( From smallest to the biggest)


- Atom: the smallest structure. It has positive, negatives and neutral charge.

-Chemical elements: they are a lot of atoms together. There are metallic and non metallic. For example: Hydrogen, Oxygen, Phosphorus…).

-Molecule: when we put some elements together (H2O, HCl…).

-Macromolecule: they are a lot of molecules together (lipids, proteins, carbohydrates…).

-Cell: the smallest structure that can do the 3 vital functions.

-Tissue: a lot of cells together. All the cells have the same function and the same origin in each tissue (muscle tissue, bone tissue…).

-Organs: They are created by tissues. All the organs have different functions but all of them are coordinated (earth, stomach…).


This theory is based on different principles:

A cell is the basic structural and functional unit in all organisms

It is the smallest structure that can do the three vital functions: nutrition, interaction and reproduction.

           Cells only can be created from other cells


To be a living organisms they must done 3 vital functions:

-Nutrition;transformthe substance we need to stay alive.

-Reproduction:involes both male and female reproductiove organs.

-Interaction:involes several systems and organs



-Number of cells: Unicellular (one cell) or multicellular (more than one cell).

-Type of cells: Prokaryotes(without nucleus)or Eukaryotes (with nucleus).

-Type of nutrition: Heterotrophic (they obtein nutrients from organic compounds) or Autotrophic(they obtain nutrients from inorganic compounds).


A-Number of cells

UNICELLULAR: Microscopic 1 cell MULTICELLULAR: MacroscopicMore than 1 cell

B-Type of cells

PROKARYOTES: Without nucleus EUKARYOTES: With nucleus

C-Type of nutrition


-They use inorganic compounds to get energy.

-Transform inorganic compounds to organic compounds (It is called photosynthesis, and it is done in chloroplasts.



-They use organic compounds to get energy.

-Transform organic compounds to inorganic compounds (It is called cellular respiration, and it is done in mitochondrion.


D-Type of reproduction


-They make an identical copy. For example: Plants, Stars…

-They do that by mitosis: The mother cell, divides into two daughter cells. Both have the same genetic information (the same DNA and the same number of chromosomes).

SEXUAL: They make a not identical copy. For example: Humans, Dogs…Parents (a female and male) are involved.Each parent has a different type of gametes (females gamete is ovum and male gametes sperm) and when they are mixed, it is created a zygote..


3main functions.

All of them are made up of cells.

The same basic structure inside the cell.

All the living things have cells.


All the living things have cells.

Each cell is different, however, all of them have them same basic structure


All the living things have cells.

Each cell is different, however, all of them have them same basic structure..

Cell membrane: its a thin layer that separated the external environment from the internal. Functions:

  • Protect the cell

  • Control the cellular growth.

  • Transport food.

  • Interaction with the environment.     

4.5TRANSPORTING PRODUCTS:/small molecules-difussion, active transport/ big molecules-endocytosis, exocytosis


All the living things have cells.

Each cell is different, however, all of them have them same basic structure.

Nucleus: genetic material is inside of it. It has the necessary information to control the cell´s functions. Only Eukaryotic cells has a nucleus. Inside it appears chromatin. (nukleus,Creating chromosomes,Be aware!)


All the living things have cells.

Each cell is different, however, all of them have them same basic structure.

Cytoplasm: its a viscose medium or substance inside the cell. It has some structures called organelles (organelles are especial compartments where most chemical functions happen).(procaryotic cells,eukaryotic cells)


All cells do 3 important functions:

-Nutrition (Respiration).cells obtain the material and energy they need to make their own cellular matter and to carry out their activities.

-Interaction.cells interact with the exterior.

-Reproduction (mitosis). cellular reproduction is a proces through which, starting from an initial cell,two new or daughter cells are obained, which  are identicalvto the mother cell

Nutrition (Respiration)


-They use oxygen.

-They obtain more energy.


-They don´t use oxygen.

-They obtain less energy.


Cells interact with their environment. When the environment changes, the cells detect those changes.

This variations or changes are known as stimuli  and the reactions as a responds.

So, cells respond to stimulis normally using movements.

Two types of movements: toward the stimulus (positive response) or away from the stimulus (negative response).

In order to move, they use cilia, flagella, pseudopods or contractions.

5.2 Reproduction


From one cell, are obtained two.

Two daughters are identical to the mother cell.

They obtain more energy.

They both have the same genetic information (the same DNA and the same number of chromosomes).




6.1 covering tissues:

  • covers body surfaces; lines body cavities, hollow organs, and ducts; and forms glandspes:

- epithelial tissues: for eample the epidermis of skin.

- Glandular tissues: for example tyroid tissues.

6.2 connective tissues:

  • hey are fibrous tissues.

  • Connective tissue gives shape to organs and holds them in place.

  • Types:Conjuntive tissues: it´s to join other tissues together.

Adipose tissues: fats.

Cartilaginous tissue: tosupport

- Bone tissue: They form bones.

  • Example: Blood, bone, tendon, ligament, adipose and areolar tissues

6.3 muscular tissues:

  • responsible for movement.

  • 3 types:

Smooth: slow and involuntary muscular tissue,Withone nucleus in their cells.

Striated: rapid and voluntary tissue. With many nucleus in their cells.

Cardiac: in the heart

6.4 blood tissues:

  • Blood tissues are found inside the blood vessels (arteries,arterioles, capillaries, venules and veins) and also with the chambers of the heart.

  • It is a liquid tissue.

6.5 nerve tissues:

  • initiates and transmits nerve impulses that coordinate body activities. So detects the external stimuli and transmit a response.

  • For example: tissues from brain and spinal cord.