Download Cell membrane

What are Cells?
Cells are the building
blocks of all living things.
A cell is the smallest unit
of living matter.
Prokaryotic Cells
Bacteria are prokaryotes. Their cells are very
small and very simple.
Eukaryotic cells
All other cells are eukaryotic cells. These
include protists, fungi, plants, and animals.
The diagram below shows link between
bacteria, archaea, and the four other kingdoms.
Cells contain parts called organelles.
These all have a specific structure and
have a special function (job).
Cell membrane
All cells are surrounded by a membrane.
Function: It separates the inside of the cell from its
environment and controls what goes in and out of
the cell. Look at the amoeba below:
Nucleus
The nuclei can be seen in the photograph of human
cheek cells below.
Function: Contains the DNA which has all the
instructions needed to make the cell work.
Cytoplasm
This is the material enclosed by the cell membrane,
not including the nucleus.
Function: where the chemical reactions happen
Cell membrane
cytoplasm
nucleus
Cell Wall
Function: to support and protect the cell.
The cell walls of these onion skin cells can be easily
seen.
Some other cell parts….
Vacuoles
Vacuoles are little sacs that store water and
dissolved substances (sap).
They are more important in plant cells. Most of
the center of a plant cell is occupied by a
central vacuole.
The central vacuole gives support because
pressure within the vacuole makes the cell
rigid (turgid). The cell wall prevents the cell
from bursting.
Chloroplasts
Plants make their food by photosynthesis.
This uses light to make sugar from CO2 and H2O. Only
certain cells contain chloroplasts, where photosynthesis
occurs.
The photograph below is an Elodea leaf (X 400). The
many green structures are chloroplasts.
Ribosomes
Ribosomes are found in many places
around the cell. You might find them
floating in the cytoplasm.
Function: Cells need to make proteins.
Ribosomes are the protein builders of
the cell.
Mitochondria
These are known as the powerhouses of
the cell and create energy for the cell.
The process of creating cell energy is
known as cellular respiration.