Plants have mitochondria, but does it mean that they have a biochemical pathway that helps them survive? A plant can survive by generating and using energy and it is important that the plant has a way to do that. This means that a plant must have a source of ATP. The mitochondria are a key part of the plants’ system for generating ATP. They have anaerobic and aerobic oxidative capabilities. In the anaerobic phase, the plant’s cells are not able to produce ATP. In the aerobic phase, however, the cell is able to produce ATP and this can allow the plant to survive.
Chloroplasts
Chloroplasts are organelles that perform photosynthesis and cellular respiration. They are also involved in the fight against diseases. Compared to mitochondria, chloroplasts are more complex. Their genomes encode more proteins, ribosomes, and transfer RNAs.
These are small disk-shaped organelles that are located inside plant cells. The structure of the chloroplast depends on morphogenesis and biosynthesis. For example, simple algae have only one chloroplast, while more complex plant cells may contain hundreds of them.
Chloroplasts have a double membrane that separates the inner and outer compartments. These membranes divide into three distinct internal compartments, namely the stroma, grana, and intermembrane space.
During photosynthesis, light energy is converted into chemical energy in chlorophyll molecules. As a result, sugars are formed, which are then used by the plant to produce food. Carbon dioxide is converted to glucose, which is then used as fuel for the plant’s cellular machinery.
Inside the stroma, there is an electrochemical gradient that drives the synthesis of adenosine triphosphate, which powers the cell’s metabolic activities. It is also a source of fuel for the cytoplasm, which contains many mitochondria.
During dark conditions, mitochondria are the main source of ATP in the leaves. This is because they have a higher carbon supply and provide abundant substrates for sucrose synthesis. Interestingly, the OE line has a higher level of ATP than the WT line. However, these differences do not explain the difference in the amount of sucrose.
During light conditions, chloroplast ATP synthases contribute 82 percent of ATP synthesis. Interestingly, their contribution to ATP is reduced with the intensity of light.
In addition to their role in photosynthesis, chloroplasts are essential for the survival and growth of plants. Chloroplasts also have their own DNA and ribosomes, and contain light-harvesting complexes and chlorophyll.
Anaerobic mitochondria
In recent years, studies of anaerobic mitochondria have led to an improved understanding of their function. The first mitochondria were isolated in the late 1970s in trichomonads, but their biochemistry was not known. However, recent work has provided an insight into how they function and how they may integrate into overall cellular physiology.
One of the most intriguing aspects of anaerobic mitochondria is that they are not strictly anaerobes. Instead, they produce ATP in the cytosol from pyruvate breakdown. This explains why they are present in many eukaryotic cells. They also serve as a Ca2+ sink, due to an electrochemical gradient during oxidative phosphorylation.
A central set of reactions involved in ATP synthesis is the citric acid cycle. Mitochondriochondriochondrion compartments are specialized for particular functions. These compartments are folded to increase their surface area, and are surrounded by an intermembrane space. An active translocase moves larger proteins across the outer membrane.
The mitochondrial proteome is an emerging area of study. Researchers have identified more than 1000 proteins. Some of these are nucleus-encoded, while others are imported via complex translocation. While a great deal of work has been done on chloroplasts, there is not as much information on the mitochondrial genomes.
Two competing theories on the origin of mitochondria exist. One theory, referred to as the hydrogen hypothesis, argues that the ancestor of all mitochondria was an H2-producing a-proteobacterium. Another, referred to as the mitochondrial endosymbiosis theory, suggests that the ancestor was a host archeon that had an endosymbiotic relationship with a symbiont.
Both theories propose that the symbiont facilitated the eukaryotic evolution from a proto-eukaryotic host. The traditional view posits that the host was an anaerobic nucleus-bearing cell.
Regulation of mitochondrial biogenesis by microRNAs
Several microRNAs (miRNAs) have been shown to play important roles in mitochondrial biogenesis. They inhibit protein translation, and repress messenger RNA translation. However, their precise regulation remains unknown. Hence, further studies are required to investigate their functions. The current study aims to identify the potential role of microRNAs in heart failure.
We identified four microRNAs that were particularly enriched in failing hearts. These miRNAs were analyzed for their expression levels. This study was supported by the National Natural Science Foundation of China.
The findings demonstrate that the expression of several mitochondrial-associated microRNAs was significantly increased in failing hearts. Additionally, these microRNAs may have an impact on the cellular mechanisms of energy metabolism. Furthermore, they may also be potential targets for diagnosis and treatment of heart failure. Moreover, they may be novel gene-independent therapeutic targets.
MicroRNAs regulate gene expression through alternative splicing. One such microRNA, miR-696, has been reported to be downregulated in exercise training and prenatal development. It has also been shown to downregulate Pgc1a in skeletal muscle. In addition, it may also be associated with mitochondrial biogenesis.
Another microRNA, miR-181a/b, is believed to coordinate the mitochondrial turnover and biogenesis. Downregulation of this microRNA leads to increased autophagy and reduced cell death. Several studies have shown that increased mitophagy protects against neurodegenerative diseases. Similarly, downregulation of this microRNA results in reduced mitochondrial damage and improved phenotypes in in vitro MD models.
Mitochondria are critical in heat generation in brown adipocytes. They are also involved in metabolism during beige differentiation. In these systems, uncoupling protein-1 plays a key role in adaptive thermogenesis against cold. Thus, increased expression of uncoupling protein-1 may increase mitochondrial function.
Cellular oxygen levels regulate the expression of Group-VII ethylene response factors
Cellular oxygen levels are an essential component of growth, survival, and development in animals and plants. Inhibition of oxygen deprivation in plants triggers hypoxia-responsive responses to stress that are beneficial to plant growth.
The master regulator of this response is a small group of transcription factors. These transcription factors belong to the class VII of ethylene response factors (ERF-VII). They have been identified in several species, including plants and animals. However, their structure and activity are highly unstable under aerobic conditions. Nevertheless, the overlapping functions of ERF-VIIs can provide insights into the adaptive molecular responses to stress.
During hypoxia, the oxidation of the amino-terminal Cysteine of the ERFVII proteins is triggered by oxygen and nitric oxide. This process allows the protein to be recognized by E3 ligases. It also triggers a noncanonical ethylene signaling pathway that controls repression of general translation and mRNA loading onto ribosomes.
In addition, ectopic expression of ERF-VIIs has been shown to activate the transcription of genes encoding HRGs necessary for survival under hypoxia. Molecular mechanisms for this response remain to be defined, but future studies will shed light on the complexity of ERF-VII signal transduction.
Group-VII ethylene response factors activate the synthesis of enzymes required for the detoxification of reactive oxygen species (ROS). Some of these enzymes also regulate carbohydrate metabolism and the defense responses.
Plants sense submergence through the integration of their O2-sensing machinery and their ethylene receptor. ADH1 is one of the commonly used markers for hypoxia responses in plants.
In addition, submergence increases the activity of the GCN2-eIF2a pathway, which is critical for energy balance. Transgenic lines overexpressing GCN2 showed enhanced tolerance to submergence and retained higher levels of ATP and NAD+.
Biological function critical to a plant’s survival
One of the most complex interactions in biology is that between plants and other organisms. Plants can serve as a filter for the air, clean the soil, provide food, and enrich the surroundings. In addition, plant life plays a vital role in maintaining a balanced ecosystem.
There are several biological functions that are crucial to a plant’s survival. Photosynthesis is a process that uses carbon dioxide and water to produce oxygen. Among the key nutrients for plant growth is nitrogen. This can be directly obtained from the soil or via symbiotic relationships with nitrogen fixing bacteria.
Water also plays a vital role in the health of plants. It is important for photosynthesis, respiration, and the manufacture of complex molecules. Potassium is the osmoticum in plant cells, and is also important for controlling the opening and closing of stomata.
Another function of water is to help maintain the shape of a cell. Cells are a tangled web of cellular organelles, and the cohesion of water molecules is essential for their uptake. Some plants can maintain their structure without water.
Aside from providing the aforementioned water filtration, plants also help filter out pollutants. To do this, they must be given adequate oxygen. The plant must also respond to changes in the soil, and these changes can be mitigated by introducing beneficial soil microorganisms.
Other important biochemical processes include protein synthesis and respiration. Proteins are complex structures that make up many living cells, tissues, and organisms. Among other things, proteins serve as a carrier of genetic information. DNA is also a self-replicating material.
Many plants have symbiotic relationships with bacteria that can help them in the long run. For example, certain species of legumes initiate symbiotic relationships with nitrogen fixing bacteroids. They enter the cortical cells of the host plant, convert atmospheric nitrogen to ammonia, and release photosynthetically derived carbohydrates.