Departamento de Biología y Geología

Departamento de Biología y Geología

Living organisms

Natural Science 2nd grade ESO

UNIT 1

The Biosphere are all the living thingswhich inhabit the Earth

frog mushroom

tulips

Science devoted to the study of living things is BIOLOGY

mushroom

Tasmania devil

A living thing is an organism that is…

1 - able to perform the three vital functions.

2 - made up of specific inorganic and organic substances (certain chemical composition).

3 - organized in CELLS.

1- performing the three vital functions:

• NUTRITION: consist of taking substances from the environment and using them for growth, energy, repair and waste elimination.

(Autotrophs vs heterotrophs)

• INTERACTION consists on perceiving changes in the environment (stimuli) and reacting to them.

1- performing the three vital functions:

• REPRODUCTION is the capacity that living things have to produce descendents with the same characteristics.

1- performing the three vital functions:

• Inorganic substances:– water– mineral salts

• Organic substances: – glucids (like glucose or cellulose),– lipids (fatty acids and cholesterol), – proteins (hemoglobin) – nucleic acids (DNA or RNA)

2- being made up of:

organism

tissue

cell

3- being organized in CELLS.

A cell is the BASIC UNIT OF LIFE that can perform the three vital functions.

Unicellular & Multicellular

• Unicellular living things have only one cell.

• Multicellular living things have many different cells.

Multicellular organisms

• The cells work together as a whole.

• There are different levels of organisation, depending on whether they have tissues, organs or systems.

THE FIVE KINGDOMS

• MONERA kingdom• PROTOCTIST kingdom• FUNGI kingdom• PLANT kingdom• ANIMAL kingdom

CELL STRUCTURE• Plasmatic membrane:

– is a thin and elastic external cover. – is composed by lipids and proteins.

*Also called plasma membrane.

• Cytoplasm: – is a liquid substance that fills cell’s interior.– is a jelly-like substance with water and different molecules

(glucids, lipids, proteins).

– is where take place the chemical reactions, necessary for CELLULAR FUNCTIONING.

– is where there are some structures, ORGANELLES (they perform many specific functions).

CELL STRUCTURE

• DNA: – is the genetic material (it contains the genetic

information).

– is a nucleic acid (with attached proteins): it is divided in units called chromosomes.

– depending on the placement of DNA, cells can be classified into:

_ prokaryotic cells and,

_ eukaryotic cells.

PROKARYOTIC CELLS

• They are very simple and very small• They lack organelles (with the exception of

RIBOSOMES) • They have another external cover outside the

plasmatic membrane: the CELLULAR WALL • Some use flagellum or pili to move• There are differences in the type of nutrition:

there are autotrophs and heterotrophs

DNA is placed in the cytoplasm

Smaller than eukaryotic cells (around 1μ m )

PROKARYOTIC CELLS

• They are bacteria

• All of them belong to the MONERA kingdom

Vibrio cholerae

Escherichia coli

Lactobacillus casei

Spirulina sp.

*µm: micrometre or micron.

EUKARYOTIC CELLS

• The NUCLEUS is a compartment with a double cover: NUCLEAR MEMBRANE.

• They are more complex cells and bigger than prokaryotic cells.

• They have a great variety of organelles.

DNA is placed in the nucleus

Usual average of human cells is between 10 and 100 μ m

Plasma membrane

Cellularwall

Golgiapparatus

Mitochondrion

NucleusEndoplasmic reticulum

Vacuole

Chloroplast

• Ribosomes (they form proteins). • Endoplasmic reticulum is related with the

ribosomes (they store the proteins).• Golgi apparatus packages proteins inside the cell

before they are sent to their destination. • Mitochondria (it produces energy).• Centrioles (exclusive for animal cell) they take

part in cell division and they control the movement of cilia and flagella.

• Lysosomes (they digest food).

EUKARYOTIC CELLS

• Chloroplasts (exclusive for plant cell) they perform photosynthesis thanks to a green molecule called chlorophyll.

• The vacuoles (very common in plant cells) usually are use for the storage of different substances.

• The cellular wall is exclusive for plant cells and it contains cellulose.

EUKARYOTIC CELLS

• The DNA is inside and could be condensed as chromosomes.

• DNA could be not condensed as chromatin.• The nucleolus is related with the formation of

ribosomes.• The nucleus has a double membrane with pores.

https://www.youtube.com/watch?v=9kQpYdCnU14

EUKARYOTIC CELLS

THE NUCLEUS

EUKARYOTIC CELLS

• There are some differences between the eukaryotic cells of different organisms.– Different organelles that they have.– Different types of nutrition.

• This is the cell of the remaining four Kingdoms: – PROTOCTIST, – FUNGI, – ANIMALS and– PLANTS

• The main types of eukaryotic cells are:– animal cells – plant cells

EUKARYOTIC CELLS

neuron Red blood cells Sperm cell

Bone cellsMuscle cells

Anton van Leeuwenhoek

1632-1723

Robert Hooke

1635-1703

Cella

Schleiden Schwann Virchow

https://www.youtube.com/watch?v=4OpBylwH9DU

The CELL THEORY

All organisms are composed by cellsCells are the basic unit of structure and function in organismsAll cells come from preexisting cells

Omnis cellula e cellula

Santiago Ramón y Cajal

1852-1934

1906 Nobel Prize

Neuron theory

-Nervous system is composed also by cells called neurons.-Cell theory was proven also with the case of nervous tissues.