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cell and molecular > 1.19 - 6.3 > Flashcards

1.19 - 6.3 Flashcards

1
Q

ex. of positional information

A
  • Barr bodies next to nuclear envelope
  • rRNA genes in nucleolus
  • Golgi bodies adjacent to RER
  • centrioles templating perpendicularly
  • dorsal-ventral gradients of proteins
  • cytoskeleton
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2
Q

what do the nurse cells of a fruit fly egg tell us

A

positional distinction may start in egg, needed to direct positional information in next generation

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3
Q

what does it mean for a cell to be polarized

A

having distinct basal and apical region, specific functions carried out in each region

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4
Q

enzymes are usually _______

A

proteins

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5
Q

biological catalysts

A

speed up reaction without being consumed, lower activation energy

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6
Q

how do enzymes usually work

A

usually organized in pathways, work toward goal in stepwise fashion

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7
Q

true or false: enzymes aren’t very specific

A

false - highly specific

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8
Q

what are essential to maintain homeostasis?

A

feedback mechanisms

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9
Q

ex. of receptor-mediated communication/feedback mechanisms

A

hormones: act at distance, slow, low concentration
nerves: neurotransmitters, rapid, high concentration

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10
Q

signal transduction pathway

A

allows event on external side of membrane to trigger response in cell

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11
Q

results of signal transduction

A
  • amplification of signal
  • response
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12
Q

what are examples of a response of signal transduction

A

regulation of gene expression in nucleus or structural change

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13
Q

many enzymes and signaling pathways are organized as what?

A

multiprotein complexes that are physical associated

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14
Q

all organisms have cells that can what?

A

grow and divide

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15
Q

how do bacteria and archaea divide

A

binary fission

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16
Q

binary fission

A
  • first ensure one copy of each daughter chromosome is in opp. ends of cell
  • growing of membrane/wall across center
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17
Q

what division protein is commonly used in binary fission

A

Ftsz

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18
Q

how do yeast and some other fungi divide

A

by budding

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19
Q

how do eukaryotes usually divide

A

mitosis and meiosis

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20
Q

binary fission, budding, and mitosis/meiosis depend upon a mechanism to ensure what?

A

each cell obtains equal sets of genetic information

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21
Q

differentiation

A

cell acquires new phenotype or produces progeny with dif phenotype

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22
Q

somatic cells

A

specialized for special function in organism, diploid

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23
Q

germ cells

A

sperm and oocytes, haploid

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24
Q

fertilized zygote is ______potent

A

toti

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25
stem cells are _____potent
both multi and pluri
26
ex. of pluripotent stem cells
embryonic stem cells
27
pluripotent
gives rise to most cells
28
totipotent
gives rise to all cells
29
multipotent
gives rise to some cells, more specific and less options
30
ex. of multipoint stem cells
adult stem cells: neural, mesenchymal, hematopoietic
31
all stem cells have what ability?
to self-renew
32
terminally differentiated cells
have lost the capacity to divide
33
compartments in a cell differ in composition of what?
membrane and internal milieus
34
how do membranes enable cells to maintain homeostasis?
- control solute concentrations across membranes - adapt to altered metabolic situations - process information - transport nutrients in and waste product out
35
membranes (other than nuclear envelope) require membrane proteins to transport what?
polar molecules, hydrophilic, large biologic molecules
36
why can't polar molecules pass freely through membrane?
because of hydrophobic interior
37
membrane proteins maintain ion concentration __________
differences
38
what do ion concentration differences create?
electrochemical gradients
39
what do electrochemical gradients do
store potential energy and process electrical signals
40
what ion concentrations are higher outside of the cell
Na+, Ca2+, Cl-
41
what ion concentrations are higher in the cell
K+
42
the inside of a resting animal cells is slightly ________ charged compared to the outside
negatively
43
2 main types of ion transport
1. channels 2. carriers
44
channel proteins
contain pore region through which solutes pass at HIGH flux rates when the channel is open
45
what are channel proteins composed of
1+ alpha subunits
46
channel proteins have:
1. solute selectivity 2. rapid rate of solute permeation 3. gating mechanism
47
ex. of channels
- ion channels - aquaporins - porins (proks, mito) - gap junctions - nuclear pore complexes - ER protein translocaters
48
channel pore
inner part of channel protein
49
channel configuration
vary from a single with pore to several to form 1 pore or several with several pores
50
true or false: most channels aren't selective for a particular solute
false
51
when some channels aren't selective for a particular solute, what are they?
general cationic or anionic channels
52
channel proteins are regulated by what?
gating
53
gating
undergoing conformational changes to open and close in response to specific stimuli
54
ex. of types of gating:
- ligand - voltage - temperature - stretch
55
true or false: gates can only be activated one time
false - thing of neuronal signaling
56
what does electrochemical gradient dictate?
the direction of movement - energetically favorable direction
57
speed of channels
fast, 10^8 per second, close of maximal rate of diffusion of ions in water
58
carrier proteins
bind solutes on one side of the membrane, undergo allosteric change, and release them on the other side of the membrane
59
are channel or carrier proteins faster
channel
60
speed of carrier proteins
10^3 per second
61
where do carrier proteins transduce energy from
- electrochemical gradients - ATP - other sources
62
why are carrier proteins involved with active transport
use energy to transport substances against concentration gradient
63
2 main types of carrier proteins
1. transporters 2. pumps
64
transporters
usually couple energy from electrochemical membrane gradients to facilitate movement of substrate across the membrane
65
3 types of transporters
1. uniporters 2. symporters (cotransporters) 3. antiporters (exchangers)
66
pumps
use energy from ATP hydrolysis and light directly to drive energetically less favorable substrate accumulation of efflux
67
2 categories of active transport
1. primary 2. secondary
68
primary active transport (pumps)
use ATP as the energy source to drive transport of solutes against electrochemical gradients
69
ex. of primary active transport
- Ca2+-ATPase - Na+/K+-ATPase
70
secondary active transport (transporters)
don't use ATP directly, use free energy stored in gradients
71
ions in a solution are ________
hydrated
72
what does it mean when ions are hydrated
surrounded by water molecules attracted by dipolar partial negative/positive charges
73
what is formed around each ion
hydration shell
74
is the hydration shell energetically favorable or expensive
favorable
75
what does the size of the hydration shell depend on
charge density and size of ion
76
do smaller ions have a higher or lower charge density?
higher
77
how do ion channels enable the partial dehydration of ions as they travel through?
ion forms weak bonds with amino acid residues, which mimics hydration shell and makes transport process energetically favorable/selective

cell and molecular (21 decks)

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