cell-basic structures of life

8/3/2019 Cell-Basic Structures of Life

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Cell-basic structures of life


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Organic/inorganic molecules

Inorganic molecules-water, CO2, CO, gases,

and salts

Organic- carbohydrates(CHO)n


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Carbohydrates-monosaccharides

Glucose-grape sugar, blood sugar

Fructose-fruit sugar-sweetest

Galactose mannose glucose


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Galactose

Galactose from Greek galaktos

"milk

Its sometimes abbreviated as Gal Its a monosaccharide whose sugar is less

sweet than glucose

Galactan is a polymer of the sugar galactosefound in hemicellulose. Galactan can be

converted to galactose by hydrolysis.


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Galactose-structural isomerism

It has both open chain structure and cyclic structure

The open-chain form has a carbonyl at the end of the chain.

Four isomers are cyclic, two of them with a pyranose (six-

membered) ring, two with a furanose (five-membered) ring


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Galactose metabolism

The Leloir pathway is a metabolic pathway for

the catabolism of D-galactose. It is named

after Luis Federico Leloir.


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Carbohydrates-disaccharides

Sucrose-glucose + fructose=table sugar, cane

sugar

Maltose-glucose + glucose =malt sugar Lactose-glucose +galactose=milk sugar


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Carbohydrates-polysaccharides

Structural- hold cells and organisms together-

cellulose, pectin, chitin

Storage-amylose, amylopectin, agar,carrageenan, starch


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summary


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Proteins(C, H, O, N)

Made up of amino acids (20 types)

Enzymes biological catalysts

Structural proteins-expansions, extensions,cell wall, cytoskeleton

Storage proteins-zein, gliadin, glutens(seeds)


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Nucleic acids (DNA and RNA)

Made up of nucleotides

Each nucleotide consists of:

1. 5 C sugar (ribose, deoxyribose)2. Nitrogenous base- purines(guanine and

adenine) and pyrimidine(cytosine, thymine

and uracil)3. Phosphate group

C-G, A-T


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Lipids

Oils-liquids at room temperature, made up of3 long fatty acid chain and glycerol (3 Calcohol) or triglyceride- unsaturated

(abundant in seeds-castor, sunflower, olive) Waxes- harder and more repellant. Ex

carnauba wax, cuticular wax, suberin

Fats are solids at room temperature.Triglycerides is composed of predominantlysaturated fatty acids.


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Prokaryotic cell


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Eukaryotic-Plant cell


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Eukaryotic-animal cell


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Discovery of cell

Anton von Leeuwenhoek- invented simple microscope

Robert Hooke-discovered cells

Robert Brown- discovered nucleus

Felix Desjardin- described cells as clear jelly like Johann Purkinje-protoplasm

Matthias Schleiden(1838)-plants are composed of cells

Theodor Schwann(1839) animals are composed of cells

Rudolf Virchow(1855) advanced that existing cells giverise to new cells


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Cell theory

All organisms are composed of cells

Cells are basic units of structure and function

in organisms Arise from preexisting cells

Two types of cells: Prokaryotes(before

nucleus) and eukaryotes(true nucleus)


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Prokaryotic cells

First form of life

Circular chromosome, not enclosed in a membrane

No organelles

Cell walls with peptidoglycan

Cell membrane

Binary fission

Ex-bacteria and Archaea

Bacterial cells have following features:

i. Outer boundary- cell wall, plasma membraneii. Cytoplasm-ribosome, thylakoids, many enzymes

iii. Nucleoid-chromosome( DNA only)


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Eukaryotic cell

Membrane bound nucleus

Larger than prokaryotes

With organelles

ex: animals, plants, protists, fungi

Lysosome in animal cells, peroxisome in plant

cells


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Parts of eukaryotic cell-cytoplasm

ER

Ribosomes

Mitochondria

Golgi complex

Lysosomes

Centrioles

Plastids pigments

Vacuoles

Microfilaments Microfilaments

Cytoplasmic inclusions


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Parts of eukaryotic cell-nucleus

Nuclear membrane

Karyolymph

Nucleoplasm

Linen network

Chromosomes

Chromatin network


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Cell wall

Outer most boundary

Found in plants but not in animals

Rigid structure for strength, protection, andsupport

Defines the shape of cell

Prevents excessive water from entering thecell


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Cell wall

Made up of:

1. Primary cell wall

2. Secondary cell wall3. Middle lamella

middle lamella is the first layer formed after

cell division, makes up the outer wall of thecell shared by adjacent cells, composed of

pectin, it is cementing substance


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Cell wall

Primary cell wall- in young and actively growingareas composed of:

1. Cellulose

2. Hemicellulose

3. Pectins

4. Glycoproteins

Secondary cell wall-formed after cell has ceased,rigid and compression strength. Its composed ofcellulose, hemicellulose and lignin


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Channels between cells

Plasmodesmata- channels/ thin areas in

primary cell walls where interconnections

between adjacent cells occur(desmotubules).

These channels are lined with pits: either

simple or bordered


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Functions of cell wall

1. Structural and mechanical support

2. Maintains cell shape

3. Resist internal turgor pressure4. Controls rate and direction of growth

5. Works for long distance transport and cell to

cell communication


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Cell membrane

Also known as plasma membrane which

serves as other lining cells

Protects and gives shape to cell Scores as passage way of nutrients in and out

of cell

Differentially permeable

Fluid mosaic model (proteins are mosaic in

fluid bilayer of phospholipids)


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Cell membrane

Proteins are embedded:

1. Channels for molecules to enter/leave cell

2. Transport water and other substances3. Receptor sites for molecules to be

transported

4. Identify other cells, disease organisms5. Attachment sites for molecules that control

cell structure and function


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protoplasm

It consists of cytoplasm and nucleus

Living substance of cell and is physical and

chemical basis of life 4 elements are found in protoplasm

C-14% O-65% H-10% N-3%

Compounds-salt, water


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cytoplasm

Substance between cell membrane and

nucleus

Main body of cytoplasm referred to ascytoplasmic matrix with fluid part called

cytosol

The matrix is composed of various organized

bodies


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Organelles-endoplasmic reticulum

Fastened to the plasma membrane and nuclearmembrane

Network systems of canals(cisternae) through

which materials pass from plasma membrane tonucleus

SER and RER

RER contains ribosomes for protein synthesis

SER lacks ribosomes for synthesis hormones andenzymes, lipids, cholesterol, and carbohydratemetabolism


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Golgi apparatus/ complex

Consists of flattened sacs(dictyosomes) which

are closely packed but attached to each other

and significant in cell excretion

Serves as ware house and finishing factory

Packages and discharges secretory products

outside the cell


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ribosomes

Small round structures without membranes

Contains large amounts of RNA and protein

synthesizing enzymes Serves as protein factory of the cell


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mitochondria

Rod-like structures with double membranes,cisternae, matrix, mitochondrial DNA is smallcircular chromosome

The powerhouse of the cell (harvest chemicalenergy from food such as sugars are carry outcellular respiration to produce energy andATP)

Responsible for oxidation of nutrients whichgenerate energy(cellular respiration)


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microbodies

cell-basic structures of life

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