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bio 102 > Quiz 3 Chap 5/6 > Flashcards

Quiz 3 Chap 5/6 Flashcards

1
Q

how is NADH significant in the electron transport chain?

A
  • NAD+ coenzyme is previously transferred electrons from organic compounds
  • each NADH represents stored energy to make ATP, NADH electron carriers pass/donate electrons to compounds in the ETC
  • carriers alternate reduced and oxidized states as they accept and donate electrons
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2
Q

how does the ETC work

A
  • O2 pulls electrons down the chain, yielding energy for ATP in a series of redox reactions
  • electrons are passed through many proteins (including cytochromes containing Fe) and drop in free energy as they go down the chain
  • this causes proteins in the cristae to pump H+ (protons) from the matrix to the intermembrane space
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3
Q

significance of ETC being a series of small steps

A

ETC functions to break the large free-energy drop from food into smaller steps, releasing energy in manageable amounts

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4
Q

ETC structure

A

multi-protein complex in the cristae (inner membrane)

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5
Q

chemiosmosis

A

use of energy in a H+ (proton) gradient to drive cellular work

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6
Q

how is ATP made via chemiosmosis, and what is a proton-motive force?

A
  • H+ moves back across the membrane via ATP synthase (turbine-like)
  • energy from this H+ gradient causes phosphorylation of ADP to ATP

proton motive force – H+ gradent

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7
Q

significance of oxygen during ETC stage

A

electrons are passed to oxygen at the end of the chain to form H2O, chain can’t function without oxygen to accept them

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8
Q

flow of energy during cellular respiration

A

glucose - NADH - ETC - proton-motive force - ATP

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9
Q

how many ATP are produced during each stage of respiration (per glucose)

A

glycolysis - 2
citric acid cycle - 2 (1 per turn, 2 turns per glucose)
oxidative phosphorylation - 26-28

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10
Q

evolutionary significance of glycolysis

A
  • occurs in nearly all organisms
  • evolved in ancient prokaryotes before there was atmospheric oxygen
  • glycolysis and citric acid cycle lead to many different catabolic/anabolic pathways

***fats and proteins can also be used for glycolysis, with additional steps before

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11
Q

structure of the plasma membrane

A
  • selective permeability, some substances pass through more easily
  • fluid mosaic model: fluid structure with a “mosaic” of various proteins embedded in it
  • like jello, phospholipids and proteins can move within the bilayer
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12
Q

how does the plasma membrane change in response to temperature?

A
  • at cool temps, membranes switch from fluid to solid (specific temp depends on type of lipids)
  • membranes rich in unsat. fats more fluid
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13
Q

importance of membrane fluidity, how they maintain it

A

membranes must be a specific fluidity in order to function properly
- steroid-cholesterol restrains movement of phospholipids in warm temps and maintains fluidity by preventing tight packing in cool temps

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14
Q

peripheral vs intergral proteins

A

peripheral: bound to surface of membrane
integral: penetrate hydrophobic core

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15
Q

6 functions for membrane proteins

A 
transport
enzymatic activity
signal transduction
cell-cell recognition
intercellular joining
attachment to cytoskeleton and extracellular matrix
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16
Q

how do cells recognize each other?

A

specific molecules on the plasma membrane (glycolipids and glycoproteins)

  • these are unique among species, individuals, and even cell types within individuals
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17
Q

which molecules pass/do not pass through plasma membrane?

A
  • hydrophobic (nonpolar) molecules dissolve in lipid bilayer and pass through membrane
  • hydrophilic and polar molecules (sugars) must be transported by proteins
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18
Q

mechanisms and benefits of facilitated diffusion

A

*speeds up passive movement of molecules and allows for the transport of polar molecules!

  • channel proteins: hydrophilic channels that allow specific molecules to cross (i.e. ion channels)
  • aquaporins: facilitate the passage of water
  • carrier proteins: bind to molecules, change the molecule’s shape to shuttle them across the membrane
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19
Q

diffusion

A

tendency for molecules to spread evenly in space without energy investment

20
Q

dynamic equilibrium

A

molecules cross both ways across a selectively permeable membrane, diffusing down their conc. gradient

21
Q

osmosis

A

diffusion of water across a selectively permeable membrane from a less concentrated (hypotonic) to a more concentrated (hypertonic) solution

22
Q

tonicity

A

ability of a solution to cause cell to lose/gain water

23
Q

types of tonicity in solutions

A

isotonic: solute same conc. as cell, no net movement
hypertonic: solute conc. greater than cell, cell loses water
hypotonic: solute conc. less than cell, cell gains water

24
Q

what tonicity environment do plant and animal cells prefer?

A

animals - isotonic (hypotonic solution can cause plasmolysis)
plants - hypotonic (prefer to be turgid, not flaccid)

25
Q

active transport and its importance

A

proteins move substances against conc. gradient, requiring ATP

  • allows cell to maintain conc. gradient different from surroundings (homeostasis)
  • sodium-potassium pump is one type
26
Q

signal transduction pathway

A

series of steps by which a signal that reaches a cell’s surface is converted into a specific cellular response

(2nd step of cell signaling)

27
Q

types of short-distance communication in animals

A

cells communicate using messenger molecules called local regulators

  • paracrine signaling: secreting cell releases local regulator molecules to many nearby target cells
  • synaptic signaling: one neuron sends neurotransmitters to a target cell
28
Q

how are hormones used in organisms?

A

*used for long-distance signaling, released by endocrine cells

animals - travel through blood
plants - often on exterior waxy coating

29
Q

what are the names of junctions between plant and animal cells?

A

plants - plasmodesmata

animals - gap junctions

30
Q

how do slime molds use short-distance signaling?

A

slime mold cells signal each other locally when using cAMP when food is scarce, causing them to come together and form a fruiting body

31
Q

how is endocrine (hormonal) signaling used to regulate blood glucose?

A
  • endocrine signaling is used when glucose falls out of 70-110 mg/mL range
  • 2 pancreatic hormones are used: insulin and glucagon
  • glucagon is used when glucose is too low; converts glycogen to glucose in the liver
  • insulin is used when glucose is too high; converts glucose back to glycogen storage in liver
32
Q

what is vasopressin and how is it used in long-distance signaling?

A
  • vasopressin is an anti-diuretic hormone made and secreted by the hypothalamus and stored by the pituitary gland
  • it travels to the kidney through blood and signals the kidney to reabsorb water, concentrating urine
33
Q

what was Earl Sutherland’s discovery about epinepherine?

A
  • epinephrine only caused the breakdown of glycogen in the presence of an enzyme when living cells were a part of the mixture
  • epinephrine needed a receptor on the cells’ plasma membrane to transmit the signal
  • cells receiving signals have 3 processes: reception, transduction, and response/regulation
34
Q

what are the 3 stages of cell signaling?

A
  1. reception
  2. signal transduction
  3. regulation
35
Q

reception

A
  • water-soluble signal molecule (ligand) binds to a highly specific receptor protein in plasma membrane, causing the protein to change shape
  • shape change is initial transduction of signal
36
Q

signal transduction

A

multi-step pathway that amplifies signals, relaying them from receptors to target molecules (proteins)
- a few molecules produce a large cellular response

  • receptor activates a protein, which activates another…until response activated
  • with each step, the signal is transduced into a different form, with shape change from a protein
37
Q

what are intracellular receptors, and which hormones typically use them?

A
  • found in cytosol or nucleus of target cells
  • activated by small, hydrophobic molecules like steroid and thyroid hormones
  • forms a hormone-receptor complex that can act as a transcription factor (turn genes on/off)
  • receptors revert back to inactive state when signal molecules leave
38
Q

regulation

A

one or more cell activities impacted

  • usually regulates synthesis of enzymes or other proteins by turning genes on/off (final activated molecule may be a transcription factor)
  • other pathways regulate the activity of enzymes (i.e. epinephrine turns on a protein that converts glycogen into glucose for quick energy)
39
Q

phosphorylation cascade

A

phosphate transferred between proteins, catalyzed by a kinase enzyme

40
Q

output response

A

cell’s response to an extracellular signal

41
Q

how does yeast use signal transduction pathways?

A
  • sometimes divides mitotically, producing differnet cell types
  • different cells recognize each other by lignins on membrane
  • binding of signal molecule to receptor causes schmoo (bud) formation
42
Q

what is apoptosis?

A

programmed/controlled cell suicide

  • requires both a “death signal” from an outside cell and a “death receptor”
  • happens when proteins that accelerate apoptosis override those that “put on the brakes”
  • cell is chopped and packaged into vesicles to be digested by a scavenger cell (so no death enzymes leak and damage neighboring cells)
43
Q

evolutionary significance of apoptosis

A
  • evolved early in animal evolution, important in shaping organisms in embryogeneis
44
Q

what can trigger apoptosis?

A
  • death-signaling ligand
  • DNA damage
  • protein misfolding in ER
45
Q

what diseases involve apoptosis?

A

Parkinson’s, Alzheimer’s, certain cancers

bio 102 (14 decks)

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