Answer:
A. His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane.
Explanation:
Pyruvate is from the breakdown of carbohydrates such as glucose through glycolysis. Glucose enters the cytosol through specific transporters (the GLUT family) and is processed by one of several pathways depending on cellular requirements. Glycolysis occurs in the cytosol and produces a limited amount of ATP, but the end product is two 3-carbon molecules of pyruvate, which maybe diverted again into many pathways depending on the requirements of the cell. In aerobic conditions, pyruvate is primarily transported into the mitochondrial matrix and converted to acetyl-coenzyme A (acetyl-CoA) and carbon dioxide by the pyruvate dehydrogenase complex (PDC).
Initially it was proposed that pyruvate was able to cross the membrane in its undissociated (acid) form but evaluation of its biochemical properties show that it is largely in its ionic form within the cell and should therefore require a transporter.
Transport of pyruvate across the outer mitochondrial membrane appears to be easily accomplished via large non-selective channels such as voltage-dependent anion channels/porin, which enable passive diffusion. Indeed, deficiencies in these channels have been suggested to block pyruvate metabolism
Answer:
A sea sponge 760 million years old
Explanation:
It's unclear exactly how long sea sponges have been around, but they are at least old enough to be the longest-existing creatures on Earth, outside the realm of microorganisms (like bactery). The oldest evidence of a sea sponge found was a fossil discovered just last year in a 760-million-year-old rock. This beat the previous record for oldest sponge fossil, a 635-milloon-year-old sponge discovered in 2009. There may be still older fossils yet to find. But finding an older species is unlikely,as these simple organisms appear to be the progenitors of much more complicated life, including the first multicellular animals.
A. B. C. D. E. F. G. H.
They are all outer planets.
Plants changing sun energy to food
Though the skeletal muscle cells are of different sizes and shapes, the main components of a skeletal muscle cell remain the same. The skeletal muscle is enveloped by a layer of connective tissue called epimysium, it protects the muscles from friction against the bones and other muscles.
The skeletal muscles are also covered by a fibrous connective tissue called endomysium that insulates each muscle fiber. Underneath the endomysium is the sarcolemma that is the cell membrane of the fibers and underneath that is the sarcoplasm that is the cytoplasm of the cell.
Each muscle fiber also comprises cylindrical organelles called myofibrils. Each muscle fiber comprises hundreds to thousands of myofibrils. The myofibrils are the bundles of myosin and actin proteins that go through the length of the muscle fiber and plays an essential role in the contraction of muscles.
The myofibrils are surrounded by a network of tubules and channels known as the sarcoplasmic reticulum, which is stored with calcium and is essential for the contraction of muscles. Each myofibril can be further dissociated into functional repeating segments known as sarcomeres.
