Mitochondria are semi-autonomous in that they are only partially dependent on the cell to replicate and grow. They have their own DNA , ribosomes , make their own proteins , and have some control over their reproduction. Similar to bacteria , mitochondria have circular DNA and replicate by a reproductive process called binary fission . Prior to replication, mitochondria merge together in a process called fusion. Fusion is needed in order to maintain stability, as without it, mitochondria will get smaller as they divide. These smaller mitochondria are not able to produce sufficient amounts of energy needed for proper cell function.
AuNP uptake, subcellular distribution and toxicity are determined by particle size, morphology and surface modification. Although AuNPs of different shapes (spherical, shells, rods, diamonds) or sizes (1-100 nm) accumulate in various cancer cells, their uptake kinetics and toxicity may vary profoundly (Fig. 1 , reviewed by [ 13 ]). Besides shape and size, AuNP-based bio-nano interactions are further modulated by their functionalization [ 11 , 43 , 44 ]. In general, positive charges on the AuNP surface stimulate cellular uptake, possibly due to electrostatic interactions with the cell surface [ 45 ]. Positive charges can also improve AuNP transport to the nucleus, because nuclear localization sequences (NLSs) of many proteins are enriched for basic amino acid residues.
Each terminal button is connected to other neurons across a small gap called a synapse. The physical and neurochemical characteristics of each synapse determines the strength and polarity of the new input signal. This is where the brain is the most flexible, and the most vulnerable. Changing the constitution of various neurotransmitter chemicals can increase or decrease the amount of stimulation that the firing axon imparts on the neighbouring dendrite. Altering the neurotransmitters can also change whether the stimulation is excitatory or inhibitory.