Quiz #3

Question 1

What is bulk transport?

Answer 1

big molecules (polysaccharides) must be transported using a bulk transport mechanism
involves formation of vesicles
membrane is flexible and can bend into different shapes including pinching off into vesicles
this requires energy

Question 2

What are the three types of endocytosis?

Answer 2

phagocytosis
pinocytosis
receptor-mediated

Question 3

What is phagocytosis?

Answer 3

cell “eating”

uses a food vacuole

Question 4

What is pinocytosis?

Answer 4

cell “drinking”

uses a vesicle

Question 5

What is receptor-mediated endocytosis?

Answer 5

mechanism involved receptors to import specific things
each receptor only binds to ligands of a particular structure
clathrin binds to these receptors on the inside of the cell, gathering them and the membrane into a “pit” shape that eventually forms a vesicle

Question 6

What is clathrin?

Answer 6

a coat protein that helps facilitate vesicle formation

Question 7

What are lipoproteins?

Answer 7

transport fats to cells via the blood stream

Question 8

What is a low density lipoprotein (LDL)?

Answer 8

low in density, but highest in cholesterol

often referred to as the “bad” cholesterol

Question 9

What is a high density lipoprotein (HDL)?

Answer 9

highest density due to high protein/lipid ratio
these particles remove excess cholesterol from blood vessels
referred to as the “good” cholesterol

Question 10

What is primary active transport?

Answer 10

systems that perform active transport using ATP directly

Question 11

What is secondary active transport?

Answer 11

systems that use carrier proteins driven by ion gradients

Question 12

What are uniporters?

Answer 12

carrier or transport proteins that transport only one type of molecule

Question 13

What are symporters?

Answer 13

carrier or transport proteins that transport two different molecules in the same direction

Question 14

What are antiporters?

Answer 14

carrier or transport proteins that transport two different molecules in opposite directions

Question 15

What are bacterial cell walls?

Answer 15

provide shape and protection from bursting in hypotonic environments
almost all bacterial cell walls contain peptidoglycan

Question 16

What are gram-positive bacteria?

Answer 16

simple cell wall structure
thick peptidoglycan
single plasma membrane

Question 17

What are gram-negative bacteria?

Answer 17

complex cell wall structure
thinner peptidoglycan
have two plasma membranes

Question 18

What is peptidoglycan?

Answer 18

a thin sheet composed of: chains of repeating disaccharide unit composed of two monosaccharides and small peptides

synthesized only in growing cells

It contains a glucose derivative that is also found in chitin

Question 19

What is transpeptidation?

Answer 19

two peptide side chains attach to each other via covalent bonds, this cross-linking reaction is called transpeptidation, and it adds strength to the layer

Question 20

What are antibodies?

Answer 20

there are many naturally occurring antibodies

some are specific to certain types of bacteria, based on their ability to target prokaryotic-specific structures

Question 21

What are some common targets of antibodies?

Answer 21

prokaryotic ribosomes (responsible for protein synthesis)
prokaryotic cell wall

Question 22

What is lysozyme?

Answer 22

antimicrobial present in our bodily fluids
enzyme that catalyzes hydrolysis of beta 1-4 linkages between NAG and NAM
peptidoglycan falls apart, cells lyse

Question 23

What is penicillin?

Answer 23

as bacterial cell grows, it synthesizes more peptidoglycan
transpeptidation reaction is catalyzed by a specific enzyme
the enzyme is inhibited by penicillin
inhibition leads to a weakened peptidoglycan
works best on gram positive cells
as the cell grows, new peptidoglycan is not formed, eventually the cell bursts

Question 24

What is a capsule?

Answer 24

mostly polysaccharides
further protects cell from environment
can be used to stick bacteria to surface
capsule is very rare in archaea

Question 25

What are the two types of pili?

Answer 25

fimbriae

sex pilus

Question 26

What is fimbriae?

Answer 26

attach to surfaces or host cells

Question 27

What is sex pilus?

Answer 27

for transfer of DNA between bacteria cells
DNA is transferred to another bacteria (bacterial conjugation)
plasmids (small circular DNA) can be transferred

Question 28

What is taxis?

Answer 28

the ability to move toward or away from stimulus

Question 29

What is chemotaxis?

Answer 29

is the movement toward or away from a chemical stimulus

Question 30

How do bacteria move?

Answer 30

motile bacteria move in a series of “runs” and “tumbles”

duration of the run is longer if the concentration of the “attractant” increases during the run

Question 31

What are flagella?

Answer 31

for movement
flagella of bacteria, archaea, and eukaryotes are composed of different proteins and likely evolved independently
rotation can be clockwise or counterclockwise
CCW = run
CW = tumble

Question 32

What are plant cell walls?

Answer 32

young plant cell secretes a thin cell wall outside the plasma membrane, the primary cell wall
as cell matures, cell wall is strengthened
some secrete hardening substances into the primary cell wall, while some add a secondary cell wall
a cell may have many layers

Question 33

What is the middle lamella?

Answer 33

between primary cell walls of adjacent plant cells

composed of sticky polysaccharides called pectin

Question 34

What is plasmodesmata?

Answer 34

because of the thick cell wall and middle lamella, plant cells are isolated from each other
to allow communication between cells, plant cell walls contain pores (tunnels) between cells
allows passage of H2O and small solutes between cells
these pores can open and close depending on the environmental conditions or age of the plant

Question 35

What do animal cells have instead of a cell wall?

Answer 35

no cell wall, but they secrete proteins and polysaccharides = extra cellular matrix (ECM)
ECM consists mostly of glycoproteins and protein fibres

Question 36

What are the different ways adjacent animal cells can be attached?

Answer 36

Tight junctions
Desmosomes
Gap junctions

Question 37

How do tight junctions connect adjacent animal cells?

Answer 37

membranes of neighboring cells are essentially fused

tight seals are formed

Question 38

How do desmosomes connect adjacent animal cells?

Answer 38

tightly fasten cells together at certain points
made of strong protein filaments that cross the intercellular space
can withstand mechanical forces

Question 39

How do gap junctions connect adjacent animal cells?

Answer 39

multi-subunit structures that form a channel between adjacent cells
allow free exchange of small molecules
this allows tissues to coordinate responses to stimuli
2 connexons form a gap junction

Question 40

What is cytoplasm?

Answer 40

interior of a prokaryotic or eukaryotic cell

Question 41

What is cytosol?

Answer 41

the fluid portion of the cytoplasm (without structures or membrane)

Question 42

What is the endosymbiont hypothesis?

Answer 42

mitochondria and chloroplasts arose by endosymbiosis

a mutually beneficial relationship derived from a cell living inside another cell

Question 43

What does the endosymbiont hypothesis say about mitochondria?

Answer 43

mitochondria: are descended from an ancient bacterium

most closely-related extant bacteria are the alpha-proteobacteria

Question 44

What does the endosymbiont hypothesis say about chloroplasts?

Answer 44

are descended from an ancient cyanobacterium (photosynthetic bacterium)

Question 45

What is the evidence for endosymbiosis?

Answer 45

mitochondria and chloroplasts have their own DNA (circular), genes are organized like prokaryotic genome, and they have their own ribosomes (similar to prokaryotic ribosomes)