The Study of Cells
• The study of cells is called what?
• Cells can only be viewed by what?
• The use of a microscope is called?
• Cell size is measured in what?
• There are 10,000 μm/cm
• Smallest cell in the body?
• Largest cell in the body is what?
A red blood cell
Female egg (oocyte)
Types of Microscopy (3)
1.uses visible light that passes through the cell?
2. uses a beam of electrons that passes through the cell. Can magnify about 100X greater than LM?
3. uses a beam of electrons which is reflected off the surface of a cell to provide a 3D study of the cell surface?
Light Microscopy (LM)
Transmission Electron Microscopy (TEM)
Scanning Electron Microscopy (SEM)
Cells Differ in Function(8)
A Prototypical Cell
What are the 3 basic regions or components of all cells in the body?
1. Plasma (cell) membrane
Plasma (Cell) Membrane
Forms an extremely thin outer border of each cell
Serves as a selective physical and chemical barrier deciding what comes into and leaves the cell
It is the “gatekeeper” that regulates the passage of gases, nutrients and wastes between the internal and external environments of the cell
Composition and Structure of Membranes
Where is it located?
Consists of 2 components?
outer membrane of the cell
What are the two layers?
Insoluable in water..What does this mean?
What are the three types of lipids in the membrane?
outer and inner
prevents cells from dissolving in water
What does each phospholipid molecule have (2 regions)?
What happens when phospholipids are exposed to an aqueous(water) environment?
• A polar(charged) region and non-polar (uncharged)region
• they always form aspontaneous phospholipid bilayer
Represents how much of all membrane lipids? Glycolipids
Represents how much of all membrane lipids?
• Strengthens and stabilizes membrane against temperature extreme
• Lipids with carbohydrate (sugar) molecules attached facing the outside of the membrane forming, in part, the glycocaylx
What are protiens composed of?
What are the two types of membrane protiens?
• Lipids provide the structure to a membrane but proteins give the individual membrane its own unique personality
• complex molecules comprised of chains of amino acids
Integral Membrane Proteins
Embedded within what?
What are glycolipids?
What do the glycoproteins and the glycolipids form?
• the phospholipid bilayer
• outside and inside of the cell
• Protiens that can have carbohydrates (sugars) attached too uter surface
• the glycocalyx on the external surface of the plasma membrane
Are they imbedded in the lipid bilayer?
They are loosly attatched to where?
• The external or internal surface of the plasma membrane
General Functions of the Plasma (Cell) Membrane (4)
Protein-Specific Functions of thePlasma (Cell) Membrane (6)
Anchorage for the cytoskeleton
1. Passive – does not require energy from the cell. Materials move from a region of higher concentration to a region of lower concentration (movement down the concentration gradient). This type ofmovement is called diffusion.
2. Active – requires energy from the cell. Materials are moved against a concentration gradient (movement up the concentration gradient).
All involve what?
What don't they require from the cell?
4 types of diffusion?
Four types of diffusion:
1. Simple diffusion
3. Facilitated diffusion
4. Bulk filtration
Types of Diffusion 1. Simple diffusion
–small and/or nonpolar (uncharged) molecules
– A good example is the movement of O2 outof the lungs (higher concentration) into the blood (lower concentration)
– The movement of CO2 from the blood(higher concentration) into the lungs (lower concentration) is another example
Types of Diffusion 2. Osmosis Applies to the movement of what? Has is the same principle to what other type of diffusion? What is that principle?
H2O moves from region of higher concentration to region of lower concentration
Types of Diffusion 3. Facilitated diffusion
Requires what? Transport protien?
either large and/or polar (charged) molecules
specific integral membrane protein
Binds to the molecule being“transported”
Types of Diffusion 4. Bulk Filtration Involves what?
diffusion of both liquids (solvents) and dissolved molecules (solutes)
• Movement of a molecule against the concentration gradient
• Opposite that of passive transport
• Requires energy from the cell
• Sometimes involves a transport protein
• A good example is the ion pump
• Both Na+ and K+ are moved in opposite directions against their concentration gradient
Active Transport by Ion Pump
What is pumped in the cell?
What is pumped out of the cell?
What does it require?
What does bulk transport do?
What does it require?
Where can it go?
Moves large molecules or bulk structures across the plasma membrane
Requires energy from the cell
Can go in either direction:
1. Exocytosis – secreted out of the cell
2. Endocytosis – uptake into the cell
Materials to be secreted out of cell packaged into vesicles. Vesicles fuse with plasma membrane and materials are secreted
Opposite that of exocytosis. Materials taken up into the cell packaged into vesicles
Types of Endocytosis 1. Phagocytosis
– nonspecific uptake of particles involving the formation of membrane extensions (pseodopodia) that surround particles to be engulfed
Types of Endocytosis
– nonspecific uptake of extracellular fluid
Types of Endocytosis
3. Receptor-mediated endocytosis
– engulfing of specific molecules that have bound to receptors on the surface of the plasma membrane
• Nonspecific term for all materials, both solid and liquid, between the plasma membrane and the nucleus. This includes (3):
-A viscous, syrup like fluid containing many different dissolved substances such as:
What does it mean?
What type of division?
Clissification of two types?
Means “little organs”
Many different types of organelles performing different functions
A type of division of labor
Membrane-Bound Organelles Surrounded by what?
Seperates what from what?
Similar to the plasma membrane. But what is the difference?
Biochemical activity within organelle is isolated from the cytosol and other organelles. Examples are (5)
contents of organelle from cytosol
Proteins are different
1. Endoplasmic reticulum
2. Golgi apparatus
What is it?
• A network of intracellular membrane-bound tunnels
• The enclosed spaces
• Walls have a smooth appearance
1. Synthesis, transport and storage of lipids including steroid hormones
2. Metabolism of carbohydrates
3. Detoxification of drugs, alcohol and poisons
Description? Why does it look like that?
What is the sole organelles that synthesize proteins within the cell?
Walls have roughened appearance
due to the attachment of ribosome to the outside of the RER membrane
Synthesize, transport and store proteins destined to be:
1. Secreted by the cell
2. Incorporated into the plasma membrane
3. Enclosed within lysosomes
Composed of what? What do they do?
Stacked cisternae whose lateral edges bulge, pinch off and give rise to small transport and secretory vesicles
Receive proteins and lipids from the RER and modify, sort and package these molecules
Protein Flow through the Golgi Apparatus
Protiens are synthesized in RER and get packaged where?
What happens once packaged?
Into transport vesicles
Transport vesicles pinch off from RER and fuse with the receiving cis-face of the Golgi apparatus. The proteins move between the cisternae of the Golgi apparatus and become modified in the cisternae. Modified proteins are then packaged in secretory vesicles. Secretory vesicles will either participate in exocytosis or become lysosomes within the cell
What are they?
What do they contain?
Vesicles generated by the Golgi apparatus
Digest and remove waste products and damaged organelles within the cell (autophagy)
• When a cell is dying it releases lysosomal enzymes that digest the cell (autolysis)
What are they?
Vesicles smaller than lysosomes
Use O2 and an enzyme (catalase) to detoxify harmful molecules taken into the cell
Description? Why does it look like this?
What is the matrix?
Bean-shaped organelles that has a double membrane. The inner membrane is folded to form shelf-like structures called cristae
The internal fluid
Produce a high energy containing molecule called ATP which is produced on the cristae
Non-Membrane-Bound Organelles..give examples (5):
3. Centrosomes and centrioles
4. Cilia and flagella
Composed of what?
What do free ribosomes do?
What do fixed ribosomes do?
Comprised of a large and small subunit
Responsible for all protein synthesis within the cell
They float unattached withinthe cytosol
Fixed ribosomes are attached to the outer surface of membranes associated with RER
Cytoskeleton..name the components (3):
2. Intermediate filaments
Involved in what?
• Maintain and change cell shape
• Participate in muscle contraction and cell division
• Provide structural support and stabilize junctions between apposed cells
They radiate from where?
• 25nm thick hollow tubes
• Radiate from centrosome (discussed next)
• Fix organelles in place; Maintain cell shape and rigidity, facilitate cell motility of cilia and flagella
Centriole? Centriole is involved in what?
Attched where? And what does it do there?
Consists of a pair of centrioles at right angles to each other
consists of nine sets of three closely aligned microtubules
Involved in organizing microtubules
Attached to chromosomes during cell division causing chromosomal migration
Cilia and Flagella
Both are capable of movement
Found on cells whose function is to move objects across the surface of those cells i.e. cells of the respiratory tree and oviduct
Longer and usually appearal one, help to propel a cell e.g., sperm
What is it?
Smaller than what?
DOES NOT MOVE
• Extensions of the cell
• Much smaller than cilia
• Found on surface of cells of the small intestine
• Increase the surface area to increase absorption of food
What is it? Where is it found?
• Large storage aggregates of complex molecules found in the cytosol
1. Melanin– a brown pigment in skin cells
2. Glycogen – long chains of stored sugars found in liver and skeletal muscle
What is it?
What does it do?
When a cell is not dividing, the nuclear DNA do what?
When the cell is in the process of dividing, the chromatin does what?
Control center for cellular activity
Contains DNA (deoxyribonucleic acid), acomplex molecule in which genes are embedded
Unwinds into fine filaments called chromatin
Coils tightly to form observable structures called chromosomes
What are nuclear pores?
Double membrane structure
Controls entry and exit of molecules from nucleus and cytoplasm
Selectively permeable channels that allow molecules in or out of the nucleus
Dark staining bodies within the nucleus
Responsible for making the components of the small and large units of the ribosome
Life Cycle of the Cell
What are the two states the cell can be in?
What happens in the first stage?
Interphase or Mitotic phase
1. Interphase – a maintenance (resting) phase between cell divisions where the following activities occur:
• Carries out normal activities
• Prepares for cell division
• Cell spends the majority of time in this phase
2. Mitotic phase – time during which the cell divides
• Cells grow, replicate new organelles, produce proteins for replication and centrioles just prior tocell division
• “Synthesis” phase where DNA replicates in preparation to cell division
• Centriole replication is complete; Other organelle production continues; Enzymes needed for cell division are synthesized
Two events that happen?
Two daughter cells are produced that are genetically identical to the original (mother) cell
• Two distinct events occur in this phase:
1. Mitosis – duplication of DNA and division of the nucleus
2. Cytokinesis – division of the cytoplasm and the mother cell
• Chromatin becomes super coiled to form chromosomes; Duplicate, identical sister chromatids are conjoined at a region called the centromere; Elongated microtubules called spindle fibers begin to grow from each centriole; End of prophase is marked by the dissolution of the nuclear envelope.
Chromosomesline up along equatorial plate; Spindle fibers attach to centromere of sister chromatids and form an oval structure array called the mitotic spindle
• Spindle fibers pull sister chromatids apart to opposite ends of the dividing cell
Nuclear envelope forms around each set ofchromosomes; Chromosomes begin to uncoil and mitotic spindle disappears; A pinched area, the cleavage furrow, appears that will complete the physical division of the daughter cells