Cell (for EDTECH 213 class 2nd Semester AY 2013-2014

CELL:ORGANIC UNIT OF LIFE

jrmguce2011

CELL basic unit of structure and function Can be:

Unicellular Multicellular

Bodies are cooperative of specialized cells Cannot survive for long on their own

How do we study cells? Invention of lenses (merchants of

Europe) Combination of lenses led to:

Telescope Microscope*

17th century: discovery and early study of cells thru*

Invention and Development of Microscopes

Anton von Leeuwenhoek Dutch biologist first to explore things: microscopic view

Pond water (detailed illustration)

ESSENTIAL SCIENTISTS Robert Hooke

English scientist Pieces of cork

Composed of thousands of chambers

After 200 years: cells were also found in other organisms

ESSENTIAL SCIENTISTS Robert Brown

(1833) Scottish Nucleus

Dark structure

Matthias Schleiden German STATED: all plants

are made up of cells

ESSENTIAL SCIENTISTS Theodor Schwann

STATED: all animals are made up of cells

Rudolf Virchow German 1855 Cells arise from the

division of pre-existing cells

The CELL THEORY

most fundamental discovery: nature of living things

forms basic framework formulated by Schwann,

Schleiden and Virchow

STATES that:

ALL LIVING THINGS ARE COMPOSED OF CELLS

CELLS ARE THE BASIC UNIT OF STRUCTURE AND FUNCTION

ALL CELLS COME FROM PRE-EXISTING CELLS

Prokaryotic VS Eukaryotic Cells

Pro- before Karyon- kernel NO NUCLEUS DNA: concentrated

in a NUCLEOID With cytoplasm w/ PM

Eu- true Karyon- kernel Has NUCLEUS With cytoplasm

Cytosol

w/ PM

ORGANELLES NUCLEUS

contains most of the genes averaging about 5µm in dm *Nuclear envelope

Encloses nucleus Double membrane (lipid bilayer with

proteins) 20 – 40 nm

Perforated by pores 100 nm in dm pore complex*

PARTS OF THE NUCLEUS *Nuclear lamina

netlike array of protein filaments maintains the shape of the nucleus

*Nucleolus Site: components of ribosomes are

synthesized and assembled Components pass through the nuclear pore

to the cytoplasm* Appears as a mass of densely stained

granules and fibers adjusting part of chromatin

FUNCTION of NUCLEUS information center of the cell

contains DNA

control protein synthesis By sending molecular messengers: mRNA

ORGANELLES RIBOSOMES

Protein factory cells with active protein synthesis

prominent nucleoli build proteins: two cytoplasmic locales

Free ribosomes: cytosol Bound ribosomes: for inclusion, transport,

packaging

ENDO-MEMBRANE SYSTEM

Membranes that are related either: direct physical continuity transfer of membrane segments

Includes: VAly PLAne GOer Nuclear Envelope ER Golgi Apparatus Lysosomes Vacuoles Plasma Membrane

Endoplasmic Reticulum

more than half the total membrane of cells

reticulum Greek word for network Two types:

Smooth ER Rough ER

Smooth ER Smooth walls of the sacs are not

studded with ribosomes Functions: SYLIP me car DE DRUP

Synthesis of lipidsMetabolism of carbohydratesDetoxification of drugs and poison

ROUGH ER studded with ribosomes FUNCTIONS:

synthesis of secretory protein membrane production (membrane factory) synthesis of proteins

Golgi Apparatus Center of: MWSS

Manufacturing Warehousing Sorting Shipping

Products from the ER are: SMS Modified Stored Sent to other destinations

flattened membranous sacs- CISTERNAE vicinity is concentrated with vesicles

Golgi apparatus- other ENDOMEMBRANE organelle CONNECTION

Parts of GA: Cis face

Receiving part (near ER) TV moves materials from ER to GA

Trans face Shipping (vesicles)

manufactures certain macromolecules Hyaluronic acid

glue animal cells together

dispatches products by Budding of vesicles

gives molecular tags (phosphate groups)

Vacuoles

membrane bound sacs in a cell food vacuole- formed by

phagocytosis Contractile vacuole

Pumps out water out

Central Vacuole- filled with liquid Tonoplast organic compounds (proteins in seed) Disposal sites for metabolic products

FUNCTIONRepository of inorganic ions

Storage of pigments

Helps to protect against predators

LYSOSOMES

membrane bounded sacs of hydrolytic enzymes

digestion of macromolecules

works best in acidic medium ~pH 5 maintains internal pH excessive leak of a large number

leads to AUTODIGESTION

hydrolytic enzymes and lysosomal membrane

by RER and Golgi Apparatus Ex. Lysosomes in an Amoeba

Exhibits PHAGOCYTOSIS Phagein Greek: to eat Kytos: vessel

Food vacuole + lysosome = digests food

AUTOPHAGY use of its own HE to digest its own

organelles Recyle its parts

happens when it engulfs an organelle after digestion

Organic monomers are returned to the cytosol

Absence of lysosomes accumulation of indigestible substrates Pompe’s Disease- glycogen Tay Sachs Disease- lipid

Other Membrane Organelles

not part of Endo-Membrane System membranes not made by ER

Free ribosomes and Ribomes of Mitochondria and Cytoplasm

contain small amounts of DNA semi- autonomous

Mitochondria

power house of the cell site of cellular respiration

Catabolic process that generates ATP* number related to cell’s metabolic

activity 1-10µm long enclosed by two membranes

Membranes*: Outer- smooth Inner**- convoluted with infoldings

(CRISTAE) Inter-membrane space Mitochondrial matrix

Chloroplast

found in plants and eukaryotic algae site of photosynthesis Solar energy – chemical energy member of plastids

Amyloplasts- colorless, stores starch Chromoplast- stores pigments

Chloroplast, xanthophyll, fucoxanthin

contains another membranous system THYLAKOIDS

flattened sacs forms GRANA bathed with stroma

Peroxisomes

specialized metabolic compartment bounded by a single membrane

sontains enzymes that produces* H2O2 as a by product

FUNCTION: use O2 to break Fatty acids detoxify alcohol

Transferring H2 from the poisons to oxygen

BUT…. H2O2 is toxic but peroxisomes have enzymes that

convert it to water grow by incorporation of proteins and

lipids made in the cytosol splits into two

Examples: Glyoxysomes

fat storing tissues of plant seeds has enzyme that initiates conversion of FA-

sugar food for the seedling