Category Environtal Studies

Mitochondria are organelles that break up food materials to make energy. Other important organelles are ribosomes, which make proteins, and endoplasmic reticulum. This is a structure, made of double membranes, that is linked to the nucleus and to the cell wall, so that chemicals can be carried around the cell. The cell wall itself is said to be semi-permeable. That means that some chemicals can pass through it into the cell but none can pass out.

Mitochondria are specialized structures unique to the cells of animals, plants and fungi. They serve as batteries, powering various functions of the cell and the organism as a whole. Though mitochondria are an integral part of the cell, evidence shows that they evolved from primitive bacteria. 

All living organisms are built with one fundamental brick: the cell. In some cases, a single cell constitutes an entire organism. Cells contain genetic material (DNA and RNA), and they carry out essential functions, such as metabolism and protein synthesis. Cells are also capable of self-replicating. However, the level of organization varies within the cells of different organisms. Based on these differences, organisms are divided into two groups: eukaryotes and prokaryotes. 

Plants, animals and fungi are all eukaryotes and have highly ordered cells. Their genetic material is packaged into a central nucleus. They also have specialized cellular components called organelles, each of which executes a specific task. Organelles such as the mitochondria, the rough endoplasmic reticulum and the Golgi serve respectively to generate energy, synthesize proteins and package proteins for transport to different parts of the cell and beyond. The nucleus, as well as most eukaryotic organelles, is bound by membranes that regulate the entry and exit of proteins, enzymes and other cellular material to and from the organelle.

Prokaryotes, on the other hand, are single-celled organisms such as bacteria and archaea. Prokaryotic cells are less structured than eukaryotic cells. They have no nucleus; instead their genetic material is free-floating within the cell. They also lack the many membrane-bound organelles found in eukaryotic cells. Thus, prokaryotes have no mitochondria.

Cells certainly are the building blocks of life, but they are very busy building blocks! Inside each cell thousands of chemical reactions are going on, so that the cell can carry out its tasks. A typical cell has a cell wall or membrane surrounding a kind of watery jelly called cytoplasm. Within the cell there are a number of parts called organelles. These do all the work that the cell is designed to do. The nucleus is a particularly important organelle. It controls all the activities of the cell.

A cell is the structural and fundamental unit of life. The study of cells from its basic structure to the functions of every cell organelle is called Cell Biology. Robert Hooke was the first Biologist who discovered cells.

All organisms are made up of cells. They may be made up of a single cell (unicellular), or many cells (multicellular).  Mycoplasmas are the smallest known cells. Cells are the building blocks of all living beings. They provide structure to the body and convert the nutrients taken from the food into energy. Cells are complex, and their components perform various functions in an organism. They are of different shapes and sizes, pretty much like bricks of the buildings. Our body is made up of cells of different shapes and sizes.

Cells are the lowest level of organisation in every life form. From organism to organism, the count of cells may vary. Humans have the number of cells compared to that of bacteria. Cells comprise several cell organelles that perform specialised functions to carry out life processes. Every organelle has a specific structure. The hereditary material of the organisms is also present in the cells.

Trees in a forest, fish in a river, horseflies on a farm, lemurs in the jungle, reeds in a pond, worms in the soil — all these plants and animals are made of the building blocks we call cells. Like these examples, many living things consist of vast numbers of cells working in concert with one another. Other forms of life, however, are made of only a single cell, such as the many species of bacteria and protozoa. Cells, whether living on their own or as part of a multicellular organism, are usually too small to be seen without a light microscope.

Cells share many common features, yet they can look wildly different. In fact, cells have adapted over billions of years to a wide array of environments and functional roles. Nerve cells, for example, have long, thin extensions that can reach for meters and serve to transmit signals rapidly. Closely fitting, brick-shaped plant cells have a rigid outer layer that helps provide the structural support that trees and other plants require. Long, tapered muscle cells have an intrinsic stretchiness that allows them to change length within contracting and relaxing biceps.

As a river flows through countryside, it rarely follows a straight line, but bends and twists following the natural contours of the ground and washing away the softest soil. Water flows fastest on the outer side of the bends, causing that bank to wash away further. In the meantime, soil being carried along in the river water, called silt, is deposited on the opposite bank. Over time, especially if there is flooding, the river may cut across the neck of the bend, creating an oxbow lake beside the river.

Oxbow lakes, sometimes called horseshoe lakes, loop lakes, or cutoff lakes, get their name from their resemblance to the U-shaped collar put around the neck of an ox for plowing. Their unique shape stems from the way in which they’re formed. An oxbow lake starts out as a curve, also known as a meander, in a river. As water travels around the curve, it flows faster on the outside of the curve and slower on the inside of the curve.

This has two effects. The water on the outside of the curve eats away at the river bank in a process called erosion. The water on the inside of the curve, on the other hand, moves more slowly and leaves behind dirt, sand, silt, and other types of sediments in a process called deposition. Over time, these processes create a curve with a distinct U or crescent shape. As the processes of erosion and deposition continue, the piece of land at the narrow ends of the curve closest to the straight path of the river gets smaller and smaller.

Eventually, the river cuts a new, straight path through that small piece of land, creating a shortcut that straightens the path of the river and leaves an oxbow lake behind. When you look at a photograph of an oxbow lake from above, you can often see how it used to be simply a bend in the river. Cut off from the main river channel, oxbow lakes don’t have any water flowing into or out of them. Without sufficient rain, they may dry up completely. Many oxbow lakes that do receive some rain turn into swamps that become thriving wildlife habitats.