Download organisation of living beings2016

BIOLOGY UNIT 1: Organisation of living beings
LEVELS OF ORGANISATION OF LIVING BEINGS (NIVELES DE
ORGANIZACIÓN DE LOS SERES VIVOS)
(What are organisms made of? ¿De qué estamos formados los seres vivos?)
Atoms or
elements
(Elementos
o átomos)
C
H
O
N
P
S
…
Small
biomolecules
Macromolecules
Parts
of a
cell
(Biomoléculas
Pequeñas)
(Macromoléculas)
Cells
Tissues
Organs
Systems
Organism
(Células)
(Tejidos)
(Órganos)
(Aparatos
o
sistemas)
(Individuo)
H2 O
O2
Lípid
Cell
Membrane
Neuron
Nervous
tissue
Mouth
Nervous
System
Me
Aminoacid
Protein
Cytoplasm
Glucose
Starch
Nucleous
Stomach
Muscle
cell
Muscle
tissue
Heart
Cat
Skeletal
system
Organelles
All living things and non-living things
are made up of chemical substances
(atoms and molecules). The most
abundant atoms in living beings are
carbon (C), hydrogen (H), oxygen (O) and
nitrogen (N). These four atoms make up
more than 95% of all living matter.
Atoms are linked together to make
molecules. The combinations of the atoms
C, H, O, N… form molecules of living
matter called biomolecules. There are two kinds of biomolecules: inorganic and organic:
- Inorganic biomolecules: they are present in living things and non-living things.
Inorganic biomolecules are mineral salts and water. Water is the most abundant substance
in all living things (life cannot exist without water).
- Organic biomolecules: they are unique to living things. Organic biomolecules are
glucides (example glucose and starch), lipids (example fats and cholesterol), proteins and
nucleic acids (DNA and RNA).
Small molecules can join together to form
macromolecules, these can join together to form the
parts of a cell: cell membrane, nucleus (contains the
genetic material) and cytoplasm with organelles, each
organelle performs a specific function, for example
mitochondrias produce energy, ribosomes synthesize
proteins and chloroplasts (only in plant cells) elaborate
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snail
organic matter through photosynthesis. Exercise: What do all cells have in common?
The cell is the basic structural and functional unit of an organism. Structural because all
living beings are made up of one (unicellular organism) or more cells (multicellular
organism) and functional because every cell can carry out all the functions of living
organisms (interaction, nutrition and reproduction). Exercise: Explain examples of a human
cell performing the 3 vital functions: interaction, nutrition and reproduction.
Tissues are groups of cells of the same type that perform a specific function. Exercise:
Explain the examples of nervous tissue and muscle tissue.
Organs are groups of tissues that
perform a specific function. Exercise: Is
the hand an organ? Explain your
answer.
Systems are groups of organs that perform a specific function. Read and repeat the
following sentences:
Digestion
Respiration
takes place in
Circulation
Excretion
is carried out by
Reproduction
Movement
Coordination of all organs and systems
The defence of our body
the digestive system
the respiratory system
the circulatory system
the excretory system
the reproductive system
the muscular and skeletal systems
the nervous and endocrine systems
the immune system
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PARTS OF A HUMAN CELL
All cells have in common a cell membrane that separates the interior of all cells from the
outside environment, a genetic material (DNA) responsible for controlling the cell’s activity and a
cytoplasm with organelles, each organelle performs a specific function. Most organelles are bound
by a single or double membrane and a few are non-membrane organelles (ribosomes, cytoskeleton
and centrioles). The animal cells (included human cells) have a nucleus that contains the genetic
information and the following organelles:
- Ribosomes: they are small non-membranous organelles that are responsible for producing
proteins. They are found either moving freely in the cytoplasm or attached to the endoplasmic
reticulum.
- Mitochondrias: they contain a double membrane and are responsible for producing energy
through cellular respiration. Cellular respiration is a set chemical reactions that produce energy
using oxygen (we obtain oxygen through the respiratory system) to break down nutrients
(carbohydrates, lipids and proteins that we obtain from food through the digestive system). During
the cellular respiration the energy stored in the nutrients is released but carbon dioxide (CO2) is
produced as a waste product (we eliminate CO2 through the respiratory system).
Cellular Respiration: Organic matter + O2 → CO2 + H2O + Energy
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Exercise: Why do we breathe? Or Why do we die if we stop breathing?
- Endoplasmic reticulum: this organelle is a network of interconnected sacs and channels
with a single membrane. It manufactures a variety of substances. There are two types:
o Rough endoplasmic reticulum: it has ribosomes attached on its membrane that
manufactures proteins.
o Smooth endoplasmic reticulum: it does not contain ribosomes and
manufactures lipids.
- Golgi apparatus: it receives proteins and lipids
(fats) from the endoplasmic reticulum (through transport
vesicles). It modifies some of them, concentrates and packs
them into vesicles. These vesicles send the substances to
different destinations (secretory vesicles) such as the cell
membrane or outside of the cell (secretion function).
- Lysosomes: they are vesicles from the Golgi apparatus with a digestive function (they contain
digestive enzymes to break down biomolecules)
- Cytoskeleton: this non-membranous organelle is a network of filaments that supports
organelles and cell shape and plays a role in cell motion.
- Centrioles: these non-membranous organelles direct the movement of the elements of the
cytoskeleton.
PARTS OF THE NUCLEUS: The nucleus has a double membrane with nuclear pores that
are openings that regulate the passage of substances into and out of the nucleus. The genetic
information (ADN) is packaged with proteins forming the chromatin that looks like long fibres
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inside the nucleus. These fibres are condensed
into chromosomes when a cell prepares to
undergo cell division in order to become two
daughter cells.
Exercise: Identify the parts of a cell numbered.
CELL SPECIALISATION
All our body cells have the same genetic information (ADN) because all of the cells derive
from an initial cell, the cell embryo or zygote (the zygote starts dividing into cells that in turn divide again.
Millions of divisions then we will have developed a body composed of millions of cells that have the same genetic
information as in the zygote). At the beginning the cells that derive from the zygote are stem cells
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(unspecialised cells) that can divide and develop into specialised cells with a specific function such
as neurons or muscle cells… Differentiation is the process of cells becoming specialised . A group of
specialised cells of the same type that perform their specialised function is a tissue. Every tissue has
one type of specialised cells and performs its specialised function.
If all our body cells have the same genetic information, why do different specialised cells
have different shape and perform different functions? Because each type of specialised cell only use
the genetic information that they need to perform their specialised function and shape.
TYPES OF TISSUES
All the cells in our body belong to one of the four basic types of tissue: nervous, muscular,
epithelial and connective.
NERVOUS TISSUE: The nervous tissue is found in the brain, the spinal cord and the nerves.
The neuron is its fundamental cell type. Neurons transmit information using electrical signals called
nerve impulses.
MUSCLE TISSUE: This tissue is the predominant component of muscles and enables the
movement of our body. The cells are elongated and are called muscular fibres. There are three types
of muscle tissue:
- Striated muscle tissue joins bones and contracts voluntarily.
- Cardiac muscle tissue makes up the walls of the heart and contracts involuntarily.
- Smooth muscle tissue move internal involuntary organs such as the stomach.
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