Cell: The Unit of Life

Two types of organisms?

(i) Unicellular

(ii) Multicellular

Define Cell.

Cell is the fundamental structural and functional unit of all living organisms.

Who discovered the first dead cell?

Robert Hooke

Who discovered the first living cell?

Anton Van Leewenhooke.

Who discovered the cell nucleus?

Robert Brown

Matthias Schleidan

German Botanist ;

observed all plants are composed of different kinds of cells which form tissue of the plant.

Theodore Schwann

German Zoologist ;

discovered the plasma membrane in animals ;

concluded cell wall is unique in plants

Ruldolf Virchow

Ommnis cellula - e - cellula (all cells arise form pre existing cells)

Cell Theory

1. All living organism are composed of cell and cell products.

2. all celss arise form pre - existing cells.

3. activities of an organism are the outcome of the sum total of activities and interactions of its constituent cells.

Two types of cells

1. Prokaryotic Cells

2. Eukaryotic Cells

differnece in Prokaryotic and Eukaryotic cells?

P( non membrane bound nucleus and organnelles, 70S ribosomes)

E( membrane bound nucleus and organelles, 80S ribosome[e xcept mitcbhondira and chloroplast])

main areana of cellular activities

cytoplasm

size of Mycoplasma

0.3 micro meter

longest cell

nerve cell

largest cell

egg of ostrich

size of bacteria

3 to 5 micro meter

RBC size

7 micrometer

eg. prokaryotic cells?

bacteria,

blue green algae,

mycoplasma,

PPLO (pleuro pnemonia like organisms)

in which type of cell the gentic material is basically naked?

Prokaryotic Cells

Which cells multiply faster?

Prokaryotic Cells

what is additional circular DNA outside genomic DNA called?

Plasmid

Advantages/Uses/Characteristics of Plamid?

1. it confers to unique charteristics( resistance to antibodies)

2. used for bacterial transformation with foreign DNA.

3 layered strcture of Cell Envelope

1. Glycocalyx

2. Cell Wall

3. Plasma Membrane

Cintents of Mesosome?

1. Tubules

2. Vesicles

3. Lamellae

covering of Glycocalyx

coating of mucus or polysaccharides macromolecules.

Slime Layer and Capsule

SL- Loose Sheath[ protects from water loss and dehydration]

Capsule- gummy, sticky charcter [ allows bacteria to hide from immune system]

Function of Cell Wall

1. provides strong structural support to prevent bursting or collapsing of bacteria

2. 2.determines the sape of the cell

Study of Cell

Cytology

why is cell walll rigid?

due to presence of ‘peptidoglycan’(murein or mucopeptide)

Selectively permeable

plasma mebrane

where is mesosome presnt

plasma membrane

how is mesosome formed?

invagination of plasma membrane into the cell

functions of mesosme?

1. Help in cell wall formation

2. DNA replication

3. distribution of daughter cells

4. respiration and secretion

5. increase surface area of plasma membrane and enzymatic content

Who introduced Gram Staining?

Christian Gram

Gram types?

Gram positive and gram negative

3 main componets of motile bacteria ( flagellum)

1. hook

2. filament

3. basal body

no. of rings in basal body

4[ L, P, S, M] proteinacious disc like structure connected by central rod

two sets of basal body

Distal [ cell wall] and proximal { plasma membrane] sets

flagellum?

thin filamentous extentions from their cell wall in motil cells

filament

longets

hollow

rigid

cyclindrical

made of flagellin protein

hook?

in P Cells { Flagellin Protein}

in E Cells { Tubulin Protein}

two more non motile bodies in bacteria?

pili and fimbriae

pili?

elongated

pilin protein

help in congugation( transfer of plsmid from one bacterium to another)

true only in gram negative

fimbriae

small

bristle like

slender tubes of helically arranged protein subunits

function: attachment

two subunits of ribosomes?

70 S and 80 S

ribosome size

15 - 20 nano meter

ribosome function?

site of protein synthesis

cytoplasmic ribosomes?

remain with the cell

ribosomes on the plasma membrane

transported out cell

polysome/ polyribosome?

chain or ribosomes on a single strand of mRNA

Inclusion Bodies

material is tored in cytoplasm in form of inclusion bodies

nucleiod?

nucleus like structure

contain genetic material of prokaryotic cells- genophore

Charcteristics / Properties of an Eukaryotic Cell

1. cytoskeltetal structure

2. membane bound organelle

3. organisation of gentic material into chromosomes

eg of uekrayotic cells

protista, fungi,plants and animals

2 layers of lipids in Plasma membrane of eukaryotic cells

1. hydrophobic (inwards,water fearing and non polar)

2. hydrophillic ( outwards, water loving and polar)

what is plasma membrane of eurkaryotic cells composed of?

lipids in a bilayer, carbohydrates, and proteins

protein:lipid in humans

52:40

who introduced the fluid mosaic modal of Plasma Membrane

singer and nolsan

Two plasma membrane proteins of eukaryotic cells

1. integral/tunnel/ransmembrane/intrisic proteins( harder to extract,buried in the membrane)

2. Peripheral/ Extrinsic proteins( lie on surface, easy to extract)

movement of phospho lipid?

lateral and flipflop

movement of protein

lateral due to large size

what is fluidity?

the ability to move iwthin the membrane is measured as its fluidity

Functions of Plasma membrane of uerkaryotic cells

1. The fluid nature is important for functiosn like - cell growth, formation of intercellular junctions, secretions,endocytocis,cell dvision etc.

2. transport of molecules through it by Active and Passive Trandport

Passive Transport

movement of molecules across the memebrane without the requirment of energy along the concentration graddent is called passive transport.

Active Transport

The uphill movement of materials across the membrane wher ethe solute particles move against their concentration gardient is called Active Transport.(requires energy/ATP)

what is plasma membrane of eukaryotic cells also knows as

Amphipathic( smth with both polar and non polar ends)

Endocytosis?

intake of materials in the form of carrier vesicles formed by invagination of plasma membrane

two types of Endocytosis

1. Pinoctosis [cell drinking]

2. Phagocytosis [cell eating]

Exocytosis

It is the process of discharge of undigested waste products to the outside of the cell through plasma membrane [Cell Vommiting/ Ephagy]

composition of cell wall of plants

• insoluble polysaccharides(cellulose)

• hemicellulose

• pectin

• proteins

composition of fungi cell wall

• chitin

componets of bacteria cell wall

• peptidoglycan

Chracteristics of Cell Wall

1. rigid

2. non living

3. surround plasma membrane

functions of cell wall

1. maintains shape of cell

2. protects cell form mechanical injury

3. wards off attacks of pathogens like virus, bacteria, fungi etc.

4. allows materials to pass in and out of cell

5. helps in cell interaction and provides barrier to undesirable macromolecules

2 cell walls

1 primary cell wall

secondary cell wall

Chracteristics of Primary Cell wall

• single layer

• thin; elastic; capable of expansion in growing cell

• grows by addition of more wall material within existing one

Charecteristics of Secondary Cell Wall

• formed after maturtaion

• causes thicining of Cell wall

• thicker; more rigid; may contain lignin and suberin

What are Pits?

the secondary cell wlal isnt uniform and he unithickened areas are called pits

Types of pits

1. Simple Pit: uniform diameter of pit cavity

2. Bordered pit: flask shaped pit cavity

What is middle lamella

• connects two adjaent cels

• thin; sticky; amorphous(no clear shape)

Plamodemata?

• cytoplasmic starnds are present in pit through which cytoplasm of one cell is in contact with another.

what makes up the endndomembrane system?

E.R

Goldi complex

Lysosome'

Vaculoles

why aren’t mitochondira, chloroplast,and plastids included in endo.. system

their functions arent cordinated

two compartments of E.R

1. Luminal Compartment (inside E.R)

2. Extra Lumina Compartment (outside E.R)

Location of E.R

nucear membrane to plasma membrane

3 structures of E.R

1. cisternae

2. vesicles

3. tubules

What is Cisternae of E.R?

• long; flattened; parallel; sac like structures

• fount in active protein synthesis cellls

tubules of e.r

• branvhed or unbranched

• free from ribsome

• found in cells involved in lipid or sterol synthesis

Vesicles of E.R.

• oval

• membane bound

• vascular

• free of ribosomes

types of E.R

1. RER

2. SER

SER

• Free of ribosomes

• smooth tubular structure

• found in muscle cell- sarcoplasmic reticulum(muscle contraction)

• desmotubule(inplasmodemata) is derived from SER

• specialised in synthesised of lipids and sterols

• detocificaion of drugs

• associated with uscle contraction and uptake of Ca2+ ions

• synthetic products of RER pass through SER onto GC

RER?

• bear ribosomes

• granular apperance

• extensive and continious with other membrane of the nucleus

• contains two glycoproteins- ribophorin I nad ribophorin II

• protein sysnthessi and secretion

• gives rise to SER

• forms hydrolytic enzymes for lysome

who observed golgi appartus first?

camillo golgi

what is golgi appartus

desly stained reticular structures present neart the nucleus of the cell

a network of interconnected membrane systems and vesicles.