the animal eucaryotic cell structure, organization and...

Faculdade de Desporto, Universidade do Porto, 1º Ciclo, 1º Ano

2010_2011

BIOQUÍMICA E BIOLOGIA CELULAR

António Ascensão, José Magalhães

The animal eucaryotic cell

Structure, organization and function

4.6 BillionYears

3.5 BillionYears

1 BillionYears

Present

Originof the earth

ProkaryoticCells

( Bacteria )

Eukaryoticcells

2 BillionYears

Appearance ofoxygen in

atmosphere

Time-span of life on earth

The Pro(karyon)tic cell

Formation of Eu(karyon)tic aerobic cells

Prokaryotic vs Eukaryotic cells

Animal vs plant cells

Notion of cellular scale

“Creepy” notion of cellular scale …

Plant cells

• Rigid structure

• Outside the plasma membrane

• Removes the ability to move

• Composed of complexes

polisaccharides (cellulose)

• Protects against the osmotic

pressure found within plants

Plant cells wall

• Chloro = green

• Photosynthetic organelle

• Transformes light from the sun in chemical energy (sugar)

• Transforms carbon dioxide (CO2) in oxygen (O2)

Plant cells chloroplast

• The very big “hole”

• Filled of water, proteins, sugar

• Reservoir, waste dump, storage region

• Keep the cell in shape by osmotic pressure

Plant cell central vacuole

Plant cells “romantic” curiosity

• A person contains about 100 trillion cells.

That’s 100,000,000,000,000 or 1 x 1014 cells

• There are about 200 different cell types in

mammals

• Cells are tiny, measuring on average about

0.002 mm (20 µm) across. That’s about 500

cells, “shoulder-to-shoulder” per mm

The animal eu(karyon)tic cell

The eu(karyon)tic cell components

Different types of cells

Adapted from “Biologia celular e molecular”, 3th edition, Lidel, 1999

• Red – Cytoskeleton;

• Green – Ribosomes;

• Blue - Membrane

It is crowed in the animal cell !!

• The plasma membrane separates the cell from the environment

• The fundamental structure of cell membranes is the amphipathic lipid bilayer (hydrophobic and hydrophilic)

• Various membrane proteins present in the different cell membranes give each membrane a specific function and identity

The plasma membrane

• Separates cell from environment

• Form compartments allowing specialization

• Regulation of transport

• Detection of signals

• Cell-cell communication

• Cell identity

Cellular membrane functions

Essential components of the biological membranes

• Phospholipids

• Glycolipids

• Proteins

• Glycoproteins

• Cholesterol

CELL MEMBRANE

Cholesterol Phospholipds Carbohydrates Proteins

Lipid bilayer Glycolipids Glycoproteins

Selective barrier StructuralStabilityCell

RecognitionImmune

Response

consists of

together form together formtogether form

functions as whose functions include

Components of the biological membranes

Particular areas of the cellular membranes specialized in specific functions :

• Cilia and flagella

• Microvillus

• Stereocillia

• Intercellular junctions

Membrane specializations

Cilia and flagella

• Beat-like, motile cellular

extensions on exposed

surfaces of certain cells

• Move substances in one

direction across cell

surfaces

Cilia structure and function

Cilia function

Cellular junctions (cell-cell and cell-matrix)

• The name is ambiguous. The cytoskeleton is the skeleton of the cell, but it’s also like the muscular system, able to change the shape of cells in a flash, and organize organelles distribution

• The three types of cytoskeleton protein filaments are:

- Actin filaments (Ø ~ 5-9 nm)

- Intermediate filaments (Ø ~ 10 nm)

- Microtubules (Ø ~ 25 nm)

The cytoskeleton

The cytoskeleton filaments

• Centrossome is an organelle near the nucleus that serves as the microtubule organizing center (MTOC) and as a regulator of cell-cycle progression

• Centrioles are small tub-shaped organelles located in the centrosome

• One is perpendicular to the other

• Pinwheel array of nine triplets of microtubules

• Organize mitotic spindle during mitosis

• Form the bases of cilia and flagella

Centrosome and Centrioles

Nuclear envelopeNuclear pores

HeterochromatinEuchromatin

• Selectively permeable double membrane barrier containing pores

• Encloses jellylike nucleoplasm, which contains essential solutes

• Outer membrane is continuous with the rough ER and is studded with ribosomes

• Inner membrane is lined with the nuclear lamina, which maintains the shape of the nucleus

• Pore complex regulates transport of large molecules into and out of the nucleus

2 meters of human DNA fits into a nucleus that’s 0.000005 meters across

Nucleus structure

Mononucleated vs polynucleated cells

• Protein synthesis (about half cell’s proteins are made here)

• Protein movement (trafficking)

• Protein folding by chaperones

The rough endoplasmic reticulum

• Granules containing protein and rRNA

• Site of protein synthesis

• Free ribosomes synthesize soluble proteins

• Membrane-bound ribosomes synthesize proteins to be incorporated into membranes or exported out of the cell

Ribosomes

• Localized near the nucleus and ER

• Collection of flattened membrane-bound sacs (4 to 6)

• Each Golgi stacks has two distinct faces (cis - entry and trans - exit)

• Groups of small vesicles are associated with Golgi

• Carbohydrate synthesis

• Modifying, sorting and packaging station of macromolecules for secretion or delivery to other organelles

Golgi Apparatus

• Cell suicide (suicide is bad for cells, but good for us!)

• Recycling cellular components

• Digesting food or cellular invaders

• The lysosome is not found in plant cells

The lysossome functions

Lysossomes enzymatic “artillery” …

Pathways of degradation in lysossomes

Lysossomes in action …

• Site of O2 utilization in cell

• Vestige of an ancient organelle that carried out all of the oxygen metabolism in primitive ancestors of eukaryotic cells

• Contain enzymes (urate oxidase and catalase) that use molecular O2 to detoxify organic substrates producing H2O2

• Catalase uses this H2O2 to oxidize other substrates (ex: alchool in liver)

• When H2O2 accumulates catalase converts it to water

• Involved in β-oxidation (fatty acids to acetyl CoA)

Peroxissomes

Are you all seeing this ??

Mitochondria is not like this at all !!

Mitochondria

• Powerhouses of the cell

• Osmotic regulators

• Regulators of cell calcium homeostasis

• Activators of the intrinsic pathway of apoptosis

• Owns DNA for protein synthesis

Mitochondria structure and functions

Adapted from “Understanden human anatomy and physiology”, 5fh Edition, McGraw-Hill, 2004

General functions of cellular components

Videos “cell organelles” (~12 min)

http://www.youtube.com/watch?v=krN1rFCgDqY&feature=related

Slide Number 1Slide Number 2Slide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Slide Number 29Slide Number 30Slide Number 31Slide Number 32Slide Number 33Slide Number 34Slide Number 35Slide Number 36Slide Number 37Slide Number 38Slide Number 39Slide Number 40Slide Number 41Slide Number 42Slide Number 43Slide Number 44Slide Number 45Slide Number 46Slide Number 47Slide Number 48Slide Number 49Slide Number 50Slide Number 51Slide Number 52Slide Number 53Slide Number 54Slide Number 55Slide Number 56Slide Number 57Slide Number 58Slide Number 59Slide Number 60Slide Number 61

the animal eucaryotic cell structure, organization and...

Documents