Biology Grade 11 - Comprehensive Notes

Cell and Sub-Cellular Organelles

• Cells are the basic units of life, exhibiting movement, respiration, homeostasis, growth, reproduction, excretion, and nutrition.
• Single-celled organisms include Amoeba and Paramecium, while complex organisms are multicellular.
• Cells vary in shape and size, correlating with their specific functions.

Cell Theory

• Robert Hooke (1665): Observed cork cells, noting empty spaces with walls, terming them 'cells'.
• Schleiden (1938): Concluded that cells are the fundamental units of plant tissues.
• Schwann: Studied animal cells, recognized similarities between plant and animal cells.
• Cell Theory Tenets:
  • Cells are the basic structural and functional units of life.
  • All organisms are composed of cells.
  • Cells arise from pre-existing cells through cellular division.
• Validation of Cell Theory:
  • Cells can survive independently for a short amount of time.
  • No entity smaller than a cell can live independently.
  • Cells cannot grow in sterile conditions (Redi & Pasteur experiments).
• Exceptions to Cell Theory:
  • Viruses: Acellular, requiring a host to be considered alive.
  • Viroids and Prions: Behave like viruses.
  • RBCs and Sieve Tube Cells: Lack nuclei, cannot divide.
  • Bacteria & Cyanobacteria: Lack well-organized nuclei.
  • Coenocytic Hyphae/Vaucheria: Multinucleate.
  • Protozoans: Acellular, not divided into cells.

Microscopy

• Microscopy: Technique to view objects not visible to the naked eye.
• Light Microscopes: Use visible light to illuminate specimens with a two-lens system; also known as compound microscopes.
  • Working Principle: Light source illuminates the object, objective lens forms a real, inverted and magnified image; eyepiece then produces final, virtual and magnified image.
  • Magnification: Increases the apparent size of an object. A 10x lens magnifies an object of 1μm to 10μm. Total magnification is calculated by multiplying objective and ocular lens values.
  • Maximum magnification of a light microscope is 1500X.
  • Resolution: Ability to distinguish between closely spaced points. Human eye resolution = 0.1mm; Light microscope resolution = 250 nm.
• Electron Microscopy: Uses electron beams for high resolution imaging.
  • Working Principle: Electron gun produces electrons focused by condenser lenses, specimen scatters beams through objective lens, creating magnified image further magnified by ocular lens.
  • Magnification: Electron microscope can magnify specimens between 1 and 50 million times.
  • Resolution, is 0.2 nm.

Comparison of Light and Electron Microscopes

• Svedberg Unit (S): Measures sedimentation rate during centrifugation, indicating molecular size and shape.
• Types of Electron Microscopes: TEM (Transmission Electron Microscope), SEM (Scanning Electron Microscope), STEM (Scanning Transmission Electron Microscope).

Ultrastructure

• Ultrastructure: Fine structure of the cell observed using an electron microscope.
• Animal Cell Organelles: Cell membrane, mitochondria, peroxisome, rough endoplasmic reticulum, ribosomes, vacuoles, centrosome, microtubules, lysosomes, intermediate filaments, smooth endoplasmic reticulum, nucleus, nucleolus, Golgi apparatus, Golgi vesicles.
• Plasma Membrane: Outer living boundary of the cell.
• Plant Cell Organelles: Cell wall, cell membrane, nucleus, nucleolus, rough endoplasmic reticulum, ribosomes, Golgi bodies/vesicles, cytoplasm, chloroplast.

Cell Wall and Plasma Membrane

Cell Wall

• Present in plant cells, prokaryotes, fungi, and some protists; absent in animal cells.
• Composed of cellulose (plants), peptidoglycan (prokaryotes), chitin (fungi).
• Functions: Protects cell, maintains shape, prevents excessive water uptake.
• Structure:
  • Primary Cell Wall: Develops during cell division, thin and flexible, composed of cellulose microfibrils, hemicelluloses, and pectin.
  • Secondary Cell Wall: Formed between the plasma membrane and primary cell wall in sclerenchyma cells, provides support.
  • Middle Lamella: Between primary walls of adjacent cells, composed of magnesium, calcium salts, and pectin.
• Pectin and Pectic Acids: Polymers involved in the structure and adhesion of cell wall layers.

Plasma Membrane

• Also called cell membrane; boundary of protoplasm, present in all living cells.
• Composition: Proteins (60-80%), lipids (20-40%), carbohydrates.
• Fluid Mosaic Model: Phospholipid bilayer with embedded proteins; proteins drift laterally.
• Lipid Part: Phospholipids arranged with hydrophobic tails facing inward, hydrophilic heads outward; includes steroids and cholesterol.
• Proteins: Transport channels, enzymes, receptors, antigens.
• Glycolipids and Glycoproteins: Cell surface markers for cell recognition.
• Functions of Plasma Membrane Proteins: Transport, enzymatic activity, signal reception, cell recognition.
• Regulation of Cell's Interaction: Controls transport of materials; maintains pH and ionic concentration.
• Techniques for Studying Cell Membrane: Biophysical imaging techniques, scanning electron microscopy (SEM).

Cell Signaling

• Process by which cells communicate with each other.

• Ligands: Signaling molecules (proteins, lipids, gases, etc.).

• Receptors: Proteins that respond to ligands; specific to signaling molecules.

• Process Pathway:

  1. Reception: Target cell detects signal molecule.
  2. Transduction: Signal conversion to bring about cellular response.
  3. Response: Triggers specific cellular responses.

• Protein Signaling Pathway:

  • Water-soluble hormones bind to receptors on the plasma membrane.
  • Initiates events, generating a second messenger (cAMP).
  • Triggers changes (enzyme activation, gene activation).

• Steroid Signaling Pathway:

  • Steroid hormones directly diffuse through the plasma membrane.
  • Bind to receptors in cytoplasm or nucleus, forming a complex.
  • Activated complex binds to DNA, acting as a transcription factor for gene expression.

Membrane Transport Mechanism

• Controls movement of solutes through biological membrane.
• Factors: Permeability, solute concentration, size, and charge of the solute.
• Types: Simple diffusion, facilitated diffusion, osmosis, active transport.

Simple Diffusion

• Movement of molecules from high to low concentration, down a concentration gradient.
• Small molecules (water, carbon dioxide, oxygen) pass through the membrane.

Facilitated Diffusion

• Molecules move from high to low concentration, aided by transport proteins.
• Channel proteins: Open and gated channels.
• Carrier proteins: Bind molecules, change shape, and release them to the other side.

Osmosis

• Movement of molecules from low to high concentration through a semipermeable membrane.

Active Transport

• Movement of molecules from low to high concentration, against a gradient, requiring energy.
• Primary Active Transport: Uses ATP (e.g., sodium-potassium pump).
• Secondary Active Transport: Uses electrochemical energy.
• Occurs in root cells, aiding in water and mineral absorption.

Cytoplasm and Organelles

• Protoplasm: Living matter of a cell, divided into cytoplasm and nucleus in eukaryotes.
• Cytoplasm: Region between nuclear membrane and plasma membrane.
  • 90% water, contains biochemicals (ions, salts, sugars, amino acids, proteins).
  • Metabolic pathways (protein synthesis, glycolysis).
  • Cytosol: Liquid phase of cytoplasm.
• Organelles: Discrete structures within cytoplasm with specific functions.

Endoplasmic Reticulum (ER)

• Extensive network of membrane-bound tubules and sacs (cisternae).
• Types:
  • Smooth ER: Lipid synthesis, detoxification.
  • Rough ER: Ribosomes attached, protein synthesis.

Ribosomes

• Particles made of ribosomal RNA and protein; carry out protein synthesis.
• Eukaryotic ribosomes (80S), prokaryotic ribosomes (70S).
• Composed of two subunits.

Golgi Complex

• Stack of flattened sacs (cisternae) with associated vesicles.
• Function: Processes cell secretions (proteins), forms lysosomes, peroxisomes, glyoxysomes; synthesizes glycoproteins and lipoproteins.

Vesicles

• Small membrane-enclosed sacs for transporting substances.
• Examples: Secretory vesicles, transport vesicles, synaptic vesicles, lysosomes.

Lysosomes

• Single-membrane vesicles containing digestive (hydrolytic) enzymes.
• Function: Digestion and removal of waste.
• Process: Fuses with vacuoles via endocytosis, phagocytosis, autophagy.
• Autophagy: Cell eating its own organelles.
• Autolysis: Programmed cell death (suicidal bags).

Peroxisomes and Glyoxysomes

• Peroxisomes: Oxidative organelles, contain enzymes (peroxidases, catalases).
• Glyoxysomes: Specialized peroxisomes in oilseed plants; involved in glyoxylate cycle.

Vacuoles

• Large vesicles from the ER and Golgi complex, responsible for turgor pressure, storage of various compounds, etc.
• Animal cells- Food vacuoles and freshwater protists have contractile vacuoles
• Plant cells- Central vacuole

Mitochondria

• Present in all eukaryotic cells; sites of cellular respiration.
• Enclosed by a double membrane.
  • Outer Membrane: Smooth with porins.
  • Inner Membrane: Folded inwards (cristae), contains ATP synthase enzymes (F0-F1 particles).
• Intermembrane space, mitochondrial matrix (contains DNA, RNA, 70S ribosomes, enzymes).

Plastids

• Classified based on pigments and development:

  • Proplastids
  • Leucoplasts (colourless- roots, stems and seeds)
  • Chromoplasts (colored pigments other than green).
  • Chloroplasts (green in plants).

  Chloroplasts

  • Site of photosynthesis; bounded by a double membrane.
  • Stroma: Contains DNA, RNA, 70S ribosomes, enzymes.
  • Thylakoids: Structure in the stroma system containing pigments like Chlorophyll.
    Smaller thylakoids & Larger thylakoids connect the grana with each other.

Centrioles

• Non-membranous organelles in animal cells.
• Composed of nine triplets of microtubules arranged circularly.
• Spindle fibers during cell division and basal bodies production.

Nucleus

• Most prominent part of the cell; contains genetic material.
• Components:
  • Nuclear Envelope: Double membrane covering with nuclear pores.
  • Nucleoplasm: Transparent semifluid ground substance.
  • Nucleolus: Non-membrane bound structure; involved in ribosome construction.
  • Chromatin: DNA and proteins; condenses into chromosomes during cell division.

Prokaryotic and Eukaryotic Cells

Stem Cells

• Cells with the potential to develop into many different types of cells.
• Types:
  • Adult stem cells
  • Embryonic stem cells (ESCs).
  • Induced pluripotent stem cells (iPSCs).
    |Classification |description|
    |:----------------|:-----------|
    Totipotent | Differentiate into all possible cell types|
    Pluripotent| Turn into almost any cell |
    Multipotent | Differentiate into a closely related family of cells|
    Oligopotent | These can differentiate into a few different cell types |
    Unipotent |These can only produce cells of one kind, which is their own type|
• Advantages of using stem cells: Provide new cells, replace specialized cells, divide to produce new and various types of cells, spinal cord injuries, diabetes etc
• Technological advancement, in lab growing
• IPSCs was first described in Yamanaka- Awarded the nobel Prize
  How to generate iPSCs? Introducing the signals that normally tell stem celles to stay in their early stage
• BCC Research predicts the global market for induced pluripotent stem cells to grow from $2.8 billion in 2021 to $4.4 billion by 2026.

Endocytosis and Exocytosis

• Active bulk transport of products across the cell membrane.
• Endocytosis: Substances are engulfed within the cell membrane, forming a vesicle with ingested material.
  • Phagocytosis: Ingestion of other cells or particles by phagocytes.
  • Pinocytosis: Cell taking in nutrients. Receptor-mediated endocytosis.
• Exocytosis: Transfer of material from inside to outside of the cell; vesicles packaged and fused with the cell membrane.

Cell Division

• Cells divide to produce new ones. Parent cells divide into daughter cells, that helps for the multiplication.

• Cell cycle comprises mitosis and cytokinesis

• Mitosis is the division of nucleus

• Cytokinesis in the division of cytoplasm

• MITOSIS process consist of five phases-prophase-prometaphase-metaphase-anaphase and the telophase
  Significance of Mitosis- Important for growht- ensures continuity of metabolism by transmitting to the daugther cells

• ensures that the daughter cell inherits the same number of choromosmes as its parent call

• Plays an important role in wound healing (regeneration of damaged cells) replaces lost cells

Molecular Biology

• Biochemistry is the study of the components and structure of chemical compounds in living organisms.
• Study of biochemistry is greatly helpful to explore the cell biology and anatomy because all, Evolution and variations in life forms are also discussed biochemically
• Three main types of bonds are covalent (mutual sharing of electrons), Ionic ( electrons transfer), and intermolecular and intramolecular interactions.( forces exits between in molecule).
• The four fundamental kinds of biological molecules 1. Carbodydrates 2. Lipids. 3. Proteins and 4.. Nucleic acid.
  Macromolecules/Polimers are high molecular weit and has repeating units (Micro molecules like monomers) are converted by condonsation water is relaesed, and by hydrolysis process water is utlilize to get smaller units
• WATER, properties make its medium of life. The properties of water that make it the medium of life are: higher polarity, hydrogen bonding, cohesion and adoption, high specific heat capasity, High heat evaporation, hydrophobic Exclusion low density of Ice,
• Carbohydrates compound of C,H,O, are organic biomolecules, sugars (saccharides). Types: monosaccharides, disaccharides and polysachharides. are very important to transfer water and the molecule
• Monosaccharides/are simple sugar, has multiple of hydroxide groups. formula (CnH2nOn) / glucose and fructose.
• Disaccharides are less sweet, can be hydrolysed, as a familiar energy resource ex sucrose, moltones, lactose
• Glycosidic bonds present in di saccharides, it is between two sugars
• Structure and other of polysaccharides starch, glycogen, cellulous and chitin. It occurs as Homosacchrides e.g., starch glycogen cellulose are food storage product. And also form Heterosaccharide e.g Agar ( made of more than sugar units)
• Protein are the function of the cell and require for their body system and also play role in structural components, They contains Carbon, Hydrogen, Oxygen and Nitrogen with phosphorous contents
• Amino acide are building blocks, contain NH2 (amine group + carboxyl group) R group is differnt from each other from each other as there are 20 Amino acids, types include
  • Essential Amino Acids
  • Non essential Amino acids
• Peptides in between more than two, with the help of NH2 group of AA1 and OH of CA group of AA2 = a dehydration reaction/ water is removed by the catalyzied enzyme
• Significance of amino acids sequence- the sequences determine how much of proteins that will involve in certain problems to be dealt and maintain the body in the certain stage. even due to point mutation (change of single or few nucleotides in DNA) the sequence of amino acid in a particular protein (polypeptide) may be disturbed
• Proteins can be formed Fibrous with fibre shape, elastic nature or it can globular shape with spherical and are highly functions.
  *Lipids the name applied to water insoluble. They contains C,H and mostly little of oxygen.
  *Acylgliceroles in fats properties- has low density and insoluble in water, functions- major part of lipids in the body. Phospholipids regulation, properties and components include transport of amino acids and steroids role of this function.
  *Acyglycerol molcular structur-are from glycerol and one, two or three fatty acids.
  *A phospholipid Molcular structur- similar to di-glyceride containing glycerol, two molecules of fatty acids. and a molecule of function of phoate
  *A terpene molecular structure- are many molecules unit in isoprene molecule. natural rubber is a poly terpene
  *Steroides are lipids with high molecular e=weight and crystalline, with atoms arraaaged in tour linked rings
  *Role and Functions
  (a) Estrogens
  MALE (e.g.. testosterone testosterone) and Female =oestrogen and progesterone)hormones and bile salt and vit D ( regulating Ca (2 positive)ions levels)
  (b) prostaglandins =are tissues local and are in tissue derived from achridomate with variable fuctioning= they induce inflamation and fever and intensify stimulation of pain
• Nucleic acids (are either deocyribonuclic acid (DNA) or ribonucleic acid (RNA)= DNA, structure, and composition are nucleotides while are RNA which means acid that does not have the acid component
  *There are two N bases, (Pyrimidins)and (Purihes) for nucleotides and are from nucleic acids
  *Mononucleotides adenosine aingle nucleotides and dimeric nucleotide examples (NAD+
  *Phosphodiester bonds occurs with with of nucleotides+ by addition of a chain + it can be added 3 and 5 carbon sides
  *watson and click suggested dougle helical DNA with all this compoonents to form a strand to pass to the next generatio of RNA
  General stucture of are DNA- contain three types include m RNA( for transfer to ribosomes) +t RNA, m.RNA- carries amino aids. and ribosomes (are with RNA r RNA) the combination of these form the central degma
  *Conjugateed molecules are combination of molecules lik.e a() glycolipids (compounded by lipids. -b- glycoprotein =compounded by proteins- and, lipoproteins with phospholipid

ENZYMES

• Enzymes are the biological polymers and catalyse biochemical and speeds up all action without getting consumed
  *Enzymes contain structure
  (a) Active Sites:- Small portions containing protein with catalytic ability. + substrate that contains -binding and can cause the conversation+ its shape design depending on the depending substrate Types of CoFactors: types - which requires for the attachment of substrate:- (1 Inorganic: Metallic ions: -F+ (positive 2 cation, MG+ (positive ) 2+ , CU+(postiive 2+(, ) ,Zn
  ,( 2. Organic molecules (a) prosthetic and (b) coENZ

*Coenzyme molecules is vitamin and inorganic factors-which are active and are also detacheable
*Co prosthetic a permanent factor. that is peramently attacvched and does not required at the completion of the enzyme
*Mechanisim of enzyme action with Es as to create a substrate complex but some times ep enzymes may go some of different models also
Enzyme models- lock key modle – an image to understand what makes the enzuymes function and then with new enzyme
(2.) – lock system (the enzyme is looked and
(3,) - Subtrate+ models- induced fit model that is for to work
(4) – the enyzme+ mole. + does the functions
*Enzymes needs – activation energy and must of high and that makes enzymes speed up which lower actination energy.
Affected Factors- of enenzymes action + temperture+ high in temperature + with humnan and thermopiles with hugh bacteris
(6) PH- range varies with low number of ph 6 and 8
Factors Affecting of Enzymatic Action enzyme concentration

The molecules in an experiment
(1) enzuymic inhibition has to have molecules for these inhibitors/ enzyme inhibits
*molecules - Cyanide etc+ antibodies. Anti bolytic etc
Inhibition
a) competitive (compete and lock them and can also block the active the enzymes site) + non campetitive(can attach any where) + feeed bach ( inhibit and in the chain)
enzymes + reaction/ they catayse -oxidates and reduces - transferases, (they transport specific function ) with carbon molecule
(4) -lysasses ( catalyze the function for covalent bonds-5) and lsomerase6. ligasies ( they join by breaking down to A TP. all there makes catylization
5.)- enzymes on basic level- proteases, diapause, amylase etc with subsrance level phospholnation to breakdow n the substrate to create phosphorylation

BIOENERGETICS

BIoenergetics is study on the energy and transfer with biological and systems
Photo synthes- light water oxygen are also very important part of these proces as it all requires for reaction
*Chlorophyl = a, Carotenodss, with the function if energy level, The chlorophyll also asoort very important light for this type of procees
-It helps in absorbing spectro copy.
-It helps to arrange this molecule- the process includes. Non cyclic, photophorylation/ cyclic photosphorlation
g3P the function and importance of this is very useful photosynthesis
olines Acetyl con enzyme A to fats
-Respiration of 36 ë ATP+ and it also differentats how plants and glucose can respirate = the proceess is that the plants do it to deal with other process

• Photo respiration= events occurs= the enzyme =RuBP = it does help them the plants to deal with respriation the carbosulate- affect the function so it must be good for carboxilating
  = Outline the process
  also

  • What does photosynthesis mean to you ?
      This is just a brief  summary but do know that there are other parts of cells. If you would like me to search and provide information to help
  

• Viruses
  Viruses contains -acellular structure and non living
  These contains 1,. Host system- that they will attack the BACTERIA
  .2 Has to replicated by completing the cycle of their replication and other cycle
  a ) It is protected by body or Host and also from the IMMUNE SYSTEM.
  3.) How it helps to completed all this process in the cycles that have been mentioned
  What is the different types of cycle= Lytic Vs Lysognic in cells and virus process
  = What is the function for usage if Bacteriocides- as this will be use to make GENETIC changes for different type of tools
  HIV
  -Explain the lyfcde cycle of HIV that includes the protein to be useful and all tht other proteins can be made for the next transimissions -HIV attacks- Tcells.. so these cells can only attack from HElPER cells
  m 1 . Isyptoms for HIV- that includes how aids. may have some of what the AIDS victims may attack
  .2 treat with ART . and with that some can be measure and treated for the transmission
  HERPES 1: Cause- it’s causd with virus
  transmission _ with all contact / symptoms- is Blister with mouth treatment - with antivirul- so one must care with contant .
  Herves 2= cause is by types and transmitted with sex compant
  Polio- cause is by what type ,= transmission way and the symptoom
  Cotton = It is the cause of fungus + its a symptom- with insecticide treatment for the inserticid

• Global Impact Virus infection have been costly during the Covi and also the the world economic losses
  Vaccines of Flue can not cover flu because it does not affect all but some. so it is not usable
  STRUCTURE. PRIONS and VIROIDS
  structure/ contains 1 is with prions and types like- protiens and prions is mostly protein , can move from other animal tissues and has transmittable nature
  Structure B /Viroids- consistis with short of RNA, circular + do NOT have the capsoimere .
  and that is the the end for this and this is the summary
  -what is the all diseases that i have caused the for porins, and from the VIROIOS and all causes for it