Download Cell Structure and Function

Cell Structure
and Function
Chapter 7.1 & 7.2
• Hooke was the first person to see a cell
under a microscope (1665).
– He named the cork cells after the cells (rooms
of his monastery).
The Cell Theory
• All living things are made of cells.
• Cells are the basic units of structure and
function in living things.
• New cells are produced from existing cells.
Types of Cells
• All cells are surrounded by a membrane
and carry biological information (DNA).
• Cells are categorized based on whether or
not they contain a nucleus.
– (Nucleus [nuclei, pl]: a large membraneenclosed structure that contains the cells’
genetic material in the form of DNA.)
• Eukaryotes are cells that contain a
nucleus.
• Prokaryotes are cells that do not contain
nuclei.
Eukaryotes
• Karyon: greek – kernal or nucleus
• Eu: greek – true
• Where is genetic material contained?
– In a membrane bound organelle (nucleus)
• Types of Organelles
– Dozens of highly specialized structures and internal
membranes
• Size
– Many 2-1000µm in size
• How old
– Evolved 1.5 billion years ago.
• Types of Organisms (examples)
– Plants, animals, fungi, and protists
Prokaryotes
• Karyon: greek – kernal or nucleus
• Pro: greek – before
• Where is genetic material contained?
– Not in a nucleus
• Types of Organelles
– None
• Size
– Most 1-10µm in size
• How old
– Evolved 3.5 billion years ago
• Types of Organisms (examples)
– bacteria
Eukaryotic Cell Structure
• Organelles: the specialized structures
inside a cell.
• Cytoplasm: the portion of the cell outside
the nucleus.
• Cell membrane: a lipid bilayer that
surrounds all cells.
• Cell wall: provides support and structure
to plant, algae, fungi, and many
prokaryotes.
– Lies outside the cell membrane.
Nucleus
• The nucleus controls most cell processes and
contains the hereditary information of DNA.
• The nucleus is surrounded by a nuclear envelope
that is composed of two membranes.
– Proteins, RNA, and other molecules can move to and from
the rest of the cell through nuclear pores.
• Chromatin is the material inside the nucleus.
– It is DNA bound to proteins.
– Chromatin condenses to form chromosomes during cell
division.
• Nucleolus is where
ribosomes begin to
assemble.
Ribosomes
• Ribosomes are small particles of RNA and protein
found throughout the cytoplasm.
• Proteins are assembled on ribosomes.
• The nucleus gives coded instructions to the
ribosomes, so they know what proteins to build.
Endoplasmic Reticulum (ER)
• An internal membrane system.
• The ER assembles the lipids that go into
building the cell membrane.
• The ER also synthesizes proteins for
export from the cell.
• There are two types of ER.
– Rough ER: has ribosomes on its surface.
• Newly made proteins leave the ribosomes and the
RER chemically modifies them.
– Smooth ER: doesn’t have ribosomes on its
surface.
• Enzymes on the SER synthesize membrane lipids
and detoxify drugs. (Liver Cells have lots of SER.)
Golgi Apparatus
• After proteins leave the RER, the Golgi apparatus
modifies, sorts, and packages the proteins.
• After the proteins are in the Golgi apparatus, they
are ready to be
– stored inside the cell
– or secreted outside of the cell.
Lysosomes
• Lysosomes are the cleanup crew of a cell.
• Lysosomes are small, enzyme filled
organelles.
• They digest (breakdown) lipids,
carbohydrates, and proteins that the rest
of the cell can use.
• They also break down organelles that are
damaged or not used anylonger.
Vacuoles
• A saclike structure that stores materials
such as
– Water
– Salts
– Proteins
– Carbohydrates
• Plants have large central vacuoles filled
with liquid.
• Animals have smaller storage vacuoles.
Mitochondria
• Mitochondria are organelles that convert
the chemical energy stored in food into
compounds that are more convenient for
the cell to use.
• Mitochondria are made up of two
membranes.
• In humans, all of our mitochondria come
from our moms.
• Contain some DNA.
Chloroplast
• Chloroplasts are organelles that capture
the energy from sunlight and convert it into
chemical energy in a process called
photosynthesis.
• Chloroplasts are surrounded by two
membranes.
• Only plants and a few other organisms
have chloroplasts.
• Contain some DNA.
Cytoskeleton
• A network of protein filaments that helps
the cell to maintain its shape.
• It also is involved in cellular movement.