rmirley's blog

There are several types of photoreceptors in plants. Some of these photoreceptors are phytochromes, cytochromes, and phototropins. Phytochromes are a class of photoreceptor that plants use to detect light and mediate a photosynthetic response. Cytochromes are photoreceptors that function as electron transfer agents in metabolic pathways. Cytochromes are compounds consisting of a heme bonded to a protein. Finally, phototropins are photoreceptors that mediate phototropic responses in higher plants. They allow plants to alter their response and growth to light.

The cell wall provides many functions to the well being of a plant. First, the cell wall is strong and durable. This helps to protect the plant from the environment as well as pathogens. This durability also helps to support the plant during growth. If it wasn’t for the strength of the cell wall, the plant would wilt and not be able to grow upright. The strength of the cell wall also helps to anchor the plant to its environment. This allows the plant to survive without being easily uprooted. Aside from mechanical function, the cell wall also aids in transporting water and nutrients throughout the plant, as well as signaling and transferring information throughout the plant.

Plants photosynthetic abilities are determined by its chlorophyll. Chlorophyll are the subunits responsible for photosynthesis in plants, as well as the pigmentation of the plant. The color of chlorophyll is determined by the wavelength of visible light that it does not absorb. Chlorophyll a is the most abundant chlorophyll in plants and is the reason most plants appear green. Chlorophyll a absorbs red light and blue light, while reflecting green/yellow light. This reflection is what we see when we look at the color of a plant. There are many types of chlorophyll, each specializing in different wavelengths of light. This causes them to portray unique colors and define the plants that have them. 

Mutations are constantly occurring in our genome from generation to generation. They lead to genetic variation between individuals of a population. Not all mutations are equal though, and most mutations go unknown and unseen by most of the population. This is because there are several different types of mutations that can occur. One of these mutations is a missense mutation, which results in a change in one DNA base pair. This causes one amino acid to become another and can either be harmful or unnoticeable. Nonsense mutations are when an amino acid is changed into a stop codon, prematurely ending the protein. This can be catastrophic for the protein involved. Finally, insertions or deletions result in frameshift mutations, which change every amino acid after the affected area. This can completely change protein function and be devastating. 

Genetic drift is a unique evolutionary force. Genetic drift acts entirely random and has no bias towards any phenotype. Populations that undergo genetic drift experience fluctuating phenotype and genotype ratios. What really sets genetic drift apart is the it always moves towards fixing a certain allele. It can be either the dominant or recessive since it is random selection. After a certain number of generations only undergoing genetic drift there will only be one allele type left. This is because as individuals are selected to reproduce, allele frequencies change. Even if both alleles start out equal, one will be favored over the other due to random chance. This will lead to a divergence that eventually leads to allele fixation. Genetic drift causes populations to differentiate. 

Phloem sap is difficult for scientists to study. This is because plants are highly evolved to minimize phloem loss in the case of external damage. When a sieve tube is penetrated, it signals throughout the plant, triggering the release of callose which clogs the pores of the sieve plate. This causes all phloem movement through the sieve tube to stop. Luckily, scientists have figured out two ways to study the phloem uninterrupted. The first is to use a normal extraction tool that has been coated in an anti-slime. This allows scientists to observe the plant’s phloem without the interruption of sliming. The second way is by zapping aphids off of the plant after they have inserted their stylet. Aphids are able to access the phloem without triggering the release of callose. By removing the aphid without removing the stylet it acts as a phloem pump. Both of these methods are effective at extracting phloem from a plant without sliming occurring. 

The cell wall provides many functions to the well being of a plant. First, the cell wall is strong and durable. This helps to protect the plant from the environment as well as pathogens. This durability also helps to support the plant during growth. If it wasn’t for the strength of the cell wall, the plant would wilt and not be able to grow upright. The strength of the cell wall also helps to anchor the plant to its environment. This allows the plant to survive without being easily uprooted. Aside from mechanical function, the cell wall also aids in transporting water and nutrients throughout the plant, as well as signaling and transferring information throughout the plant.

There are three major components of the cell wall. These components are cellulose, hemicellulose, and pectin. Each of these components is made up of different monomers. Cellulose consists of β (1-4) linked D-glucose. Hemicellulose consists of glucose, xylose, mannose, galactose, rhamnose, and arabinose. Finally, pectin consists of α-(1-4)-linked D-galacturonic acid. Of all of these components in the cell wall, cellulose is the most abundant and strongest. 

Sieve tube elements and sieve plates are two completely different elements in a plant, despite the similar names. Sieve tube elements are components that form end to end to create sieve tubes, while sieve plates form between the sieve tubes. The sieve plate has micropores in it that connect the adjacent sieve tubes, allowing for material exchange between each tube. Normally this would pose a risk to the plant because one damaged sieve tube would cause the whole plant to “bleed out” as all of the water and nutrients it was transporting would be lost. To combat this, the plant can detect when the sieve tube is damaged and secrete callose, which can seal the pores in the sieve plate to stop nutrient and water transfer in that tube. This process acts much like coagulation in the human body.

There are three main phases of the Calvin cycle: carbon fixation, reduction, and regeneration. During carbon fixation, a CO2 molecule combines with a RuBP molecule. This forms 3-PGA, which is catalyzed by rubisco. Reduction is the second stage in which ATP and NADPH are used to convert the 3-PGA into G3P. This is because the NADPH donates electrons to the 3-PGA to reduce it to G3P. Finally, during regeneration, some of the G3P molecules are used to make glucose, while the others are recycled to regenerate the RuBP acceptor. This process requires ATP and involves a complex network of reactions. This allows the cycle to start over again and continue on.