biology cell organelles

Properties of Lipids

Many of these have oily fatty acid chains attached to chemical groups that interact strongly with water. The fatty acid portions of these are hydrophobic or water-hating, while the opposite end of the molecule is hydrophillic or water-loving. When these are mixed with water, their hydrophobic fatty acid tails cluster together while their hydrophillic heads are attracted to water. A bilayer of this is the result. The head groups are exposed to water while the fatty acid tails form an oily layer inside the membrane from which water is excluded.

Chromosomes

contain the genetic information that is passed from one generation of cells to the next. Most of the time, these threadlike things are spread throughout the nucleus in the firm of chromatin- a complex of DNA bound to proteins. When a cell divides, these things of theirs condense and can be seen under s microscope.

The nuclear envelope

dotted with thousands of nuclear pores which allow material to move in and out of the nucleus. Like messages, instructions, and blueprints moving in and out of a main office a steady stream of proteins, RNA, and other molecules move through the nuclear pores to and from the rest of the cell.

golgi complex or apparatus

proteins produced in the rough ER move next into it. The proteins are bundled into tiny vesicles that bud from the ER and carry them to this. It modifies, sorts, and packages proteins and other materials from the ER for storage in the cell or release outside the cell. It is somewhat like a customization shop where the finishing touches are put on proteins before they are ready to leavethe "factory". From this, proteins are "shipped" to their final destination inside or outside the cell. stack of pancakes or wifi symbol

cell membrane

something in all cells that regulates what enters and leaves the cell and also protects and supports the cell. The composition of nearly all cell membranes is a double layered sheet called a lipid bilayer which gives cell membranes a flexible structure and forms a strong barrier between the cell and its surroundings.

Centrioles

structures found in animal cells are also formed from tubulins. These are located near the nucleus and help to organize cell division. They are not found in plant cells.

chloroplast

the biological equivalents of solar power plants. They capture the energy from sunlight and convert it into food that contains chemical energy in a process called photosynthesis. Plants and other organisms contain this. Two membranes surround this. Inside the organelle are large stacks of other membranes which contain the green pigment chlorophyll.

cytoplasm

the fluid portion of the cell outside of the nucleus. Prokaryotic cells have this as well, even though they do not have a nucleus.

cell wall

the main function of this is to provide support and protection for the cell. Prokaryotes, plants,algae, and fungi have this. Animal cells do not have this. They lie outside the cell membrane and most are porous enough to allow water, oxygen, carbon dioxide, and certain other substances to pass through easily.

nuclear membrane

the membrane surrounding the nucleus

smooth endoplasmic reticulum

the other portion of the ER is known as this because ribosomes are not found on its surface. In many cells this contains collections of enzymes that perform specialized tasks, including the synthesis of membrane lipids and the detoxification of drugs.

rough endoplasmic reticulum

the portion of the ER involved in the synthesis of proteins is called this because ribosomes are found on its surface. Newly made proteins leave these ribosomes and are inserted into this where they may be chemically modified.

Microfilaments

threadlike structures made up of a protein called actin. They form extensive networks in some cells and produce a tough, flexible framework that supports the cell. They also help cells move. Assembly and disassembly of this is responsible for the cytoplasmic movements that allow cells, such as amoebas, to crawl along surfaces.

Vesicles

Nearly all eukaryotic cells contain smaller membrane-enclosed structures called this. These are used to store and move materials between cell organelles, as well as to and from the cell surface.

nucleus

This contains nearly all of the cells DNA and with it the coded instructions for making proteins and other important molecules. It is surrounded by a nuclear envelope composed of two membranes.

Cell organization

This contains nearly all of the cells DNA and with it the coded instructions for making proteins and other important molecules. The eukaryotic cell can be divided into two major parts; the nucleus and the cytoplasm. Many cellular structures act as if they are specialized organs.These structures are known as organelles, literally little organs. Understanding what each organelle does will help us to understand the cell as a whole.

vacuole

a large, sac like, membrane-enclosed structure that stores materials such as water, salts, proteins, and carbohydrates. They're found in many plant cells as a single, central, large one filled with liquid. They're also found in some unicellular organisms and some animals. The pressure of this central thing in these cells helps to increase their rigidity, making it possible to support heavy structures such as leaves and flowers. The paramecium contains an organelle called a contractile this. By contracting rhythmically, this specialized thing pumps excess water out of the cell.

Cellular boundaries

a working factory has walls and a roof to protect it from the enviroment outside, and also to serve as a barrier that keeps its products safe and secure until they're ready to be shipped out. Similarly, cells are surrounded by a barrier better known as the cell membrane.

Organelles that capture and release energy

all living things require a source of energy. Most cells are powered by food molecules that are built using energy from the sun. Chloroplasts and mitochondria are both involved in energy conversion processes within the cell.

Organelles that build proteins

cells need to build new molecules all the time, especially proteins which catalyze chemical reactions and make up important structures in the cell. Because proteins carry out so many of the essential functions of living things, a big part pf the cell is devoted to their production and distribution. Proteins are synthesized on ribosomes, sometimes in association with the rough endoplasmic reticulum in eukaruotes.

cytoskeleton

eukaryotic cells are given their shape and internal organization by a network of protein filaments known as this. Certain parts of this also help to transport materials between different parts of the cell, much like a conveyor belt that carries materials from one part of a factory to another. Microfilaments and microtubules are two of the principal protein filaments that make up this.

endoplasmic reticulum

eukaryotic cells contain an internal membrane known as this or ER. This is where lipid components of the cell membrane are assembled, along with proteins and other materials that are exported from the cell.

Microtubulin

hollow structures made up of proteins known as tubulins. They play critical roles in maintaining cell shape. These are also important in cell division, where they form a structure known as the micotic spindle, which helps to separate chromosomes. They help to build projections from the cell surface which are known as cilia and flagella that enable cells to swim rapidly through liquids. They're arranged in a 9+2 pattern.

mitochondria

nearly all eukaryotic cells including plants contain this. They are the power plants of the cell. They convert the chemical energy stored in food into compounds that are more convenient for the cell to use. Two membranes, an outer and an inner enclose this. The inner membrane is folded up inside the organelle. One of the most interseting aspects of the this is the way this is inherited. In humans, all or nearly all of our these come from the cytoplasm of the ovum or egg cell. You get your these from mom. Chloroplasts and this contain their own genetic information in the form of small DNA molecues. The endosymbiotic theory suggests that chloroplasts and this may have descended from independent microorganisms. Powerhouse of the cell

plant cells have

ribosomes, golgi complex, cytoplasm, nucleus, nucleolus, nuclear membrane, cell membrane, cell wall, mitochondria, rough endoplasmic reticulum, smooth endoplsmic reticulum, vacuoles, and chloroplast

lysosome

small organelles filled with enzymes that function as the cell's cleanup crew. They perform the vital function of removing junk from that might otherwise accumulate and clutter up the cell. One function is to break down lipids, carbohydrates, and proteins into small molecules that can be used by the rest of the cell. They're also involved in breaking down organelles that have outlived their usefulness.

ribosome

small particles of RNA and protein found throughout the cytoplasm in all cells. They produce proteins by following coded instructions that come from DNA. Each is like a small machine in a factory, turning out proteins on orders that come from its DNA "the boss".

Comparing the cell to a factory

the eukaryotic cell is much like a modern version of a factory. Specialized machines and assembly lines of the factory can be compared to the different organelles of the cell.

Organelles that store, cleanup, and support

vacuoles and vessicles, lysosomes, the cytoskeleton, microfilaments, and mirotubulins

animal cells have

vacuoles, lysosomes, ribosomes, gogli complex, cytoplasm, nucleus, nucleolus, nuclear membrane, cell membrane, mitochondria, smooth endoplasmic reticulum, rough endoplasmic reticulum, and centrioles.

nucleolus

where the assembly of ribosomes begins. A small, dense region contained in the nucleus.