Question

what is cell organells?

Answer 1

DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).
The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Human DNA consists of about 3 billion bases, and more than 99 percent of those bases are the same in all people. The order, or sequence, of these bases determines the information available for building and maintaining an organism, similar to the way in which letters of the alphabet appear in a certain order to form words and sentences.
DNA bases pair up with each other, A with T and C with G, to form units called base pairs. Each base is also attached to a sugar molecule and a phosphate molecule. Together, a base, sugar, and phosphate are called a nucleotide. Nucleotides are arranged in two long strands that form a spiral called a double helix. The structure of the double helix is somewhat like a ladder, with the base pairs forming the ladder’s rungs and the sugar and phosphate molecules forming the vertical sidepieces of the ladder.
An important property of DNA is that it can replicate, or make copies of itself. Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases. This is critical when cells divide because each new cell needs to have an exact copy of the DNA present in the old cell.

DNA is a double helix formed by base pairs attached to a sugar-phosphate backbone.
For more information about DNA:
The National Human Genome Research Institute fact sheet Deoxyribonucleic Acid (DNA) provides an introduction to this molecule.
For additional information about the structure of DNA, please refer to the chapter called What Is A Genome? in the NCBI Science Primer. Scroll down to the heading “The Physical Structure of the Human Genome.”
The New Genetics, a publication of the National Institute of General Medical Sciences, discusses the structure of DNA and how it was discovered.

Answer 2

thanks aditya.

Answer 3

"Cells are the structural and functional units of all living organisms. Some organisms, such as bacteria, are unicellular, consisting of a single cell. Other organisms, such as humans, are multicellular, or have many cells"

Visit: http://www.ncbi.nlm.nih.gov/About/primer/genetics_cell.html

Answer 4

adityarockzz r u sure that it is the answer of question - WHAT IS CELL?

Answer 5

i'm not sure that that description it's the right one.

Answer 6

cells are the building blocks of life

Answer 7

The cell is the basic unit of structure and function in all living things.

Answer 8

JST RPLY

Answer 9

The organelles are the structures inside the cells like Mitochondria, ribosomes, the nucleus, etc.
Here's a good page that lists some of them and what they do: http://www.ehow.com/facts_5340983_list-cell-organelles-functions.html

adityarockzz answered great about what is DNA, why, I'm not sure.

Answer 10

THANKS LOLS

Answer 11

CELL ORGANELLES - NOTES

CELL THEORY

Cells are the basic unit of life.

The Cell Theory states that:

1) All organisms are made up of one or more cells and the products of those cells.

2) All cells carry out life activities ( require energy, grow, have a limited size).

3) New cells arise only from other living cells by the process of cell division.



THE THREE MAIN COMPONENTS OF ANY PLANT OR ANIMAL CELL ARE:

1. PLASMA MEMBRANE/ CELL MEMBRANE

Structure- a bilipid membraneous layer composed of proteins and carbohydrates. It is fluid like.

Function - the cell membrane separates the cell from its external environment, and is selectively permeable (controls what gets in and out). It protects the cell and provides stability.

Proteins are found embedded within the plasma membrane, with some extending all the way through in order to transport materials.

Carbohydrates are attached to proteins and lipids on the outer lipid layer.



2. CYTOPLASM

Structure - The jelly-like substance composed of mainly water and found between the cell membrane and nucleus. The cytoplasm makes up most of the "body" of a cell and is constantly streaming.

Function - Organelles are found here and substances like salts may be dissolved in the cytoplasm.



3. NUCLEUS

Structure - The largest organelle in the cell. It is dark and round, and is surrounded by a double membrane called the nuclear envelope/membrane. In spots the nuclear envelope fuses to form pores which are selectively permeable. The nucleus contains genetic information (DNA) on special strands called chromosomes.

Function - The nucleus is the "control center" of the cell, for cell metabolism and reproduction.



THE FOLLOWING ORGANELLES ARE FOUND IN BOTH PLANT AND ANIMAL CELLS.

1. "ER" OR ENDOPLASMIC RETICULUM

The Endoplasmic Reticulum is a network of membranous canals filled with fluid. They carry materials throughout the cell. The ER is the "transport system" of the cell.

There are two types of ER: rough ER and smooth ER.

Rough Endoplasmic Reticulum is lined with ribosomes and is rough in appearance and smooth endoplasmic reticulum contains no ribosomes and is smooth in appearance.



2. RIBOSOMES

Ribosomes are small particles which are found individually in the cytoplasm and also line the membranes of the rough endoplasmic reticulum. Ribosomes produce protein. They could be thought of as "factories" in the cell.



3. GOLGI BODY / APPARATUS

Golgi bodies are stacks of flattened membranous stacks (they look like pancakes!). The Golgi Body temporarily stores protein which can then leave the cell via vesiciles pinching off from the Golgi.



4. LYSOSOMES

Lysosomes are small sac-like structures surrounded by a single membrane and containing strong digestive enzymes which when released can break down worn out organelles or food. The lysosome is also known as a suicide sac.



5. MITOCHONDRIA

The mitochondria are round "tube-like" organelles that are surrounded by a double membrane, with the inner membrane being highly folded. the mitochondria are often referred to as the "powerhouse" of the cell. the mitochondria releases food energy from food molecules to be used by the cell. This process is called respiration. Some cells( muscle cells) require more energy than other cells and so would have many more mitochondria.



6. VACUOLES

Vacuoles are fluid filled organelles enclosed by a membrane. They can store materials such as food, water, sugar, minerals and waste products.



ANIMAL CELLS ORGANELLES NOT FOUND IN PLANT CELLS:

CILIA AND FLAGELLA

Both cilia and flagella are hair-like organelles which extend from the surface of many animal cells. the structure is identical in both, except that flagella are longer and whiplike and cilia are shorter. There are usually only a few flagella on a cell, while cilia may cover the entire surface of a cell. The function of cilia and flagella ionclude locomotion for one-celled organisms and to move substances over cell surfaces in multi-celled organisms.



ORGANELLES AND OTHER FEATURES FOUND ONLY IN PLANT CELLS:

1. CELL WALL

The cell wall is a rigid organelle composed of cellulose and lying just outside the cell membrane. The cell wall gives the plant cell it's box-like shape. it also protects the cell. The cell wall contains pores which allow materials to pass to and from the cell membrane.



2. PLASTIDS

Plastids are double membrane bound organelles. It is in plastids that plants make and store food. Plastids are found in the cytoplasm and there are two main types:

Leucoplasts - colorless organelles which store starch or other plant nutrients. ( example - starch stored in a potato)

Chromoplasts - contain different colored pigments. The most important type of chromoplast is the chloroplast, which contains the green pigment chlorophyll. This is important in the process of photosynthesis.



3. CENTRAL VACUOLE

The central vacuole is a large fluid-filled vacuole found in plants.

BACK

Answer 12

Most people probably have a general idea of what a cell is, but they might not realize all of the functions that go on inside of these microscopic spaces. Every cell has small organelles within it that perform different tasks.

Answer 13

They are small organs within the cell. For example, a mitochondria is an organelle because it carries out a specific function (making energy).

Answer 14

a specialized part of a cell; analogous to an organ; "the first organelle to be identified was the nucleus" hope this helps :)