1.I Explain the theory of Endosymbiosis and give an example of evidence that sup
ID: 32506 • Letter: 1
Question
1.I Explain the theory of Endosymbiosis and give an example of evidence that supports it. 2. A) Let's say you are going to design a cell, would you make it large or small? Explain your choice. B) How come eukaryotic cells are more efficient than a prokaryotic cell despite being larger? 3. Explain why the cell membrane is modeled as a Fluid Mosaic: A) Why is it called fluid, and B) how can organisms adjust the fluidity of their cellular membranes to the temperature of the environment they inhabit (cold vs warm habitats)? 4. Compare osmosis, simple diffusion, facilitated diffusion and active transport: a) describe their differences and b) explain when cells have to use each one. s. Some animals are meaning that they maintain the osmolarity of their body fluids equal to that of the external environment. Hydroids, a type of cnidarian, are osmoconformers. a) What would happen if you take a marine hydroid and transfer it into a freshwater aquarium? b) What would happen if you take a freshwater hydroid and transfer it oconformers, such as sharks, can move from saltwater to freshwater, hypothesize what adaptations these organisms have in order to tolerate a change in the osmolarity in their surrounding environment. 6. plain your answer in terms of and specify the direction of water movement. a) what group of depends the most on cell signaling? (choose between: prokaryotes, eukaryotes, Book ProExplanation / Answer
1)
Endosymbiosis theory proposes that organelles like mitochondria and chloroplasts have formed due to establishment of ancient bacteria inside the primitive eukaryotic cells. These bacterial cells, over years of evolution, have changed and transformed as organelles carrying out important functions for the host cells. The occurrence of endosymbiotic relationships, like infective particles, in modern species is direct evidence that endosymbiosis can happen in a spontaneous fashion even today.
Hence, endosymbiotic relations that could have happened millions of years ago have evolved to form eukaryotic organelles like mitochondria and chloroplasts. Based on the Endosymbiosis theory, it is believed that mitochondria were evolved from a bacteria called Rickettsia rickettsii and chloroplast evolved from blue cyanobacteria.
2)
A) If I would design a cell, then I would like make it large, because large cells can accommodate more amount of genome and several cell organelles for their survival.
B) The eukaryotic cells are more efficient than prokaryotic cells, because they have more cell organelles with distinct functions. Eukaryotic cells would make their energy efficiently than prokaryotes.
3)
Cell membrane is a phospholipid-based bi-layer that surrounds and encapsulates the cell. It is also composed of proteins and Sterols. Proteins that are present in fusing with plasma membrane are called fusion proteins. For example, different types of channels and pumps and some enzymes are also coming under fusion proteins.
Cholesterol is an important steroid; it helps form plasma membrane for maintenance of fluidity. Too much cholesterol makes the membrane becomes more fluid. Thus, lack of cholesterol makes the membrane becomes rigid.
A) The cell membrane have fluid like nature due to presence of proteins, cholesterol and fatty acids, the movement of proteins and cholesterol over a fatty acids bed resembles like a fluid.
B) At colder temperatures, the membranes are rich with cholesterol and phospholipids. The phospholipids are the main lipids maintain the membrane fluidity.
Organisms at hot temperature have sphingolipids rich membranes. An over-abundance of sphingolipids relative to phospholipids stiffens the membrane. Thus, the membrane becomes rigid.
4)
Passive transport is a type of transport where molecules move across the membrane. This form of transport does not require energy to occur. Simple diffusion is the transport that can move small and nonpolar molecules across the membrane, from an area of higher concentration to one of lower concentration. Osmosis is a specific type of simple diffusion that relates to the movement of water molecules. Facilitated diffusion will use transport proteins to move molecules across the plasma membrane.
6)
Integrins are the group of transmembrane receptors which are large and responsible for the attachment of the cell to its surrounding environment such as the extracellular matrix (ECM) or to its neighboring cells. These integrins play a key role in the signal transduction. They help in the transmission of the signal about the chemical composition of the extracellular matrix into the cell. These are also involved in the regulation of other cell cycle.
In signal transduction process, these integrins modulate the cell signaling pathways by acting along with the receptor tyrosine kinases (RTKs). The interaction between RTK and integrins are generally irreversible (unidirectional) and are supportive. These integrins regulate the RTKs in regulating specific adaptors onto the plasma membrane.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.