Prokaryotes• Smallest Cells • Lack a nucleus – DNA is located in an area called

the nucleoid• Contain plasmids – small circular pieces of DNA

Eukaryotes• Plasma membrane– Barrier that surrounds

the cytoplasm of the cell

• Organelles – Internal structures that

carry out specialized functions

– Bounded by a membrane (exception ribosome, centriole)

• Cytosol– Liquid portion of the

cell

Examples of Cells

Amoeba Proteus

Plant Stem

Red Blood Cell

Nerve Cell

Bacteria

Plant and Animal Cell

Nucleus • Command centre of the cell

• Contains DNA blueprints for making proteins

• Surrounded by nuclear envoleope – Protects DNA from

chemical reactions • Nucelolus – Area of chromatin

(uncoiled DNA strands) that produces ribosomes

• Surrounds the nucleus • Double membrane – two lipid bilayers folded

together• Nuclear pores– Link inner and outer membrane

• Proteins embedded– Function as transporters and

receptors – Controls passage of molecules

(proteins/RNA) between nucleus and cytosol

• Water and gases enter and exit the membrane freely

Nuclear Envelope

• Group of interacting organelles between the nucleus and plasma membrane

• Functions– Build lipids, enzymes, and other proteins – Transportation – Destroy toxins – Recycle waste

The Endomembrane System

Ribosomes • Assembled inside

nucleus • Made up of RNA and

proteins • Two Types – Free floating – found in

cytoplasm – Attached to ER

• Ribosomes make proteins

Endoplasmic Reticulum • Continuous compartment that

folds repeatedly into flattened sacs and tubes Rough ER– Contains ribosomes

• Synthesis of proteins

– Once synthesized, proteins fold and take shape inside ER

Smooth ER– Contains no ribosomes – Produce most of cells membrane

lipids– Break down carbohydrates, fatty

acids, and drugs and poisons– Transports vesicles to plasma

membrane or Golgi body

Golgi Bodies• Folded membrane (looks

like stack of pancakes) • Completion of proteins

and lipids making them fully functional– Attach phosphate groups,

sugars– Cleave polypeptide chains

• use inside or outside of cell

Mitochondria • Double bound

membrane organelle• Powerhouse of cell • Two compartments– Mitochondrial matrix– Intermembrane space

• Contain their own DNA and ribosomes– Synthesize ATP

Vesicles • Transportation/ destruction

• Peroxisome – Break down fatty acids,

detoxify alcohol• Vacuoles– Dispose of waste, debris

and toxic materials– Keep turgor pressure

inside plant cell• Lysosomes – fuse with vacuole to

dispose of worn out cell components (use of enzymes)

Cytoskeleton• Made up of many protein

filaments– Gives shape to cell– Organizes organelles– Move cell structures

• Include – Microtubules– Microfilaments– Intermediate filaments

• Microtubules– Consist of subunits of tubulin

(protein)– Form dynamic scaffolding for many

cellular processes (Cellular division)

• Microfilaments– Fibre– Consists of subunits of actin

(protein)– Strengthen and change shape of

eukaryotic cells (Muscle contraction)

• Intermediate filaments– Most stable – Consist of fibrous proteins – Strengthen and maintain cell and

tissue structure

Microtubules and Microfilaments

Centrosomes • Assembles and co-

ordinates activity of spindle fibres when the cell divides

• Contains pair of centrioles (microtubule)

Cilia, Flagella, Pseudopods• Organized array of microtubules• Flagella

– Whiplike structure – Propels cells (sperm)

• Cilia– Hair like structure – Sweeping action moves particles

(lining of airway) (Motile)– Sensory antenna for cell (Primary)

• Pseudopod (false feet)– Lobe formations – Amoeba

• Prokaryotes – Contain pili – hollow appendages that

stick to other cells to swap information

Cell Wall (Plant Cells) • Located around plasma

membrane• Consists of cellulose

fibres • Protects supports and

gives shape to the cell • Waxy cuticle – Limits water loss on

hot/dry days

Plastids (Plant Cells)• Chloroplasts– Double membrane bound

organelle– Stroma – semifluid interior,

contains enzymes and DNA– Specialize in photosynthesis – Contain chlorophyll

• Chromoplasts– Store orange and red

carotenoids– Responsible for beautiful

colours in autumn• Amyloplasts

• Store starch grains

• Mixture of fibrous proteins and polysaccharides that surround cells

• Supports and anchors cells • Separates tissues• Cell signaling • Plants - Cellulose• Animals

– Carbohydrates and proteins – Collagen (most abundant protein

in body • Cells interact via cell junctions

– Tight junctions– Desmosome – Gap junctions

Extracellular Matrix

Plasma Membranehttp://www.johnkyrk.com/cellmembrane.html

• Transports raw materials into the cell • Transport finished product and wastes out of cell • Prevent entry of unwanted matter into cell

Plasma Membrane • Described by the Fluid

Mosaic Model as:• Composed of a

phospholipid bilayer• Semi-permeable –

regulates substances in and out of cell with the help of transport proteins

• Glycolipid/Glycoprotein– Carbohydrate groups

attached to protein and lipid components

– Cell recognition– Hormone function – Provide energy – Maintain stability of

membrane

Phospholipids

• Hydrophilic Head– Phosphate group– Polar group

• Hydrophobic Tail– Fatty acids

• Align themselves in aqueous solution

Fluidity • Cholesterol allows cells to

function in a wide range of temperatures

• High temperature – Maintains rigidity in oily

membrane • Low temperature– Keeps membrane

fluid/flexible – Prevents from freezing

• Integral Membrane Proteins (transmembrane)– Exposed to aqueous

environment on both sides of the membrane

• Peripheral Membrane Proteins – Located on surface of a

membrane – No interaction with

hydrophobic core – Held to surface by hydrogen

/ ionic bonds

Membrane Protein (Integral/Peripheral)

• Transport– Hydrophilic protein channel– Shape shifting

• Enzymes – Metabolic processes

• Receptor – Bind to specific chemicals

(hormones) – Binding activates secondary

messenger inside cell • Tethered/Anchor – Attachment points for

cytoskeleton– Docking stations for vesicles

Membrane Proteins (Function)