CELL THEORY

Cell Theory

• All living things are made up of cells

• Cells are the basic unit of structure and function in an organism

•  Cells come from pre-existing cells

Modern Cell Theory

• Cells carry genetic material which is passed from cell to cell during cell division

• All cells are basically same in structure and chemical composition

• Energy Flow (Biochemical processes) occurs within the cell.

Matthias Jakob Schleiden (1804-1881)

• 1838 A German Botanist introduced the concept that plants are made up of cell

Theodore Schwann (1810-1882)

• A German Physician and Physiologist

• 1839, He concluded that animals are also made up of cells

Robert Hooke (1635-1703)

• Observed cork cells under a microscope

• Cork comes from the outer bark of the cork oak tree and is mostly made of dead tissues. Early 19^th century this observation has led to the formulation of cell theory and became widely accepted that all living things are made up of cell

Anton Van Leeuwenhoek (1632-1723)

• Discovered bacteria and other microscopic organisms in rainwater (Protozoa and fungi) which he called animalcules.

• His observation has led to the diversity and significance of microorganism which eventually led to the development of cell theory.

Rudolf Virchow (1821-1902)

• German Physician

• 1858 Discovered that cells divide to form new cells and concluded that cells come from pre-existing cells

Homeostasis

• An organism’s ability to keep a constant internal state is called________

• Maintenance of these conditions, is important because most cells of an organism require a specific set of conditions to function normally.

Chemical Energy

• It is stored in the bonds present in food molecules, and it will be converted by the cells into more usable forms.

Responsiveness to their Environment

• A cell must first be able to determine the changes that have taken place before deciding the necessary responses that will ultimately result in the maintenance of normal internal conditions.

Protection and Support

Immune cells impart protection against pathogens and other foreign bodies that may enter the general circulation

Cell membrane or plasma membrane

• Cells primary Barrier

• separates the internal environment from external environment.

• Controls the passage of organic molecule, ions, water, and oxygen into and out of the cell

Phospholipid

are ‘’amphipathic’’ molecules meaning the have both hydrophilic head (water-loving) and hydrophobic tails (water-fearing). This arrangement creates stable barrier.

Each of the phospholipids consists of the following:

Head Region

• phosphate group

• hydrophilic

Tail Region

• two fatty acid chains

• hydrophobic

Cholesterol

• It help to regulate the fluidity of membrane, preventing it from becoming too rigid at low temperature or too fluid at high temperature 

Glycoproteins

• Protein with carbohydrates attached

Glycolipids

• Lipid with carbohydrates attached

Channel Proteins

passageway of certain molecules

Carrier Proteins

change conformation to transport molecules

cell recognition proteins

detect invading pathogens

Acceptor Proteins

binding of molecules to trigger responses

Fluid Mosaic Model

describes the membrane structure

• different molecules such as proteins, sugars, and cholesterol

• fluidity due to its natural viscosity

Selective Permeability

is an important property of the lipid bilayer, in which it only allows certain molecules to move into and out of the cell

Cytoskeleton

• This consists of a network of protein fibers that gives the cell its structural framework

• The cytoskeletal elements can be observed by using fluorescence techniques.

• In addition to providing a structural framework to the cell, the cytoskeleton also serves other functions such as movement of organelles, macromolecules, and chromosomes

Microtubules

• These consist of helically arranged globular proteins called tubulin

• It radiates from the centrosomes

• Form spindle fibers that move chromosomes

Microfilaments

• They consist of long fibers of actin protein, making them the thinnest cytoskeleton

• They help facilitate cell and organelle movement

• They can help change the shape of the cell

Intermediate Filaments

• Helps maintain cell shape

• Anchors the nucleus

Cytoplasm

• This is where all different subcellular structures are suspended

• It is composed of the cytosol, a semifluid solution that consists of water 70 to 80% and inorganic and organic molecules

Cell Wall

• Structure - A rigid Membrane surrounding plants cells made up mostly cellulos

• Functions - Gives the cell Protection, Support, and Structure

Organelle

• Also known as little organs

• Specialized structure found within the cell which performs specific functions vital to cellular life

Mitochondria

• The powerhouse of the cell

• Responsible for the conversion of light energy to chemical energy of sugars in photosynthetic process of plants

Cell Membrane

• Outermost layer of an animal cell and in a plants

• Regulate the entrance and exit of substance in the cell

Nucleus

• bounded by a membrane. Located in almost the center of the cell

• Control or regulates all chemical reaction within the cell

Peroxisome

• A small round organelle enclosed in cell membrane. They carry out oxidation reaction that break down fatty acids.

• It also detoxifies many poisons in the body.

Vacuole

Membranous sacs

These serve as a storage of water, organic nutrients, variety of salts, sugar & some weak acids., responsible for cell enlargement and water balance

Chloroplast

Double membrane organelles with inner folds called thylakoids and has similar characteristics with mitochondria

Responsible for the conversion of light energy to chemical energy of sugars in the photosynthetic process in plants

Lysosome

Single walled membranous sacs

Responsible for digestion of nutrients, bacteria and damaged cells or programmed cell death during embryonic development

Endoplasmic Reticulum

Series of membranous channels that forms a continuous network extending from the cell membrane to the nucleus

Rough ER Main role is to produce proteins.

Smooth ER. This organelle produces lipids

Gilgi Body

Cluster of flattened membranous sacs that are continuous with the channels of the

SER

These serve functions similar to a warehouse and processing center, processing products of the ER

Ribosome

A large complex of protein and RNA

Synthesize protein molecules to build cell structures or to function as enzymes

Nucleus

spherical strucure round in the cell's nucleus

Synthesize ribosomal RNA (rRNA) and assemble ribosome