The CellCell TypesCell Parts

Diffusion & Osmosis

Cell Types

P lan t A n im a l F u n g i P ro tis ta

E u karyo teH ave N u c leu s

B ac te riaK in d g om M on era

P rokaryo teN o N u c leu s

C e ll Typ es

Prokaryotic Cells (Prokaryotes)

Bacteria

http://micro.magnet.fsu.edu/cells/bacteriacell.html

Capsule• a protective covering• made up of polysaccharides (complex carbohydrates). • keep the bacterium from drying out and to protect it from

phagocytosis (engulfing) by larger microorganisms. • The capsule is a major virulence factor in the major

disease-causing bacteria, such as Escherichia coli and Streptococcus pneumoniae. Nonencapsulated mutants of these organisms are avirulent, i.e. they don't cause disease.

Cell Wall• composed of peptidoglycan, a protein-sugar. • gives the cell its shape • surrounds the cytoplasmic membrane, protecting it from

the environment. • helps to anchor appendages like the pili and flagella,

which originate in the cytoplasm membrane and protrude through the wall to the outside.

• responsible for keeping the cell from bursting when there are large differences in osmotic pressure between the cytoplasm and the environment.

Nucleoid• A region of cytoplasm where the chromosomal

DNA is located. • It is not a membrane bound nucleus• Most bacteria have a single, circular

chromosome that is responsible for replication, although a few species do have two or more.

• Smaller circular auxiliary DNA strands, called plasmids, are also found in the cytoplasm.

Pili• Small hairlike projections emerging from the

outside cell surface. • Assist the bacteria in attaching to other cells and

surfaces, such as teeth, intestines, and rocks. • Without pili, many disease-causing bacteria lose

their ability to infect because they're unable to attach to host tissue.

Prokaryotic Ribosomes• Site of protein synthesis• Prokaryotic are smaller and have a slightly

different composition and molecular structure. • Bacterial ribosomes are never bound to other

organelles as they sometimes are (bound to the endoplasmic reticulum) in eukaryotes

• free-standing structures distributed throughout the cytoplasm.

Eukaryotic Cells (Eukaryotes)

Nucleus & Membrane Bound Organelles

Animal Cell

Cell Membrane

VacuoleCytoplasm

Nucleus

Nucleolus

RibosomeRough Endoplasmic Reticulum

Nuclear Membrane

LysosomeGolgi Apparatus

Mitochondria

SmoothEndoplasmic Reticulum

Centriole

Plant Cell

Cell Membrane

Vacuole

Cytoplasm

NucleusNucleolus

Ribosome

Rough Endoplasmic Reticulum

Nuclear MembraneGolgi Apparatus

Mitochondria

SmoothEndoplasmic Reticulum Chloroplast

Cell Wall

Cell Membrane• Control what comes in and out• Protects and supports the cell • Phospholipid Bi-layer• Proteins – act as channels to pass molecules

into or out of the cell and others act as pumps to “push” molecules from one side to the other.

• Cholesterol molecules prevent phospholipids from sticking to each other

• Fluid Mosaic

Phospholipid Bilayer

Cell Membrane

Cell Membrane

• Carbohydrate chains• Act like chemical ID cards – allows cells to

recognize each other.

Cell Wall

• Plants, algae, some bacteria • Helps support and protect cell• 2 or more layers thick

– Outer layer is where cells meet – gluey substance – pectin

– Primary cell wall is next – made of cellulose

Nucleus

• large dark structure• Not all cells have a nucleus

– Eukaryotes– Prokaryotes

• Information center and holds DNA (genetic code)• Chromosomes – DNA and Proteins – Genetic

code

Nucleolus

• Inside Nucleus• Made of RNA• Makes Ribosomes

– Ribosomes are the site of protein synthesis

Cytoplasm

• Jelly like substance• Holds organelles• Most reactions happen here

Mitochondria

• Powerhouse of the cell• Break down sugars for energy

– Convert ADP to ATP• 2 Membranes

– Outer surrounds mitochondria– Inner increases surface area – more efficient

Mitochondria

Chloroplast

• Only in plant cells• Have Chlorophyll• Convert Sun energy into chemical energy

Chloroplast

Ribosome

• Composed of RNA and protein • some attached to membranes, some free • smallest organelles

  25 nanometers (1 billionth of a meter)

Endoplasmic Reticulum

• Network of channels – ER• Transports materials through the inside of the

cell• Smooth and rough ER – Rough has Ribosomes

all around it• Synthesised proteins are moved to Golgi

Apparatus for modification

Golgi Apparatus

 Golgi for Italian scientist Camillo Golgi • Looks like flattened stack of pancakes • Modifies, collects, packages, and distributes

proteins

Lysosomes – The Cleanup Crew

• Lysosomes help digest particles – contain enzymes and chemicals necessary for digestion

• Break down organelles that have outlived their usefulness

• Formed by Golgi Apparatus • Only in Animal Cells

CELL• The basic unit of structure &

function in living organisms

Anton Van Leeuwenhoek

1632-1723 Was a merchant that ground up glass to

make lenses

•Invented microscope

•Made over 500 in his lifetime

•1st person to examine bacteria

Van Leeuwenhoek’s sketches of a nerve

Robert Hooke• 1635-1702• Used Van Leeuwenhoek’s microscopes• Named cells after looking at cork

Robert Hooke’s Cork

Robert Brown• 1773-1858

• Discovered the nucleus in plant cells (1833)

Matthias Schleiden

• 1804-1881

• Discovered all plants are made up of cells

(1838)

Theodor Schwann

• 1810-1882

• Discovered that all animals are made up of cells (1839)

Rudolph Virchow

• 1821-1902

• Proposed that all cells come from pre-existing cells (1855)

The Cell Theory

The cell theory states:

A. All living things are composed of cells

B. Cells are the basic units of structure & function in living things

C. All cells come from preexisting cells

Lynn Margoulis

• Proposed that certain organelles were once free-living organisms themselves (1970)

Movement of Materials Through the Cell Membrane

• Cells are in a liquid environment • Why is this important?

– Easier for materials to get into and out of the cells

Passive Transport

• Requires no energy• Occurs due to natural concentration gradient• Molecules move from high concentration to low

concentration (DOWN the gradient)

3 Types Diffusion Osmosis Faciliated Diffusion

Diffusion

Diffusion:

• Can’t have cell membrane too effective – How would materials get into or out of the cell?

• What materials would we want to get into or out of the cell? – Oxygen, Carbon Dioxide, Food, Wastes

• Molecules are constantly moving. They spread out as volume permits

Diffusion:

• Diffusion – the process by which molecules of a substance move from areas of higher concentration to areas of lower concentration

Selectively Permeable:

• Molecules can pass through a solid if it contains spaces large enough

• Window screen can keep out flies, but lets air in and out it acts as a barrier

• If only certain substances can pass through, but not others, it is said to be selectively permeable

Selectively Permeable:

• Substances present in unequal amounts on either side

• Each substance moves toward area of lower concentration

• Equilibrium – when concentration is equal throughout, or on both sides of the membrane

Equilibrium:

• Does equilibrium mean the molecules stoped moving?

• NO!

Osmosis:

• Molecules that can dissolve in the lipid bilayer of the cell membrane can pass through easily. Most other molecules do not.

• Water does • The diffusion of water molecules through a

selectively permeable membrane is called osmosis

Osmosis:

• What happens to raisins if you soak them in water overnight?

• Moves water from more dilute to more concentrated side

• Osmotic pressure – can be serious for cell – can rupture cell

Cells in Isotonic Solution

Isotonic Solutions

• If the concentration of solute (salt) is equal on both sides, the water will move back in forth but it won't have any result on the overall amount of water on either side.

• "ISO" means the same

Cells in Hypertonic Solution

Hypertonic Solutions

• The word "HYPER" means more, in this case there are more solute (salt) molecules outside the cell, which causes the water to be sucked in that direction.

• In plant cells, the central vacuole loses water and the cells shrink, causing wilting.

• In animal cells, the cells also shrink.• In both cases, the cell may die.• This is why it is dangerous to drink sea water

Cells in Hypotonic Solution

Hypotonic Solutions

• The word "HYPO" means less, in this case there are less solute (salt) molecules outside the cell, since salt sucks, water will move into the cell.

• The cell will gain water and grow larger. In plant cells, the central vacuoles will fill and the plant becomes stiff and rigid, the cell wall keeps the plant from bursting

• In animal cells, the cell may be in danger of bursting, organelles called CONTRACTILE VACUOLES will pump water out of the cell to prevent this.

Osmosis Review

Plasmolysis

• When a plant cell is in a hypertonic solution and the cell membrane pulls away from the cell wall

Plasmolysis

Water Potential

• is the symbol for water potential

• p is pressure potential

• s is solute potential

Water Potential

=p + s

Water Potential

• Dissolving soulutes in water reduces

Water Potential

• (Water Potential) pure water = zero at 1 atmosphere

Water PotentialPure Water =p + s or =0+0=0Potato Cell =p + s or =0+(-9)=-9

Water Potential

• Since -9 is less than 0, water will move from higher concentration (Water) to lower concentration (Potato Cell)

Water Potential

s = -iCRT• i = ionization constant (Sucrose =1)• C= Molar concentration of sucrose at

equilibrium• R=pressure constant (0.0831)• T=temperature (K=ºCelsius + 273)

Facilitated Diffusion:

• Diffusion and osmosis – passive (no energy required)

• materials carried across membrane by protein molecules to speed up diffusion

• Fast, specific, and no energy required – still diffusion

• Only occurs with concentration gradient

Facilitated DiffusionProtein Channel or Pore

Facilitated DiffusionProtein Carrier

Active Transport

• Requires cell energy (ATP) to move molecules AGAINST the concentration gradient; from an area of LOW concentration to an area of HIGH concentration

• Sodium–Potassium pump (Exchange 3 sodium ions for 2 potassium ions)

• Hydrogen ion, or proton pump (Pump hydrogen ion against the concentration gradient)

Phosphorylation

The addition of a phosphate (PO4) group (From ATP) to a protein or a small molecule

This changes the protein shape

Active Transport (Uniport)

Active Transport Na-K Pump

Na-K Pump Antiport

Glucose-Sodium Symport

Proton (Hydrogen Ion) Pump

Bulk Media Transport

• Endocytosis – Vesicle is created from the invagination of the plasma membrane, which pinches off bringing large molecules into the cell

• Pinocytosis – Cell drinking (endocytosis)• Phagocytosis – Cell eating (endocytosis)• Receptor Mediated Endocytosis – Substrate binds to receptor

found on the plasma membrance to be brought into the cell• Exocytosis – Vesicle binds to the plasma membrane

releasing the contents outside of the cell

Endocytosis

Pinocytosis

Phagocytosis

Receptor Mediated Endocytosis

Exocytosis