Quiz 3 Chap 5/6

Question 1

how is NADH significant in the electron transport chain?

Answer 1

• 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

Question 2

how does the ETC work

Answer 2

• 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

Question 3

significance of ETC being a series of small steps

Answer 3

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

Question 4

ETC structure

Answer 4

multi-protein complex in the cristae (inner membrane)

Question 5

chemiosmosis

Answer 5

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

Question 6

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

Answer 6

• 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

Question 7

significance of oxygen during ETC stage

Answer 7

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

Question 8

flow of energy during cellular respiration

Answer 8

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

Question 9

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

Answer 9

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

Question 10

evolutionary significance of glycolysis

Answer 10

• 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

Question 11

structure of the plasma membrane

Answer 11

• 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

Question 12

how does the plasma membrane change in response to temperature?

Answer 12

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

Question 13

importance of membrane fluidity, how they maintain it

Answer 13

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

Question 14

peripheral vs intergral proteins

Answer 14

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

Question 15

6 functions for membrane proteins

Answer 15

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

Question 16

how do cells recognize each other?

Answer 16

specific molecules on the plasma membrane (glycolipids and glycoproteins)

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

Question 17

which molecules pass/do not pass through plasma membrane?

Answer 17

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

Question 18

mechanisms and benefits of facilitated diffusion

Answer 18

*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

Question 19

diffusion

Answer 19

tendency for molecules to spread evenly in space without energy investment

Question 20

dynamic equilibrium

Answer 20

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

Question 21

osmosis

Answer 21

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

Question 22

tonicity

Answer 22

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

Question 23

types of tonicity in solutions

Answer 23

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

Question 24

what tonicity environment do plant and animal cells prefer?

Answer 24

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

Question 25

active transport and its importance

Answer 25

proteins move substances against conc. gradient, requiring ATP - allows cell to maintain conc. gradient different from surroundings (homeostasis) - sodium-potassium pump is one type

Question 26

signal transduction pathway

Answer 26

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)

Question 27

types of short-distance communication in animals

Answer 27

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

Question 28

how are hormones used in organisms?

Answer 28

*used for long-distance signaling, released by endocrine cells animals - travel through blood plants - often on exterior waxy coating

Question 29

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

Answer 29

plants - plasmodesmata | animals - gap junctions

Question 30

how do slime molds use short-distance signaling?

Answer 30

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

Question 31

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

Answer 31

- 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

Question 32

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

Answer 32

- 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

Question 33

what was Earl Sutherland's discovery about epinepherine?

Answer 33

- 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

Question 34

what are the 3 stages of cell signaling?

Answer 34

1. reception 2. signal transduction 3. regulation

Question 35

reception

Answer 35

- 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

Question 36

signal transduction

Answer 36

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

Question 37

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

Answer 37

- 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

Question 38

regulation

Answer 38

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)

Question 39

phosphorylation cascade

Answer 39

phosphate transferred between proteins, catalyzed by a kinase enzyme

Question 40

output response

Answer 40

cell's response to an extracellular signal

Question 41

how does yeast use signal transduction pathways?

Answer 41

- 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

Question 42

what is apoptosis?

Answer 42

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)

Question 43

evolutionary significance of apoptosis

Answer 43

- evolved early in animal evolution, important in shaping organisms in embryogeneis

Question 44

what can trigger apoptosis?

Answer 44

- death-signaling ligand - DNA damage - protein misfolding in ER

Question 45

what diseases involve apoptosis?

Answer 45

Parkinson's, Alzheimer's, certain cancers