PRICKLY PEAR CACTUSPrickly pear cacti (genus Opuntia, many species) are North American desert succulents that have flat, fleshy, leaf-shaped pads and large spines (modified leaves) growing from tubercles (small bumps on the pads). PLEISTOCENEThe Pleistocene was an epoch of geologic time that lasted from 1.8 million to 11,000 years ago; it was a period of widespread glaciation and large Ice Age animals (caled Pleistocene Megafauna)
Mitochondria also carry their own DNA to make their own proteins, independent of the rest of the cell; like bacteria, mitochondria also incorporate their DNA into loops. Additionally, certain antibiotics, while innocuous to eukaryotic cells, affect protein synthesis in both mitochondria and bacteria, indicating that the mechanism of protein synthesis in mitochondria is similar to that of bacteria rather than eukaryotic cells
Chloroplast: Structure and Function
The role of chloroplasts in photosynthesis has been illustrated below followed by a description of the roles of different components of chloroplasts The envelope of the chloroplasts is semi-permeable, and it regulates the entry and exit of molecules from the chloroplast. The internal portion of the thylakoid is called the thylakoid lumen, and contains plastocyanins and other molecules required for the transport of electrons
ATP: The Perfect Energy Currency for the Cell
Plants can also produce ATP in this manner in their mitochondria but plants can also produce ATP by using the energy of sunlight in chloroplasts as discussed later. Now that scientists understand how some of these highly organized molecules function and why they are required for life, their origin must be explained
Mitochondria - CreationWiki, the encyclopedia of creation science
This process is known as a proton leak or mitochondrial uncoupling and happens because of the facilitated diffusion of protons into the matrix, mediated by a proton channel called thermogenin. As hydrogen ions are forced out of the complex the wheel revolves, allowing each of the three active sites on the synthase to convert one ADP molecule into an ATP molecule
Compare and contrast the structure and function of Chloroplasts and mitochondria - A-Level Science - Marked by Teachers.com
Cellular organelles Structure and Function 4 star(s) It is described as smooth because it is associated with smooth oily fats, and it lacks the covering of ribosomes as found on the RER. A Level Biology revision notes the cytoplasm o This starts translation of mRNA for protein synthesise (assembly of amino acids into proteins) * Free ribosomes make proteins used in the cytoplasm
Chloroplast Membranes - Shmoop Biology
This electrical energy is then passed from one membrane protein to another, providing the power to pump protons from the stroma into the thylakoid lumen.Just like in the mitochondria, the protons (hydrogen ions, or H+) rush back across the membrane into the stroma, and ATP synthase, an enzyme, converts the generated energy into ATP. At this point, ATP and other products produced by the thylakoid membrane proteins are combined with molecules of carbon dioxide (CO2) in the stroma to make glucose
BC Online: 8C - ATP and Ox-Phos Reactions
The DGo for hydrolysis of ATP is dependent on the divalent ion concentration and pH, which affect the the stabilization and the magnitude of the charge states of the reactants and products. The charge density on the reactants is greater than that of the products Theoretical studies show that the products are more hydrated than the reactants
CATABOLIC METABOLISM: THE SYNTHESIS OF ATP (Bioenergetics)
Glycerol is a close relative of the three-carbon compounds involved in the catabolism of glucose and may be completely oxidized to CO2 and water by glycolysis and the tricarboxylic acid cycle. In brief, pyruvate is first oxidatively decarboxylated to yield CO2, NADH, and an acetyl group attached in an ester linkage to a thiol on a large molecule, known as coenzyme A, or CoA
An example pf commensalism is bromeliads (plants living on trees in rainforests) and frogs; the frogs get shelter and water from the bromeliad but the bromeliad is unaffected. C C3 PLANTA C3 plant is one that produces phosphoglyceric acid, (a molecule that has three carbon atoms) as a stable intermediary in the first step in photosynthesis (the Calvin Cycle)
Plants can also produce ATP in this manner in their mitochondria but plants can also produce ATP by using the energy of sunlight in chloroplasts as discussed later. Now that scientists understand how some of these highly organized molecules function and why they are required for life, their origin must be explained
ATP Synthase
In all cases, ATP synthases harness the electrochemical energy from a transmembrane proton or sodium (Na+) gradient to combine ADP and inorganic phosphate (Pi) to make ATP (Ackerman, Tzagoloff, 2005). Certain mutations in one of these three amino acids can cause complete loss of enzyme function, specifically a change from glutamic acid to leucine or cysteine and a change from histidine to serine, cysteine, leucine, or tyrosine
Although essential for ATP production by mitochondria, recent findings have confirmed that the c-subunit of the ATP synthase also houses a large conductance uncoupling channel, the mitochondrial permeability transition pore (mPTP), the persistent opening of which produces osmotic dysregulation of the inner mitochondrial membrane and cell death. Although corrected proofs do not have all bibliographic details available yet, they can already be cited using the year of online publication and the DOI , as follows: author(s), article title, Publication (year), DOI
Photosynthesis 1
In the light reactions, excited electrons from chlorophyll flow through a cytochrome transport system along membranes of the thylakoid disks (thylakoid membranes). When the guard cells lose water pressure on a hot day, they deflate and push together, thus closing off the stoma and reducing water loss (transpiration) through the leaf
Their DNA is circular, as it is in the prokaryotes, and their ribosomes and reproductive methods (binary fission) are more like those of the prokaryotes. In higher plants, lamellae, internal membranes with stacks (each termed a granum) of closed hollow disks called thylakoids, are also usually dispersed throughout the stroma
Chloroplasts and Other Plastids - The Cell - NCBI Bookshelf
In chloroplasts, the proton gradient is (more...)The Chloroplast GenomeLike mitochondria, chloroplasts contain their own genetic system, reflecting their evolutionary origins from photosynthetic bacteria. Other plastids, which are involved in different aspects of plant cell metabolism, are bounded by the two membranes of the plastid envelope but lack both the thylakoid membranes and other components of the photosynthetic apparatus.The different types of plastids are frequently classified according to the kinds of pigments they contain
The thylakoid membranes contain chlorophyll and other pigments arranged in antenna arrays to capture light energy for two photosystems called Photosystem I and Photosystem II. In most plants, both photosystems are used in an electron transport process that yields energy in the form of ATP and reduced coenzymes to the stroma of the chloroplast to be used in the synthesis of carbohydrates
The Transport of Proteins into Mitochondria and Chloroplasts - Molecular Biology of the Cell - NCBI Bookshelf
The electrochemical gradient is maintained by the pumping of H+ from the matrix to the intermembrane space, driven by electron transport processes in the inner membrane. (A) In the thermal ratchet model, the translocating polypeptide chain slides back and forth, driven by thermal motion, and it is successively trapped in the matrix by hsp70 binding
This structural organisation is shown on a modest scale in Figure 1.7, but extreme examples are evident in chloroplasts of shade-adapted species grown in low light (Chapter 12). By titrating the loss of such amines from the external medium when preparations where shifted from dark to light, they were able to infer the amount retained inside
Cellular Respiration
This has strengthened the theory that mitochondria are the evolutionary descendants of a bacterium that established an endosymbiotic relationship with the ancestors of eukaryotic cells early in the history of life on earth. (Defects in either process can produce serious, even fatal, illness.) The Outer Membrane The outer membrane contains many complexes of integral membrane proteins that form channels through which a variety of molecules and ions move in and out of the mitochondrion
Arrangement of Photosystem II and ATP Synthase in Chloroplast Membranes of Spinach and Pea
The particles appeared to be arranged in rows when viewed in cross sections through the appressed thylakoids (Figures 3G and 3I), whereas the nonappressed membranes, which are, in effect, grana end membranes, contain ATP synthases (Figure 3I), as expected. (D) Stroma thylakoids either are continuous with a grana thylakoid (green arrowheads) or bifurcate to merge with two adjacent grana thylakoids (blue arrowheads)
The pmf across the inner membrane of the organelle is coupled to the chemical synthesis of ATP from ADP and phosphate by a rotary mechanism illustrated in the Figure. It sits in the inner membranes of the organelle, where it uses the transmembrane proton motive force (pmf) generated by the oxidation of nutrients as a source of energy for making ATP
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