Chapter 7 Cell Structure and Function
Cell Theory1. All living things are made of cells2. Cells are the basic units of structure
and function in living things3. New cells are produced from existing
cells
How do we see cells?The microscope:
◦Light microscope Produce magnified images by focusing
visible light rays Magnifies up to 1,500 X using visible light
◦Electron microscope Produce magnified images by focusing
beams of electrons Magnifies up to 1,500,000 X using
electrons Traditionally require a vacuum to operate,
cannot see living cells
How Big are Cells?Cells come in a large variety of shapes
and sizesMost are between 5 and 50
micrometers
Two Major Cell TypesProkaryotes
◦Very small cells WITHOUT a nucleus◦Bacteria
Two Major Cell TypesEukaryotes
◦Larger more complex cells with one or more nuclei
◦Everything not bacteria
Two Major Cell Types
Parts of the CellCytoplasmNucleusRibosomesEndoplasmic reticulum (ER)- rough and smoothGolgi apparatusLysosomes (and vacuoles)MitochondriaCytoskeleton and CentriolesCell membrane and cell wallSpecialized parts (chloroplasts, cilia, flaggella)
The Parts of the CellOrganelles are the membrane bound
structure in a eukaryote that carries out some function for the cell. Ex. nucleus and mitochondria
Cytoplasm is the gel-like substance outside the nucleus
The NucleusA large membrane-enclosed structure
containing DNA
The NucleusDNA appears granular most of the
time and is called chromatin; it condenses to form chromosomes during cell division
Two major parts of the nucleus◦Nuclear envelope is a double
membrane with pores that surrounds the nucleus
◦Nucleolus is the dense region of the nucleus where ribosomes are made (most nuclei have a nucleolus)
RibosomesRibosomes are the small particles of
RNA and protein where proteins are made in the cell
The Endoplasmic Reticulum (ER)The ER is the site where lipid parts of
the cell membrane are assembled, as well as proteins and other materials that are exported from the cell
Two types:◦Rough ER has ribosomes and
functions in protein production (synthesis)
◦Smooth ER has no ribosomes and functions in lipid production or detoxification
The Endoplasmic Reticulum (ER)
The Golgi ApparatusThe Golgi functions to modify, sort,
and package proteins and other materials for storage in the cell or secretion from the cell
The Golgi Apparatus
MitochondriaMitochondria helps convert food
energy into cellular energy
Lysosomes and VacuolesLysosomes are enzyme filled
organelles that function to digest food for the cell and to get rid of old organelles
Vacuoles are important in storage (water, salts, proteins, carbs)
ChloroplastsChloroplasts capture energy from
sunlight and convert it into chemical energy
Cytoskeleton and CentriolesCytoskeleton is the network of protein
filaments that maintain the cell’s shape and aid in movement
Centrioles help organize cell division (not found in plants)
Cilia and FlagellaCilia are short projections made from
the microtubules that function in movement
Flagella are long projections from the microtubules that function in movement
Cell WallProvides support and protection in
bacteria, plants, fungi, and some Protists (Not Animals)
Made of cellulose in plants
Cell Wall
Cell Membrane (Plasma membrane)The cell membrane regulates what
enters and leaves the cell and also provides protection and support
Found in all cells and made of phospholipids
Diffusion and the Cell MembraneDiffusion is the movement of particles
from an area of higher concentration to lower concentration◦Requires NO energy
Diffusion and the Cell MembraneConcentration is the mass divided by
the volume (mass/volume) grams/mL, or g/cm3
Osmosis is the diffusion of water through a selectively permeable membrane
Diffusion and the Cell Membrane
Diffusion and the Cell MembraneIsotonic solution is one that the
concentrations are the same on both sides of the membrane
Hypertonic solution is the more concentrated solution (more sugar molecules)
Hypotonic solution is the less concentrated solution (less sugar molecules)◦Water will net diffuse to the side that
is more concentrated
Diffusion and the Cell Membrane
Diffusion and the Cell Membrane
Diffusion and the Cell MembraneFacilitated diffusion is the diffusion
through protein channels without using energy
Diffusion and the Cell MembraneActive transport is the movement of
particles that requires energy
Passive transport is the movement of particles without using energy
Diffusion and the Cell Membrane
Diffusion and the Cell MembraneEndocytosis takes material into a cell
by engulfment (requires energy); a vacuole forms on the inside of the cell after engulfment◦Phagocytosis takes food or solid
particles into the cell◦Pinocytosis takes liquid into the cell
Exocytosis releases material from a cell (requires energy)
Diffusion and the Cell Membrane
Unicellular vs. MulticellularUnicellular organisms is an organism
made of one cell. Examples: Bacteria and many Protists
Multicellular organisms is an organism made of many cells that are specialized
Cell Differentiation (Specialization)Cell differentiation occurs when cells
develop in alternative ways to perform different tasks◦Go Go Stem Cells◦Example: Red blood cells are
specialized to transport oxygen. Pancreatic cells produce certain proteins. Guard cells in plants open and close the stomata
◦Stem cell animation
Organization of LifeCell- collection of living matter
enclosed by a barrier; basic unit of lifeTissues- group of similar cells that
perform a particular functionOrgan- many group of tissues that
work together to function as an organOrgan system- a group of organs that
work together perform a specific function, like digestion
Organization of Life