Essential Cell Bio Day One

Question 1

4 major features of eukaryotic cells

Answer 1

1) membrane compartmentalize functions to increase efficiency (organelles)
2) cytoskeleton elements maintain organization
3) cell surface recognizes + interprets environment
4) cell organizes into higher order communities

Question 2

3 parts of cytoskeleton

Answer 2

1) microfilaments
2) intermediate filaments
3) microtubules

Question 3

Microfilaments

Answer 3

(actin)
serve as rails for motor proteins, support cell structure and movement; smallest; 2 ropes twisted around each other.

Question 4

Intermediate filaments

Answer 4

(keratins)
provide tensile strength and structure for cells; ropelike; has multiple isoforms

scaffold

Question 5

Microtubules

Answer 5

(tubulin)
hollow polymers that establish cell shape and serve as tracks that facilitate vesicles and organelles movement within the cell.

–> chromosomes

Question 6

Cytoplasmic compartment

Answer 6

ribosomes, RNA, proteins, metabolites, and signaling cascades all exist/occur in the cytoplasm

very little space between structures, complex

Question 7

RBC size

Answer 7

8 microns

Question 8

how nucleus + ER came to be

Answer 8

invagination of plasma membrane around DNA attached to plasma membrane

Question 9

how mitochondria came to be

Answer 9

engulfment of prokaryotic cell

Question 10

how we know the history of mitochondria from prokaryotes

Answer 10

mitochondria has DNA

mitochondria has own ribosomes (both resemble prokaryote)

double membrane

drugs affecting bacteria, also affect mitochondria (ie. HIV, TB)

Question 11

x is the most demanding tissue of the mitochondria

Answer 11

x= the brain

Question 12

4 components of bilayer membrane

Answer 12

1) phospholipids
2) cholesterol
3) glycoproteins
4) glycolipids

Question 13

phospholipid components

Answer 13

1) polar head (phosphate, glycerol, = charged)
2) hydrophobic tail (fatty acid chains)

Question 14

glycolipids

Answer 14

Membrane lipid molecule with a short carbohydrate chain attached to the head group.
Marker for cellular recognition

Question 15

glycoproteins

Answer 15

Proteins that have >1 sugar on it, usually on the extracellular side of the cell

Question 16

if you change (a) then it can change the function of the phospholipid

Answer 16

a) polar head

Question 17

What 3 things change membrane fluidity ?

Answer 17

1) how long the fatty acid tail is
2) saturation vs. unsaturation (double bonds) in FA tail
3) cholesterol

Question 18

saturated vs. unsaturated and effect of fluidity

Answer 18

saturated= straight, no double bonds, NOT fluid, ie. lard

unsaturated= kinks, double bonds, FLUID, ie. olive oil

Question 19

if cholesterol is in between unsaturated FA, then fluidity (a)

Answer 19

a) decreases

Question 20

if cholesterol is in between saturated FA, then fluidity (a)

Answer 20

a) increases

Question 21

The mobility (diffusion) of membrane depends on….

Answer 21

1) size of molecule
2) interactions with other molecules
3) temperature
4) lipid composition (tails, cholesterol)

Question 22

the longer the FA tail, the (a) fluid

Answer 22

LESS

Question 23

Phospholipid asymmetry

Answer 23

phospholipid facing inside vs. outside are DIFFERENT

Question 24

Phosphatidylserine

Answer 24

switches from cytosolic to extracellular during apoptosis

Question 25

4 Types of membrane proteins

Answer 25

1) transmembrane 2) membrane- associated 3) lipid-linked protein 4) protein attached

Question 26

transmembrane (aka integral protein) and relation to helices

Answer 26

crosses whole membrane (has hydrophobic and hydrophilic parts) alpha helices creates transmembrane domain--\> multiple alphas helices results in pores to transport specific ions

Question 27

Alpha helices in transmembrane protein have a (a) to span the transmembrane domain

Answer 27

a) nonpolar side

Question 28

Membrane associated proteins

Answer 28

has domain bound in membrane but does not span the full bilayer

Question 29

lipid linked protein

Answer 29

protein covalently attached to lipid that is embedded in membrane

Question 30

protein attached

Answer 30

relevant protein attached to another protein that spans the membrane

Question 31

cytoplasm is (a) environment which (b) disulfide bonds

Answer 31

a) reducing b) breaks

Question 32

3 distinquishing features of the plasma membrane surfaces

Answer 32

1) glycocalyx 2) cholesterol/ lipid rafts 3) cytoskeleton interactions

Question 33

glycocalyx

Answer 33

coating on cell membrane composed of glycoproteins, glycolipids and other sugar residues

Question 34

cholesterol / lipid rafts

Answer 34

concentrations of lipids in the plasma membrane cell signal machinery long FA, more saturated tails increased cholesterol, glycolipid and glycoproteins longer than normal transmembrane domain

Question 35

cytoskeleton interactions

Answer 35

proteins between cytoskeleton and plasma membrane involved in cell shape and stabilization

Question 36

organization of the nucleus

Answer 36

nucleolus, nuclear envelope (inner and outer), nuclear pore, chromatin

Question 37

nuclear pore

Answer 37

allows entering and exit of things from the nucleus (perforates the nuclear envelope) very selective in permeability = unique environment looks like a basket

Question 38

nucleolus

Answer 38

makes rRNA

Question 39

(x % ) of proteins made go to the ER and proteins targeted for the ER can become (a) or (B)

Answer 39

20% a) translocated across ER membrane into ER lumen b) become embedded in ER membrane (overall ER is beginning of pathway where can be secretory or transmembrane proteins)

Question 40

Features of secreted membrane proteins

Answer 40

water soluble, cross ER membrane into ER lumen, can go to be secreted at cell surface or lumen of an organelle have signal sequence

Question 41

Features of transmembrane proteins

Answer 41

have signal sequence (start and stop) have hydrophobic amino acids to help (bc have to span lipid bilayer)

Question 42

HOW proteins are transported into the ER

Answer 42

setting the scene: mRNA being translated at a ribosome 1) SRP binds the signal sequence on the polypeptide being translated from mRNA, which slows translation at the ribosome 2) SRP/ ribosome complex binds to the SRP receptor in the ER membrane 3) SRP then is released by translocator protein and passes ribosome over 4) translocation channel inserts polypeptide into membrane --\> can either transfer polypeptide all the way through (secreted) or can have stop sequence to keep it partially in membrane 5) signal peptidase cleaves signal sequence

Question 43

3 types of post-translational processing in the ER

Answer 43

1) protein folding 2) N-linked oligosaccharide initiation 3) GPI modification

Question 44

what happens in protein folding of post-translational processing in the ER

Answer 44

chaperones help disulfide bonds form and stabilize the protein bc when it leaves the cell the pH is gonna change due to degradative enzymes outside the cell

Question 45

oligosaccharide initiation is (a)- linked which means it is a covalent attachment of short oligosaccharide side chains to the (b) of asparagine in target protein

Answer 45

a) N b) NH2

Question 46

GPI modification of post translational processing in ER

Answer 46

lipid attaches to protein anchors protein and allows it to be connected to membrane

Question 47

Regions and functions of the Golgi

Answer 47

glycosylation (adding and removing sugars) sorting cis (entry) --\> medial --\> trans (exit) series of flattened cisternae

Question 48

What is an example of glycosylation that happens in golgi?

Answer 48

Blood type! making A antigen (GalNActransferase) vs. B antigen (Galtransferases)

Question 49

Where does the golgi sort ER products to? (3)

Answer 49

1) diversion to lysosomes 2) Regulated secretion: signal mediated diversion to secretory vesicles 3) Constitutive secretion: plasma membranes

Question 50

What is this?

Answer 50

Mitochondria in cytoplasm top arrows: actin filament bottom arrows: microtubule connection

Question 51

What two things does this show?

Answer 51

1) mitochondria has double membrane 2) has cristae

Question 52

What does this show?

Answer 52

outer nuclear membrane with a ribosome studded rough ER

Question 53

What does this show?

Answer 53

lipid bilayer in RBC

Question 54

What is the main thick black part showing?

Answer 54

glycocalyx

Question 55

What is this looking at and from what perspective?

Answer 55

nuclear baskets from inside nucleus

Question 56

(actin) serve as rails for motor proteins, support cell structure and movement; smallest; 2 ropes twisted around each other.

Answer 56

Microfilaments

Question 57

(keratins) provide tensile strength and structure for cells; ropelike; has multiple isoforms scaffold

Answer 57

Intermediate filaments

Question 58

(tubulin) hollow polymers that establish cell shape and serve as tracks that facilitate vesicles and organelles movement within the cell. --\> chromosomes

Answer 58

Microtubules