Download Cellular level of organization

Cellular level of Organization
Lecture content
1. Generalized view of a cell
2. Cell membrane
3. Organelles: Mitochondria
Lysosome
Nucleus and related structures
Endoplasmic Reticulum
Golgi apparatus
Ribosome
4. Exocytosis & Endocytosis
5. Transport across cell membrane:
-Diffusion
-facilitated diffusion
-Osmosis
-Active transport
6. Body fluid cpmpartments:
Composition of body fluid
7. Cell division: Mitosis & Cytokinesis
1. Generalized view of a cell
Number of structures (Organelles ) are common to most cells:
-
Nucleus
Mitochondria
Lysosome
Endoplasmic reticulum
Ribosome
Golgi Apparatus
2. Cell Membrane: also known as plasma membrane
Semipermeable in nature.Nucleus and all organelles are covered by
membrane.Made up of Protein and lipid (lipid bilayer). Proteins act as
‘pump’ ‘channels’ and ‘enzyme’
3. Organelles:
a. Nucleus: Made up in large part by Chromosomes.
Each chromosome is made up of DNA & other proteins
Nucleolus is rich in RNA
b. Mitochondria: Sausage shaped structure
Called power generating unit of the cell
Supplies energy in the form of ATP
Also synthesize proteins.
Contains numerous enzymes
c. Lysosome: Large irregular structure
Contain variety of strong enzymes
Lysosomal membrane protects the cell
Functions as Digestive enzyme in the cell
Digest bacteria when taken up by WBCs
d. Cell membrane: or plasma membrane
Semepermeable in nature
Made up of lipids and proteins( Lipid bilayer)
Proteins act as ‘pump’ , ‘channels’ , & ‘ receptors’.
e. Endoplasmic reticulum:
Two types: i. Rough—contains ribosomes
Synthesize proteins
ii. Smooth: Synthesize steroids
in skeletal muscles, it stores calcium
f. Golgi Apparatus: Present near nucleus
It has inner ‘CIS’ and outer ‘TRANSsides
Transfer protein from the CIS side to the TRANS
side from the rough endoplasmic reticulum
Proteins come out of the cells by ‘Exocytosis’
g. Ribosome: Site of protein synthesis
Found in 3 forms: mRNA, tRNA & rRNA
Free ribosomes, mitochondrial ribosomes
4. Exocytosis and Endocytosis
a. Exocytosis: Vesical membrane fuse with the cell membrane
Area of fusion then breaks estruding protein as secretory
granules
Process needs energy and calcium
b. Endocytosis: It is opposite of Exocytosis. Two types
i.Phagocytosis ; Process of engulfing solid particle
ii.Pinocytosis: Here the particle is in solution
5. Transport across cell membrane
Primary forces are:
1. Passive: Diffusion
Facilitated diffusion
Solvant drag
Osmosis
2. Active: Active transport
Secondary active transport
a. Diffusion: When solute particles or gas move from an area of
higher concentration to an area of lower
concentration through a semipermeable membrane
until equilibrium .
b. Facilitated diffusion: It is a carrier mediated transport. It is
Diffusion with the help of carrier protein
c. Solvant drag: When solvant flows in one direction (bulk flow)
Solvant tends to drag some solute
d. Osmosis: process where solvant(Water) flows from a solution
of lower concentration to a solution of higher
concentration through a semipermeable membrane
till equilibrium.
e. Tonicity: i.Isotonic when the tonicity of a given solution is same
as that of a reference solution.
ii.Hypotonic: When the tonicity of a given solution is
less than that of a reference solution
iii.Hypertonic: It is opposite of hypotonic solution
f. Active transport: Process where solute moves against electrochemical gradient ( From lower concentration to higher concentration) with expenditure of energy.
g. Secondary active transport: because transport indirectly uses
energy obtained from ATP. It is two types:
a. Antiport:when one ion is exchanged for another ion in the
opposite direction
b. Symport: when two substances enter the cell in the same
direction. Example: Sodium and Glucose
6. Body fluid compartments: TBW is made up of
60% of body Wt
Two main compartments:
i.Extracellular fluid (ECF); is about 20% of
body weight. ECF consists of
Interstitial fluid-------15%
Plasma -----------------5%
Transcellular fluid 9CSF, Aquaous Humour)
ii. Intracellular fluid (ICF): is about 40% of body wt.
6a.Composition of ECF and ICF
ECF
ICF
Na+ 142 mEq/L
14 mEq/L
K+ 4-5 mEq/L
145-150 mEq/L
Mg+ 3 mEq/
26mEq/L
Protein
16
74
7. Cell Division
Two types: Somatic cell division & Reproductive cell division
Somatic cell division: Nuclear cell division (Mitosis)
Cytoplasmic cell division (Cytokinesis)
Somatic cell cycle: 2 Major phases
a. Interphase
b. Mitotic phase
Interphase consists of: G1; S & G2 Phase
Mitotic phase consists of: Mitosis & Cytokinesis
Mitosis consists of: Prophase
Metaphase
Anaphase
Telophase
7a. DNA Replication: double helical structure is uncoiled
-Two strands separate
-Exposed base picks up a complimentary base
-Uncoiling & base pairing continues until2 of the
original DNA strands are joined with newly
formed DNA strand
-Now original DNA molecule has become 2
Identical DNA molecules