How the living matter is organized

1.- Levels of organization2.- What are living beings made of?3.- Cell structure and function

The organization of lifeLiving matter is very complex. This is one of the characteristics which most differenciates it from inert or inanimate matter. We can discover several levels of complexity which are known as Levels of organization. Each level of organization gives the matter which makes it up certain properties which cannot be found in lower levels.

Types of levels of organizationWe can find the following levels of organization in living matter:

Atom: is the smallest particle that mantains its physical and chemical properties. Ex: oxygen, nitrogen.Molecule: when two or more atoms are bonded together. Ex: water, carbon dioxide. Macromolecule: when two or more molecules are bonded together to form large molecules. Ex: proteins, lipids, carbohydrates. Organelles: several macromolecules bonded together form these building blocks of a cell. Ex: mitochondria, nucleus.

Cells: the smallest unit of life, a cell is a collection of organelles functioning together. Ex: bacteria, animal, plant cell.Tissues: a collection of cells working together to perform a specific job. Ex: epithelial, connective.Organs: two or more types of tissues that work together to complete a specific task. Ex: heart, stomach.Systems: several organs working in unison to achieve a common goal. Ex: digestive, cardiovascular.Organism: several organ systems functioning together. Ex: human.Population: groups of individual organisms of the same species living in the same zone and at the same time. Ex: a swarm of bees. Community: populations of different species of organisms.Ecosystem: the physical components of environment (abiotic factors), all organisms living in an area (biotic factors) and their interactions. Ex: a tropical rain forest.Biome: a collection of ecosystems with similar climates. Ex: desert, tundra.Biosphere: all tha biomes on the planet Earth. Ex: the Earth`s living occupants.

1.- Levels of organization

Below this level begins what scientists consider living or alive

1 Å (angstrom) = 0,1 nm1 nm (nanometre) = 0,001 µm1µm (micron) = 0,001 mm1mm = 0,001 m1 m = 0,001 Km

Scale of life: from the smallest to the biggest

Units of measurement for the levels of organization

2.- What are living beings made of?

Chemical compounds in cellsElements: an element is any substance that cannot be broken down into simpler substances. Oxygen and nitrogen are examples of elements. The smallest unit of an element is called atom. An element is made up of only one kind of atom. The elements found in living things include carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur.

Compounds: when two or more elements combine chemically, they form a compound. Carbon dioxide is a compound made up of the elements carbon and oxygen. Most elements in living things occur in the form of compounds. The smallest unit of many compounds is called a molecule. A molecule of carbon dioxide consists of one carbon atom and two oxygen atoms. Water is another compound. Each water molecule is made up of two hydrogen atoms and one oxygen atom.

Organic and Inorganic Compounds: many of the compounds found in living things contain the elelment carbon. Most compounds that contain carbon are called organic compounds. Some important groups of organic compounds found in living things are carbohydrates, lipids, proteins, and nucleic acids. As you know, many of these compounds are found in the foods you eat. This is not surprising, since the foods you eat come from living things. Compounds that don´t contain the element carbon are called inorganic compounds. Water and sodium chloride (table salt), are familiar examples of inorganic compounds. Organisms contain many inorganic compounds as well as organic compounds.

Oxygen

Hydrogen

Water Molecule

A water molecule is made up of one atom of oxygen and two atoms of hydrogen.

Oxygen

Carbon

Carbon Dioxide Molecule

The air bubbles contain carbon dioxide. A carbon dioxide molecule has one atom of carbon and two atoms of oxygen.

Inorganic compounds1. Water

There is no life without water. In fact, more than half of our body is liquid water. Some beings, like jelly fish, are made up of 96 % of water, whereas seeds only have 20 %.

Water palys many important roles in cells. For example, most chemical reactions in cells involve substances that are disolved in water. Also, water molecules themselves take part in many chemical reactions in cells. Most chemical reactions within cells could not take place without water.

Water also helps cells keep their size and shape. In fact, a cell without water would be like a balloon without air. In addition, because water changes temperature slowly, it helps keep the temperature of cells from changing rapidily.

Mostly waterAbout two-thirds of the human body is water.

2. Mineral salts

They make up the hard and solid parts of living beings (skeletons and shells).Many mineral salts are in dissolutions in the form of ions and they take part in chemical

reactions.They maintain the salinity of the body.They allow the transmission of nervous impulses.They form part of significant molecules such as hemoglobin.

SkeletonsThey are made up of a mineral salt known as calcium phosphate.

Shells of molluscsThey are made up of a mineral salt known as calcium carbonate.

Organic compounds1. CarbohydratesThey are organic compounds of carbon, hydrogen and oxygen.

Functions of carbohydrates:

Primary among those is that they serve as energy sources for both plants and animals

Source of carbon in metabolic processes

Storage form of energyStructural elements of cells and

tissues

On the basis of the chemical complexity carbohydrates areclassified as ...

Monosaccharides: a single unit of sugar (simple sugars), they are the smallest carbohydrates. The common monosaccharides are:

Disaccharides: are formed by two monosaccharides linked together (double sugars). The common disaccharides are:

Glucose (C6H12O6): it is the main sugar used by cells to produce energy and it is often referred to as blood sugar.

Fructose / Galactose: both are absorbed and converted into glucose by the liver. Sources of fructose include fruit and honey.

Ribose: ribose and its related deoxyribose are the building blocks of nucleic acids (RNA and DNA).

Polysaccharides: formed of long chains of monosaccharide units linked together. The common polysaccharides are: starch (storage form of energy in plants made up of glucose units), glycogen (storage form of energy in animals made up of many glucose units), cellulose ( it is a constituent of plant cell walls and it is not digestable because we lack enzymes for it). Chitin ( some insects make their skeletons with this carbohydrate).

Lactose: it is found in the milk. It has a glucose and a galactosesugar.

Maltose: it is composed of two glucose molecules. It is known as beer sugar.

Sucrose: it is composed ofglucose and fructose. It is the table sugar.

DNAmolecule

sugar

bases

Phosphategroup

2. LipidsLipids are a group of very different substances, including oils, fats, waxes, cholesterol.They are organic compounds of carbon, hydrogen, oxygen and, in some cases, small amounts of phosphorous.

Functions of lipids:

Like carbohydrates, lipids are energy-rich organic compounds. Lipids contain even more energy than carbohydrates. Cells store energy in lipids for later use.

They are structural elements of cells. Cell membranes are made mainly of lipids.

3. ProteinsThey are large organic molecules made of of carbon, hydrogen, oxygen, nitogen, and, in some cases, sulfur. Protein molecules are made up of smaller molecules called amino acids. Although there are only 20 common amino acids, cells can combine them in different ways to form thousands of different proteins.

Functions of proteins:

Much of the structure of cells is made up of proteins. Proteins form parts of cell membranes. Proteins also make up many of the organelles within the cell.

The proteins known as enzymes perform important functions in the chemical reactions that take place in cells. An enzyme is a type of protein that speeds up a chemical reaction in a living thing.

They carry substances from one part of the body to another. For example, haemoglobin transprts oxygen in the blood.

Inmune protection: the antibodies that allow us to defend ourselves from viruses and bacteria are proteins.

4. Nucleic AcidsNucleic acids are very long organicmolecules made of carbon, hydrogen, oxygen, nitrogen and phosphorous. Nucleic acids contain the instructions that cells need to carry out all the functions of life.There are two kinds of nucleic acids. Deoxyribonucleic acid, or DNA, is the genetic material that carries information about an organism and is passed from parent to offspring. The information in DNA also directs all the cell`s functions. Most of the DNA in a cell is found in the chromatin in the nucleus. Ribonucleic acid, or RNA, plays an important role in the production of proteins. RNA is found in the cytoplasm as well as in the nucleus.

Chain of amino acids

Protein molecule

3.- Cell Structure and function

An overview of cellsYou are made of cells. All living things are made up of one or more cells. Cells are the smallest units of structure and function in living things. This means that cells form the parts of an organism and carry out all of an organism’s processes, or functions. Some functions in organisms include:

Obtain food and oxygenPerform chemical reactions (make energy)Eliminate carbon dioxide and wastesSynthesize proteins and cell componentsControl exchange of materialsAdapt, respond to environmental changesReproduce (except nerve and muscle)

Cells are involved in all these functions.

Organisms that exist as single cells are called unicellular and organisms that are made up of groups of cells working together are called multicellular.

Principles of the Cell Theory:

All living things are made of one or more cells.

Cells are the basic unit of structure and function in organisms

Cells come only from the reproduction of existing cells.

ProkaryoticSimple cellsSmall cellsDo not have a nucleus No membrane-bound organellesMore primitive than eukaryoticThey only form unicellular organismsEx: bacteria

EukaryoticComplex cellsLarger cellsDo have a true nucleusMembrane-bound organellesEvolved from ProkaryoticThey can form both unicellular and multicellular

organismsEx: animal, plant, fungi, protozoans

Types of cellsThere are several ways to classify cells, but the main division is between prokaryotic and eukaryotic cells. There are big differences between them:

Prokaryotic Cell

Animal (Eukaryotic) Cell

Looking inside cellsAll cells contain three basic parts:

Cell membrane: forms the outside boundary of the cell.Nucleus: the cell’s control center, directing all of the cell’s

activities.Cytoplasm: a gel-like fluid between the cell membrane

and the nucleus. Many cell’s specialized structures or cell organelles are found in the cytoplasm.

Enter the cellCell Membrane:

It surrounds the cell and separates the cytoplasm of the cell from its environment.Protects the cell and controls what enters and leaves. Cell membranes are

selectively permeable only allowing certain materials to enter or leave. Food and oxygen enter the cell through the cell membrane. Harmful waste products leave the cell through the cell membrane. It also prevents harmful materials from entering the cell.

It is made up of lipids and proteins.

Cell Wall:

The cell wall is a rigid layer that surrounds the cell membrane of plant cells and prokaryotic cells (bacteria). It is made mostly of a strong material called cellulose. The cell wall provides and maintains the shape of these cells and serves as a protective barrier.

Cell Membrane

The cell membrane is made up of two lipid layers

A channel in the cell membrane. It is made up of certain proteins whose function is to control the movement of food and water into the cell.

The NucleusThis is the largest and most easily visible structure in a cell. As you sail inside the cell, a large, oval structure comes into view. This structure acts as the “brain” of the cell.

Nuclear envelope: notice in figure that the nucleus is surrounded by a membrane called the nuclear envelope.It is a double-membrane structure that protects the nucleus. Materials pass in and out of the nucleus through pores in the nuclear envelope.

Nucleolus: This is a spherical structure in which ribosomes are made. Ribosomes are the organelles where proteins are produced. Proteins are important chemicals in cells.

Nucleoplasm: the viscous liquid within nucleus. It is similar to the cytoplasm found outside the nucleus. It contains the chromatin, which is composed of DNA and proteins.The chains of DNA contain the genetic information of the cell, in other words, instrunctions for carrying out the cell’s activities.

Organelles in the cytoplasmMitochondria: most of the cell’s energy is produced within these rod—shaped organelles. They convert energy in food molecules to energy the cell can use to carry out its functions.

Endoplasmic Reticulum: a network of membranes that stores, separates and transports substances within the cell.

Rough Endoplasmic Reticulum: close to the nucleus and in contact with the nuclear envelope. It has ribosomes attached to its membranes and makes proteins to be secreted by the cell.

Smooth Endoplasmic Reticulum: more distant from the nucleus and with no ribosomes. It makes lipids, processes carbohydrates and modifies toxic chemicals in the cell.

Ribosomes: these small tiny ball-like structures function as factories toproduce proteins. Ribosomes may be attached to the Endopalsmic Reticulum, or they may float in the cytoplasm.

Golgi Apparatus: flattened sacs and tubes where protein molecules arestored, changed, packaged and distributed throughout the cell.

Chloroplasts: only the cells of plants and some other organisms have these organelles. Green oval-shaped structures that capture energy from sunlight and use it to produce food for the cell (photosynthesis). Chloroplasts make leaves green.

Vacuoles: large water-filled sacs floating in the cytoplasm. They are the storage areas of cells. Most plant cells have one large vacuole. Some animal cells do not have vacuoles; others do. Vacuoles store food and other materials needed by the cell. Vacuoles can also store waste products.

Lysosomes: are small, round structures containing chemicals that break down certain materials in the cell.

Chloroplasts

Endoplasmic Reticulum

GolgiApparatus

Mitochondria

Ribosomes

Plant and Animal Cells