase

Front 24

Give an example of a lysosomal protein

Back 24

nuclease, protease, glycosidase, lipase, or phosphatase

Front 25

Give an example of a secreted protein

Back 25

insulin, growth factors, hormones, fibronectin, laminin

Front 26

Where is the only place that co-translational transport occurs?

Back 26

ER

Front 27

The ER does not produce protein products destined for ______ and ________

Back 27

peroxisomes and mitochondria

Front 28

What protein modifications occur in the ER

Back 28

signal sequence cleavage
attachment of N-linked oligosaccharides to some proteins (co-translational)
hydroxylation of precollagen on proline and lyzine
disulfide bonds
folding
quaternary structure formation

Front 29

Where would smooth ER be more abundant in the body?

Back 29

testosterone secreting Leydig cells in testes
(b/c smooth ER carries out lipid metabolism such as steroids)
hepatocytes
sythesize the lipid components of lipproteins and detoxyfy lipid-soluble drugs.

Front 30

What are three reasons for protein sorting

Back 30

organelle growth
replacement of organelle proteins (maintenence)
secretion of proteins from the cell

Front 31

What are the three methods of import of proteins into cell

Back 31

gated transport
transmembrane transport
vesicular transport