biology

Cell Division

Process where one cell divides into two or more daughter cells.

A vital biological process.

Tetrads

4

2 main types of cell division

mitosis

meiosis

Mitosis

identical body cells

used for growth, repair and replacement

is the stage where the cell divides its nucleus. This

process is called mitosis. It produces two identical daughter.

happens in four stages:

Prophase, Metaphase, Anaphase, Telophase (PMAT)

Meiosis

Produces genetically different daughter cells (gametes)

Creates genetic variation

Apoptosis

Programmed cell death

Removes damaged or unnecessary cells

Necrosis

Uncontrolled cell death

Caused by injury, infection, or lack of blood supply

Causes inflammation

Cancer

Occurs when the cell cycle loses control.

Tumor

Benign

Non-cancerous

Tumor

Malignant

Cancerous

3 INTERPHASE

G1 → S → G2

Cell cycle checkpoints interphase

g1 check point

spindle assembly check point

g2 checkpoint

Interphase

(Longest Stage)

Mphase

Mitosis

Cytokinesis

G1

-First stage

‎-Cell grows larger

‎-"Preparation stage"

-mitochondria and ribosome increase in numbers

S Phase (Synthesis)

DNA replicates

Chromosomes duplicate

Sister chromatids form

Joined by the centromere

G2 Phase

‎-Cell grows more

‎-DNA checked and repaired

‎- cell prepares for mitosis

‎

M-Phase

‎- Produces 2 identical daughter cells

PMAT

Prophase, Metaphase, Anaphase, Telophase

Prophase

Chromatin condenses into chromosomes

‎Sister chromatids visible

‎-Nucleolus disappears

‎-Nuclear envelope breaks down

‎-Centrosomes move apart

‎-Spindle fibers form

Metaphase(middle)

-Chromosomes line up in the CENTER (metaphase plate)

‎-Ready for separation

Anaphase

‎-Centromeres split

‎-Sister chromatids separate

‎-Move to opposite poles

‎-Each chromatid becomes an individual chromosome

Telophase

‎-Final stage

‎-Nuclear membranes reform

‎-Two nuclei are formed

Cytokinesis

‎Division of the cytoplasm.

‎Animal Cell

‎Cleavage furrow forms

‎Plant Cell

‎Cell plate forms

‎Result:

‎Two identical daughter cells

Binary Fission (Prokaryotes)

‎Occurs in bacteria.

‎Steps:

‎DNA replicates

‎Cell elongates

‎Septum forms

‎Two identical daughter cells produced

MEIOSIS

‎Purpose:

‎Produce gametes (egg and sperm)

‎Reduce chromosome number to haploid (n)

‎Increase genetic variation

MEIOSIS 1: REDUCTION DIVISION

Meiosis I is a specialized cell division process fundamental to sexually reproducing organisms.

It primarily functions as a "reductional division," meaning it halves the number of chromosomes within a cell.

female male karyotype

46 chromosomes

2

Prophase I

crossing over

involving the physical

exchange of genetic material

between non-sister

chromatids.

occurs,

• This exchange creates new

combinations of genes on the

chromosomes, significantly

increasing genetic variation.

Homologous chromosomes

(the pairs inherited from each

parent) begin to physically

align and pair up along their

entire length in a process

called synapsis.

• The paired homologous

chromosomes form a structure

known as a bivalent or a

tetrad

chromatids presen

Metaphase 1

tetrads line up on the cell's equator

independent assortment

Anaphase 1

move opposite poles

sister chromatids remain attached

chromosomes redu

LIGHT MICROSCOPE (colored)

‎- use a beam of visible light

‎- use glass lenses

‎- magnify specimens up to 2,000 times

‎- ideal for observing living cells and larger cellular structures.

‎1. ) SIMPLE MICROSCOPE

‎- one lens only

‎- can magnify up to around 200x

2.) COMPOUND MICROSCOPE

‎- two or more lenses (objectives and lenses)

‎- can magnify up to 1,000-2,000×

3.)  DISSECTING MICROSCOPE

‎- two eyepieces

‎- used for observing larger, solid,  specimens.

ELECTRON MICROSCOPE (black and white)

- beam of electrons instead of light, allowing for much higher magnification resolution.

‎-Fixed position

‎1.) Transmission Electron Microscope (TEM)

‎- Electrons pass through a very thin specimen.

‎- 2d, detailed internal images of cell structures.

‎- Magnification: up to 2 million.

‎Used to study cell organelles, viruses, and molecular structures

‎- thin

‎2. ) Scanning Electron Microscope (SEM)

‎- Electrons bounce off the surface of the specimen.

‎- 3D

‎- Up to 100,000-500,000k

‎- Used for studying surface details of materials, insects, and tissues

Cell

‎-is the basic unit of life.

‎-Smallest known world hat perform life’s

‎functions

Major structure of cell

‎• Cell membrane

‎• Chromosome

‎• Cytoplasm

‎Life Processes

‎• Responsiveness

‎• Grow and Develop

‎• Reproduction

‎• Pass on traits to its offspring

‎• Metabolism

‎• Homeostasis

‎• Maintaining boundaries

‎• Movement

‎• Made of cells

‎• Digestion & Excretion

PROKARYOTIC CELL

- Small and simple

‎- 0.1 to 5.0 µm in size

‎- Unicellular

‎- Nucleus is absent

‎- Circular DNA

‎- Single haploid (n) chromosome

‎- Lack membrane-bound organelles

‎- Reproduce both sexually and asexually

‎- Cell division by binary fission

‎- Examples are bacteria and archaea cells

‎

Prokaryotic

PRO - before

‎KARYON - nut/kernel (cell nucleus)

‎No true nucleus

EUKARYOTIC CELLS

‎- Large and complex

‎- 10 to 100 µm in size

‎- Unicellular or multicellular

‎- Nucleus is present

‎- Linear DNA

‎- chromosome Paired diploid (2n)

‎- Has membrane-bound organelles

‎- Mostly reproduce sexually

‎- Cell division by mitosis

‎- Examples are plant and animal cells, including humans

Eukaryotic

Eu-true

‎Karyon -nut/kernel (cell nucleus)

‎True nucleus

The ORGANELLES

are very small ‎(Microscopic ),  perform various

‎functions for a cell and found in

‎the cytoplasm

Cell membrane

‎- Phospholipid bilayer

‎- Embedded proteins

Cytoplasm

‎-Organelles

‎-Nucleus

‎-Mitochondrion

‎-ERS

‎-Golgi bodies

‎-Vesicles

Cell Membrane (Plasma Membrane)

-Surrounds outside of all cells

Phospholipid

‎Hydrophilic head – water-loving

‎Hydrophobic tails – water-fearing

Hydrophilic head

water-loving

Hydrophobic tails

Water fearing

Cell Wall

Outside the cell membrane

‎Gives support, protection, and shape

‎Present in plants, fungi, and bacteria

‎Absent in animal cells

Cytoplasm

‎- Jelly-like substance inside the cell

‎- Site of many chemical reactions

‎Nucleus

- Control center of the cell

‎- Contains DNA

‎- Controls cell activities

Nucleolus

‎- found inside the nucleus

‎- Produces ribosomes

‎- Rich in RNA

Mitochondria - plural

‎Mitochondrion

‎- Powerhouse of the cell

‎- Produces ATP (energy)

‎- Site of cellular respiration

‎Rough ER (RER)

‎Has ribosomes

‎Protein synthesis

‎Protein transport

Smooth ER (SER)

No ribosomes

Lipid synthesis

Detoxification

Calcium storage

Ribosomes

Site of protein synthesis

Can be:

Free ribosomes

Attached to Rough ER

Golgi Apparatus (Golgi Bodies)

Receives proteins from Rough ER

Modifies proteins

Packages proteins

Sorts proteins

Sends proteins through vesicles

Vesicles

Membrane-bound sacs

Storage and transport of materials

Move substances between ER, Golgi apparatus, and cell membrane

Lysosomes

Contain digestive enzymes

Digest food particles

Destroy bacteria

Recycle worn-out organelles

Apoptosis (programmed cell death)

Cilia

Short

Hair-like

Moves substances across the cell surface

Flagella

Long

Whip-like

Helps the cell move

Vacuoles

Storage of water, food, and waste

Large central vacuole in plants

Small vacuoles in animals

Centrioles

Found mainly in animal cells

Forms spindle fibers

Helps separate chromosomes during cell division

Chloroplasts

Found in plant cells

Site of photosynthesis

Contains chlorophyll

ROBERT HOOKE (1665)

‎-Published Micrographia.

‎-Coined the term "Cell" after observing cork tissue under a 30× microscope.

ANTON VAN LEEUWENHOEK (1670s)

Discovered single-celled organisms ("animalcules").

‎Opened the microscopic world.

‎Known as the Father of Microscopy / Father of Microbiology.

‎-300x magnification

MATTHIAS SCHLEIDEN (1838)

-Botanist (studies plants).

‎-all plants are made up of cells.

‎THEODOR SCHWANN (1839)

‎Zoologist (studies animals).

‎Proposed that all animals are made of cells.

RUDOLF VIRCHOW (1855)

‎Proposed "Omnis Cellula e Cellula."

‎Meaning: All cells arise from pre-existing cells.

Fundamental Principles (Cell Theory)

‎MATHIAS SCHLEIDEN

‎1. All living things are made up of one or more cells.

‎THEODOR SCHWANN

‎2. The cell is the basic unit of life.

‎RUDOLF VIRCHOW

‎3. New cells arise from pre-existing cells.

MICROSCOPE

‎‎Derived from Greek work

‎Micro - "mikros" means extremely small

‎Scope - "skopein" means to observe

‎Tool to observe small objects

1590s - simple compound

Hans and Zacharias Janssen

1609 - compound microscope

‎Galileo Galilei

1665- light microscope

‎Robert Hooke Slices of cork (cell)

1670s - single-lens microscope

‎Antonie van Leeuwenhoek

1930s - first electron microscope

‎Ernst Ruska and Max Knoll

matrix

mitochondria

cristae

inner

Cell or Plasma Membrane

• Composed of

double layer of

phospholipids

and proteins

• Surrounds

outside of ALL

cells

• Controls what

enters or leaves

the cell

• Living layer

Membrane Functions

• Gives shape to the cell

• Separates the cell from its environment

• Serves as recognition sites acting as antigenic determinants

which render the cell surface its immunological properties

• Serves as a selective barrier to prevent harmful substance

to disperse freely

• It allows some substances to pass while excluding other

Types of Transport Mechanisms

in the Selective Passage of Particles

Inside the Cells

Passive Processes

Passive Processes

• Movement of substances from an area with a higher

• concentration to an area with a lower concentration without

• using cellular energy (ATP)

• Energy source: Kinetic energy

Examples of Passive Process:

Simple diffusion

Osmosis

Facilitated diffusion

Filtration

Simple Diffusion

net movement of particles from an area of higher concentration to an area with a lower concentration, that is, along their concentration gradient

Ex. Oxygen (O₂), Carbon dioxide (CO₂)

Osmosis

simple diffusion of

water through a selectively

permeable membrane

The usual definition of osmosis

is the movement of solvent

particles, such as water

molecules, through a

membrane. The water molecules

will travel in greater numbers per

unit of time from the place where

their number is highest to where

it is lowest.

Passive Transport: Osmosis

Hypotonic Solution

Isotonic Solution

Hypertonic Solution

Dialysis

REMOVES METABOLIC WASTE PRODUCTS, TOXINS, EXCESS FLUID & ELECTROLYTES from BLOOD

REQUIRED DUE to END-STAGE RENAL DISEASE

Is used for the diffusion of molecules of the soluble constituents (solutes) through a permeable membrane.

Facilitated Diffusion

same as simple diffusion, but the diffusing

substance is attached to a lipid

soluble carrier protein.

Facilitated diffusion provides a

means for certain substances,

notably glucose, that are both lipidinsoluble and too large to pass

through the membrane pores, to

enter the cell. A protein “carrier” is

needed as a transport vehicle.

4. Filtration

movement of water and solutes through a semi-permeable membrane from an area with higher hydrostatic pressure to an area with a lower hydrostatic pressure, that is, along a pressure gradient.

Filtration is the passage of a substance across a semi-permeable membrane as a result of mechanical force (e.g. gravity, blood pressure. Filtration separates larger molecules from small ones. The process of filtration that occurs in the kidney thus allows proteins, which are of a large molecular size, to be retained by the body, whereas waste materials of smaller molecular weight may be excreted

Active Process

Movement of substances with or against the concentration gradient which requires the expenditure of energy

Energy source: Hydrolysis of ATP

ex of Active Process

Active transport (solute

pumping) – Movement of

substances using ATP

(energy).

• Direction: Low

concentration → High

concentration (against the

concentration gradient)

2 Exocytosis

3 Endocytosis

3.1. Phagocytosis

3.2 Pinocytosis

3.3. Receptor Mediated Endocytosis

Exocytosis

• Exo (“out of the cell”) moves

substances out of the cell.

• secretion or ejection of

substances enclosed in a

membranous vesicle which fuses

with the plasma membrane and

ruptures, releasing the substance

to the exterior

Examples:

• Hormone secretion

• Neurotransmitter release

• Enzyme secretion

• Waste removal

Endocytosis

(“into the cell”)

includes those ATP requiring

processes that take up, engulf

extracellular substances by

enclosing them in a small

membranous vesicle.

• Once the vesicle or sac is

formed, it detaches from the

plasma membrane and moves

into the cytoplasm where it

fuses with a lysosome and its

contents are digested by

lysosomal enzymes.

Phagocytosis

cell eating, insoluble substances

are engulfed and are enclosed in a vesicle known as phagosome

Certain white blood cells and other “professional” phagocytes of the body act as scavenger cells that police and protect the body body by ingesting bacteria and other foreign debris as well as dead body cells.

Pinocytosis

cell drinking,

engulfment of small amount of fluid

enclosed in pinocytic vesicles

In this process the plasma membrane

invaginates to form a tiny pit and then its

edges fuse around the droplet of

extracellular fluid containing dissolved

proteins or fats.Unlike phagocytosis, it is

a routine activity of most cells.

It is especially important in cells that

function in absorption (for example, cells

forming the lining of the small intestine

and kidney tubule cells).

rReceptor Mediated Endocytosis

external substances

binds to membrane receptors and are engulfed with their

receptors