Cell Biology And Metabolism Flashcards
1
Q
Can proteins and lipids move from one side of bilateral to the other?
A
No, proteins and the polar head groups of lipids do not pass readily through the hydrophobic interior of the bilayer
2
Q
What does the fluid mosaic model describe/propose?
A
- Describes the behaviour of molecules in cell membranes
- Proposes that the lipid bilayer is a fluid structure that allows molecules to move laterally within membrane and is a mosaic of two types of molecules -> lipids and proteins
3
Q
Who created fluid mosaic theory? When?
A
Biologists S. Jonathan Singer and Garth Nicolson in 1972
4
Q
Saturated vs. Unsaturated Fatty Acids? Examples?
A
Saturated (no double bonds) - less mobile within membrane, tend to be solid at room temp (butter, animal fats)
Unsaturated (double bond present) - mobile, liquid at room temp (plant and fish oils)
5
Q
2 ways proteins associate with membranes?
A
- Integral membrane proteins - permanently associated with membrane and cannot be removed w out destroying membrane itself -> span membrane, thus have both hydrophilic/phobic regions.
- Peripheral membrane proteins - temporarily associated w membrane and can easily be experimentally separated -> associated w either internal or external side of membrane
* mostly hydrophilic and interact w polar heads of lipid bilayer, or w hydrophilic regions of integral membrane proteins
6
Q
What maintains homeostasis? Why?
A
Plasma membrane - is selectively permeable
7
Q
Reasons why the plasma membrane selectively permeable? What can easily move across?
A
- The hydrophobic interior of lipid bilayer prevents ions and charged polar molecules from moving across it
- Many macromolecules such as proteins and polysaccharides are too large to cross plasma membrane on their own
- Gases like O2 and CO2, and non-polar molecules like lipids, can move across lipid bilayer
- Small, uncharged polar molecules like water, move can move through bilayer to a certain extent
8
Q
What particle is insignificant to be moving across membrane?
A
- small, uncharged particles like H2O
9
Q
What is used to facilitate movement of molecules?
A
Protein channels and transporters
10
Q
Simple vs. Facilitated diffusion + examples
A
Simple -
Ex: - O2 and CO2 diffuse freely b/c there are different [ ] in and out of the cell
- hydrophobic molecules like triacylglycerols diffuse b/c lipid bilayer is also hydrophobic
Facilitated -
Ex: -
11
Q
Define osmotic pressure
A
- Pressure/force needed to prevent H2O from moving from one sol’n into another by osmosis
- A way of describing tendency of a sol’n to “draw H2O in” by osmosis
12
Q
When does osmosis end?/How can it be prevented?
A
When there is no more [ ] gradient, or movement is opposed by another force (pressure due to gravity or cell wall -> for plants, fungi, and bacteria)
13
Q
Hypotonic sol’n animal cell vs. Hypotonic sol’n plant cell
A
Animal cell - H2O enters by osmosis and swells until it bursts
Plant cell - H2O enters by osmosis, increasing turgor pressure by cell wall to stop osmosis
14
Q
What organelle is responsible for plants wilting, and why plant cells are larger than animal cells
A
Vacuole - loss of H2O from vacuole reduces turgor pressure, so cells cannot maintain shape within cell wall
15
Q
Cell wall made of ______ in fungi
A
Chitin (polymer of sugar)
16
Q
Cell wall made of ______ in bacteria
A
Peptidoglycan (polymer of amino acids and sugar)
17
Q
Cell wall made of ______ in algae and plants
A
Cellulose (polymer of sugar)
18
Q
What 2 other substances found in other cell walls?
A
Silicon or calcium carbonate
19
Q
Do bacteria have internal membranes?
A
Not commonly, but photosynthetic bacteria have internal membranes that are specialized for harnessing light E
20
Q
What is an example of a chemical modification occurring within the Golgi body? What is the importance of this process?
A
Glycosylation - sugars are covalently linked to lipids or specific amino acids of proteins, forming glycoproteins
- as they move through the Golgi apparatus, they encounter different enzymes in each region that add or trim sugars
- the sugars attached to the protein can protect the protein from enzyme digestion by blocking access to peptide chain (glycoproteins form a coating over plasma membrane)
- the shapes of sugars allow glycoproteins and glycolipids to be recognized by other cells and molecules in external environment (blood types A, B, AB, O)
21
Q
Why do vesicles go in reverse, from Golgi body to ER in some cases?
A
To retrieve proteins in the ER or Golgi that were accidentally moved forward, and to recycle membrane components
22
Q
What is the optimal pH for activity of enzymes? What organelle delivers the specialized proteins that regulate pH?
A
pH of 5. Golgi sorts + delivers proton pumps to lysosomal membranes
23
Q
Where do breakdown products go after being degraded in the lysosome?
A
Proteins transport them across membrane to cytosol for use by cell (e.g. amino acids and sugars)
24
Q
pH of normal cellular environment? What cannot function here?
A
pH ~7. Lysosomal enzymes. If at 5 like lysosomes, the other enzymes and proteins (would unfold and degrade)
25
Where do transmembrane proteins go after signal-anchor sequencing?
Can stay in membrane of ER, or end up in other internal membranes or plasma membrane, where they serve as transporters, pumps, receptors, or enzymes
26
How does a protein end up 1) free in the cytosol, 2) embedded in the plasma membrane, or 3) secreted from the cell?
1) directed to final destination through particular amino acid sequences (called signal sequences)
- these proteins are sorted after being translated
2) proteins destined for nucleus, mitochondria, and chloroplasts have specific signal sequences (e.g. nuclear localization directs proteins to nucleus)
- proteins w no signal sequence remain in cytosol
- proteins produced by ribosomes on RER end up in lumen or embedded in membrane
3) sorted as they are translated by a ribosome in the cytosol, but a signal sequence in the growing protein directs ribosome to a channel on RER
- as the protein is translated, it is threaded through the channel
- thus, are destined for ER lumen, Golgi apparatus, lysosomes, or secreted out of cell
27
3 similarities between mitochondria and chloroplasts?
1. Involved in energy metabolism
2. Descendants of free-living bacteria
3. Surrounded by double membrane, and contain circular genomes
28
What is the result of phospholipids being composed of both hydrophobic and hydrophilic regions?
They spontaneously form structures such as micelles and bilayers when placed in aq environments
29
Membranes are ____. This means membrane components can move_____.
Fluid. Laterally in the plane of the membrane.
30
What is membrane fluidity influenced by?
Length of fatty acid chains, presence of C=C double bonds in fatty acid chains, and the amount of cholesterol
31
Transmembrane proteins
Span the membrane
32
Peripheral proteins
Temporarily associated with one or the other layer of lipid bilayer
33
Differences between Passive and Active transport?
Passive: movement of molecules by diffusion, random movement of molecules
- net movement of molecules from [high] -> [low]
- can occur by diffusion directly through plasma membrane (simple), or aided by protein transporters (facilitated)
Active: move molecules from regions of [low] -> [high], and requires E
- primary active uses E stored in ATP, secondary active uses E stored in an electrochemical gradient
34
Animals maintain (1)________ through the (2)_________. Plants, fungi, and bacteria use a (3)________, to maintain (4)___________?
(1) size and shape. (2) actions of protein pumps that actively move ions in and out of cell. (3) cell wall outside plasma membrane. (4) size and shape.
35
Eukaryotes include _______, _______, ______, and ______.
Plants, animals, fungi, and protists
36
Golgi apparatus communicates with ____ by _____. It receives proteins and lipids from the _____ and directs them to their ___________.
Endoplasmic Reticulum. Transport vesicles. ER. Final destinations.
37
Proteins made on free ribosomes vs. Proteins made on ribosomes on RER
Free: sorted after translation
- sorted by means of a signal sequence
- destined for cytosol, mitochondria, chloroplasts, or nucleus
RER: sorted during translation
- signal sequence recognized by a signal-recognition particle (SRP)
- these proteins end up as transmembrane proteins, reside in the interior of organelles, or are secreted
38
____ is the backbone of the ____ molecules that make up cells. These ___________ compounds are used as a stable form of E storage.
Carbon. Organic. Carbon-based.
39
What influences the direction of a rxn (fwd or reverse)?
The concentrations of reactants and products
- [high] reactant or [low] product favours fwd rxn, vice versa
40
What factors affect the free energy difference?
1. [ ] of reactants + products
2. pH of solution in which the rxn occurs
3. Temperature
4. Pressure
41
How does increasing temperature affect change in free energy (G) of a chemical reaction?
Increases value of TS, which decreases G, thus makes it more likely that a reaction will proceed without a net input of energy
42
How can glucose be readily broken down in cells?
Enzymes (chemical catalysts)
43
How do you reach the transition state in a reaction?
Reactant must absorb E from its surroundings (uphill portion of curve) ->
44
Activation energy (EA)
Energy input necessary to reach transition state
45
There is an ___ correlation between the ___ of a reaction and the ___ of the ___.
Inverse. Rate. Height. Energy barrier.
46
What is used to overcome the energy barrier of a reaction?
Heat (source of E)
47
How do enzymes accomplish their functions chemical reaction, unchanged?
By forming a complex with the reactants and products
48
2 types of inhibitors
1. Irreversible - form covalent bonds with enzymes and irreversibly inactivate them
2. Reversible - form weak bonds with enzymes and therefore easily dissociate from them
49
What is negative feedback? What is it used for?
- final product inhibits the first step
- stimulus acts on a sensor that communicates with an effector, producing a response that opposes initial stimulus
- used to maintain steady conditions (homeostasis)
50
Where are allosteric enzymes usually found?
- Near or at the start of a metabolic pathway
- Or at crossroads between two metabolic pathways
51
3 characteristics of enzymes, and how does each permit chemical reactions to occur in cells?
1. Enzymes reduce activation E of a rxn / E input necessary to reach transition state
- by stabilizing transition state and decreasing G (free E)
2. Enzymes are catalysts that participate in a chemical rxn, forming complexes with products and reactants, but not consumed in the process
- highly specific, they usually catalyze only 1 rxn, recognizing a specific substrate
3. Inhibitors and activators can influence enzyme activity
52
Which of the following do enzymes change? G, rxn rate, types of products, activation E, the laws of thermodynamics
Only increase rxn rate and decrease activation E
53
How does protein folding allow for enzyme specificity?
- enzyme will only act on those substrates that bind to its active site (converts substrate -> product)
- enzyme has to fold into its correct shape for the active site to be the right shape to bind its substrate
54
Direction of a chemical rxn is influenced by the ____ of ____ and ____.
[ ]. Reactants. Products.
55
What are the 3 thermodynamic parameters defining a chemical reaction?
Gibbs free E, (G), Enthalpy (H), Entropy (S)
56
Exergonic vs. Endergonic rxns?
Exergonic - spontaneous (-change in G) and release E
Endergonic - non spontaneous (+change in G) and require E
57
Steps for oxidative phosphorylation?
Passing e- along ETC to final e- acceptor O2, pumping p+ across membrane, and using p+ electrochemical gradient to drive synthesis of ATP
58
After oxygen receives the electrons in the ETC, what is the result?
Formation of H2O
59
When is the change in free energy (G) the greatest in cellular respiration?
The steps that generate reduced e- carriers instead of producing ATP directly
60
Where do cellular respiration rxns occur in bacteria? Where is the ETC located?
Cytoplasm for rxns, plasma membrane for ETC
61
Briefly explain the four major stages of cellular respiration
1. Glycolysis - glucose partially broken down and modest amt of E (in form of ATP and carriers) is released, producing pyruvate
2. Pyruvate Oxidation - pyruvate is converted to acetyl-coenzyme A, and CO2 + carriers produced
3. Citric Acid Cycle - acetyl-CoA broken down and CO2, ATP, and reduced e- carriers produced
4. Oxidative Phosphorylation - carriers from steps 1-3 donate their e- to ETC
- transfers e- along membrane proteins to final e- acceptor (O2), to make ATP
- O2 is consumed and H2O is produced
62
2 ways that ATP is produced in cell respiration?
1. Substrate-level phosphorylation - phosphorylated organic molecule directly transfers phosphate to ADP
- a little bit of ATP produced
2. Oxidative phosphorylation - ATP generated indirectly through reduction of carriers, transfer of e- from carriers to ETC, and synthesis of ATP from ADP + Pi
63
Which stage of cell respiration is anaerobic (does not use O2)
Glycolysis
64
Which molecules contain chemical E from the original glucose molecule, at the end of glycolysis?
Pyruvate, ATP, and NADH
65
What are the features of a cell?
- store and transmit info w DNA
- reproduce by copying DNA
- can exist as an independent life form
66
Steps of DNA -> Protein
DNA (transcription) -> RNA (translation) -> Protein
67
Proteins definition
- structural and functional molecules that do work of a cell, structure support, and catalyze chemical rxns
68
Central dogma
Idea that info flows from nucleic acids (RNA/DNA) to proteins
69
Gene
- unit of hereditary
- DNA sequence that affects 1 or more traits in an organism
- usually thru encoded protein or non coding RNA
70
What influences the ability of an organism’s DNA to be stably and reliably passed to offspring?
Double stranded helical structure
71
Risks of DNA replication?
Environment and mutations
72
Plasma membrane
- surrounds cytoplasm of cell, separating inside from out
- composed of lipids, proteins, and carbs
- fluid, not static
- carbs usually attached to glycolipids/glycoproteins
73
Nucleus
Stores DNA within chromosomes, enclosed by nuclear envelope
74
Nuclear envelope
Double layer that separates chromosomes from cytoplasm and other contents
75
Cytoplasm
Contents of cell other than nucleus
76
2 methods to gain E in organisms?
1. Sun 2. Chemical compounds
77
Metabolism
Chemical rxns by which cells convert E from environment into another to build / break down molecules
- releases stored E to make ATP
78
Viruses
Agents that infects cells
79
Why aren’t viruses the smallest units of life?
- cannot harness E from environment, thus cannot read + use genetic info or regulate passage of substances
- they use cells to replicate
80
3 domains of life + briefly explain
1. Bacteria - mostly single celled with circular chromosome but no nucleus
- divide by binary fission
- contain plasmids (small circular molecules or DNA that contain a few genes)
- commonly transferred between bacteria through pili -> a hollow, thread-like structure that connects bacteria to transfer plasmids by conjugation (genes for antibiotic resistance do this)
2. Archaea - flourish under extreme environments
3. Eukarya - cells have true nucleus + divide by mitosis
81
1) Prokaryotes vs. 2) Eukaryotes
Nucleus: 1) no, nucleoid instead. 2) Yes
Transcription location: 1) cytoplasm 2) nucleus
Translation location: 1) cytoplasm 2) cytoplasm
Cell membrane addition: 1) hopanoids 2) sterols (cholesterol)
Size: 1) small (1-2mm) 2) larger (10-20mm)
Ratio of surface area to volume: 1) high 2) low
Internal organization: 1) no organelles 2) contains organelles
82
What are prokaryotes composed of?
Ribosomes, nucleoid, capsule, flagellum, cell wall, cell membrane
83
Plasmodesmata
Channels that allow passage of large molecules like mRNA and proteins between neighbouring molecules
84
What are the mono and disaccharides?
Monosaccharides - galactose, fructose, mannose
Disaccharides - maltose, lactose, sucrose
85
Horizontal gene transfer
How cells interact w each other
86
Endomembrane system
- contains nuclear envelope, ER, Golgi apparatus, lysosomes, vesicles, and plasma membrane
87
Cell theory
- all organisms are made up of cells
- the cell is the fundamental unit of life
- cells come from pre-existing cells
88
Cytosol
- in plasma, membrane, but outside organelles
- jelly like envelope that surrounds organelles
89
Phospholipids
- major type of lipid in cell membrane
- made of glycerol, attached to phosphate head and 2 fatty acid tails (ampipathetic) -> hydrophobic and philic
90
3 structures phospholipids can make in aq environments? Explain
1. Micelle - sphere structure, head is large and bulky with 1 hydrophobic tail buried
- nonpolar tails interact w each other
- wedge shape
2. Bilayer - rectangular, effective membrane
- head is small, not bulky, with 2 hydrophobic tails
3. Liposome - when phospholipids spontaneously form these enclosed bilayers
- pH ensures heads are ionized (charged) form
- used to place molecules within it
91
Cholesterol
- component of animal cell membranes
- increases membrane fluidity at low temp, preventing them from tightly packing
92
Lipid raft
- lipids assembled in a defined patch in cell membrane
93
Lipid flip flop
- very rare spontaneous transfer of lipid between bilayers
- some component exchange occurs and thus the 2 layers differ in composition
94
How do we know proteins can move in membrane?
- with FRAP (fluorescence recovery after photobleaching)
95
4 functions of membrane proteins + explain
1. Transporters - move ions or molecules across membrane
2. Receptors - sometimes found in cytoplasm, receives signals from environment
3. Enzymes - catalyze chemical rxns
4. Anchors - attach to other proteins to maintain cell structure and shape
96
2 types of membrane proteins
1. Integral (transmembrane) proteins - permanently associated with cell membrane
2. Peripheral - temporarily associated with one of the lipid bilayers or with integral membrane proteins through weak non covalent interactions (H-bonding)
97
What are the 2 membrane transporters?
Channels and carriers
98
Which way does water move during osmosis?
[low] -> [high] because as [solute] increases, H2O decreases
99
Effects of osmosis
1. Hypertonic - [solute] high outside of cell, water leaves cell and shrinks
2. Isotonic - normal, cells maintain same conc. in and out
3. Hypotonic - [solute] high inside cell, swells
4. Very Hypotonic - lysed (RBC bursts and dies)
100
How is water absorbed in contractile vacuoles?
Through aquaporins, or first take in protons with proton pumps with water following by osmosis
101
Exocytosis vs endocytosis
Exo - vesicle budded off form endomembrane system
- can fuse with plasma membrane and deliver its contents into extra cellular space
Endo - material from outside cell brought into vesicle that can fuse with other organelles
102
A ___ ___ enables vesicles to ___ with their target membranes. ____ machinery senses ____ ____ and triggers vesicle ____.
Protein complex. Fuse. Molecular. Calcium ions (Ca2+). Fusion.
103
Cytoskeleton
Network of protein filaments and other associated proteins that provide structure internally for cells
104
Peroxisomes
Break down specific organic molecules (fatty acids) and synthesize other organic molecules (cholesterol, phospholipids, etc.)
105
Nuclear pores
Allow molecules to move in and out of cell
- essential for nucleus and cell communication
106
Proteins in ribosomes that are bound to RER vs. free living in cytosol
Bound to RER - sorted as they are translated
- molecule can go to lumen, embedded in membrane, or secreted out of cell
- only if amino-terminal signal sequence present
107
The 3 protein destinies for free ribosomes
1. No signal peptide - remains in cytosol
2. Amino-terminal signal (at ends) - to chloroplast or mitochondria
3. Internal signal (middle of protein) - to nucleus. Uses nuclear localization signal to move through nuclear pore
108
Nuclear localization signal
Allows proteins to move through nuclear pores
109
4 steps of entry into ER lumen?
1. Signal-recognition particle (SRP, RNA protein complex) binds to signal sequence in amino-terminal end and stops translation
2. SRP binds to SRP receptor on RER membrane
3. SRP receptor brings ribosome to transmembrane channel
- SRP dissociates, protein synthesis (translation) resumes, peptide threaded through channel
4. Protein ends up in lumen of ER, to stay, or be transported to lumen of another organelle, or be secreted out of cell
110
Signal anchor sequence properties
Hydrophobic and diffuses laterally in the lipid bilayer (proteins destined for membrane)
111
Lysosomes use ___ to degrade proteins, nucleic acids, lipids and carbs
Enzymes
112
What is the 3rd internal membrane in chloroplasts
Thylakoid membrane - contains light pigments, site of photosynthetic ETC
113
Major differences between animal and plant cells?
Plants have cell wall, vacuole, chloroplasts, autotroph
Animals have cholesterol, and heterotroph
114
Where does CO2 come from during respiration?
Pyruvate oxidation and citric acid cycle
115
How much ATP produced from anaerobic metabolism (fermentation)
2 ATP, no e- carriers
116
What 2 products can be produced by fermentation / what is the rxn?
Pyruvate -> ethanol or lactate
117
What are the benefits of fermentation?
1. Can provide quick burst of ATP (faster than aerobic respiration)
2. Higher efficiency in extreme environments (ocean sediments, little O2)
118
What is microsporidia?
Very small parasite fungus -> lives in cell of host (mitosome organelle
bc they do not have mitochondria)
119
What are hydeogenosomes? Where are they found? Size?
Double membrane H2 (instead of O2) producing mitochondrial homologs found in some anaerobic microbial eukaryotes (~0.5mm diameter)
120
Triaglycerols (lipids) are broken down into (1)_____ and (2)_____ . The (3)_____ are shortened by (4)____ that removes (5)____ from their ends to produce (6)____.
1. Glycerol
2. Fatty acids
3. Fatty acids
4. Beta oxidation
5. 2 carbon units
6. Acteyl-CoA
121
Fatty acids are a good source of ____, but cannot be used by ____ and _____ cells, because they cannot ____ ____ , only _____.
Energy. RBC. Brain. Burn fat. Sugars.
122
Palmitic Acid has _____ carbons, and produces _____ ATP.
16. 106.
123
High [ ] of (1)____ such as (2)____ and (3)_____ indicate a (4)____ E state in the cell, and (5)_____ the respiratory pathways.
1. Substrates
2. NAD+
3. ADP
4. Low
5. Stimulate
124
High [ ] of (1)____ such as (2)____ and (3)____ indicate a (4)____ E state in the cell and (5)_____ the respiratory pathways.
1. Products
2. ATP
3. NADH
4. High
5. Inhibit
125
Conversion of fructose 6-phosphate -> fructose 1,6-biphosphate is an ____ rxn, which is controlled and catalyzed by the enzyme ____.
Irreversible. PFK-1.
126
PFK-1
Allosteric enzyme (activators and inhibitors),
Catalyzes rxn 3 of glycolysis
127
[high] of ____ and ____ (allosteric controls) will ____ PFK-1 by ____ it, to start glycolysis.
ADP. AMP. Activate. Binding.
128
[high] of ____ and ____ (intermediate in citric acid cycle) bind to PFK-1 enzyme to ____ ATP production.
ATP. Citrate. Inhibit.
129
Aerobic vs. Anaerobic respiration differences
1. Products - 2ATP and lactic acid + ethanol produced in anaerobic, 32 ATP and H2O + O2 produced in aerobic
2. Energy
130
What are the 2 sources needed to make carbs in photosynthesis?
ATP and NADPH
131
Cellular respiration is an (1)_____ rxn, producing (2)____ and (3)_____ and releasing (4)____. Photosynthesis is an (5)_____ rxn, producing (6)_____ and (7)_____.
1. Exergonic (spontaneous -G)
2. Glucose + 6O2 -> 6CO2
3. + 6H2O
4. Energy
5. Endergonic (non-spontaneous +G)
6. 6CO2 + 6H2O -> glucose
7. + 6O2
132
What is the Calvin cycle, what are the 3 steps?
3 step process that uses CO2 to make carbs
1. Carboxylation - adding CO2 to 5C RuBP, catalyzed by enzyme rubisco
- 6C molecule formed then broken down into 2 3C molecules of 3PGA
2. Reduction - ATP and NADPH provide E to make 6 3C triose phosphate
- ATP phosphorylates 3PGA
- NADPH gives 2e- to 3PGA
- ONLY 1 triose obtained, 5 used in step 3
3. Regeneration of RuBP - 12/15 steps in Calvin cycle
5 (3C triose) —> 3 (5C RuBP)
- 3 ATP + 3NADH CONSUMED FOR EACH CO2 INCORPORATES BY RUBISCO
133
We can visibly see light from _____ to _____ nm of wavelength.
400 - 700.
134
Structure of chlorophyll
1. Light absorbing head (Mg at center)
2. Long hydrocarbon tail -> allows pigment to enter lipid membrane
135
____ in chlorophyll a. ____ in chlorophyll b.
CH3. CHO.
136
When e- absorbs light E and becomes excited, ____ and ____ are released when returning to ground state.
Heat. Fluorescent light.
137
Capturing sunlight into chemical forms
Light harvesting rxns use sunlight to make ATP and NADPH for the Calvin Cycle
138
Why almost all plants can do photosynthesis while others don’t?
Because they contain photosystems
139
Categorize the following by energy source and carbon source: cyanobacteria, plants, heliobacteria, hydrogen bacteria, most bacteria, most green nonsulfur bacteria, sulfur-oxidizing bacteria, animals
Photoautotrophs - cyanobacteria and plants
Photoheterotrophs - heliobacteria and most green nonsulfur bacteria
Chemoautotrophs - sulfur oxidizing bacteria and hydrogen bacteria
Chemohetertrophs - most bacteria and animals
140
What are the 3 components involved in transition of e- from photo systems?
1. PQ- Carrie’s e- from PSII to cyt
2. Cyt - allows e- to move across photo systems
3. PC - Carrie’s e- from Cyt to PSI
141
2 sources of proteins in photosynthesis?
1. Cyt b6f - protons go from stroma to lumen through this complex
2. H2O - protons produced through water oxidation
142
To increase ATP in photosynthesis, electrons are moved through _____ that increases ATP and decreases ____.
Ferredoxin. NADPH.
143
What are the 2 photosynthetic challenges?
1. Excess light E - (too much NADPH) high energy e- lose safe place to go, increasing ROS
2. Oxygenase activity of Rubsico - photorespiration occurs when rubisco adds O2 instead of CO2 to RuBP (bc rubisco can use both O2 and CO2 as substrates)
144
ROS. How can it be resolved?
Reactive Oxygen Species - when short supply of NADP+, light E or e- can be transferred to O2, making reactive ion that damages cells
- can be resolved with xanthophylls (yellow-orange pigments that slow formation of reactive O2 by releasing heat and slowing e- entering)
- antioxidants detoxify / reduce ROS into H2O, which is harmless to plants
145
How can photorespiration be avoided?
With an extra C4 cycle that increases CO2 before entering Calvin cycle, happens much faster than Calvin cycle
146
What are the 2 hypothesis for evolution of 2 photo systems? 2 steps of evolution of photosynthesis?
Hypothesis
1. Horizontal gene transfer (peer genes, not parents)
2. Duplication and divergence
2 steps: photosystems and endosymbiosis
147
What are the 3 ways to get genes from peers (HGT)?
1. Conjugation - DNA plasmid donated to recipient cell by a pilus connecting them (antibiotic resistance do this)
2. Transformation - dead cell DNA released to recipient cell
3. Transduction - DNA transferred by a virus
148
How do bacterial cells pick up DNA from environment?
Harpoon DNA
149
Can carotenoid genes be produced in animals?
No
150
What is the origin of carotenoid pigment genes?
Found in aphid genomes in fungi, suggests fungal origin
151
Can white plants perform photosynthesis, if not, what is their carbon source?
No, there is a lack of pigments, can steal from autotrophic/photosynthetic plants by using fungi as a bridge
152
Cell division and its requirements
A single parental cell splits into 2 daughter cells
1. 2 daughter cells must receive full genetic info from parent
2. Parent cell must be large enough to divide
153
Binary fission in eukaryotes (small, simple life forms do this)
1. Circular bacteria DNA attached by proteins to inner membrane
2. DNA replication begins in both directions
3. New DNA molecule attached by a protein as well
4. Cell elongates and separates DNA’s
5. Cell division begins and makes new membrane
6. When cell is 2x it’s size, constrictions occurs and separates daughter cells
154
Eukaryotes vs. Prokaryotes, genome features and DNA location
Eukaryotes - Genome large and linear, DNA in nucleus
Prokaryotes- Genome small and circular, DNA in cytoplasm
155
DNA is organized with ____ and other proteins into ____. This can then form _____.
Histones. Chromatin. Chromosomes.
156
Why do offspring of same parents share different genetic info?
Crossover and random orientation of homologous pairs
157
Nondisjuction
Error in meiosis, failure of chromosomes to split during anaphase of cell division
1st division - 2 gametes have none, 2 gametes have 2 each
2nd division - 2 have 1 each (normal) and 1 has 2, 1 has none
158
Trisomy 21
Down syndrome - caused by nondisjunction (3 chromosomes instead of 2 in 21)
159
True or false, nondisjuction is more common in fungi than humans
True
160
Cyclins
Control cell cycle by binding to kinases to prevent more cell division
- makes cyclin CDK complex, protein comes and degrades cyclin when cell division is needed
161
CDK
Cyclin-dependent kinases - enzymes activates by cyclin to promote cell division
162
Cyclin ___ in mitosis, ___ in interphase.
Increases. Decreases.
163
Cyclin A,B,D,E-CDK differences
A - S phase, initiates DNA synthesis by preventing reassembling of the same proteins
B - M phase, initiates breakdown of nuclear envelope during prophase in mitosis, and formation of mitotic spindles in mitosis
D and E - G1 in (D) and (E), S in (E)
- promote histone proteins to package DNA at the end of G1 (prepare cell for S phase -> DNA replication)
164
3 checkpoints for cell cycle
1. G1 - checks for DNA damage before entering S phase
2. End of G2 - checks for unreplicated DNA before mitosis
3. Spindle assembly - M phase, before anaphase, check if chromosomes attached to spindle
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P53
At DNA damage checkpoint, DNA damage activates protein kinases that phosphorylate p53. Increased p53 turns on CDK inhibitor to stop cell cycle, gives time to repair DNA
166
Proto-oncogenes vs. Oncogene vs. Tumor repressors
Proto-oncogenes: normal genes important in cell division, can become cancerous if mutated
Oncogene: altered version of proto-oncogene that is cancer-causing
Tumour repressors: encode proteins whose normal activities inhibit cell division (must be in agreement with proto-oncogenes)
167
Can viruses cause cancer?
Yes
168
Cancer causing pathogens
Helicobacter pylori (bacteria), HBV, HCV, HPV (viruses)
169
1st tumor repressor gene inactivated creates ____ cancer. 2nd creates _____ cancer. 3rd creates _____.
Benign. Malignant. Metastatic.
170
Fungus Cordycepin -> NUC-7738
NUC-7738 extreme case of symbiosis. Cordycepin inhibits DEK expression (In GI tumours) to make cancer cells die and increase APTOSIS (break down cancer)
171
CRISPR
Clustered Regularly Interspaced Short Palindromic Repeats - acts as scissors that cut precisely in genome
- normal T cell modified by CRISPR to attack cancer
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Cell cycle consists of ___ phase and ____.
M. Interphase.
173
Cell division steps (mitosis)
1. Prophase - chromosomes condense, centrsomomes radiate microtubules and migrate to opposite poles
2. Prometaphase - spindles attach to kinetic horse on chromosomes
3. Metaphase - chromosomes align in center of cell
4. Anaphase - sister chromatids after centromere splits separate and travel to opposite ends
5. Telophase and cytokinesis - nuclear envelope reforms, chromosomes condense, cytoplasm divides
174
Cell cycle steps
1. G0 phase - cells not dividing
2. G1 phase
3. S phase - DNA synthesis
4. G2 phase
5. M phase
(Interphase between G0 and G2)
175
What kind of proteins involved in cell cycle?
Cell-cycle proteins - kinases and cyclins
176
Fungi are autotrophic eukaryotes that feed by absorption and reproduce asexually. Yes or no?
No , they are heterotrophic and can produce both asexually and sexually and disperse by spores
177
Coenocytic
Hyphae have many nuclei but no cell wall to separate them (benefit)
178
Yeast
Single-celled fungi, divide by budding, common in plants
179
Fungi convert dead matter back into _____ and _____
CO2 and H2O
180
Cellulose, why can’t it be easily used?
Rich source of carbon and energy, molecules tightly packed together and lignin is hard to digest by enzymes because of its shape
181
How can cellulose be used?
1. Break apart
2. Group based on structure
3. Use enzymes to degrade them
182
Mycorrhizal fungi and the 2 types
Supply plant roots with nutrients like phosphorus from soil, and receive carbs from host (mutualistic)
1. Ecto - surround but do not penetrate cell
2. Endo - AM fungi penetrate root cell to form highly branched tissues (arbusucles)
This increases surface area to collect nutrients
183
Saprotrophic fungus
Grow out of debris, leaves, and trees
184
Endophytes
Fungi that live within leaves and grow within cell walls and in spaces between cells. Insects protect fungi, fungi gives them food
185
Lichens, how do they reproduce?
Symbiotes between fungi and photosynthetic organisms (green algae or cyanobacterium)
- produce asexually by fragmentation or formation of single cell dispersal units
186
Asexual vs. Sexual reproduction in fungi
Asexual - production of haploid spores by mitosis
Sexual - fusion of haploid cells tips to form diploid zygote with meoisis
- haploid nuclei retain independent identities, w diff nuclei in same cell (HETEROKARYOTIC STAGE)
- ends with nuclei fusion (karyogamy) which creates diploid zygote (spore)
187
Parasexual cycle of fungi
- crossing over of DNA during mitosis
*HAPLOID CHROMOSOMES RESTORED BY LOSS OF CHROMOSOMES, NOT MEOISIS CELL DIVISION*
1. Difference between this and sexual is that there is no meoisis
2. 2 hyphae cells become one with 2 nuclei (karyogamy)
3. Cross over with mitosis and lose excess chromosomes
188
Difference of fungal cells compared to plants and animals
1. Chitin - fungi contain chitin in cell wall bc no chloroplasts
2. Nutrition - osmotic feeding style
189
Separotrophic fungi, examples?
Not easy to observe (endophytes, aquatic fungi)
190
Conspicuous fungi, examples?
Easy to observe (mushrooms, plant-pathogenic fungi)
191
Chytrids
1000 species
- Opisthokonts broad group of fungi and animals (superclade)
- chytrids are decomposers, few are pathogens, found in most environments
- single cells with walls of chitin
- no hyphae or mycelium
- lack heterokaryotic stage but form flagellated gametes (aquatic)
- short, micronucleated structure
192
Zygomycetes
1000 species
- some decompose, and mycoparasites
- rhizopus digest C compounds
- grow mycelium and produce aerial spores
- pilobolus forms germination of haploid to make tall stalks (sporangiospore)
- thick wall (zygospore)
- HEAD THROWER FUNGUS
193
Glomeromycetes
200 species
- monophyletic, occur in associated with plant roots
- geocyphin
- parasexual, never sexual
- sense plant root growth, initiate mycelium growth
194
Dikarya
* EVERY MITOTIC DIVISION BRINGS A NEW SEPTUM *
- thus proliferate dikaryotic stage
- all edible mushrooms and yeast species and wood rotting fungi and pathogens of crops and humans
1. Ascomycetes - “sac” fungi bc nuclear fusion in meoisis elongates ASCUS
- moral is example, lichens, penicillin
2. Basidiomycetes - “club” fungi bc nuclear fusion in meoisis takes place in club-shaped cell called basidium
- shiitake mushrooms
195
Differences between ascomycetes and basidiomycetes
1. Septal pores
2. Reproduction - dikaryotic stage brief in asco, slow in basidio
196
Sexual cycle of ascomycetes
1. Plasmogamy
2. Karyogamy
3. Meiosis makes 4 haploid nuclei, and mitosis divides to make 8 spores
4. Dispersal and germination (to make a new mycelium)
197
Asci
Contain 8 haploid spores, eject them when mature
198
Ascomycetes ergot
Common pathogen of rye and grasses cause poisoning and symptoms
199
3 major groups of basidiomycetes
1. Smuts
2. Mushrooms
3. Rusts
200
Fruiting bodies of basidiomycetes
Stinkhorn, puffball, bracket fungi (polypore), can start as egg shell
201
Basidiomycete life cycle
Live by forming ectomycorrhizal associations or decomposing wood and other substrates
- fruiting body made entirely of dikaryotic hyphae (unlike asco)
- nuclear fusion in basidio (like Asci)
- haploids after meiosis do not do mitosis
202
Ug99
Basidiomycetes plant pathogen, defeats black stem rust of wheat
203
Why are some mushrooms toxic to human beings? Give an example
Toxins bind to RNA polymerase II and can travel to blood and reach organs (block transcription)
- amatoxins inhibit RNA polymerase
204
In the ETC, E from electrons is transformed into ___ before being used to make ATP.
A proton gradient
205
Most ATP produced during cellular respiration is through _____
Oxidative phosphorylation
206
Regeneration phase in Calvin makes ___ molecules RuBP from ___ molecules of triose phosphate
3. 5.
207
Highest DNA in each cell, lowest DNA in each cell in cell cycle?
Highest - S phase (DNA replication)
Lowest - M phase (mitosis splits DNA)
208
If DNA synthesis inhibitors were added, what stage would be affected in the cell cycle?
G1
209
Haploid or diploid: asexual fungi life cycle
Haploid
210
Haploid or diploid: mycelium
Haploid
211
Haploid or diploid: spores
Haploid
212
Haploid or diploid: zygotes
Diploid
213
Steps of photosynthesis in ETC
PSII -> PQ -> Cytb6f -> PC -> PSI -> Fd -> ATP Synthase
214
Stages of mitosis in order
Interphase - DNA copied and centrosomes replicated
Prophase - chromosomes condense, spindles form
Prometaphase - nuclear envelope breaks, microtubules attach to kinetochores
Metaphase - chromosomes go in the middle
Anaphase - chromosomes separate and move to opposite ends of pole
Telophase and Cytokinesis - cell elongates, cleavage of cell to make 2 cells, daughter nuclei form
215
DNA is packed around _____ proteins
Histone
216
Lysosomes maintain ____ [ ] of H+ with _____ _____ pump
High. ATP proton.
217
Order of chromosome building
Chromatin -> chromatid -> chromosome -> homologous chromosome
218
What does it mean when a cell is multinucleate?
No cytokinesis
219
In photosynthetic challenge 2, what is the input and output?
O2 input - rubisco functions as oxygenase
Carb output - fewer carbs exit as 3c molecules (1 3PGA and 1 2PGA made)
- 2PGA (2) makes (1) 3PGA
220
What is affected when assembly of microtubules is blocked?
Meta and prophase
