The Cell The smallest unit of life that can perform all life processes.
Life is macromolecules that can perform unique functions because they are enclosed in a structural compartment that is separate from the external environment. This separation allows living things to maintain a constant internal environment (homeostasis).
All living organisms are composed of cells that can: Respond to their environment Grow, develop and reproduce Metabolize Maintain homeostasis
A little bit of history
cells Robert Hooke
little wretched beasties Antone van Leeuwenhoek - lenses
Anton van Leeuwenhoek (1673) Made microscopes with better magnification First person to observe living cells Spirogyra
The Cell Theory (3 parts) Matthias Schleiden (botonist) Theodor Schwann (zoologist) 1. All organisms are made of one or more cells. 2. The cell is the basic unit of all living things.
All organisms are made of one or more cells The cell is the basic unit of all living things Redi spontaneous generation 3. All cells come from pre-existing cells Pasteur spontaneous generation
Cell Theory 1. The cell is the basic unit of life. 2. All life forms are made of one or more cells. 3. Cells only arise from pre-existing cells.
Why are cells so special? Able to differentiate Stem cell = general, unspecialized cell Becomes specialized with time Examples: skin cells, macrophage cells, neurons
Differentiation
You can use different terms to describe the type of cell(s) you re looking at. 3 different sets of words:
1) Unicellular vs. Multicellular Unicellular Uni = one One cell Multicellular Multi = many Many cells
2) Prokaryote vs Eukaryote prokaryote Cells that DO NOT have a cell membrane around their nucleus. eukaryote Cells that have a membrane around their nucleus. example Bacteria Plant and Animal Cells Eukaryote cells usually 10X larger than Prokaryote cells.
2) Prokaryote vs Eukaryote Prokaryotic Cells No nucleus- DNA unbound No membrane-bound organelles All unicellular organisms All microscopic Eukaryotic Cells Have nucleus with DNA Organelles membranebound Unicellular OR multicellular organisms microscopic OR macroscopic
Amoeba sisters pro & eukaryotes
3. Plant or Animal Have cell walls Have chloroplasts Have large vacuoles Tend to have a square shape Animal No cell walls Have small vacuoles, if any Not so square Plant
Eukaryotic Cell structures: structure and function Hank crash course
Organelles Structures within cells that have specific jobs Little organs
plant cell wall cellulose
cell wall
cell membranes a dynamic structure fluid mosaic model
functions: Separates cell from its environment Allows cell to maintain homeostasis Acts as selectively permeable membrane (regulates molecules entering and leaving the cell) Cell-cell communication Surface markers - recognition Amoeba sisters - homeostasis
Made of phospholipid bilayer with embedded proteins Harvard animation
Phospholipid bilayer
The protein part of the cell membrane provides: communication, "I.D." tags, anchors to microtubules, gates of exchange for large molecules and pumps for maintaining ionic balance.
Special designs for specific function: The typical cell membrane vs different types of membranes better suited for function In a typical membrane, there is the passive phospholipid bilayer part (75-95%) and the active protein part (5-25%). Those cells that have to do more exchanging of materials, such as glandular cells, have more of the protein membrane. Those cells that have minimal exchange of materials, such as fat cells, have less protein membrane.
the cell membrane semi-fluid Selectively permeable
microfilaments & microtubules structure movement
Cytoskeleton Function: Framework for the cellshape, organize, and support cell Other: made of proteins
Cilia and Flagella Function: assist in movement Other: Cilia- short, hair-like Flagella- long, tail-like
centrioles
Molecular "tags" on microtubules direct traffic inside cells
Cytoplasm Function: fill the spaces between organelles and the plasma membrane
the nucleus contains the genetic material
Nucleus Function: store and protect genetic info (DNA) NOT THE BRAIN- just stores the info Other: Chromosomes: DNA wound up with proteins Nuclear envelope: double membrane with pores
endomembrane system
endoplasmic reticulum
rough ER transports newly synthesized proteins alters proteins folds into tertiary structures
smooth ER site for synthesis of lipids and steroids site for hydrolysis of glycogen modifies (detox.) small molecules
golgi apparatus recieves proteins from ER further modifications Concentrates, packages, sorts proteins Polysacc. for plant cell walls synthesized
secreting side receiving side
Vesicles and vacuoles The function and importance of vacuoles varies greatly according to the type of cell in which they are present.
functions of the vacuole include: Isolating materials that might be harmful or a threat to the cell. Breaking down products taken into the cell to be used in metabolism. Exporting unwanted substances from the cell. Allows plants to support structures such as leaves and flowers. Exporting manufactured products from the cell.
endocytosis and exocytosis taking in expelling pinocytosis phagocytosis Uses energy Encloses material in vesicles
exocytosis Vesicle membranes are also phospholipid bilayer
special vesicles and vacuoles peroxisomes the most common vesicle in cells found in all eukaryotes contain enzymes to rid the cell of hydrogen peroxide (convert the hydrogen peroxide to water) some detoxify alcohol and other harmful compounds by transferring hydrogen from the poisons to molecules of oxygen (oxidation). others initiate production of phospholipids
special vesicles and vacuoles contain hydrolytic enzymes - break down cellular waste products, fats, carbohydrates, proteins, and other macromolecules into simple compounds, which are then transferred back into the cytoplasm as new cell-building materials lysosomes
autophagy - recycles the cell's organic material
special vesicles and vacuoles Helps maintain homeostasis for water balance (osmotic equilibrium) central vacuole contractile vacuole
central vacuole (plants ONLY) Maintaining internal hydrostatic pressure or turgor within the cell
contractile vacuole (animals ONLY) found in certain unicellular organisms pumps fluid from in the cell to the outside by alternately filling and then contracting
ribosomes site of protein synthesis
Mitochondria Function: supply energy by converting food to ATP Other: Highly folded membranes Has own DNA and ribosomes
chloroplasts
Chloroplast Function: carry out photosynthesis, which turns light energy to chemical energy Other: has own DNA and ribosomes
Slide share examples The Cell is like CELL ANALOGY PROJECT
City 1 City 2 springfield House analogy Amusement park