Two weeks ago we featured the process of photosynthesis in Photosynthesis – Simple Cell Part 13. Today, we are going to look at the chloroplast, where photosynthesis takes place. Evolutionary scientists believe that photosynthesis and chloroplasts are among the earliest of cell structures to have evolved. So as you read this week’s installment and recall the prior article on photosynthesis, decide for yourself if it would be possible for chloroplasts and the process of photosynthesis to have evolved by random chance.
Chloroplasts are organelles found in cyanobacteria and plant cells. The prevailing evolutionary theory says that chloroplasts were originally cyanobacteria that were taken into another cell through the process of endosymbiosis. The cyanobacteria replicated themselves inside the host cell so that when the host cell divided, there were cyanobacteria contained in both new daughter cells and the rest is history. They think this may explain how chloroplasts came about, but it doesn’t answer the original problem of how photosynthesis evolved in the first place.
Like other cells and mitochondria, chloroplasts have a dual membrane. The outer membrane is smooth and fairly permeable to most molecules. The Inner membrane is also smooth but not nearly as permeable as the outer membrane. A number of important membrane bound proteins are contained in the inner membrane. Many of these membrane bound proteins are essential in regulating what goes in and out of the chloroplast.
The inside of the chloroplast is made up of the thylakoid membranes, grana (granum – singular), lumen, stroma, and the intergrana or stroma thylakoids.
The thylakoid membranes are the site where the light dependent reactions of photosynthesis take place. They form a complex system of stacks that look like bingo chips. These stacks of chip-like structures are known as grana (plural) or granum (singular). The section of membrane that connects the grana together is called the intergrana or stroma thylakoids. Each chloroplast may contain up to 100 grana. The more grana thylakoid in the chloroplast, the more photosynthesis takes place.
The area inside the thylakoid membrane is called the lumen. Proton pumps in the thylakoid membrane pumps hydrogen ions across the membrane, creating acidic conditions within the lumen. This acidic gradient plays an important part in the process of photophosphorylation aspect of photosynthesis.
What occurs in the thylakoid membranes is one of the greatest miracles of design in the plant kingdom. Contained in the thylakoid membranes are a series of membrane bound proteins that carry on the photosynthetic process. Since photosynthesis was discussed in Part 13 of this series I will not go into any more detail on it here.
When a seed begins to sprout, cellular structures known as proplastids begin to form. Before the seedling emerges into the light, the proplastids develop into etioplasts. Etioplasts are comprised of structures called prolamellar which in turn are comprised of a partially crystalline membrane. As the seedling emerges from the ground and into the daylight, the prolamellar bodies are converted into thylakoids. If a seed is planted too deep and the seedling cannot reach the daylight in time, the etioplasts will not transform into thylakoids and the plant dies.
Part of the thylakoid formation requires a specific protein, VIPP1 or Vesicle Inducing Protein in Plastids 1. The absence of VIPP1 will result in the failure of the thylakoids to form resulting in the death of the plant. Insufficient amounts of VIPP1 will result in reduced amounts of thylakoid production, which will yield paler looking and slower growing plants.
Couple Part 13 on photosynthesis along with this article and you get another glimpse of the overwhelming complexity of God’s design in nature. Yet, realize that evolutionists believe that chloroplasts and photosynthesis evolved among some of the earliest one-celled primordial organisms. And these are the people that tell their children not to believe in fairy tales?