Cells and Heredity
Cells and Organelles
Cell Structures
• Organic and inorganic molecules join to
form cells.
• Cells are the smallest functional unit in an
organism.
• Every living organism is made up of at
least one cell.
Cell Structures
• Cells contain many smaller membrane
bound structures called organelles.
• Organelles are specialized and each does
a different job.
• They work together like the different parts
of a factory.
Cell Structures
• Most organelles are found in both plant
and animal cells.
• Cell walls and chloroplasts are found only
in plant cells.
• Lysosomes and centrioles are found only
in animal cells.
Cell Structures
Cell Structures
• The cell membrane forms a boundary for
the cell.
• In plant cells it is just inside the cell wall.
• In animal cells it is the outer boundary.
• The cell membrane controls what enters or
leaves the cell.
• the cytoplasm is a gelatin like substance.
• Most cell processes occur in the
cytoplasm.
Cell Structures
• The nucleus controls cell activities.
• The nucleus is bound by a membrane.
• Chromosomes are found inside the
nucleus.
• The chromosomes contain DNA and
contains the information needed by each
cell to function.
Cell Structures
• The nucleolus is a dense region of DNA
and RNA found inside the nucleus.
• It is where ribosomes are produced.
Cell Structures
• The endoplasmic reticulum- ER forms a maze of
passageways.
• The ER is used to transport proteins and other
materials.
• Attached to the surface are ribosomes.
• The ribosomes are small grainlike structures.
• Ribosomes are also found floating in the
cytoplasm.
• Ribosomes function to produce proteins.
Cell Structures
• The Golgi bodies are flattened sacs or tubes.
• They package proteins and other materials and
send to other parts of the cell.
• The mitochondria are rod shaped structures.
• The mitochondria are where energy is produced.
• Very active cells such as muscle cells have
many mitochondria.
Cell Structures
• Peroxisomes are small round structures
that contain chemicals.
• The peroxisomes produce energy for the
cell.
• They produce much less energy than the
mitochondria.
• In plants, they are important in seed
germination.
Cell Structures
• Vacuoles are water filled sacs in the
cytoplasm.
• They are for water storage.
• Most plant cells have a single large
vacuole.
• They keep the plant cells plump and firm
• Animal cells may contain small vacuoles
or none at all.
Cell Structures
• Cell walls are found in plants only.
• The cell wall contains cellulose and is a
rigid, nonliving framework.
• The cell wall gives the plant cell it’s shape
and structure.
• Chloroplasts are also only in plant cells.
• Chloroplasts use sunlight to convert
carbon dioxide and water into sugar and
oxygen.
Cell Structures
• Animal cells contain lysosomes.
• They are small round structures that
contain enzymes.
• The lysosomes break down old cell parts
and food particles.
Cell Structures
• Animal cells also contain centrioles.
• They are small rodlike structures that are
in pairs.
• They are used in cell division.
• They help form spindle fibers to guide
chromosomes.
Cell Structures
• Cells that are similar form tissues.
• Tissues that have the same structure and
function form organs.
• Organs that are similar and work together
form systems.
• The organ systems form the complete
organism.