Transcript cell-intro-powerpoint-for-notes

• A cell is the basic unit of structure and
function in all living things.
• It needs water and nutrients to survive.
• It is found in all living things: bacteria,
plants, and animals.
• It is NOT found in non-living things.
1665
Robert Hooke:
Looked at a slice of cork
through a microscope and
discovered tiny boxes
which he called “cells.”
1673
Anton von
Leeuwenhoek:
looked at pond scum
through a microscope
and discovered singlecelled organisms called
protists.
1838
Matthias Schleiden:
studied plants and concluded that all
plant parts were made of cells.
1839
Theodor Schwann:
studied animals and concluded
that all animal tissues are made of
cells.
1858
Rudolf Virchow:
discovered that cells could only
come from other cells.
With all these discoveries, Schwann and
Virchow came up with the cell theory:
1. All organisms are made of cells
2. The cell is the Basic unit of all living
things
3. All cells Come from existing cells
• Most cells are so
tiny that you have
to use a
microscope to see
them.
• Because of the surface area-to-volume
ratio:
–Cells take in nutrients and get rid of
wastes through their outside surface.
–BUT the volume (space inside) grows
faster than the surface area (the cell’s
surface).
–If the volume becomes too big, the
cell cannot survive because….
• it can’t get enough nutrients in &
• can’t get rid of wastes fast enough.
Therefore, a cell only grows to a
certain size.
•If you blow into a balloon, the volume
increases.
•Eventually, the balloon’s surface
cannot stretch anymore.
•When this happens, the balloon
cannot continue to exist and will pop.
•Likewise, if a cell’s volume increases too
much, the cell’s surface will not be able to
get nutrients in or wastes out fast enough
and it will die.
• Some cells are big because they
don’t need to take in nutrients or get
rid of wastes.
• Ie. Chicken egg is a cell
The Cell
Two Categories of Cells
Prokaryotic Cells - A single celled organism that
does not have a nucleus covering its DNA or
membrane covered organelles. Example: Bacteria
PRO rhymes with NO – no nucleus
Eukaryotic Cells - an organism made up of cells
(multi-cellular) that have a nucleus enclosed by a
membrane. Example: Plants and Animals
The Cell
All Cells have 4 components (part; element;
ingredient) in common
Cell Membrane
Organelles
Cytoplasm
DNA
The Cell
Plant Cell
Animal Cell
The Cell
Cell Membrane – The cell membrane is the
outermost part of the animal cell. It controls
the flow of materials in and out of the cell and
protects the cell from its environment.
Organelles – The parts within the cell that
perform specific functions.
Organelles
The Cell
Cell Membrane
The Cell
Cytoplasm – The cytoplasm is a ‘jelly’ like
substance the organelles float in inside the cell
membrane.
DNA – The genetic material that carries the
information to build and maintain cells.
DNA
The Cell
Cytoplasm
The Cell
Questions:
What are 4 things that all cells have in common?
What is the difference between Prokaryotic and
Eukaryotic cells?
What is one purpose of the cell membrane?
Describe cytoplasm – what could you compare it
to?
Two Kinds of Cells: Prokaryotes: Bacteria and Archaea –
textbook pages 64-65
Prokaryotes are single celled organisms that do not
have a nucleus or “membrane-bound” organelles.
Bacteria
• most common prokaryote
• smallest cells known
• live almost everywhere
• no membrane-covered organelles but they do have
ribosomes
• have a cell wall with the cell membrane just inside of
it
• DNA is this cell is a long, circular molecule shaped like
a twisted rubber band
Two Kinds of Cells: Prokaryotes: Bacteria and
Archaea – textbook pages 64-65
Archaea:
• Single-celled organism
• Their ribosomes are different from those of
bacteria
• Three types of archaea:
• Heat-loving – extremophile – live in very hot
water, like in hot springs
• Salt-loving – extremophile-live in areas that
are extremely salty
• Methane-making – live deep in ocean near
volcanic vents
Eukaryotic Cells
• 10 times larger than most bacterial cells
• Have a nucleus – one type of membranebound organelle
• The nucleus holds the DNA
• These cells have other organelles that each
have a specific job
• Most Eukaryotes are multicellular
• Plants, animals, including humans are
eukaryotes
• Eukaryotes can be single celled like amoebas
and yeast or multicellular like green algae and
mushrooms
• No nucleus
• 2 types: bacteria &
archebacteria
• Smallest cells
• Organelles:
• DNA & ribosomes
only
• Use flagellum (tail)
to move
• Most prokaryotes are
Unicellular (only 1 cell)
• Have a nucleus
Examples:
• plants, animals, and
humans
• Largest cells (10x
*DNA
larger than bacteria
•ribosomes, *
cells!)
cell
membranes
•cytoplasm
• DNA in nucleus
• Many organelles
• Most eukaryotes are
multi-cellular (made of
more than 1 cell)
BACTERIAL CELLS
• Usually smaller
than plant &
animal cells
• Have a cell wall,
cell membrane,
ribosomes,
cytoplasm, &
DNA.
•Does NOT
contain a nucleus
so it is a
PROKARYOTE