Test 2 Flashcards
(193 cards)
1
Q
Metabolism
A
Is the totality of an organism’s chemical reactions
2
Q
catabolic pathways
A
break down complex molecules into simpler compounds
release energy
3
Q
anabolic pathways
A
build complicated molecules from simpler ones
consume energy
4
Q
kinetic energy
A
associated with motion
5
Q
potential energy
A
stored in the location of the matter
includes chem energy stored in molecular structure
6
Q
thermodynamics
A
the study of energy transformations
7
Q
1st law of thermodynamics
A
Energy can be transferred and transformed but it cannot be created nor destroyed
8
Q
2nd Law of Thermodynamics
A
Spontaneous changes that do not require outside energy increase the entropy, or disorder, or the universe
9
Q
Biological order and disorder
A
living systems
- increase the entropy of the universe
- use energy to maintain order
10
Q
Free Energy Change
A
(Delta G)
Tells us whether the reaction occurs spontaneously
Directly related to the enthalpy change and the change in entropy (Delta G=Delta H-TDeltaS)
11
Q
Free energy- living system
A
The energy that can do work under cellular conditions
12
Q
Entropy
A
(Delta S)
Disorder of the system
13
Q
Enthalpy
A
(Delta H)
Heat of the reaction
14
Q
During a spontaneous change…
A
Free energy decreases and the stability increases
(Delta G
15
Q
During a non-spontaneous change…
A
Free energy has to be added and the stability decreases
Delta G>0
16
Q
Exergonic
A
Spontaneous
Net release of free energy
17
Q
Endergonic
A
Non-spontaneous
Net absorption of free energy
18
Q
3 kinds of work in a cell
A
Mechanical
Transport
Chemical
19
Q
Cellular work powered by?
A
Hydrolysis of ATP
20
Q
How is ATP used to store energy?
A
- Energy coupling is key
- ATP hydrolysis is exergonic
- Phosphate bonds in ATP are normal “high energy” bonds (difference is in free energies of compounds before and after ATP hydrolysis)
- Crowding of (-) charged phosphates contributes to “high energy” of ATP
21
Q
ATP
A
Adenosine triphosphate
-cells energy shuttle, provides energy for cellular functions
22
Q
When is energy released from ATP?
What’s produced?
A
When the terminal phosphate is broken
-Produces, inorganic phosphate, adenosine diphosphate(ADP) and energy
23
Q
ATP as “molecular spring”
A
Phosphate groups are negative and are repulsed by one another. It takes energy to bring the three phosphate groups together and like a compressed spring, that invested energy will be returned when it releases
24
Q
How does ATP perform work?
A
It drives endergonic reactions by phophorylation (transferring a phosphate to other molecules)
by causing conformational changes in molecules
by making unstable rxn intermediates that turn ender into exergonic
25
What is a catalyst?
a chemical agent that speeds up a reaction w/o being consumed by the reaction
26
What is an enzyme?
a catalytic protein
| -speeds up metabolic reactions by lowering energy barriers
27
Why do reactions need catalysts?
Every chemical reaction b/w molecules involves both bond breaking and bond forming
28
What is Activation Energy?
The initial amount of energy needed to start a chemical reaction
-often supplied in the form of heat from the surroundings in a system
29
What is a substrate?
The reactant an enzyme acts on
- The enyzme binds to its substrate, forming an enzyme-substrate complex
- substrate specificity of enzymes varies, they sometimes catalyze chemically similar reactions
30
Where do substrates bind?
The active site
31
What is induced fit of a substrate?
Brings the chemical groups of the active site into positions that enhance their ability to catalyze the chemical reaction
32
How can active sites lower the activation energy barrier?
- orienting substrates correctly
- straining substrate bonds
- providing a favorable microenvironment
- covalently bonding to the substrate
33
Local conditions of enzyme activity?
Each enzyme has an optimal temp, pH in which it can function
34
What are cofactors?
Non protein enzyme helpers
35
What are coenzymes?
Organic cofactors
36
What are enzyme inhibitors?
Competitive inhibitors- bind to the active site of an enzyme, competing w/ the substrate
Noncompetitive inhibitors- bind to another part o the enzyme, changing the function
37
What is allosteric regulation?
The term used to describe any case in which a protein's function at one site is affected by binding of a regulatory molecule at another site
38
What is cooperativity?
a form of allosteric regulation that can amplify enzyme activity
39
Where are enzymes in the cell?
- grouped into complexes
- incorporated into membranes
- contained inside organelles
40
How do catabolic pathways yield energy?
- by oxidizing organic fuels
| - due to transfer of electrons
41
Is the breakdown of organic molecules exergonic or endergonic?
exergonic
42
What is fermentation?
A catabolic process- a partial degradation of sugars that occurs w/o oxygen
43
What is cellular respiration?
The most prevalent and efficient catabolic pathway
- consumes oxygen and organic molecules such as glucose
- yields to ATP
- to keep working, cells must regenerate ATP
44
Redox reactions
-transfer electrons from one reactant to another by oxidation and reduction
45
Oxidation
A substance loses electrons (is oxidized)
46
Reduction
A substance gains electrons (is reduced)
47
Oxidation of organic molecules during cellular respiration
- Glucose is oxidized and oxygen is reduced
| - Happens in a series of steps involving NAD+ and the e- transport chain
48
What is NAD+?
A coenzyme
| -electrons from organic compounds are usually transferred to NAD+ first
49
What is NADH?
The reduced form of NAD+
| -passes the electrons to the electron transport chain
50
Why do electron transfer reactions occur in small steps?
-if not stepwise a large release of energy occurs (probs explosion)
51
What does the electron transport chain do?
Passes electrons in a series of steps instead of in one explosive reaction
-uses the energy from the electron transfer to form ATP
52
What are the stages of cellular respiration?
Glycolysis
The citric acid cycle
Oxidative phosphorylation
53
What does glycolysis do?
Harvests energy by oxidizing (breaking down) glucose into two molecules of pyruvate
- Means "splitting sugar"
- Occurs in the cytoplasm of the cell
54
What does the citric acid cycle do?
Completes the energy-yielding oxidation (breakdown) of organic molecules (glucose)
-takes place in the matrix of the mitochondrion
55
What does oxidative phosphorylation do?
Generates ATP
| -is driven by the electron transport chain
56
How do gylcolysis and the citric acid cylce generate ATP?
Substrate-level phosphorylation
57
Two main phases or gylcolysis?
Energy investment phase
| Energy payoff phase
58
Enzymes in energy investment phase of glycolysis?
```
Hexokinase
Phosphoglucoisomerase
Phosphofructokinase
Aldolase
Isomerase
```
59
Ensymes in the energy payoff phase of glycolysis?
```
Triose phosphate dehydrogenase
Phosphoglycerokinase
Phosphoglyceromutase
Enolase
Pyruvate kinase
```
60
How many ATP are invested verses produced in glycolysis?
2 ATP invested, 4 gained
| Net=2
61
Before the citric acid cycle can begin what must occur?
Pyruvate must be converted to acetyl CoA, which links the cycle to glycolysis
62
Ribosomes
Complexes that synthesis proteins
Made of ribosomal DNA
decipher codons and interpret info in DNA
63
Cytosol
Semi-fluid, jellylike substance in all cells
64
Golgi apparatus
- Organelle active in synthesis, modification, sorting and secretion of cell products
- Warehouse for receiving, sorting, shipping some manufacturing
- receives many of the transport vesicles produced in rough ER
- consists of flattened membranous sacs called cisternae
- trans side: shipping
- cis side: receiving
65
Lysosome
membranous sac of hydrolytic enzymes
| -can digest all kinds of macromolecules
66
Chloroplast
Photosynthetic organelle, converts energy of sunlight to chemical energy stored in sugar molecules
67
Endomembrane system
Nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vesicles and vacuoles, plasma membrane
Synthesizes proteins, transports proteins into membranes of organelles or out of cell, metabolism and movement of lipids, detox of poisons
68
Endoplasmic reticulum
Network of membranous tubules and sacs called cisternae
| accounts for more than half the total membrane in many eukaryotic cells (continuous w/ nuclear envelope)
69
Phagocytosis
Lysosome digesting food (intracellular)
70
Autophagy
Lysosome breaking down damaged organelles
71
Mitochondrion
Organelle where cellular respiration occurs and most ATP is generated
-found in nearly all eukaryotic cells
72
Citric Acid Cycle
1. Acetyl group added to oxaloacetate and CoA is regererated
2. Isomerization (water, no energy required)
3. Citrate loses CO2, NAD+ is reduced to NADH
4. Substrate-level phosphoyrlation makes GTP, and converts it to ATP
5. Last two H transfered to FADH2 (More EN than NADH)
6. Substrates are rearranged and oxidized, another NADH is made and oxaloacetate is regenerated
73
Oxidative phosphorylation
Chemiosmosis couples electron transport to ATP synthesis
74
NADH oxidation
Exergonic (-53kcal/mol)
| -energy released in small steps as opposed to one inefficient burst
75
Role of NADH and FADH2 in electron transport chain
both donate electrons to the electron transport chain, which powers ATP synthesis via oxidative phosphorylation
-electrons from both lose energy in several steps
76
What happens at the end of the electron transport chain?
e- are passed to oxygen, forming water
77
ATP synthase
the enzyme that actually makes ATP
78
ATP synthase and e- transport chain
At certain steps in the chain:
- exergonic transfer of e- causes protein complexes to pump H+ from mitochondria to intermembrane space
- H+ wants to move back to mitochondria, and ATP synthase complexes are the only sites on the membrane to allow that
- This H+ gradient stores energy, drives chemiosmosis, is proton motive force
79
Chemiosmosis
an energy-coupling mechanism that uses energy in the form of a H+ gradient across a membrane to drive cellular work
80
How much H+ and ATP does NADH pump?
10 H+
| 3 ATPs
81
How much H+ and ATP does FADH2?
6 H+
| 2 ATPs
82
What percentage of energy in a glucose molecule is transferred to ATP during cellular respiration?
40%
-686 kcal/mol (energy in glucose molecule)
total 36-38 ATPs produced
83
Fermentation vs. respiration
- Glycolysis can produce ATP w/ or w/o O2
- No oxygen- cells still produce ATP through fermentation; NAD+ must be regenerated or glycolysis will shut down
- Oxygen- cellular respiration produces ATP
84
Fermentation consists of
Glycolysis plus reactions that regenerate NAD+, which can be reused by glycolysis
85
Types of fermentation
Alcohol
| Lactic acid
86
Alcohol fermentation
Pyruvate is converted to ethanol in two steps, one of which releases CO2
Baking and brewing (CO2 rises dough)
87
Lactic acid fermentation
Pyruvate is reduced directly to NADH to form lactate as a waste product
(dairy industry, muscles)
88
Does fermentation or cellular respiration produce more ATP?
respiration
89
When did gylcolysis evolve?
In ancient prokarylotes (3.5 billion years ago) before there was O2 (2.7 billion years ago)
-important for energy production even when oxygen supply is scarce
90
Light microscopes
LMs
pass visible light through a specimen
magnify cellular structures with lenses
91
Scanning electron microscopes
SEM
focus a beam of electrons onto a specimen surface
-provides for a detailed study of the surface of a specimen
92
Transmission electron microscopes
TEM
focus a beam of electrons through a specimen
-provides for detailed study of the internal ultrastructure of cells
93
Cell fractionation
Tissue Cells
Homogenate
Pellet rich in nuclei and cellular debris
Pellet rich in mitochondria (and chloroplasts if plant)
Pellet rich in "microsomes" (pieces of plasma membranes and cells' internal membranes)
Pellet rich in ribosomes
94
All cells have...
```
semifluid substance called cytosol
chromosomes
ribosomes
DNA
bound by plasma membrane
```
95
Prokayotic cells -DNA
no nucleus
| DNA located in region-nulceoid
96
Eukaryotic cells-DNA
true nucleus, bounded by a membranous nuclear envelope
| generally bigger than prokaryotic cells
97
Size of cells
A smaller cell has a higher surface area to volume ratio, which facilitates the exchange of materials in and out of the cell
98
Smooth ER
lacks ribosomes
- synthesizes lipids
- metabolizes carbs
- stores calcium
- detoxifies poision
99
Rough ER
has bound ribosomes
| -produces proteins and membranes, which are distributed by transport vesicles
100
Vacuoles
diverse maintenance compartments
| -a plant of fungal cell may have one or several
101
types of vacuoles
food
contractile
central
102
food vacuoles
formed by phagocytosis
103
contractile vacuoles
pump excess water out of protist cells
104
central vacuoles
found in plant cells
| -hold reserves of important organic compounds and water
105
Chloroplasts
- found only in plants, leaves and other green organs and algae!
- site of photosynthesis
- contain chlorophyll
- specialized member of family closely related to plant organelles called plastids
106
Two mitochondria membranes
smooth outer
| inner folded into cristae
107
Chloroplast structure includes
- Thylakoids, membranous sacs
| - Stroma, the internal fluid
108
Peroxisomes
produce hydrogen peroxide and convert it to water
109
Cytoskeleton
network of fibers (extending throughout the cytoplasm) that organizes structures and activities in the cell and gives mechanical support to the cell
110
Three fibers of cytoskeleton
Microtubules
Microfilaments
Intemediate Filaments
111
Microtubules
```
(Tubulin Polymers)
Hollow tubes
Tubulin
-Maintenence of cell shape
-Cell motility
-Chromosome movement in cell division
-organelle movements
```
112
Microfilaments
```
(Actin Filaments)
Two intertwined strands
Actin
-Maintenence of cell shape
-Changes in cell shape
-Muscle contraction
-Cytoplasmic streaming
-Cell motility
-Cell division
```
113
Intermediate Filaments
Fibrous proteins supercelled into thicker cells
One of several different proteins of the keratin family
-Maintenance of cell shape
-Anchorage of nucleus and certain other organelles
-formation of nuclear lamina
114
Centrosome
- a "microtubule-organizing center"
| - contains a pair of centrioles
115
Cilia and flagella
- contain specialized arrangements of microtubules
- are locomotor appendages to some cells
- share common ultrastructure
116
dynein
protein responsible for the bending movement of cilia and flagella
117
Where are microfilaments found?
microvilli
118
Myosin
protein in microfilaments that function in cellular motility (in addition to actin)
119
cellular membranes
are fluid mosaics of lipids and proteins
120
phospholipids
- the most abundant lipid in plasma membrane
| - amphipathic, contain both hydrophobic and hydrophilic regions
121
Davson-Danielli sandwich model
membrane made up of a phospholipid bilayer sandwiched between two protein layers
supported by electron microscope pics
122
Singer and Nelson model
proposed that membrane proteins are dispersed and individually inserted into phospholipid bilayer
123
Freeze-Fracture
-supported fluid mosaic model of membrane structure
124
Lateral movement w/in bilayer
10^7 times per second
125
Flip flop movement w/in bilayer
once a month
126
protein movement w/in plasma membrane
can drift w/in the bilayer
127
fluid vs. viscous
unsaturated hydrocarbon tails with kinks vs. saturated hydrocarbon tails
128
Cholesterol and membrane fluiditity
The steroid cholesterol has different effects on membrane fluidity at different temperature; helps retain the fluidity at low temps
129
Integral proteins
- penetrate the hydrophobic core of the lipid bilayer
- are often transmembrane proteins, completely spanning the membrane
- "inside out proteins"
130
Peripheral proteins
-appendages loosely bound to the surface of the membrane
131
Six major functions of membrane proteins
```
Transport
Enzymatic activity
Signal transduction
Cell-cell recognition
Intercellular joining
Attachment to the cytoskeleton and extracelluar matrix (ECM)
```
132
Cell-cell recognition
- a cells ability to distinguish one type of neighboring cell from another
- membrane carbs interact w/ the surface molecules of other cells, facilitating cell-cell recognition
133
Crossing the lipid bilayer
- hydrophobic molecules: lipid soluble and can pass through the membrane rapidly
- polar molecules do not cross rapidly
- transport proteins allow passage of hydrophilic substances
134
Diffusion
passive transport
| -the tendency for molecules of any substance to spread out evenly in available space
135
Osmosis
the movement of water across a semipermeable membrane; it is affected by the concentration gradient of dissolved substances
136
Tonicity
- the ability of a solution to cause a cell to gain or lose water
- great impact on cells w/o walls
- governed by differences in solute concentrations in vs. out of cell
137
Isotonic solution
Concentration of solutes is the same as it is inside the cell
No net movement of water
138
Hypertonic solution
The concentration of solutes is greater than it is inside the cell
The cell will lose water
139
Hypotonic solution
The concentration of solutes is less that it is inside of the cell
The cell will gain water
140
Turgid
(plant cell)
It is in a hypotonic environment
Firm healthy state
141
Flaccid
(plant cell)
| In an isotonic environment
142
Plasmolyzed
(plant cell)
| In a hypertonic environment, insides shrink
143
Lysed
Animal cell in a hypotonic solution (could burst)
144
Shriveled
Animal cell in hypertonic solution
145
Facilitated diffusion
Transport proteins speed the movement of molecules across the plasma membrane
channel and carrier proteins
146
Channel proteins
Provide corridors that allow a specific molecule or ion to cross the membrane
147
Carrier proteins
Undergo a subtle change in shape that translocates the solute-binding site across the membrane
148
Active transport
uses energy (ATP) to move substances against their concentration gradient
149
Sodium Potassium Pump
A type of active transport system
150
Membrane potential
the voltage difference across a membrane
151
Electrochemical gradient
caused by the concentration electrial gradient of ions across a membrane
152
Electrogenic pump
a transport protein that generates the voltage across a membrane
153
Cotransport
occurs when active transport of a specific solute indirectly drives the active transport of another solute (active transport driven by a concentration gradient)
154
Exocytosis
(Bulk transport of large proteins)
| Transport vesicles migrate to the plasma membrane, fuse with it, and release their contents
155
Endocytosis
(Bulk transport of large proteins)
| The cell takes in macromolecules by forming new vesicles from the plasma membrane
156
Types of endocytosis
Phagocytosis
Pinocytosis
Receptor-mediated endocytosis
157
Signal transduction pathways
convert signals on a cell's surface into cellular responses
| -are similar in microbes and mammals, suggesting early origin
158
Plasmodesmata
junctions between plant cells that connect the cytoplasm of adjacent cells
159
Gap junctions
junctions between animal cells that connect the cytoplasm of adjacent cells
160
Local signaling
- animals cells may communicate via direct contact
- May use local regulators
* Paracrine signaling: local regulator diffuses through extracellular fluid
* Synaptic signaling: Nerve cell releases neurotransmitter which diffuses across synapse
161
Long distance singaling
-Both plants and animals use hormones
162
Cell signaling process (3 steps)
Reception
Transduction
Response
163
Reception (cell signaling)
A signal molecule (ligand) binds to a receptor protein (highly specific) causing it to change shape
164
Intracellular receptors
- cytoplasmic or nuclear proteins
- small hydrophobic signal molecules use these receptors and can readily cross the membrane
- only works if both ligands and receptors are present
165
Steroid hormones
- bind to intracellular receptors
| - receptors are transcription factors
166
Receptors in the plasma membrane
G-protein-coupled receptors
Tyrosine kinases
ion channel receptors
167
Transduction (cell signaling)
Cascades of molecular interactions relay signals from receptors to target molecules in the cell
-at each step, the signal is transducted to a diffrent form, commonly a conformational change in a protein
168
Protein phosphorylation and dephosphorylation
- A series of protein kinases add a phosphate to the next one in line, activating it
- Phosphatase enzymes then remove the phosphates
169
Second messengers
(ligands are "first")
are small, nonprotein, water-soluble molecules or ions
cyclic AMP (cAMP): made from ATP
170
G-proteins
trigger the formation of cAMP, which then acts as a second messenger
171
calcium ions
when released into the cytosol of a cell act as a second messenger in many different pathways
172
inositol triphosphate
| diacylglycerol
second messenger that can trigger and increase in calcium in the cytosol (IP3)
173
Nuclear response
other pathways regulate genes by activating transcription factors that turn genes on or off
174
Pathway branching
"cross-talk"
| helps the cell coordinate incoming signals
175
Scaffolding proteins
inrease the signal transduction efficiency
| stack of protein kinases
176
Phosphofructokinase is an allosteric enzyme that catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate, an early step of glycolysis. In the presence of oxygen, an increase in the amount ATP in a cell would be expected to
inhibit the enzyme and thus slow the rates of glycolysis and the citric acid cycle
177
Which of the following statements is true concerning catabolic pathways
They are usually coupled with anabolic pathways to which they supply energy in the form of ATP
178
If an enzyme is added to a solution where its substrates and products are in equilibrium, what would occur?
Nothing; the reaction would stay at equilibrium. Would speed up in both directions
179
Of the following, which is probably the most common route for membrane flow in the endomembrane system?
rough ER → vesicles → Golgi → plasma membrane
180
an animal cell that lacks the ability to produce GTP
It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane
181
Does a nucleolus contain functional ribosomes?
No
182
Does a chloroplast contain functional ribosomes?
Yes
183
What is most important for the glycoproteins and glycolipids of animal cell membranes?
cell-cell recognitions
184
organelles other than nucleus that contain dna
mitochondria and chloroplasts (cellular respiration and photosynthesis)
185
Paracrine signaling
involves secreting cells acting on nearby target cells by discharging a local regulator into the extracellular fluid
186
Primary role of oxygen in cellular respiration
act as an acceptor for electrons and hydrogen, forming water
187
Molecules that can potentially be converted to intermediates of glycolysis and/or the citric acid cycle include
```
amino acids
proteins
gylcerol and fatty acids
glucose and sucrose
starch and glycogen
```
188
Carbon dioxide (CO2) is released during which of the following stages of cellular respiration
Oxidation of pyruvate to aetyl CoA and the citric acid cycle
189
Membrane receptors that attach phosphates to specific animo acids in proteins are
called receptor tyrosine-kinases
190
Second messengers
cAMP
calcium ions
DAG
IP3
191
Adenylyl cyclase has the opposite effect of?
phosphodiesterase
192
The activation of receptor tyrosine kinases is always characterized b
dimerization and phosphoylation
193
An inhibitor of phosphodiesterase activity would have which of the following effects
prolong the effect of epinephrine by maintaining elevated cAMP levels in the cytoplasm
