This document summarizes the structure and functions of the cell and its organelles. It describes the key components of the cell membrane including lipids, proteins, and carbohydrates. It outlines the structure and roles of important organelles such as the nucleus, endoplasmic reticulum, Golgi complex, mitochondria, lysosomes, cytoskeleton, and transport mechanisms within the cell membrane. The document provides a detailed overview of the form and function of the basic units of cellular structure.

1. CELL STRUCTURE
• CELL--cell membrane or plasma membrane it contain
protoplasm (nucleoplasm in center+ cytoplasm in out of nucleus)
• cytoplasm is fluid base(cytosol or hyaloplasm)--cytoplasm
contain orangelles
• many organelles contain membrane encloses space -
contain(vaculoplasm)
• CELL MEMBRANE-7.5nm thick--trilaminar appearance(2
denser zone separated by a lighter zone)-----selective
permeablity-lipid,protein,carbohydrates
• LIPID---(mainly phospholipid)--1
head(phosphate,choline,gylcerol)+2 tails(fatty acid)-head are
polar & hydrophillic&darker--tail are non polar &
hydrophobic&lighter---i.e. fluid mosaic model forming bi-
layer(singer&nicolson)------cell membrane can readily changes
structure due its fluid nature

2. • phospholipid
types:phosphatidylcholine,sphingomylein,phosphatidylse
rine,phosphatidylethanolamine
• cholestrol -stability to membrane
• gylcolipid: galactocerebroside (important in myelin)--
ganglionosides
• PROTEINS-inside protein-outside protein-
transmembrane protein(with or without channel)
• function- integrity(cytoskeletsl filament attachement
provide cell to cell adhesion in ECF)-receptor-
transport(pumps,passive channels ,change shapeof
protein)-enzymes

3. • CARBOHYDRATES--attach to protein(glycoprotein)+attach to
lipid(glycolipid)---found external surface of plasma membrane
and form the cell boundary--cell coat or glycocaly
• function:adhesion of nearby cells & ecf molecules---this is
antigen presenting layer(MHC antigent)--in RBC blood
grouping antigen are present---gylcocalyx are mostly negative
charged.
• FUNCTION OF CELL MEMBRANE-gives shape--transport in
& out--sensory surface(depolarization) mainly in muscles and
nerve cells----receptors
(hormones&neurotransmitters)--specialization in some cell
(rods and cones)

4. transport in cell membrane
• smaller molecule-simple diffusion
• larger molecule-enter cell by
endocytosis(invaginates cell membrane--
surround the molecule--separate from cell
membrane form endocytic vesciles--enter and
move within the cell)
--pinocytosis-pinocytic vescile - fluid absorption in
to cell
--phagocytosis--engulf foregin bodies by bacteria
--exocytosis-exocytic vesciles-reverse endocytosis

5. • creation of vesicles create a constant transfer of cell
membrane
• fusogenic protein-area where the creation of vesicles this
make fusion of membrane around the vesicles
• area of receptor mediated endocytosis are depressed
area called COATED PITS--the floor of caoted pits have
CLATHRIN PROTEIN(fn:form scaffolding on developing
vesicles and make it separation from the cell membrane).
• TRANSCYTOSIS(flat cells)--transfer material direct to
entire thickness of cell --through the invagination called
CAVEOLAE(protein:caveolin)-don't form vesicles

6. contacts btwn cells
• gap btwn cells- 20nm
• classification of cell contacts-1.unspecialized contact
2.specialized contact-1.anchoring or adhesive junction
{1.adhesive spots or macula adheres-2.adhesive belts or
zonula adherens-3.adhesive strips or fascia adherens}
2.occulding junction or zonula occuldens
3.communicating junction or gap junction
4.hemidesmosomes or focal spots
1.UNSPECIALIZED-Glycoprotein molecule (CAM-cell
adhesion molecule) connect with intermediate protein in
cytosolic ends & get attached to cytoskeleton on other
end of CAM get attached to similar CAM in other cell.

7. • CAM -1.calcium dependented(cadherins,selectins,integrins)
2.calcium independented(neural CAM, Inter CAM)
• intermediate protein-catenins,vinculin,alpha-actinin
• SPECIALIZED
1.ANCHORING-binds cells mechanically
1.ADHESIVE SPOTS(desmosomes)--where strong anchorage is
needed ..eg. epidermis-desmosomes are small circumscribes
area of attachement--plasma layer thickened due to dense
layer of protein(area of desmosomes) intermediate protein.
--thickened area gap(25nm)-this area connected by fibrils from
CAM
--desmosomes(cytoskeleton-intermediate protein(thicken area--
CAM-FIBRILS-another CAM nearby cell)
--CAM integrins(desmogleins I,II) & interlink protein
(desmoplakins)

8. 2.ADHESIVE BELTS-apices of epithelial cell--similar to
desmosomes but differ in small circumscribed area into bands or
belts---gap not filled by filaments-CAM(cadherins)--present deep
to occulding junction.
3.ADHESIVE STRIPS-area of attachements presents with
strips(smooth muscle,intercalated discs of cardiac discs,junctn
btwn glial cell & nerves.)
4.HEMIDESMOSOMES--similar to desmosomes present thicken
at cell membrane only one sides.
cytoskeleton-intermediate protein(keratin)--CAM(integrins)-
extracellular structures----{location :basal epidermal cells lie
aganist connective tissue}
5. FOCAL SPOTS-local adhesion of cell to EXTRACELLULAR
MATRIX--Transient nature(btwn WBC and vessels wall)
CAM(integrins)-intermediate protein(bind integrins to actin
filaments)--IM proteins (ALPHA actinin, vinculin & talin).

9. • TIGHT JUNCTION:-apices of epithelial cell & endothelial
cells -- 2 plasma membrane get tightly attached--this also a
barrier junction --stop permeating intestinal content into
intercelluar spaces ..
• functions:cell membrane adjoin by CAM that in form of
STITCHES
1.this junction separate the zone of secretion or absorption
from normal zone
2.prevent lateral migration of proteins that are helpfull in above
mentioned function
3.prevent back diffusion of transported substances
4.leaky tight junction(if incomplete closing of gap)-it allows slow
diffusion of molecule across it.

10. • JUNCTIONAL COMPLEX:macula adherence,zonula
adherens,zonnula occuldens are arranged in descending
order at apices of epithelial cell
• GAP junction or COMMUNICATING or macula
communicatens:no contact btwn the 2 plasma membrane but
acutal gap 20nm is decreased into 3nm
• structure of gap would BEAD-LIKE STRUCTURE connects
two cytoplasm thorough a canal in each bead
• each channel have 6 protein named CONNEXONS or
NEXINS
• CONNEXINS of one cell connect to another another cell
connexins
• change in pH or calcium ion concentration can close the gap
junction. it found on neurons

11. cell organelles
• MEMBRANE BOUND ORGANELLE-endoplasmic
reticulum,golgi complex,mitochondria,membrane bound
vesicles(phagosomes,lysosomes,peroxisomes,exocytic
vesicles)
• NON-MEMBRANE BOUND ORGANELLE-
ribosomes,cytoskeleton(microfilament,microtuble,intermediate
filament)
1.ENDOPLASMIC RETICULUM-interconnected membrane with
nucleus that form channels or cisternae-it contain 2 channels -
one channel in outside (hyaloplasm or cytosol) & inside
channel (vaculoplasm)
fun:synthesis proteins, gylcoprotein,lipoproteins(eg.Ig from
plasma cells)

12. • ER-rough(granular)--due to attach of
ribosomes,smooth(agranular)-perinuclear space btwn inner
and outer membrane of ER.
• RER-protein synthesis
• SER-further processing of PROTEIN,also synthesis
lipid(phospholipid)
• ribosomes & enzymes present in outer surface of
ER ....product synthesized are present in inner membrane.
• RIBOSOMES-may be with ER or free in cytoplasm
--single ribosomes-monosomes
--group ribosomes-polyribosomes
--each ribosomes contain protein& RNA
--made up 2 subunits=small(40s)&large(60s)--based on
sedementation rates
--func:synthesis protein

13. • MITOCHONDRIA(power house ofcell)-RBC don't contain mitochondria--it
vary in size , number from cell to cell-- in large cell it with high oxidative
metabolism
• smooth outer membrane& inner membrane btwn them intermembranous
space
• inner membrane high folded CRISTAE & space bounded by inner
membrane contain granular material MATRIX
• matrix contain ENZYMES..It also contain RNA & DNA
• FACT:all mitochondria derived from those in fertilized ovum and enterly of
maternal orgin
• enzymes play role in krebs or TCA cycle
• enzymes for TCA located in MATRIX
• enzymes for respiratory chain& ATP production located in INNER
MITOCHONDRIAL MEMBRANE.
• enzymes for coversion of ADP to ATP located in INTERMEMBRANOUS
SPACE
• enzymes for lipid synthesis and fatty acid metabolism located in OUTER
MEMBRANE

14. • mitochondrial cytopathy syndrome-abnormal mitochondrial
DNA--muscle weakness,degenerative lesion of brain, high
level latic acid. diagnosis:para-crystalline inclusions
• GOLGI COMPEX--SILVER SALT stain to make visible..flattend
sacs stacks one over another..at end of stacks it contain small
vesicles--cisternae of golgi is independent--material from ER
to golgi through vesicles..
• 3 regions of golgi 1.cis face(near nucleus)
2.medial face(btwn trans&cis)
3.trans face(near cell membran)
--material from RER to SER to golgi(cisface)to get
phosphorylated then to medial face (added sugar residues to
protein) form protein carbohydrate complex & finally to trans
face and make protein sorting,packaging &secretion
--membrane contain enzymes for forming above mention function
--process of putrefication due to protein processing.

15. MEMBRANE BOUND
VESICLES
• vesicles-small membraned storage containers present
along the cytoplasm for transport from one part to another
or one cell to another.
• PHAGOSOMES-foregin material engulf PHAGOCYTOSIS-
-membrane bound vesciles contain ingested particles
• PINOCYTIC VESICLES-fluid absorption into cell similar TO
phagocytosis
• EXOCYTIC VESICLES-get out of material from cell or may
be REVERSE PINOCYTOSIS
• SECRETORY GRANULES-vesicles contain the secretion
of cells & it commonly derived from golgi
• OTHER VESICLES-lipid,carbhydrate vesciles store in
cytoplasm

16. LYSOSOMES
• destroy foregin particles of cell or its own.
• vesicles of lysosomes contain enzymes-
LIPASES,PROTEASES,ACID PHOSPHATASE(40 different
enzymes like this).
• it denoted as ACID VESICLES SYSTEM(the vesicles
membrane contain H+ATPase)
• following steps shows the formation of different lysosomes
--membrane of vesciles contain the H+ pump make high acidic
inside the vesicles.
--ACID HYDROLASE(synthesis in ER)-- move to GOLGI(enzymes
are packed into vesicle in inactive state)--enzymes with inactive
in vesicless called PRIMARY LYSOSOMES
--this Inactive vesicles fused with cell membrane
vesicels(ENDOSOMES)--this cell membrane protein fusion
needed for make a active vesicles by increase their acid
environment--SECONDARY LYSOSOMES OR

17. • H+ ion pump need to create acidic environment.
• PHAGOLYSOSOMES-lysosomes fuse with phagosomes--
enzymes in lysosomes act on material in phagosomes
• MULTIVESICULAR BODIES-many small vesicles with in the
vesicles due to the fusion of lysosomes with PINOCYTIC
VESICLES
• RESIDULAL BODIES-remaning particles after the
phagosomes & pinocytic digestion .
• NO lysosomes in RBC
• LYSOSOMAL GLYCOGEN STORAGE DISEASE- genetic
defect due to absence of specific acid hydrolase lead to
accumulation of specific substances(eg:TAY-sachs disease)
• PEROXISOMES--Vesicles contain enzymes that form
hydrogen peroxide by react with other substances
--h2o2 detoxify by oxidation

18. --enzymes of peroxisomes involve in oxidation very long chain
fatty acids.
--peroxisomes found mainly in LIVER & RENAL CELLS
--ADRENOLEUKODYSTROPHY--rare autosomal recessive
disease...degeneration of brain,kidney,liver...due to insufficent
oxidation of long chain fatty acids.
--ZELLWEGER SYNDROME--formation of empty peroxisomes
due to defect in transportation of protein to peroxisomes
--PRIMARY HYPEROXALURIA--defect in peroxisomal
METABOLISM of GLYOXYLATE from glycine.
CYTOSKELETON---Fibrillar network -maintain cell
structure,motility,transport across the cell,adhesion
--elements of
cytoskeleton(Microfilament+microtubles+intermediate filaments)

19. • MICROFILAMENT(5nm)--made up of ACTIN--individual
molecule of actin are globular(G-ACTIN)--form long chain of
actin (F-actin),actin filaments or microfilaments
--meshwork of actin subjacent to cell membrane called -CELL
CORTEX(meshwork joined by protein FILAMIN)
--CELL CORTEX maintain shape and also shape by act on actin
it can also change the shape
--microvilli also have an actin filament and protrusion on cell
surface.
• MICROTUBLES(25nm)--made up of TUBULIN(ALPHA & BETA
subunits)--tubulin join in chain to form the PROTOFILAMENT-
wall of microtuble made up of 13 PROTOFILAMENT- these
protofilament are stabilized by MICROTUBLE ASSOCIATED
PROTEINS (MAPs)
--microtubles in forming CENTRIOLES have MICROTUBLE
ORGANIZING CENTER
fnc:stability of cell membrane--prevent ER from collapsing

20. contd--take part in transport of materials..some
protein(DYNEIN,KINESIN)..these are membrane proteins they
attach to microtubles and move along the tubules....this transport
found mainly in AXONS
--cell division tubules are changed into MITOTIC SPINDLE
--CILIA made of tubules
•INTERMEDIATE FILAMENTS(10nm) --made up of
different filaments in different cell..like(CYTOKERATIN in
epithelial, NEUROFILAMENT PROTEIN in neurons, DESMINS in
muscle,GLIAL FIBRILLARY ACIDIC PROTEIN in astrocytes,
LAMININ in nuclear lamina &VIMENTIN(many types of cell)
--functn:adhesion,intermediateprotein present in desmosomes
and hemidesmosomes
--filaments in skin epithelium change to form KERATIN..this is
main constitutent of hair &nail
--neurofilament of neuron,..neurofibrillis in help to maintain its
cylindrical shape of axons

21. contd--nuclear lamina contain IM filaments
--KARTAGENER SYNDROME-defect in organization of
MICROTUBLES--that immobilize CILIA of respiratory epithelium
unable to clear the secretion of bronchus
--ALZHEIMERS disease-defect in assembly of IM FILAMENTS --
Defect in IM filaments of neurons cause accumlation of tangles in
neurons
.....intercellular deposition of masses lead to cell death lead
nerurons loss of brain (dementia)
• CENTRIOLES- pair of structures for cell division--
CENTROSOMES(in dense cytoplasm as 2 dots when seen
through light microscope)
--when EM to see centrioles , it arranged in circles in NINE
groups, each group contain 3 TUBULES
--func:mitotic spidle in cell division--cilia--flagella--specilaized
cellprojection like AXIAL filament OF SPERMATOZOA, which all
have (9+2 ) configuration of MICROTUBULES

22. NUCLEUS
• RBC dont contain nucleus---its a
denser ,larger ,center ,different shape organelle in the cell.
• nuclear component: {chromatin+nucleolus+nuclear
membrane+nucleoplasm}
• CHROMATIN--BASOPHILIC AREA--delicate network fibers ---
- HETEROCHROMATIN{irregular dark masses--closed-face
nuclei}--- EUCHROMATIN{loose network & stains slightly--
open-face nuclei}
• nature of chromatin---made up of DNA & HISTONES protein &
non-histone protein---DNA highly packed genetic information
too long that form chromatin---FILAMENTS of DNA coil
around HISTONE COMPLEX is called NUCLEOSOMES---
NUCLEOSOMES WITH LINKER DNA form long chains form
the chromatin--after this SUPERCOILING occurs this make
50mm DNA to thicker structure CHROMOSOME of 5um

23. • contd--HETEROCHROMATIN(chromatin fibers are tighly
coiled form solid mass)--EUCHROMATIN(coiling not so
marked)
--in cell division the entire chromatin become tightly coiled and
take on appearance short thick rod called
CHROMOSOMES(DNA & protein)...protein are stablize the
chromosomes
---5 types of histones--H1,H2A,H2B,H3&H4--2 MOLECULES of
H2A,H2B,H3&H4 form NUCLEOSOME CORE(granular
mass)--dna filament round twice the core...DNA FILAMENT of
one nucleosome have 146 nucleotitdes pairs--LINKER DNA
contain 50 nucleotide pairs
• NUCLEOLI-DARKER structure in nucleus (single or multiple)-
--it give slightly reddish tinge when treated with H&E stains
--differeniated from heterochromatin by seeing regular shape of
nuceloli

24. --nucleoli are LARGER in cell with highly metabolically active---
nucleoli contain high RNA--synthesize ribosomal RNA- template
for ribosomal synthesis are located in related chromosomes---
FIRST long fibres form RNA that composed in fibrous zone of
nucleoli--2nd the long fibres are broen into small pices of
RIBOSOMAL SUBUNITS that composed in granular zone--3rd
RNA leaves the nucleolus through nuclear pore pass to
cytoplasm and the protein synthesis is started.
--parts of NUCLEOLI through EM view:central(PARS
FILAMENTOSA)--outer(PARS GRANULOSA) both this zones
found in PARS AMORPHOSA---nucleolar organizing
center(PARS CHROMOSOMA) this region contain parts of
chromosomes.
•NUCLEOPLASM-space in btwn nucleus and other substances
found spacieous are filled by a BASE substance called
NUCLEOPLASM

25. • NUCLEAR MEMBRANE--double layer surrounded the
nucleus--INNER & OUTER MEMBRANE-btwn this found
PERINUCLEAR SPACES--this space continous with ER
spaces---inner layer of nuclear membrane connects with the
end of chromosomes.
• deep to inner layer a layer of protein & filamnets called-
NUCLEAR LAMINA.
• LAMININS are protein in inner nucler membrane give
attachements to filaments in nuclear lamina....this maintain
shape of nucleus.
• gaps in nuclear membrane called NUCLEAR PORE
• each pore surrounded dense protein arranged in form of
EIGHT COMPLEX...protein&pore together known as PORE
COMPLEX
• PORE SIZE 80nm AND passage of particle less than 9nm
• typical nucleus have-- 3000-4000 pores
• pore transport- proteins,ribosomes from nucleus

26. CHROMOSOMES
• chromatin condensed to form CHROMOSOMES during cell
division
• man- diploid chromosomes-46-23 pairs
• haploid chromosomes-23-in spermatozoa&ova
• AUTOSOMES(44)+SEX CHROMOSOMES(2)
• Sex chromosomes (X,Y) in men, (X,X)in women.
• 2 chromosomes same forming a pair called HOMOLOGOUS
CHROMOSOMES
• SEX CHROMOSOMES of men (HETEROGAMETIC), women
(HOMOGAMETIC)
• STRUCTURE OF CHROMOSOMES:-Chromatids (2 parallel
rods of chromosomes) ..each chromatids joined by
CENTROMERE OR KINETOCHORE..in this region the
chromatin of each chromatid get highly coiled and constricted

27. • centromere usually not present in midway of 2 ends of
chromatid...one chromatid is said to LONG ARM & other to be
SHORT ARM---TYPES-1.submetacentric(one arm long & one
arm short)--2.acrocentric(one arm much shorter than
other)..3.metacentric(both arm are same)...4.telocentric(only
one arm is present and the chromosome have the
centrosomes in one end)
• SECONDARY CONSTRICTION--present at one end of
chromosomes(nucleolar organizing centers)
• SATELLITE BODY-part distal to secondary constriction
• identification of all chromosomes made by the dark and light
staining ..there we see the transverse bands
• DISTINGUSIH of chromosomes only in MITOSIS...during
interphase they are in the form of threads..THREADS name
CHROMONEMATA

28. SIGNIFICANCE OF
CHROMOSOMES
• Inherited information stored in CHROMATIN.
• functional segments of chromosomes-GENES
• GENES are unit to store information
• cell function,body function are all depend on PROTEIN
synthesis..eg.(Enzymes,hormones,antibodies all are proteins)
• so from this all cell constitue different proteins..by this protein
we divide individuality and species...devlopement and
functioning of all cells..
• chromosomes contain DNA ..store information and direct
activites on what type of protein to be synthesized.

29. KARYOTYPING
• IDENTIFY of each chromosome pattern or map is called
KARYOTYPING.
• PROCEDURE-blood sample in a medium where lymphocytes
can grow ..... after that (colchicine , colcemid ) are added to
sample which stop the cell division and make the
chromosome more distnict...then hypotonic solution is added
to cell and make it swell...then view under microsope
slide .....photographed....arranged in patterns of mapping of
photographs .....and look for chromosomal abnormality..
• total DNA content of cell =6x10^9 nucleotides pair of this
chromosome 1 (LARGEST CHROMOSOME) contain
2.5x10^8 nucleotides pair---Y chromosome(SMALLEST
CHROMOSOME) contain 5x10^7 nucleotides pairs
• KINETOCHORE--specialized region of centromere
surrounded bya protein mass..thsi region for attachement for
spindle............ends of chromosome called TELOMERES.

30. DNA
• double helix structure of double strand
• each strand contain chain OF NUCLEOTIDES.....phosphate
attach to sugar DEOXYRIBOSE..BASE attach to SUGAR..2
strands are joined base
• DNA BASE(ADENINE,GUANINE,CYTOSINE,THYMINE)
• base-base link(ADENINE+THYMINE)(CYTOSINE+GUANINE)
• ORDER of four bases link determine the type of protein it
synthesis....every protein have amino acid sequences which
detemines its nature OF PROTEIN..which all controlled by
DNA.
• 5 carbon atoms in deoxyribose...C3 attach to C5 of another
molecule through PHOSPHATE link..each strand have 5'end &
3'end.------5'end of left chain attach to 3'end of right chain
• C1 give attachement to base form base-base link

31. RNA
• RNA differ from DNA in some points--
sugar is RIBOSE not DEOXYRIBOSE---instead of THYMINE it
contain URACIL.
---It present In both cytoplasm & nucleus
---forms :1.messanger RNA(mRNA)
2.transfer RNA(tRNA)
3.ribosomal RNA(rRNA)
--mRNA act as intermediate btwn DNA & amino aciD of
cytoplasm to synthesis protein from amino acid.
--SYNTHESIS OF PROTEIN:-
--each amino acid represents in the DNA molecule by a
sequences of 3 bases (triplet code)
--4 bases in DNA ...64 combinationS are formed with the bases

32. • the dna molecule that bears code for complete polypeptide
chain constitue a STRUCTURAL GENE OR CISTRON.
• STEPS IN PROTEIN SYNTHESIS:-
---separation of 2 DNA strands---mRNA is synthesized by one
strand of DNA..C=G,A=T in DNA , in mRNA(A=U) are
produced....TRANSCRIPTION(code for amino acid
SEQUENCE to be linked is passed from DNA of chromosomes
to mRNA)....Transcription take place under influence of RNA
polymerase....CODON(part of mRNA strand bears the code for
one amino acid )....mRNA now Separate from DNA strand &
moves from nucleus to cytoplasm...in cytoplasm mRNA
attached to RIBOSOMES........cytoplasm also contain another
form RNA called tRNA....there are about 20 different types RNA
corresponding to 20 AMINO ACIDS......one side of tRNA
contain amino acid & another side contain code for three bases
called ANTICODON.....this are complementay bases for the
mRNA....tRNA with amino acids arranged along with mRNA.
THIS IS DETERMINE BY mRNA CODE .this is called

33. • Amino acids arranged in order in which their
codes are arranged mRNA or code in DNA
molecule...amino acids and proteins are joined
together by A POLYPEPTIDE CHAIN.
• CENTRAL DOGMA OF MOLECULAR
BIOLOGY(DNAtoRNAtoPROTEIN).