Cell Bio Exam 2
connexon
- clustered in membrane to form multisubunit complex called
Cell wall structure
-Plant cell skeleton -Cellulose hemicellulose -Pectin -Microfibrils
IF architecture
1. Each monomer has a pair of globular terminal domians separated by logn alpha-helical region 2. Pairs of monomers are associated in parallel orientation to form dimers 3. Dimers associate in an anti-parallel staggered fashion to form tetramers- basic subunit in IF assembly 4. 8 tetramers associate to form unit length of IF 5. Elongated IFs are formed from the end-to-end association of these unit lengths
Glycolysis steps
1. Glucose is phosphorylated twice to form fructose 1-6, bisphosphate. 2. 6 Carbon bisphosphate is broken down into 2, 3-Carbon monophosphates. 3. The 3-Carbon aldehyde is oxidized to form an acid as the electrons removed from the substrate are used to reduce the coenzyme NAD+ to NADH. C1 acid is phosphorylated to form acyl phosphate, which has a high phosphate-group transfer level. 4. The C1 phosphate group is transferred to ADP forming ATP by substrate-level phosphorylation. 2 ATPs are formed per glucose oxidized. 4. This results in rearrangement and dehydration of the substrate to form enol phosphate at the C2 position that has high phosphate group-transfer potential. 5. Phosphate group is transferred to ADP forming ATP by substrate-level phosphorylation, generating a ketone at the C2 position. Two ATPs are formed per glucose oxidized.
What is the net yield of glycolysis?
2 ATP, 2 NADH, 2 pyruvate
What does the calvin cycle consume?
2 Molecules of NADPH & 3 molecules of ATP for every molecule of CO2 fixed
What happens to NADH and FADH2?
2 pyruvate molecules are formed per glucose that enters glycolysis. Complete oxidation of pyruvate in Krebs cycle produces 10 NADH, 2 FADH2, 4 ATP molecules. NADH and FADH2 are used to make more ATP
Dimer of IF
2 strands of NH2 and COOH together
What is the maximal net gain of ATP in glycolysis?
36, including GTP made by each round of TCA cycle
Actin
3rd major type of cytoskeletal element that is involved in intracellular motile processes Organized into ordered arrays, highly branched networks, and tightly anchored bundles
What does the complete oxidation of one pyruvate molecule produce?
4 NADH (one from the CoA rxn, 3 from Krebs Cycle) 1 FADH2 1 GTP- easily converted to ATP
Tetramer of IF
4 strands of monomers consisting of NH2 and COOH on the same side, offset to one another
What is the Krebs Cycle?
8 small carboxylic acids involved in redox reactions that produce CO2.
C4 Plants
A plant that prefaces the Calvin cycle with reactions that incorporate CO2 into four-carbon compounds, the end product of which supplies CO2 for the Calvin cycle.
C3 Plants
A plant that uses the Calvin cycle for the initial steps that incorporate CO2 into organic material, forming a three-carbon compound as the first stable intermediate.
What is photosynthesis?
A redox reaction (reduction/oxidation) transferring an electron from water to CO2 6 CO2 + 12 H20 = Sugar + 6 H20 + 6 02
oxidative phosphorylation in the mitochondria
ATP formation driven by energy released from electrons removed during substrate oxidation used to form ion gradient across inner mitochondrial membrane
What is one method of producing ATP?
ATP synthase using proton gradient produced by ETC to power ATP production by oxidative phosphorylation, which is linked to the oxidation of NADH and FADH2
Carotenoids
Absorb light in the blue-green region of the spectrum
How do you rank oxidizing agents?
According to electron affinity: greater electron affinity - stronger oxidizing agent
Overall reaction of TCA cycle
Acetyl CoA + 2 H2O + FAD + 3 NAD+ GDP + Pi —> 3 CO2 + FADH2 + 3 NADH + 3 H+ GTP + HS—CoA
How are actin subunits added?
Actin subunits are added to the plus end and removed from the minus end in a steady state.
Carboxylation
Adds carboxyl group to the Ribo 1-5 bisphosphate to create unstable, transient 2-carboxy-3-ketoarabinitol-1,5-bisphosphate
What are the two types of adhesive junctions?
Adherens junctions and desmosomes.
Constitutive Secretion
Always happening, materials are transported in secretory vesicles and discharged in a continual manner.
Disease associated with high level of Microtubule-Associated proteins
Alzheimer's disease: High level of phosphorylation of one particular MAP, calle tau, has been implicated in Alzheimer's disesase
Where can proteins that are broken down into amino acids go?
Amino groups are removed and excreted, and carbon compounds remain and can be converted to pyruvate, acetyl coA, and other intermediates of Glycolysis or TCA.
What are gap junctions made of?
An integral membrane protein called connexin
Microfilament assemble and disassembly
Assembly and disassembly in vitro depends on concentration of actin monomers
Why is glucose a key intermediary in cell metabolism?
Because cells uses glucose to build fats, carbs, and other compounds.
Why do thylakoid membranes contain a large percentage of glycolipids?
Because glycolipids make the membrane highly fluid for diffusion of protein complexes
Why is oxygen the best electron acceptor?
Because of its low potential energy in its electrons.
Why is glycolysis more efficient than fermentation?
Because the electron acceptors in fermentation are much more reduced than oxygen. Only 2 ATP molecules are produced per glucose molecule, as compared to 30 ATP molecules per glucose molecule in aerobic respiration.
Why does the number of ATP produced vary?
Because the number of ATP produced depends on [ATP]/[ADP] ratio & actual cell activities at time
D1 and D2
Bind the P680 chlorophyll and perform reactions to oxidize H2O
What does D1 and D2 do in PSII?
Bind the p680 chlorophyll and perform reactions to oxidize H2O
Examples of TJs
Bladder wall, brain capillaries, skin - to protect us from continual water loss.
Photosystem II
Boosts electrons from below energy level of water to a midpoint
Photosystem I
Boosts electrons to a level above NADP+
How does actin form Actin filaments?
By ATP polymerization of Actin
Where is light harvested?
By a pigment protein called Light Harvesting Complex II
How do the flow of electrons from water pass to the PSII?
By a redox potential of p680+ pulling electrons through water known as photolysis
How do microfilament cytoskeletons control equilibrium?
By assembly and disassembly of microfilaments
How do cells recover glucose?
By breaking down molecules such as fats, carbohydrates, and other compounds
How do MFs seal wounds?
By broad projections of epithelial cells that pull the cell sheet over the damaged area
How does fermentation allow glycolysis to continue?
By converting NADH back to NAD+. NAD+ is necessary in glycolysis.
How is the proton motive force created?
By the ETC pumping protons from the matrix to the intermembrane space.
How does PSII obtain electrons
By using absorbed light energy to split water and remove electrons and generate a proton gradient.
What are the 3 important stages of the Calvin Cycle
Carboxylation Reduction Regeneration
Vesicular transport model
Cargo is shuttled from the Cis golgi network to the Trans golgi network in vesicles
What do NADH and FADH do?
Carry high potential electrons to participate in a series of redox reactions
Carbohydrate synthesis in CAM plants
Carry out light reactions and CO2 fixation at different times of the day using the PEP carboxylase enzyme. Plants keep stomata closed during the day to reduce water loss.
What does pyruvate dehydrogenase do?
Catalyze the reaction between pyruvate and CoA that results in reduction of NAD+ and oxidation of CO2
Glycocalyx
Cell coat Mediates cell-cell and cell-substratum interactions; mechanical protection for cells; barrier to particles moving toward plasma membrane Are short sugar chains that project outward from virtually all integral proteins & some lipids in plasma membrane
What does phosphorylation do to the shape of proteins
Change of shape
Where does photosynthesis in eukaryote take place?
Chloroplast
Basal bodies
Cilium or Flagellum originate from other Microtubules in a structure Identical in structure to centrioles Can turn into centrioles and vice versa
Faces of golgi complex
Cis face of the Golgi faces the ER Trans face of the golgi faces the ECM
Current model
Cis maturation model with vesicle retrograde transport. Golgi cisternae serves as a primary anterograde carrier
Cisternal maturation model
Cistern matures as it moves from the cis face to the trans face
What is the first and last molecule in the TCA cycle formed from the glycolysis of pyruvate?
Citrate and oxaloacetate
Adherens junctions
Common in epithelia, like the lining of the intestine
Fibronectin
Connect cells to matrices that contain fibrillar collagen -Consists of linear array of distinct building blocks; human fibronectin molecules consists of 2 similar polypeptides joined by a pair of disulfide bonds located near the C-termini. -Important when tissues are involved in embryonic development; guides migrating cells during embryogenesis
Laminin
Consists of 3 different polypeptide chains linked by disulfide bonds organized into a cross with 3 short arms and 1 long arm -greatly influences cell's potential for migration, growth and differentiation -Guides embryonic axon tips as they grow outward from CNS to distant targets
Conjugated system
Consists of alternating single and double bonds along the porphyrin ring from a cloud. Conjugated bond systems absorb energy of a range of wavelengths
basement membrane (basal lamina)
Continuous sheet that underlies epithelial tissue and surrounds blood vessels -Helps maintain cell attachment -Serves as substratum for cell migration -Forms a barrier to macromolecules
What are the 2 groups of myosin?
Conventiontional (Type II) and Unconventional
Cyclic vs noncyclic photophosphorylation
Cyclic phosphorylation is carried out by PSI independently of PSII. Cyclic photophosphorylation is thought to provide additional ATP required for carbohydrate synthesis. Noncyclic: Movement of electrons during the formation of oxygen because ions move in a linear path.
Requires a dynactin adaptor to interact with membrane-bounded cargo
Cytoplasmic Dynien
What are the unconventional myosins associated with?
Cytoplasmic vesicles and organelles
Proteases
Degrade extracellular matrix components -Activation occurs by proteolytic cleavage of a propeptide on the protease.
What are secreted materials stored in?
Densely packed, membrane-bound secretory granules
Microtubules as structural supports and organizers:
Determine shape of cell (by distribution of MT), maintain internal organization of cell, function in axonal transport, and play a role in axonal growth during embryogenesis
How are protofilaments made?
Dimeric building blocks consisting of one alpha and one beta tubulin subunits
What do microtubules determine?
Distribution of microtubules determine the shape of that cell. In animal cells, microtubules extend in a radial array outward from the nucleus, giving cell a round, flattened shape
Chloroplast
Double membrane where the outer membrane contains porins and is permeable to large molecules while the inner membrane contains light-absorbing pigment, electron carriers, and ATP synthesizing enzymes
Where does NADH and FADH carry electrons?
ETC in the inner mitochondrial membrane of eukaryotes and cell membrane of prokaryotes
Heterotrophs
Earliest living organism, survived on nutrients from environment
Action spectrum:
Efficiency of light wavelengths to promote photosynthesis
Flavoproteins
Electron carrier derived from riboflavin. Polypeptide tightly bound to one of 2 related prosthetic groups.
Plastoquinone
Electron carrier in the reaction center. Electron is then moved to the stromal side of the membrane.
What is NAD+?
Electron carrier that is reduced to NADH that donates electrons to more oxidized molecules.
What happens to the electrons as the go through each step of glycolysis?
Electrons lose potential energy and the energy released is used to pump protons across the membrane to form a strong electrochemical gradient.
Regulated secretion location
Endocrine cells (hormones), pancreatic acinar cells (digestive enzymes), nerve cells (neurotransmitters)
Synapatic junctions
Epithelia and cardiac muscle are notoriously difficult to separate from one another, because they are held together tightly by specialized Ca2+ dependent adhesive junctions
Oxidizing/Reducing agents
Exists in pairs and differ in their number of electrons (NAD+, NADH)
Actin Filament structure
F-actin, microfilament, is a 2 stranded structure with 2 helical grooves running along its length
What passes through inner mitochondrial membrane?
FADH2 and NADH electrons pass through ETC of inner mitochondrial membrane and pumps protons across membrane setting up electrochemical gradient. Electrons pass from molecules binding them more loosely to thos binding them more tightly; as this happens. the chain of reactions releases energy.
What can enter the krebs cycle?
Fats which can be broken down into glycerol and phosphorylated to form an intermediate of glycolysis and acetyl coA
What is the enzyme that reduces NADP+ to NADPH in PSI?
Ferredoxin-NADP+ reductase
What leads to a drop in ATP-acitn?
Filament assembly
Tubulin subunits
Fit tightly together, organized in a linear array, and asymmetric and polar
Where do plastoquinone pass electrons?
From PQ to PQ until it reaches the stromal side of the membrane
Conventional Type II Myosin
Generate force in muscles and some non-muscle cells. Composed of 2 heavy chains, 2 light chains, and 2 globular heads known for their catalytic sites.
What happens in glycolysis?
Glucose is broken down into 2, 3-Carbon molecules of pyruvate and the potential energy released to phosphorylate ADP into ATP
What can enter the glycolytic pathway?
Glycogen, starch, simple sugars
How does Glycolytic NADH transport electrons into the mitochondria?
Glycolytic NADH cannot pass into mitochondria, but its electrons reduce a low MW metabolie that: 1. Enters mitochondria (malate-aspartate shuttle) reducing NAD+ to NADH 2. Transfers electrons to FAD (glycerol phosphate shuttle) to produce FADH2. Or by turning NADH and FADH2 into ATP via Chemiosmosis
GFP
Green fluorescent protein used to observe protein synthesis in the cell
Unconventional myosins
Have only a single head and are unable to assemble into filaments in vitro
Intermediate Filaments (IF)
Heterogenous group of proteins divided into 5 major classes Used in the construction of filaments
Carbohydrates and fats are highly reduced or highly oxidized?
Highly reduced
Structure and composition of microtubules
Hollow, relatively rigid, tubular -made from tubulin protein
How do cadherins bind?
Homophillically by binding to the same cadherins present in the surface of neighboring cells. -Transmit signals from ECM to cytoplasm -Involved in morphogenesis
Cytoplasmic dynien
Huge protein with a globular, force generating head -Minus end-directed microtubular motor.
Where is the machinery required for motor activity in Conventional Type II myosin?
In a single head.
How are microtubule proteins arranged?
In longitudinal row called protofilaments -Have 13 protofilaments aligned side by side in a circular pattern within the wall of the tubule.
Where is starch synthesized?
In the chloroplast
Where is sucrose synthesized?
In the cytosol which is the transportable form of carbohydrate.
Where are most TCA enzymes located?
In the mitochondrial matrix in eukaryotes
C3 Pathway, AKA Calvin Cycle:
Includes: Carboxylation of RuBP to form PGA Reduction of PGA to GAP using NADPH and ATP from light reactions Regeneration of RuBP
Microtubule-Associated Proteins
Increase stability and promote microtubule assembly by linking tubulin subunits together
What do the initial steps of glycolysis use and produce?
Initial steps produce 2 ATP molecules, but 4 ATP molecules are produced by substrate-level phosphorylation in the second half of glycolysis
Where is NADH oxidized?
Inner mitochondrial membrane in eukaryotes and plasma membrane of prokaryotes.
Carbohydrate Synthesis in C4 Plants
Involves production of PEP which combines with CO2 to make 4-C compounds oxaloacetate or malate Plants utilizing this pathway are C4 plants
What happens to free energy of compounds in glycolysis and krebs cycle?
It gradually decreases due to ATP synthesis and larger drops with the production of NADH and FADH2
Where does oxygen go in photosynthesis?
It is released as by product.
Porphyrin ring
Light absorbing head molecule that contains chlorophyll pigments that are hydrophilic while the phytol chain is hydrophobic. Phytol chain is anchored in the thylakoid membrane
What does photosynthesis use to oxidize water?
Low energy electrons to form ATP and NADPH, which are reduced to CO2 to carbohydrate
What does ATP synthase do?
Makes ATP by using the proton gradient energy to phosphorylate ADP as protons go back across the membrane
Autotrophs
Manufacture organic nutrients from CO2 and H2S
What do reduced compounds typically have?
Many C-H bonds with high potential in energy
What do oxidized molecules typically have?
Many C-O with low potential energy
Regulated secretion
Materials are stored in vesicles and discharged in response to a stimulus
Endocytic pathway
Materials move from the outer surface of the cell to compartments, such as endosomes and lysosomes
Three filamentous structures
Microtubules, Actin filaments, Intermediate Filaments
Where does the Krebs Cycle occur?
Mitochondrial matrix, outside cristae.
Myosin
Molecular motor of actin filaments. Myosin tail is divergent
Matrix metalloproteinase (MMP)
Most abundant proteases and can degrade all major classes of ECM proteins -Can activate one another by cleaving off their propeptides. -Results in cascade-like effect of protease activation that can lead to rapid degradation of ECM proteins
What is myosin's sole known function
Motor for actin
COP I coated vesicles
Move materials "retrograde" or backwards to the ER or from the trans golgi to the cis golgi cisternae
COP II coated vesicles
Move materials from ER forward to the ERGIC intermediate compartment and Golgi Complex
Clathrin-coated vesicles
Move materials from TGN to endosomes, lysosomes, and plant vacuoles
Photophosphorylation
Movement of electrons during formation of oxygen is called noncyclic photophosphorylation because ions move in a linear path.
Cilium motion
Moves in a direction perpendicular to the cilium itself
NAD+ in NAD+ NADH couple
NAD+ is a weak oxidizing agent
Monomer of IF
NH2 end and COOH end
What do IFs include?
Neurofilaments, a major component of the network supporting neurons
Assembly of Microtubules from alpha/beta dimers occurs in 2 distinct phases
Nucleation- Slower phase Elongation- rapid phase
O2 in O2 H2O couple
O2 is a strong oxidizing agent
Light dependent reactiona
Occur in which sunlight is absorbed, converting it into ATP and NADPH
Fermentation
Occurs in the cytoplasm when pyruvate accepts electrons from NADH instead of oxygen.
ECM
Organized network of extracellular materials found beyond the immediate vicinity of membrane -Holds cells together -Key regulatory role in determining cell shape & activities -Prominent in connective tissues (cartilage, bones, tendons)
What is the first of glycolysis?
Oxidation of glucose
Where does energy to make ATP come from in Cellular Respiration?
Oxidation of sugars and other reduced compounds. This energy is used to phosphorylate ADP to make ATP
What does the Krebs cycle need to oxidize pyruvate?
Oxygen
What is the final electron acceptor at the end of the ETC?
Oxygen
What happens to oxygen after hydrolyzed from water in PSII?
Oxygen is released as a waste.
PSI operations: Production of NADPH
PSI consists of reaction core center. Photons harvested by antenna pigments in PSI (LHCI) oxidizes chlorophyll a, forming P700 Redox potential of P700 reduces NADP
What does photosynthesis oxidize?
Photosynthesis oxidizes water to oxygen; respiration reduces oxygen to form water
Where do electrons flow from PSII?
Plastoquinone
What does the tail portion of Conventional Type II myosin do?
Plays a structural role allowing protein to form filaments
IgSF
Polypeptide chains composed of similar domains present on lymphocyte surfaces as integral proteins.
C3 Plant Carbohydrate synthesis
Produce 3-Carbon intermediate as the first compound to be identified during carbon dioxide fixation. CO2 is condensed with a 5-C compound, ribulose 1,5-bisphosphate, to form a six-carbon molecule which then splits into 2 molecules of PGA
What does PSI do?
Produce NADPH, redox potential of absorbed light reduces NADP
From PSII to PSI
Production of O2 leads to formation of two molecules of PQH2 Reduced PQH2 diffuses through thylakoid membrane and binds to cytochrome b and releases protons into the lumen of the thylakoid. Plastocyanin transfers electrons to P700+
Biosynthetic Pathway
Proteins are synthesized in the ER, modified at the Golgi complex, and transported to various destinations
Cytochromes
Proteins containing heme prosthetic groups. Heme iron undergoes reversible transition between Fe3+ and Fe2+
Secretory pathway
Proteins synthesized in the ER are discharged from the cell
Transported materials in biosynthetic or secretory pathway
Proteins, lipids, complex polysaccharides
pyruvate dehydrogenase pathway
Pyruvate -> Pyruvate dehydrogenase (slows Kreb cycle when ATP, acetyl CoA, and NADH are in abundance, speeds Kreb cycle when NAD+, CoA, and AMP are scarce.) -> Acetyl CoA -> Krebs Cycle
How is the Krebs cycle regulated?
Pyruvate dehydrogenase regulates the Krebs Cycle by feedback inhibition by ATP, acetyl CoA, & NADH. Pyruvate dehydrogenase is activated by NAD+, CoA, and Adenosine Monophosphate. Thus, the Krebs Cycle is slowed when ATP and NADH are abundant, and speeded up when ATP and NADH are scarce.
How does pyruvate convert to Acetyl CoA?
Pyruvate reacts with coenzyme A (CoA) to produce acetyl CoA.
Selectins
Recognize and bind oligosaccharides that project from surface of other cells -Binding to carbohydrate ligand requires calcium
Flow of electrons from water to PSII
Redox potential of P680+ pulls electrons from water (photolysis) Protons produced in photolysis are retained in the thylakoid lumen.
Reaction Center of PSII
Referred to as P680, and that of PSI as P700 standing for the wavelengths where absorption is stronger.
Respiration
Removes high energy electrons from reduced organic substrates to form ATP and NADH
Centrosome function
Responsible for initiating microtubules in animal cells
What catalyzes the splitting of the 6-C molecule of RuBP
Rubisco Most abundant protein on earth. Low turnover number Fixes 3 molecules of CO2 per second
Tight junctions
Seal Extracellular space -Found in layers of cells that adhere tightly to one another to form a thin cellular sheet -Serve as barrier to free diffusion of water and solutes from extracellular compartment on one side of the epithelial sheet to that on the other side
Four integral membrane proteins that play major role in cell-cell adhesion
Selectins, members of Immunoglobulin Superfamily (IgSF), members of the integrin family, cadherins
Roles of the cytoskeleton
Serves as a scaffold providing structural support serves as internal framework to organize organelles within cell directs cellular locomotion and movement of materials within cell Provides anchoring site for mRNA, serves as signal transducer, essential to cell division
Gap junctions
Sites between animal cells that are specialized for intercellular communication
Cytoskeleton
Skeletal system of a eukaryotic cell
What happens to the pyruvate once oxidized?
Some of the energy is released to reduce NAD+ to NADH, reduce FAD to FADH2, and phosphorylate ADP to ATP
How are the various types of cargo routed to their appropriate destinations?
Sorting signals encoded in the amino acid sequence of the proteins or in the attached oligosaccharides.
ER Exit Sites (ERESs)
Specialized domains of the ER that begins the biosynthetic pathway
Microtubule Organizing Centers (MTOCs)
Specialized structures for the nucleation of microtubules
Golgi complex definition
Stack of flattened cisternae with several functionally distinct compartments
What are Intermediate Filaments?
Strong, flexible, ropelike fibers that provide mechanical strength to cells that are subjected to physical stress
Keratin containing IFs
Structural proteins of epithelial cells
What is the second method of producing ATP?
Substrate level phosphorylation which occurs when ATP is produced by the enzyme catalyzed transfer of a phosphate group from an intermediate substrate to ADP
Iron
Sulfur proteins, iron-containing proteins; accept and donate a single electron; iron atoms are not found in heme group but are linked to inorganic sulfide ions as part of an iron-sulfur center
Kinesins
Tetramer of 2 identical heavy chains and 2 identical light chains Each includes a pair of globular heads connected to a rod-like stalk PLUS end directed microtubular motor based on its movement
What is cellular respiration
The combination of glycolysis, the Krebs cycle, and the ETC
Mitochondrial Matrix
The compartment of the mitochondrion enclosed by the inner membrane and containing many enzymes, ribosomes, circular double stranded DNA, and substrates for the Krebs cycle. Also Calcium Phosphate storage sites.
What is the reduction of CO2 to carbohydrate via photosynthesis coupled to?
The consumption of NADPH and AT produced during dark reactions
Flow of electrons
The flow of electrons is from H2O to NADP+ is referred to as the Z scheme
What does the production of O2 lead to in hydrolysis in PSII?
The formation of 2 molecules of PQH2, reduced PQH diffuses through thylakoid and binds to cytochrome b and releases protons into the lumen of the thylakoid Electrons from chytocrome b are passed to plastocyanin and plastocyanin transfers electrons to p700+
Photosynthesis
The only process of biological importance that can harvest the energy of sunlight and convert it to chemical energy
Microtubules as agents of intracellular motility
They facilitate movement of vesicles between compartments
How do microtubules function as structural support?
They provide mechanical support by resisting forces that might compress or bend fibers
Absorption spectrum:
Three photosynthetic pigments of higher plants
Chloroplast structure
Thylakoid (Thylakoid lumen, Granum, Stroma lamellae, Grana lamellae, Outer envelope, Inner envelope, Intermembrane space,
What is mitochondria's role in ATP formation?
To extract energy from organic materials and store it temporarily in the form of electrical energy.
What is the function of Keratin containing IFs?
To organize and maintain cellular architecture and absorb mechanical stress Protect barrier of skin, epithelial cells of liver and pancreas
Where are Keratin containing IFs tethered?
To the nuclear envelope in the center of the cell and anchored at the outer edge by desmosomes and hemidesmosomes
Hemidesmosomes
Type of interaction of cells with noncellular substrates -anchor cells to the basement membrane -mainly keratin, which brings support to cell and tissue -contain dense plaque with keratin filaments -keratin is linked to ECM by membrane-spanning integrins
Focal Adhesions
Type of interaction of cells with noncellular substrates: -Commonly seen with cells grown in vitro -Scattered points of contact between cells and the surface of the culture dish -Contains clusters of integrins -Found in muscles and tendons
Photorespiration
Uptake of O2 and release of CO2 Rubisco catalyzes the attachment of O2 to RuBP to produce 2-phosphoglycolate Glycolate is then transferred to the peroxisome and leads to release of CO2 Accounts for loss of up to 50% of fixed CO2 Rate of photorespiration depends ON THE CO2/O2 RATIO
Dark Reactions
Use energy stored in ATP and NADPH to produce carbohydrate.
Photoautotrophs
Use radiant energy to make organic compounds
Folded Cristae
Used to maximize surface area for Electron transport system
PSII
Uses absorbed light energy to remove electrons and generate a proton gradient.
How does lactic acid fermentation work?
When there is no oxygen intermediate, pyruvate accepts electrons from NADH, producing 2 lactate per glucose.
Primary electron acceptor
Where electrons are transferred.
Do motile cells need Microfilaments?
YES! All cells that move and exhibit motility need Microfilaments -MFs are also involved in intracellular motile processes such as vesicle/organelle movement, phagocytosis, and cytokinesis
Does actin require ATP for assembly?
YES, mf.
Do plant cells rely on microfilaments/
YES, plant cells rely mostly on Microfilaments, rather microtubules for long-distance transport of cytoplasmic vesicles and organelles
Are actin subunits polar?
Yes, all actin filament subunits are pointed in the same direction, so the entire Microfilament has polarity.
Do actin filaments have different structural characteristics and dynamic properties? What are they?
Yes, one of the microfilaments appears pointed and the other appears "barbed".... -lol dr. barbosa doesn't know wtf barbed means Orientation of the arrowheads formed by actin provide information about direction of the microfilament movement
Do IgSF mediate calcium-independent cell-cell adhesion?
Yes, some IgSF mediate calcium-independent cell-cell adhesion
Are intermediate filaments interconnected?
Yes, to other cytoskeletal filaments by thin, wispy cross-bridges
Photosynthesis is
a process that allows green plants, algae, and photosynthetic bacteria to convert solar energy into chemical energy. The first stage of photosynthesis is to convert the light energy into ATP and NADPH
RGD
an amino acid sequence in fibronectin to which a cell binds via receptors for platelet aggregation
Mitochondria
bean-shaped or threadlike organelles with double membranes, important in ATP synthesis. Has own type of DNA.
Pesticide killers
bind to core protein of PSII where light reactions serve as targets of herbicides.
How does myosin create energy
by hydrolyzing ATP
Reducing agents
can also be ranked: lower affinity - stronger reducing agent 1. High electron-transfer potential (NADH) are strong reducing agents 2. Low electron-transfer potential (H20) are weak reducing agents
Components of the ECM
collagen, proteoglycans, fibronectin, laminin
Centrosomes
complex structure that contains 2 barrerl-shaped centrioles surrounded by amorphous, electron dense pericentriolar material
Microfilaments
composed of actin and a involved in cell motility.
Glyoxysomes
contain some of the same enzymes as peroxisomes (catalse, fatty axid oxidase)
Desmosomes
disk-shaped adhesive junctions that are numerous in tissues subjected to mechanical stress (skin, cardiac muscle, gingiva, uterine cervix epithelial layers).
Plasmodesmata
found in plant cells and connects plasma membrane from neighboring cells -Cytoplasmic channels that pass through cell walls of adjacent cells -Allow larger molecules to pass between cells
Net Reaction of Glycolysis
glucose + 2 ADP + 2 Pi + 2 NAD+ -> 2 pyruvate + 2 ATP + 2 NADH + 2 H+ + 2 H2O
Is hydrolysis of ATP to ADP and phosphate exergonic or endergonic
highly exergonic - 7.3 kcal of energy per mole of ATP hydrolyzed
Cadherins
large family of glycoproteins mediating Ca2+ dependent cell-cell adhesion.
Ubiquinone
lipid soluble with long hydrophobic chain
Copper Atoms
located within single protein of inner mitochondrial membrane; they alternate between Cu2+ and Cu1+ oxidation states
Flagella motion
longer than cilia, move in waveforms
Collagen
most abundant, provides high tensile strength
Axonal transport
movement of neurotransmitters across the cell, movement away from the cell body and toward the cell body, mediate tracks for a variety of motor proteins.
CAM plants
plants close their stomata during the day, collect CO2 at night, and store the CO2 in the form of acids until it is needed during the day for photosynthesis
Actin monomers (G-actin)
polymerizes to form stiff filament made of 2 strands of actin molecules wound around each other in double helix
Proteoglycans
protein-polysaccharide complex core protein attached GAG's -Form porous hydrated gels to resist crushing forces -ECM of bone is made of collagen & proteoglycans, but is hardened by impregnation with calcium phosphate salts
ER Export Signals
proteins that contain domains that regulate ER exporting -Found in cytosolic tails of transported proteins
Palade and Jamieson- Autoradiography
revealed that the ER is the site where secretory protein synthesis occurs.
ADAMs (Disintegrin and Metalloproteinases)
second class of protease that degrade ECM -These proteases also bind to integrin ECM receptors and help regulate ECM assembly as well as its degradation.
Peroxisome
site of synthesis and degradation of hydrogen peroxide. Often have dense, crystalline core of oxidative enzymes.
Cis golgi network function
sort proteins for the ER or next Golgi station
Trans Golgi network function
sorting proteins to the plasma membrane or intracellular destinations
Key Cytoskeleton functions
structural support, intracellular transport, contractility and motility, spatial organization
Glycolysis
the breakdown of glucose by enzymes, releasing energy and pyruvic acid.
Chemoautotrophs
use energy from inorganic molecules
Autoradiography
visualizes biochemical processes by radioactively labeling molecules
How many ATPs do NADH and FADH2 make?
~3 ATPs & ~2 ATPs, respectively