Chloroplast | BioNinja
Structure and function of mitochondria and chloroplasts. scientists think host cells and bacteria formed endosymbiotic relationships long ago, when individual . Chloroplast evolution, structure and functions . establishment of the primary endosymbiotic relationship between plastid and host cytoplasms. A chloroplast is a basic organelle that in a sense is one of the most important organelles to us, and we don't even have them! In this lesson, we.
Aerobic respiration strictly refers to the steps of cellular respiration known as the Krebs cycle, electron transport chain, and oxidative phosphorylation. These steps normally occur in eukaryotic cells after glycolysis has been carried out.
The 3-carbon end products of glycolysis, pyruvate, are the starting points for aerobic respiration. Pyruvate first has its carboxyl group removed, creating CO2 gas as a waste product. The acetate is attached to coenzyme A to form the complex acetyl CoA. Acetyl CoA enters the mitochondrial matrix and is fed into the Krebs cycle.
In the first step of the Krebs cycle, Acetyl CoA gives its acetate away to combine with oxaloacetate, a C4 compound left over from the last cycle, to form citrate, a C6 compound. Coenzyme A exits the cycle to be recycled for further use. The electron transport chain takes place in multiprotein complexes imbedded within the phospholipid bilayers of mitochondria's inner membranes.
The flavoprotein then passes the electrons to ubiquinone Qwhich carry them to the first of many proteins in the cytochrome family that make up the rest of the electron transport chain. FADH2 actually gives its two electrons to Q via an iron-sulfur proteinnot the flavoprotein.
The last step in the electron transport chain is when cytochrome a3 gives the electrons to oxygen. Oxygen, then, is the final acceptor of electrons in the chain, and once it is reduced, it quickly picks up two hydrogen ions and forms water, a waste product of aerobic respiration. One of these points is the flavoprotein, before the electrons are handed off to Q. The final stage of aerobic respiration is oxidative phosphorylation, which is made possible by the electron transport chain.
Explain oxidative phosphorylation in terms of chemiosmosis. The pumps are reduced, giving them energy to pump protons into the inner membrane space.
The electrons are transferred along a chain of pumps, continuously losing energy. Thus, protons diffuse back into the matrix through facilitated diffusion of ATP synthase channel protein and enzyme. As the protons pass along this protein channel, the kinetic energy of the protons causes the ATP synthase molecule to turn slightly, exposing active sites that create ATP by binding ADP with inorganic phosphate molecules.
The result is 36 ATP produced by oxidative phosphorylation. Explain the relationship between the structure of mitochondrion and its function. Mitochondrion have a large inner matrix, allowing for the Krebs cycle to occur. After the Krebs Cycle is complete, the mitochondria has a fairly small inner membrane space where protons are pumped into.
Due to its size, diffusion of protons back into the matrix occurs quickly, resulting in ATP produced at a faster rate.
The inner membrane contains many electron transport chains of proton pumps and ATP synthase enzymes, allowing for much ATP to be produced. The membranes are also structured to prevent the protons from diffusing though the membrane, forcing them to enter the matrix only through ATP synthase molecules. Describe the central role of acetyl CoA in carbohydrate and fat metabolism. Both carbohydrate and fat metabolism is accomplished by splitting the molecules into 2 carbon structures.
These structures are then attached to Coenzyme A, creating Acetyl CoA and allowing the molecules to pass into the inner matrix of the mitochondrion in order to complete the Krebs Cycle and chemiosmosis. Draw the structure of a chloroplast as seen in electron micrographs Chloroplast - 5 picometers State that photosynthesis consists of light-dependent and light-independent reactions. Light strikes on an antenna pigment in a thylakoid within a chloroplast in Photosystem 2. The chlorophyll pigments in the thylakoid absorb light energy, raising electrons to a higher energy level.
The energy is passed along antenna pigments until it reaches a P molecule. The energy excites an electron on the P molecule which is transferred to the reaction center and electron transport chain.
Chloroplast | Structure, Chloroplast Function | [email protected]
The major components of a chloroplast are as illustrated and explained below. Envelope The chloroplast envelope is double-membrane structure comprising an outer and an inner membrane.
Each of these membranes is a phospholipid bilayer, and is 6 - 8 nm thick. A 10 - 20 nm thick space present between the two membranes is known as intermembrane space. Stroma The aqueous matrix present inside this double-membrane envelope is called the stroma. The internal components as well as several solutes are dispersed into the stroma. The stroma is especially rich in proteins, and contains several enzymes necessary for vital cellular processes.
The chloroplast DNA is also present in the stroma along with ribosomes and other molecules required for protein synthesis. Starch synthesized through photosynthesis is stored in the stroma in the form of granules.
Thylakoids In addition to the two membranes that form the envelope, chloroplasts contain a third internal membrane system called thylakoid membrane. Thylakoids are the internal, membrane-bound compartments formed by such thylakoid membranes.
The internal portion of the thylakoid is called the thylakoid lumen, and contains plastocyanins and other molecules required for the transport of electrons. Grana Some of the thylakoids are arranged in the form of discs stacked one above the other. These stacks are termed grana, and are connected to each other through inter grana thylakoids and stroma thylakoids. Photosystems Present in the thylakoid membranes, these are the structural and functional units for harnessing solar energy.
A photosystem comprises a reaction center surrounded by light-harvesting or antenna complexes that contain chlorophyll, carotenoids, and other photosynthetic pigments, as well as the associated proteins.
Peripheral Reticulum The chloroplasts of certain plants contain an additional set of membranous tubules called peripheral reticulum that originate from the inner membrane of the envelope. Tiny vesicles bud off from the inner membrane of the chloroplast, and assemble to form the tubules of peripheral reticulum. Functions Chloroplasts are the sites for photosynthesis, which comprises a set of light-dependent and light-independent reactions to harness solar energy and convert it into chemical energy.
826 Explain the relationship between the structure of the chloroplast and its function
In addition to this the components of chloroplast participate in several regulatory functions of the cell as well as in photorespiration. The role of chloroplasts in photosynthesis has been illustrated below followed by a description of the roles of different components of chloroplasts The envelope of the chloroplasts is semi-permeable, and it regulates the entry and exit of molecules from the chloroplast. The outer and inner membranes have specialized intermembrane proteins for the transport of large molecules in and out of the chloroplasts.
- IB Biology/Cell Respiration and Photosynthesis
- Chloroplast: Structure and Function
- Mitochondria and chloroplasts
In addition, they are the site for synthesis of certain lipid molecules as well pigments like carotenoids that are required for light harvesting.