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