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Biology and Geology
ESO 3
YEAR 2014-15
unit 1: Cells and tissues
HUMANS AS MULTICELLULAR ORGANISM
A CELL
It is the smallest unit of a living thing capable
of performing the three vital functions:
- nutrition
- interaction
- reproduction
There are two types of living things
Unicellular organism(colonies)
Multicellular organism
Levels of organisation
Cells
Tissues
Organs
Systems
The organism
Levels of organization in humans
TYPES OF CELLS
Clasify the type of cell by looking where the
genetic material is:
Prokaryotic cells
Eukaryotic cells (Animal and Plant Cells)
Prokaryotic cells
Prokaryotic Cells
In prokaryotic cells the DNA floats in the
cytoplasm. This cell type is characteristic of
bacteria.
It has plasmatic membrane, cytoplasm and
DNA (it is the substance that contains the
genetic information for the characteristics of
the cell and how it functions).
Prokaryotic cells
They measure between 1 and 10 micrometer
in length.
We find plasmids (small fragments of DNA),
ribosomes, mesosomes (folds in the cell
membrane), a rigid outer cover called cell
wall and some species have flagella or
fimbria.
Eukaryotic cell
The DNA of eukaryotik cells is found inside
an organelle called the nucleus.
Eukaryotic cell (animal)
Organelles of eukaryotic cells (animal)
Cell membrane
Cytoplasm
Nucleus
Mitochondria
Ribosomes
Endoplasmic reticulum (rough and smooth)
Golgy body
Organelles of eukaryotic cells (animal)
Vesicles
Lysosomes
Cytoeskeleton
Centrioles
Sometimes flagela or cilia.
Cheek cell
Eukaryotic cell (plants)
Onion Cell
Organelles of eukaryotic cells (plants)
Cell wall
Cell membrane
Cytoplasm
Nucleus
Mitochondria
Ribosomes
Endoplasmic reticulum (rough and smooth)
Golgy body
Organelles of eukaryotic cells (plants)
Vesicles
Lysosomes
Cytoeskeleton
Vacuole
Choroplast
Type of nutrition in cells
Autotrophic cells; They produces their own
food. They produce organic nutrients from
inorganic substances.
Heterotrophic cells; They obtain organic
nutrients by feeding on other living things or
their derivates.
HUMAN CELLS
Humans cells nutrition is heterotrophic. They
are eukariotic cells which means that they
have a cell membrane, cytoplasm and
nucleus.
Cells vary a great deal in their size and
shape depending on their function.
Types of human cells
The cell membrane
It is a very thing elastic layer that cover the
cell.
Function: it controls which substances go in
and out, detects stimuli from the
environement and enables cells to
communicate with each other.
The cell or plasmatic membrane
The cytoplasm
It is a gel-like subtstance which fill the cell. It
contains the organelles.
Function: a lo of chemical reactions take
place in the cytoplasm.
The nucleus
The nucleus
The DNA is organised in the nucleus. The
DNA is joined to proteins to make it stronger
and more compact. This association is called
chromatin.
The nucleus is surrounded by a porous
double membrane and contains a substance
similar to cytoplasm (nucleoplasm) and the
nucleolus where ribosomes are formed.
The cytoskeleton
It is a network of filaments that gives shape
to the cell and enables it to move.
Mitochondria
Mitochondria
Function: Cellular respiration. Energy is
obtained in a process where food is burnt
using up oxigen and carbon dioxide is
released.
Ribosomes
They make cell proteins.
Golgi body
It processes and packages substances. The
vesicles transport the substances to other
parts of the cell or to the outside of the cell.
Endoplasmic reticulum
It transports proteins made by the ribosomes
and them to the Golgi body.
Lysosomes and others vesicles
Lysosomes carry out cellular digestion,
converting substances into other subtances
which are useful in the cell.
Vesicles: they store or transport substances
made by the Golgi body.
Centrioles
They have two main functions:
- to control the movement of the
chromosomes during the mitosis and
meiosis.
- to take part in the formation of the cilia and
flagella.
Organelles found in plant cells
Big vacuoles
Chloroplasts
Cell wall
Big Vacuoles
The sap inside the vacuole exerts pressure
on the inside of the cell, which is very
important because it maintains the plant
cell´s rigidity.
Chloroplasts
They perform photosynthesis.
Cell wall
It protects and gives rigidity to the cells.
Human tissues
The tissue is an aggregate of cells that have
a similar structure and function.
Organs
An organ is a grouping of tissues to carry out
a certain function. For example: the heart,
the stomach or the brain.
Major organ systems
They are groups of organs which cooperate
to perform a common activity. For instance:
the digestive system or the respiratory
system.
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