2. Natural Science 2nd grade ESO
UNIT 1
Living organisms
Departamento de
Biología y Geología
3. The Biosphere are all the living things
which inhabit the Earth
frog
mushroom
tulips
4. Science devoted to the study
of living things is BIOLOGY
Tasmania devil
mushroom
5. 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.
6. 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)
7. 1- performing the three vital functions:
• INTERACTION consists on perceiving
changes in the environment (stimuli) and
reacting to them.
8. 1- performing the three vital functions:
• REPRODUCTION is the capacity that
living things have to produce descendents
with the same characteristics.
9. 2- being made up of:
• Inorganic substances:
– water
– mineral salts
• Organic substances:
– glucids (like glucose or cellulose),
– lipids (fatty acids and cholesterol),
– proteins (hemoglobin)
– nucleic acids (DNA or RNA)
10. 3- being organized in CELLS.
A cell is the BASIC UNIT OF LIFE that can
perform the three vital functions.
tissue
cell
organism
11. Unicellular & Multicellular
• Unicellular living
things have only one
cell.
• Multicellular living
things have many
different cells.
12. Multicellular organisms
• The cells work together as a whole.
• There are different levels of organisation,
depending on whether they have tissues,
organs or systems.
16. 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).
17. 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.
18. PROKARYOTIC CELLS
DNA is placed in the cytoplasm
• 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
27. EUKARYOTIC CELLS
DNA is placed in the nucleus
• 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.
32. EUKARYOTIC CELLS
• 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).
33. 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.
34. EUKARYOTIC CELLS
THE NUCLEUS
• 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
35.
36.
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38. 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
54. The CELL THEORY
All organisms are composed by cells
Cells are the basic unit of structure
and function in organisms
All cells come from preexisting cells
Omnis cellula e cellula