Question

Discuss the significant changes that are represented in the evolution of the prokaryote cell type into the eukaryote cell. Include in your description major differences and improvements What is the evidence that the Chloroplasts and Mitochondria found in the eukaryotic plant cells are prokaryote endosymbiants? Describe the key steps in the process by which the gene in the DNA results in the production of enzyme sucrase by an eucharyote cell such as an amoeba. Include for use in the cytoplasm and for use extemal to the cell. 1. 2. 3.

Answer 1

#1 Prokaryote are considered to be the most primitive type of cells. With time these cells have undergone numerous changes - mutations, adaptations, natural selections to evolve into eukaryotes. These eukaryotic cells are more complex and prevalent than the prokaryotic cells.

• Flexibility in membranes (or outer boundaries) - In order to protect from outside environment single celled organisms possess protective layer (cel wall). prokaryotes possess capsules and sticky coats for adherence to the surface. eukaryotes possess much flexible outer membranes to expand n size and they are comparatively much larger in size than primitive prokaryotes. Flexibility allows bending and folding and increase the surface area for gasous and nutrients exchange. These eukaryotic membranes favour large particles endocytosis and exocytosis.
• Formation of cytoskeleton - prokaryotes possess protiens that are structurally similar to eukaryotic protiens involved in cytoskeleton formation.It is evident that these prokaryotic protiens underwent certain mutations, and assemble together to form eukaryotic cytoskeleton structure.  In eukaryotes , cytoskeleton is the framework of cell, which maintains the shape of the cell, microtubules and microfilaments are involved in mitosis (spindle formation) and different movements of nutrients, protiens and waste material inside the cell.
• Nucleus evolution - prokaryotes do not possess membrane bound nucleus, and its genetic material is concentrated in a ring shape in cyoplasm near the membrane. As a result of evolution of flexible boundaries the cell can bend or fold, it is considered that this boundary surrounded the DNA and pinch it off to form a nuclear envelope. The single ring shaped DNA of prokaryotes evolved over time and condense to form chromosoes of eukaryotic cell. This adaptaion was found faovurable  as this will maintain the untangled state of DNA. Now chromosomes can accordingly wind or unwind at the diffrent stages of cell cycle.
• Bound Ribosomes- Ribosomes in prokaryotic cells are in free state and in eukaryotes they are also present on endoplasic reticulum.
• eukaryotic cells are larger their nutritioal demands also increased with production of more protiens via translation and transcription. There is requirement for more waste removal. For this the cell, forms vacoules that stores digestive enzymes and destroy the damaged ribosomes, proteins and other waste material.
• Endosymbiosis - "Theory given by Lynn Margulis proposed that the mitochondria and chloroplast are once prokaryotic cells".

#2 evidence for endosymbiotic theory. According to which chloroplast and mitochondria are prokaryotic endosymbiants:

Chloroplasts of Photosynthetic eukaryotes Mitochondria of Eukarvotic cells ProkaryotesEukaryotes ultiple linear chromosomes 1 single, circular chromosome 1 single, circular chromosome 1 single, circular chromosome DNA Binary Fission (1 cell splits into Mitosis Binary Fission (1 cell splits into 2) (1 cell splits into 2) Binary Fission REPLICATION "70 S" "70 S" "80 S" "70 S" RIBOSOME ot found in the Found in the plasma membrane around cell ma membrane around cell (found only in the cell's mitochondria and chloroplasts) Found in the plasma membrane around mitochondrion Found in the plasma membrane around ELECTRON TRANSPORT CHAIN chloroplast SIZE 0 microns 50 - 500 microns 1-10 microns 1-1 1-10 microns APPROXIMATE

these all points show that there is much similarity between prokaryotes and chlorplast and mitochondria.