Cellular Organelles I | Biology | Quiz | Visionlearning
Mitochondria And Chloroplasts: Example Question #1. What is . Eventually, this relationship evolved into modern eukaryotic cells and mitochondria. There is a. There is compelling evidence that mitochondria and chloroplasts were once dependent on one another for survival, resulting in a permanent relationship. The many similarities between mitochondria and chloroplasts make more by eukaryotic cells and developed a symbiotic relationship with their host cells.
Mitochondria and chloroplasts likely began as bacteria that were engulfed by larger cells the endosymbiont theory.
Introduction You may know that your body is made up of cells trillions and trillions of them. You may also know that the reason you need to eat food—such as veggies—is so that you have the energy to do things like play sports, study, walk, and even breathe. 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.
The Evolution of the Cell
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.
- Cellular Organelles I: Membrane-bound Organelles
- Mitochondria and chloroplasts
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. The membrane of a thylakoid disc contains light-harvesting complexes that include chlorophyll, a pigment that gives plants their green color.
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. Soon afterward, new oxygen-breathing life forms came onto the scene. With a population of increasingly diverse bacterial life, the stage was set for some amazing things to happen.
Bacteria are single-celled organisms with a circular DNA molecule and no organelles. The Endosymbiotic Theory There is compelling evidence that mitochondria and chloroplasts were once primitive bacterial cells.
This evidence is described in the endosymbiotic theory. How did this theory get its name?
Science Quiz: Biology: Chloroplasts
Symbiosis occurs when two different species benefit from living and working together. When one organism actually lives inside the other it's called endosymbiosis. The endosymbiotic theory describes how a large host cell and ingested bacteria could easily become dependent on one another for survival, resulting in a permanent relationship.
Over millions of years of evolution, mitochondria and chloroplasts have become more specialized and today they cannot live outside the cell. It's Just a Theory In everyday speech, people use the word theory to mean an opinion or speculation not necessarily based on facts.
But in the field of science, a theory is a well established explanation based on extensive experimentation and observation.The Chloroplast
Scientific theories are developed and verified by the scientific community and are generally accepted as fact. And both organelles use their DNA to produce many proteins and enzymes required for their function.
A double membrane surrounds both mitochondria and chloroplasts, further evidence that each was ingested by a primitive host. The two organelles also reproduce like bacteria, replicating their own DNA and directing their own division.