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Cells
Definition of a cell – smallest unit of an organism that can perform life functions
History of the cell and cell theory
1. Robert Hooke – looked at cork cell under a microscope made of little
empty boxes and called them cells.
2. Matthias Schleiden – studied plant parts- concluded that all plants are made
up of cells
3. Theodor Schwann – studied animal cells- concluded all animals were made
up of cells
4. Rudolf Virchow – hypothesized that new cells don’t form on their own.
Cells divide to form new cells
5. Anton van Leeuwenhoek – used simple microscopes to observe tiny
animalculeslater named bacteria
Cell Theory
1. All organisms are made up of one or more cells
2. Cells are the basic unit of structure and function in all organisms
3. All cells come from cells that already exist
Characteristics of a cell
1. Membrane and cytoplasm- all cells have a membrane and are filled with a
gel like material called cytoplasm
2. Organelles
- most organelles are surrounded by a membrane
- some organelles break down food
- some organelles move waste products
- some organelles store materials
3. Nucleus or nuclear material- all cells have something that controls the life
activities of the cell
-Prokaryotes- have NO membrane around nuclear material
SCRAMBLED EGG- PRO MEANS NO
MONERAN KINGDOM- BACTERIA
-Eukaryotes- have a membrane around their nuclear material, known as a
true nucleus
FRIED EGG- EU MEANS TRUE
ANIMAL, PLANT, FUNGI, PROTIST KINGDOMS
4. Cells come in different shapes and sizes
-Nerve cells- may be one-meter long- fine extensions send impulses through
the body
-White blood cells – can change shape to attack and surround disease
causing agents
-Red blood cells – 1/10 the size of an egg cell which is about the size of a
dot of an i- small flexible disk shape for squeezing through tiny blood
vessels
-Plant vessel cells- long hollow with holes for transporting minerals and
water
Organic compounds- there are 4 groups of organic compounds that make up all living
things
1. Carbohydrates – when carbs are broken down energy is released and used
to power cell processes
2. Proteins – used for building cell parts- made of amino acids can be enzymes
that speed up chemical reactions in cells
3. Lipids – store and release energy in larger amounts than carbohydrates
4. Nucleic Acids- large organic molecules that store important information in
the cells
- DNA – directs all cell activities- found in chromosomes
- RNA – carries information for making proteins- found in cytoplasm
METABOLIC PROCESSES- ALL CELLS UNDERGO
Respiration
Ingestion
Digestion
Excretion
CELL PARTS AND FUNCTIONS
CELL MEMBRANE
FLEXIBLE STRUCTURE THAT FORMS THE outer boundary of the cell
and allows only certain materials to move into and out of the cell. (Permeable
membrane)
MADE OF a double layer of fats with some proteins scattered throughout.
MAINTAINS CHEMICAL balance between materials inside and outside the
cell. Food and oxygen move into the cell through the membrane. Waste products
also leave through the membrane.
CELL WALLS
RIGID STRUCTURE FOUND outside the cell membrane that supports and
protects the plant cell.
FOUND ONLY IN plant cells.
MADE OF bundles of tough cellulose fibers and other materials made by
the cell.
CHLOROPLASTS
WHERE LIGHT ENERGY IS TURNED INTO chemical energy IN THE
FORM OF A sugar, glucose DURING THE PROCESS OF photosynthesis.
FOUND ONLY in plant cells.
CHLOROPHYLL
CARBON DIXIDE + WATER + LIGHT ENERGY
GLUCOSE + OXYGEN
CYTOPLASM
GEL-LIKE MATERIAL CONTAINS large amount of water and many
chemicals and structures that carry out life processes in the cell.
Constantly moves or streams called cytoplasmic streaming.
NUCLEUS
DIRECTS ALL CELL activities
CONTAINS THE genetic blueprint on long strands of chromatin (made up
of proteins and DNA- a chemical that controls the activities of the cell.
NUCLEAR MEMBRANE SEPARATES THE NUCLEUS FROM THE
CYTOPLASM. materials enter and leave through openings in the membrane.
NUCLEOLUS IS FOUND in the nucleus.
ENDOPLASMIC RETICULUMFOLDED membrane THAT MOVES MATERIALS around in the cell.
EXTENDS FROM nucleus to the cell membrane
RIBOSOMES
cells MAKE THEIR OWN PROTEIN ON these small structures .
The nucleus sent directions to the ribosomes and ribosomes are made in the
nucleolus.
some are free floating in the cytoplasm and some are attached to the
endoplasmic reticulum.
GOLGI BODIES
STACKS OF MEMBRANE COVERED SACS THAT move proteins to the
outside of the cell. They are the packaging and secreting organelles of the cell.
MITOCHONDRIA (mitochondrion)
BREAKS DOWN FOOD MOLECULES TO RELEASE energy for the cell
“POWERHOUSE OF THE CELL”
MUSCLE CELLS have a large numbers of mitochondria because they are more
active and require more energy.
LYSOSOMES
CONTAIN CHEMICALS THAT digest wastes and worn out cell parts
SURROUNDED BY a membrane to keep from breaking down the cell itself.
VACUOLES
STORAGE AREA FOR CELLS for water food or waste products
VERY large IN PLANT CELLS AND VERY small IN ANIMAL CELLS.
CENTRIOLESfound only in animal cells important for cell division