IB Biology Notes - Photosynthesis
State that photosynthesis consists of the light-dependent and light- independent reactions Explain the relationship between the structure of the chloroplast and its function Explain the concept of limiting factors in photosynthesis, with reference to light intensity, temperature and concentration of carbon. 2 electrons: replace electrons lost by chlorophyll a to ETS: chl a+ + 2 e-s > chl a e. 6. Explain the relationship between the structure of the chloroplast and its function. stroma pH = 8/ basic where Calvin cycle enzymes function optimally. What is a Chloroplast? The role of chloroplasts in photosynthesis is mainly to contain most of the similar to the mitochondria, except that it creates its own food that . Ch 8. Cell Communication: Tutoring Go to Cell Communication: I ; Meiosis II: Definition, Stages & Comparison to Meiosis I
But what exactly happens in your body to turn the food energy stored in broccoli into a form that your body can use? And how does energy end up stored in the broccoli to begin with, anyway? The answers to these questions have a lot to do with two important organelles: Chloroplasts are organelles found in the broccoli's cells, along with those of other plants and algae.
They capture light energy and store it as fuel molecules in the plant's tissues. Mitochondria are found inside of your cells, along with the cells of plants. They convert the energy stored in molecules from the broccoli or other fuel molecules into a form the cell can use. Let's take a closer look at these two very important organelles. Chloroplasts Chloroplasts are found only in plants and photosynthetic algae. Humans and other animals do not have chloroplasts. The chloroplast's job is to carry out a process called photosynthesis.
In photosynthesis, light energy is collected and used to build sugars from carbon dioxide. The sugars produced in photosynthesis may be used by the plant cell, or may be consumed by animals that eat the plant, such as humans. The energy contained in these sugars is harvested through a process called cellular respiration, which happens in the mitochondria of both plant and animal cells. Chloroplasts are disc-shaped organelles found in the cytosol of a cell.
They have outer and inner membranes with an intermembrane space between them. Diagram of a chloroplast, showing the outer membrane, inner membrane, intermembrane space, stroma, and thylakoids arranged in stacks called grana.
Thylakoid discs are hollow, and the space inside a disc is called the thylakoid space or lumen, while the fluid-filled space surrounding the thylakoids is called the stroma. You can learn more about chloroplasts, chlorophyll, and photosynthesis in the photosynthesis topic section.
Mitochondria Mitochondria singular, mitochondrion are often called the powerhouses or energy factories of the cell. The process of making ATP using chemical energy from fuels such as sugars is called cellular respirationand many of its steps happen inside the mitochondria.
The mitochondria are suspended in the jelly-like cytosol of the cell. They are oval-shaped and have two membranes: Electron micrograph of a mitochondrion, showing matrix, cristae, outer membrane, and inner membrane.
Modification of work by Matthew Britton; scale-bar data from Matt Russell.
The matrix contains mitochondrial DNA and ribosomes. We'll talk shortly about why mitochondria and chloroplasts have their own DNA and ribosomes. The multi-compartment structure of the mitochondrion may seem complicated to us. That's true, but it turns out to be very useful for cellular respirationallowing reactions to be kept separate and different concentrations of molecules to be maintained in different "rooms.
IB Biology/Cell Respiration and Photosynthesis - Wikibooks, open books for an open world
Electrons from fuel molecules, such as the sugar glucose, are stripped off in reactions that take place in the cytosol and in the mitochondrial matrix. These electrons are captured by special molecules called electron carriers and deposited into the electron transport chaina series of proteins embedded in the inner mitochondrial membrane.
As protons flow back down their gradient and into the matrix, they pass through an enzyme called ATP synthase, which harnesses the flow of protons to generate ATP.
This process of generating ATP using the proton gradient generated by the electron transport chain is called oxidative phosphorylation. Billions of years ago, a eukaryotic cell engulfed a cyanobacteria, which survived inside the cell, and later on evolved to become the chloroplast.
Plants and certain algae are characterized by the unique ability of photosynthesis, the synthesis of food molecules in the presence of sunlight. This ability is conferred through the presence of specialized organelles called chloroplasts, commonly referred to as the 'kitchens' of plant cells.
Chloroplasts are plastids that contain a network of membranes embedded into a liquid matrix, and harbor the photosynthetic pigment called chlorophyll. It is this pigment that imparts a green color to plant parts, and serves to capture light energy. A detailed account of the structure and functions of chloroplasts has been provided below.
Structure Chloroplasts are located in the parenchyma cells of plants as well as in autotrophic algae. Although their dimensions are almost similar in all plants, the algal chloroplasts show a variation in their size as well as shape.
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.
Mitochondria and chloroplasts
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.