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Do you know that….• The average human being is composed of
around 100 Trillion individual cells!!!• Each cell has about 10,000 times as many
molecules as the Milky Way has stars• Three-hundred-million cells die in the
human body every minute
Discovery of Cells
• 1665- English Scientist, Robert Hooke, discovered cells while looking at a thin slice of cork.
• He described the cells as tiny boxes or a honeycomb
• He thought that cells only existed in plants and fungi
Anton van Leuwenhoek
• 1673- Used a handmade microscope to observe pond scum & discovered single-celled organisms
• He called them “animalcules”• He also observed blood cells from
fish, birds, frogs, dogs, and humans• Therefore, it was known that cells
are found in animals as well as plants
• Father of Microscopy
Development of Cell Theory
• 1838- German Botanist, Matthias Schleiden, concluded that all plant parts are made of cells
• 1839- German physiologist, Theodor Schwann, who was a close friend of Schleiden, stated that all animal tissues are composed of cells.
Development of Cell Theory
• 1858- Rudolf Virchow, German physician, after extensive study of cellular pathology, concluded that cells must arise from preexisting cells.
1. All organisms are composed of one or more cells. (Schleiden & Schwann)(1838-39)
2. The cell is the basic unit of life in all living things. (Schleiden & Schwann)(1838-39)3. All cells are produced by the division of preexisting cells. (Virchow)(1858)
The 3 Basic Components of the Cell Theory
Modern Cell Theory
Modern Cell Theory contains 4 statements, in addition to the original Cell Theory:
1.The cell contains hereditary information(DNA) which is passed on from cell to cell during cell division.
2.All cells are basically the same in chemical composition and metabolic activities.
3. All basic chemical & physiological functions are carried out inside the cells.(movement, digestion,etc)
4. Cell activity depends on the activities of sub-cellular structures within the cell(organelles, nucleus, plasma membrane)
Modern Cell Theory
Modern Microscopes–Types
• Light microscope (400-1000X)• Confocal/Fluorescence microscope (500X)
• Electron microscope (1000-10000X)
MICROSCOPE
The light microscope enables us to see the overall shape and structure of a cell
•combined the laser scanning method with the 3D detection of biological objects labeled with fluorescent markers
•achieves a controlled and highly limited depth of focus
Confocal/Fluorescence microscope
Scanning electron microscope (SEM)
• They use a beam of electrons instead of light– allows greater
magnification – reveals cellular
details-produces an image of the 3D structure of the surface of a specimen
Transmission electron microscope (TEM)
DIVERSITY OF CELLS
Two Fundamentally Different Types of Cells
The PRESENCE OR ABSENCE of a NUCLEUS is
important for Classifying Cells.
Prokaryotes – Domain Bacteria
-> Single cell organisms-> No nucleus, no compartments-> Peptidoglycan cell walls-> Binary fission-> For energy, use organic chemicals, inorganic chemicals, or photosynthesis
-> Lack peptidoglycan-> Live in extreme environments Include:
MethanogensExtreme halophilesExtreme thermophiles
-> Role in disease not well understood—this group has only recently been discovered
Prokaryotes – Domain Archea
Eukaryotes
• Structural Differences– Plants have choloroplasts, a
large central vacuole and a cell wall
– Plant cells do not have centrioles
– Plant cells have plasmodesmata
– Animal cells have gap junctions
• Physiological Differences– Plant cells have
photosynthesis in addition to respiration
– During mitosis a cell plate is formed in plant cells
– Starch is molecule for energy storage while in animal cells it is glycogen
– Large central vacuole stores more water and carbohydrates then animal cell vacuoles
Different Cell Parts
In cells, various specialized functions occur in specific places. These places are called organelles (small organs)
Plasma Membrane
FLUID MOSAIC MODEL
• Cell membrane separates living cell from nonliving surroundings– thin barrier = 8nm thick
• Controls traffic in & out of the cell– selectively permeable– allows some substances to cross more easily
than others• hydrophobic vs hydrophilic
• Made of phospholipids, proteins & other macromolecules
Phospholipid Bilayer• Lipids
– Organic compounds– Fats + Oils– Non-polar– Insoluble in water (Not
attracted to water)Phosphate Head
– Polar– Water-soluble (Attracted to
water)
Phosphate Group
Glycerol Backbone
Water-Soluble
Water-Insoluble
Here is what a phospholipid bi-layer looks like as a sphere
FATTY ACIDS
POLARHEAD
• The internal composition of the cell is maintained because the plasma membrane is selectively permeable to small molecules.
• Only small, relatively hydrophobic molecules are able to diffuse across a phospholipid bilayer at significant rates by using passive diffusion.
Permeability of phospholipid bilayers
Transport Across Membranes
Transport Across Membranes: PASSIVE
DIFFUSIONThe movement of molecules or ions from a region where they are at a high concentration to a region of lower concentration
• Gases (oxygen, carbon dioxide)
• Water molecules (rate slow due to polarity)
• Lipids (steroid hormones)
• Lipid soluble molecules (hydrocarbons, alcohols, some vitamins)
• Small noncharged molecules (NH3)
SIMPLE DIFFUSION
• Ions
(Na+, K+, Cl-)
• Sugars (Glucose)
• Amino Acids
• Small water soluble molecules
• Water (faster rate)
FACILITATED DIFFUSION
How do molecules move through the plasma membrane by facilitated
diffusion?
• Channel and Carrier proteins are specific:• Channel Proteins allow ions, small solutes, and
water to pass• Carrier Proteins move glucose and amino acids• Facilitated diffusion is rate limited, by the
number of proteins channels/carriers present in the membrane.
– Osmosis is the diffusion of water across a differentially permeable membrane.
– Osmotic pressure is the pressure that develops in a system due to osmosis.
OSMOSIS
Concentration of water• Direction of osmosis is determined
by comparing total solute concentrations– Hypertonic - more solute, less water
– Hypotonic - less solute, more water
– Isotonic - equal solute, equal water
hypotonic hypertonic
water
net movement of water
Active Transport
“The Doorman”“The Doorman”
conformational change
• Cells may need to move molecules against concentration gradient– shape change transports solute from
one side of membrane to other – protein “pump”– “costs” energy = ATP
ATP
low
high
Endocytosis
Vesicles form as a way to transport molecules into a cell
a. Phagocytosis Large,particulate matter (Bacteria, viruses, and aged or dead cells).
b. PinocytosisLiquids and small particles dissolved in liquid
Exocytosis Vesicles form as a way to
transport molecules out of a cell
Cytoplasm
• Thick, clear liquid residing between the cell membrane holding organelles
•many of the complex chemical reactions/ metabolic pathways take place here such as:
Glycolysisgluconeogenesis biosynthesis of sugars, fatty acids, and amino acids
Mitochondria* site of cellular respiration * POWERHOUSE OF A CELL
Where energy is released from nutrients* there are MANY in a single cell* has two layers, makes up a double membrane
Act similar to electric power plant
Up to 300 to 800 per cell
Come from cytoplasm in EGG
You inherited your mitochondria from your mother
certain organelles originated as free-living bacteria that were taken inside another cell as endosymbionts. Mitochondria developed from proteobacteria
Can replicate itself: BINARY FISSION
ENDOSYMBIOSIS
(1) outer membrane It is fairly smooth. It is composed of
phospholipid bilayer protein.
it has channel protein: hole protein , permit that small molecule substance freely pass.
The ultrastructure of mitochondrion
(2)inner membrane they are more proteins than phospholipids.it has no hole protein , so penetrability is weak.
(3) intermembrane space it contains enzymes. It can
catalyze ATP to create ADP.
(4)MatrixEnzymes are abundant in the matrix . It also contains mitochondrial genetic system including DNA and ribosome.
(5) elementary particle it also call ATP synthase.
it lies in the inner membrane.
The Functions of mitochondrion
•Production of ATP through respiration•cellular metabolism
citric acid cycle or the Krebs Cycle
Chloroplasts
chloroplastsin plant cell
cross sectionof leafleaves
chloroplast
absorbsunlight & CO2
makeenergy & sugar
chloroplastscontainchlorophyll
CO2
Structure
• Chloroplasts– double membrane– stroma
• fluid-filled interior– thylakoid sacs– grana stacks
• Thylakoid membrane contains– chlorophyll molecules– electron transport chain
outer membraneinner membrane
thylakoidgranum
stroma
Nucleus* surrounded by a nuclear membrane
* only found in EUKARYOTES
* contains genetic material (DNA) in the form of chromosomes that controls the activities of the cell
* serves as the information and administrative center of the cell
•Nucleoplasm•Nuclear envelope•Nuclear pores•Chromatin
DNA + associated proteins
•Nucleolus internal structure of
nucleus, site of ribosome assembly•Chromatin vs. Chromosome
Nucleus: Structure
The Major Functions of the Nucleus
•stores the cell's hereditary material, or DNA•coordinates the cell's activities
-intermediary metabolism-growth-protein synthesis-reproduction (cell
division)
Endoplasmic Reticulum (ER)- a series of interconnecting channels associated
with storage, synthesis, and transport of substances within the cell
two types:A) rough--the 'ER' studded with ribosomesB) smooth--the 'ER' without any ribosomes
Rough endoplasmic reticulumproduction and processing of
specific proteins at ribosomal sites.
•carbohydrate metabolism•regulation of calcium ions•synthesis of steroids and lipids•drug detoxification•metabolism of steroids
Smooth endoplasmic reticulum
RibosomesProtein Synthesis"translates" the genetic information from ` RNA into proteins
•looks like a stack of flattened pancakes
• All of the proteins and lipids synthesized by the RER and SER are sent to the golgi.
•sorts, modifies, and packages the products of the RER and SER before sending them to their final destination inside or outside of the cell.
Golgi Apparatus
Vacuole" a "space" in a cell that contains water or other materials; usually for storageA) food vacuoles--store foodB) contractile vacuoles-- squeeze out excess water
Centrioles
•found in animal cells; rare in plants•cylindrical structures (like cans) found in the cytoplasm that appears to function during cell division (reproduction) •involved in the organization of the mitotic spindle and in the completion of cytokinesis
Cell Wall•found mostly in plant cells (some monerans, protists, and fungi too)•a non-living structure which surrounds and supports a cell•made of cellulose, a complex carbohydrate
Lysosome “Suicidal bags of the cell”a vacuole that contains digestive
enzymes; helps in the process of nutrition by breaking down nutrients in the cell
Peroxisomes•helps to rid the body of the host organism of toxins•breakdown of very long chain fatty acids through beta-oxidation
Cilia and Flagella•these are hair-like organelles that extend from the surface of many different types of cells
A)cilia--are typically smaller than flagella, but they cover the outside of the organismB)flagella--are much longer than cilia, but there usually are few on a single cell
•these structures usually aid in movement•they can also help sweep materials along the outside of a cell