Admin Team
06 May

1. PROKARYOTIC CELL & NUCLEOID

What are Prokaryotic Cells?

Prokaryotic cells are primitive and simple cells that:

  • do not possess a true nucleus
  • do not have membrane-bound organelles

Examples

  • Bacteria
  • Cyanobacteria (Blue-Green Algae)

Nucleoid

In prokaryotes, genetic material is present in an irregular region called:

Nucleoid

Important Features

  • Contains DNA
  • Not surrounded by nuclear membrane
  • Controls cellular activities

Difference from Nucleus

NucleoidNucleus
No nuclear membraneMembrane-bound
Found in prokaryotesFound in eukaryotes
Primitive structureAdvanced structure

2. MITOCHONDRIA – POWERHOUSE OF CELL

Definition

Mitochondria are membrane-bound organelles responsible for energy production.


Main Function

Cellular Respiration

Food molecules are oxidized to produce:

ATP (Adenosine Triphosphate)

ATP is called:

Energy currency of the cell.

Why called Powerhouse?

Because mitochondria produce most of the energy needed by cells.


Important Features

  • Double membrane
  • Own DNA and ribosomes
  • Semi-autonomous organelle

3. CYTOSKELETON

Definition

Cytoskeleton is a network of protein fibres present inside the cytoplasm.


Functions

  • Maintains cell shape
  • Provides structural support
  • Helps in movement of organelles
  • Helps in cell division

Components

  • Microtubules
  • Microfilaments
  • Intermediate filaments

4. SMOOTH ENDOPLASMIC RETICULUM (SER)

Definition

Smooth ER is a membranous network without ribosomes.


Functions

Lipid Synthesis

Produces:

  • fats
  • phospholipids
  • steroids

Detoxification

Especially important in:

Liver cells

It detoxifies:

  • drugs
  • poisons
  • harmful chemicals

5. VACUOLES

Definition

Vacuoles are membrane-bound sacs filled with fluid.


Functions

  • Storage of water
  • Storage of food and chemicals
  • Maintains turgor pressure
  • Helps in enlargement of plant cells

Important Point

Plant cells contain:

Large central vacuole

Animal cells contain:

Small vacuoles

6. LYSOSOMES

Definition

Lysosomes are membrane-bound sacs containing digestive enzymes.


Functions

  • Digestion of food particles
  • Destruction of pathogens
  • Removal of damaged organelles

Why abundant in WBCs?

White blood cells destroy bacteria through:

Phagocytosis

Hence they require numerous lysosomes.


Suicide Bags

Lysosomes are called:

“Suicidal Bags”

because they can digest their own cell during damage.


7. LACTASE & LACTOSE INTOLERANCE

Lactose

Lactose is:

Milk sugar

Lactase Enzyme

Function

Breaks:Lactose→Glucose+GalactoseLactose \rightarrow Glucose + GalactoseLactose→Glucose+Galactose


Lactose Intolerance

In many adults:

  • lactase production decreases
  • milk cannot be digested properly

Symptoms:

  • bloating
  • gas
  • stomach pain

8. HUMAN HEART & BLOOD FLOW

Chambers of Heart

ChamberFunction
Right AtriumReceives deoxygenated blood
Right VentriclePumps blood to lungs
Left AtriumReceives oxygenated blood
Left VentriclePumps oxygenated blood to body

Important Blood Flow

Lungs→Pulmonary Veins→Left AtriumLungs \rightarrow Pulmonary\ Veins \rightarrow Left\ AtriumLungs→Pulmonary Veins→Left AtriumThus:

Left atrium receives oxygen-rich blood first.

9. PENICILLIN & BACTERIAL CELL WALL

Penicillin

Penicillin is:

An antibiotic

discovered by:

Alexander Fleming

Mechanism of Action

Penicillin inhibits:

Cell wall synthesis in bacteria

Why Human Cells Are Safe?

Human cells:

  • do not possess cell walls
  • only have plasma membrane

Hence penicillin selectively affects bacteria.


10. IMPORTANT DISEASES

DiseaseTypeCause
PolioViralPoliovirus
DengueViralDengue virus
Athlete’s FootFungalFungal infection

11. CAROTENOIDS

Definition

Carotenoids are accessory pigments found in plants.


Functions

Coloration

Responsible for:

  • yellow color
  • orange color
  • autumn leaf colors

Photoprotection

Protect chlorophyll from:

Photo-oxidation

Human Eye Protection

Act as:

Antioxidants

Example:

  • Beta carotene

Important Point

❌ Carotenoids are NOT reaction centres.

Reaction Centre Contains

Chlorophyll-a

12. GENETICS – INHERITED vs ACQUIRED TRAITS

Inherited Traits

Traits transferred genetically from parents.

Examples

  • Curly hair
  • Freckles
  • Earlobe type

Acquired Traits

Traits developed during lifetime.

Examples

  • Chess skills
  • Swimming ability
  • Language proficiency

Important Concept

Acquired traits:

are not inherited genetically.

13. ORGANIC FARMING

Definition

Organic farming avoids:

  • chemical fertilizers
  • chemical pesticides

and uses natural methods.


14. VERMICOMPOST

Definition

Compost produced using earthworms.


Advantages

  • Rich in nutrients
  • Improves soil fertility
  • Eco-friendly

15. BIOFERTILIZERS & BIOPESTICIDES

Biofertilizers

Microorganisms that improve soil fertility.

Examples

  • Rhizobium
  • Azotobacter

Biopesticides

Natural pest-control agents.

Advantages

  • Environment friendly
  • Non-toxic

16. CROP ROTATION

Definition

Growing different crops alternately on same field.


Advantages

  • Controls pests
  • Controls weeds
  • Maintains soil fertility
  • Reduces diseases

MOST IMPORTANT ONE-LINERS

  • Nucleoid contains DNA in prokaryotes.
  • Mitochondria are the powerhouse of the cell.
  • Smooth ER detoxifies poisons.
  • Vacuoles maintain turgor pressure.
  • Lysosomes are suicidal bags.
  • Lactase digests lactose.
  • Left atrium receives oxygenated blood first.
  • Penicillin targets bacterial cell wall.
  • Carotenoids are accessory pigments.
  • Organic farming uses biofertilizers and crop rotation.

QUICK REVISION TABLE

TopicKey Point
NucleoidDNA region in prokaryotes
MitochondriaATP production
CytoskeletonCell shape
Smooth ERDetoxification
VacuolesStorage
LysosomesDigestion
LactaseDigests lactose
Left AtriumReceives oxygenated blood
PenicillinActs on bacterial cell wall
CarotenoidsPhotoprotection
VermicompostNutrient-rich manure
Crop RotationPest control
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