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1. CELLS-A BASICSTUDYINBIOLOGY
-for all Organismlife starts as a single cell.
-Cells got Specialized for various tasks carrying outnumerous lifeactivities.
-All living beings are made up of cells.
-cell is the structuraland functional unit
-All cells alike in chemical composition and metabolic processes.
- All living beings arise froma pre-existing cell
- Smallest: red blood cells in human body
-Longestcells :are the nervecells.
- largest cells are the birds eggs (Ostrich egg)
- 200 differenttypes ot cells
-37.2 trillion cells in the whole body.
-100 billion nerve cells in the brain cortex.
-25 trillion red blood cells.
CELL SHAPES
-red blood cells are circular biconcave,
-White blood cells are amoeboid
-Nerve cells are long to conduct “impulse”
-Guard cells of stomatal pores bean-shaped to open and close it.
STRUCTURE OF CELL
1 Cell membrane
-all living membranehaving fine pores.
-semi-permeable / selectively permeable
-Plant cell non-living layer called the cell wall,
2 Cytoplasm
- inside the cell membraneand outside the nucleus.
-semi-liquid
-chemical reactions catalyzed by enzymes occur in it .
-contains severalorganelles and
-cytosol, which constitutes mainly the liquid medium.
3 Nucleus
-sphericalbody lying in the cytoplasm.
-a double layered nuclear membranewith nuclear pores
-ground substanceof the nucleus is a semisolid – substance(nucleoplasm)

2. - contains one or more round-shaped nucleoli
-nucleoplasm contains dark colored fibers called chromatin fibers
-chromatin fibers condense into shortthick chromosomes
4 Protoplasmor protoplast: collectively living parts of a cell which consist
cytoplasm, nucleus and other living bodies
5 Organelles are the specialized membrane bound structures in a cell
concerned with definite functions. Same both plant and animal cells
Except cell wall and chloroplasts only plant &centrioles presentin animal cells
6 ex: Nucleus nucleolus, mitochondria, endoplasmic reticulum, ribosomes,
Golgi bodies, lysosomes, vacuoles, cell membrane.
Cell membrane 1 Outermost 1 Separates the
2Next.to cell wall contents
3living membrane, 2. Regulates entry
4fine pores 3 Maintains shapeof the cell
5 Semi-permeable.
6Lipoproteins./cell
Wall cellulose
Cell wall l. Outermost Gives rigidity and shape
2. Non-living rigid layer Entry without any
3. Freely permeable. hinderance
4. composed of cellulose protection
Cytoplasm Insidethe plasma membrane
excluding nucleus
Organelles contained in it
performdifferent functions-
mixture of water and soluble-
organic and organic compounds
All metabolic activities occur in
it
Various organelles. Medium for initial steps of
respiration

3. Golgiapparatus Flattened membranesacs
Consists of tubules,
vesicles and vacuoles.
Seat of cellular respiration and
stores energy, 2. Synthesis of
respiratory enzymes.
Ribosomes Small granules 1. Protein synthesis.
scattered or attaced to endoplasmic
reticulum
Single walled, dense sphericalbodies
Composed mainly RNA.
Lysosomes membrane sacs
bubbled of
Intracellular digestion
((Suicide bags)) fromGolgi body. Destroy foreign substance
Cont. 40 different
types of enzymes
When Cell is old rapidly destroy organelles
side
Digest cartilage during formation of bones
Centrosome Region surrounding the centrioles, Initiates and regulates
cell division-
Contains one or two centrioles,
surrounded by microtubules.
Forms spindlefibers, with
the help of asters
Plastids Chloroplasts containing the green
pigment chlorophyll.
Chloroplasts (green) trap
solar energy
(Severalkinds) Double membraned, proteinaceous
matrix, contain DNA.
Eucoplasts – store starch.
Disc-likestructures called
thylakoids contain chlorophyll.
Endoplasmic Of double_membraned tubules Supportiveframework
reticulum Continuous with plasma memb. on Synthasis and transport
Outsideand Nuclear memb. inside of protines and fats
May be_smooth or rough
(attached ribosomes).
Endoplasmic
reticulum
Double membraned Tubules, Supportiveframework

5. Mitochondria Sausagelike Double walled Release energy from
inner wall thrown into folds(cristae) Pyruvic acid
Have their on DNA Seat of cellular respiration
contain their own ribosome Synthasis of resp enzymes
Nucleus Largestcell organelle l. Regulates cell
Spherical and dense. functions.
Pores to allow substances to enter and
leave.
If removed, the cell
dies.
Network of thread-like structures called
chromatin fibres which contain DNA
Contains
chromosomes
Nucleolus Or more round-shaped Produces ribosomes.
Substructureinsidenucleus Participates in protein synthesis
Forming and storing RNA.
Dictates ribosomes to
synthesiseproteins.
Chromatin fibres A fine thread like network Carry genes Carriers
Which condenses into
chromosomes during cell division
Which are carriers of
hereditary information.
Made up of DNA
Vacuoles Clear spaces with Wt etc Storageof water
(Non living) Plant cells have few but large Give Turgidity to plant cell
Animal cells havesmaller ones Contain pigments like
Covered by tonoplast anthocyanin
Granules
(Non living)
Small particles, crystals or
droplets.
Store starch (in plant cells),
Store Glycogen (in animal cell)
Fat-containing granules
Serveas food.