Chapter 2 Anatomy

• Cytology
• Microscope
• Microscopy
• Micrometers
• A red blood cell
• Female egg (oocyte)

• Light Microscopy (LM)
• Transmission Electron Microscopy (TEM)
• Scanning Electron Microscopy (SEM)

• Covering
• Lining
• Storage
• Movement
• Connection
• Defense
• Communication
• Reproduction

• 1. Plasma (cell) membrane
• 2. Cytoplasm
• 3. Nucleus

• 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

• outer membrane of the cell
• 1. Lipids
• 2. Proteins

• outer and inner
• prevents cells from dissolving in water
• 1. Phospholipids
• 2. Cholesterol
• 3. Glycolipids

• • A polar(charged) region and non-polar (uncharged)region
• • they always form aspontaneous phospholipid bilayer

• Cholesterol
• • Strengthens and stabilizes membrane against temperature extreme
• • 20%
• Glycolipids
• • Lipids with carbohydrate (sugar) molecules attached facing the outside of the membrane forming, in part, the glycocaylx
• • 5-10%

• • 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
• 1. Integral
• 2. Peripheral

• • 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

• • No
• • The external or internal surface of the plasma membrane

• Communication
• Intercellular connection
• Physical barrier
• Selective permeability

• Transport
• Intercellular attachment
• Anchorage for the cytoskeleton
• Enzyme activity
• Cell-cell recognition
• Signal transduction

• 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).

• Diffusion
• Energy
• Four types of diffusion:
• 1. Simple diffusion
• 2. Osmosis
• 3. Facilitated diffusion
• 4. Bulk filtration

• –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

• of H2O
• Simple
• H2O moves from region of higher concentration to region of lower concentration

• either large and/or polar (charged) molecules
• specific integral membrane protein
• Binds to the molecule being“transported”

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

• K+
• Na+
• Requires energy

• 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

– nonspecific uptake of particles involving the formation of membrane extensions (pseodopodia) that surround particles to be engulfed

– nonspecific uptake of extracellular fluid

– engulfing of specific molecules that have bound to receptors on the surface of the plasma membrane

• Cytosol
• Organelles
• Inclusions

• Ions
• Nutrients
• Proteins
• Carbohydrates
• Amino acids

• Means “little organs”
• Many different types of organelles performing different functions
• A type of division of labor
• 1. Membrane-bound
• 2. Non-membrane-bound

• A membrane
• contents of organelle from cytosol
• Proteins are different
• 1. Endoplasmic reticulum
• 2. Golgi apparatus
• 3. Lysosomes
• 4. Peroxisomes
• 5. Mitochondria

• • 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

• Walls have roughened appearance
• due to the attachment of ribosome to the outside of the RER membrane
• Ribosomes
• Synthesize, transport and store proteins destined to be:
• 1. Secreted by the cell
• 2. Incorporated into the plasma membrane
• 3. Enclosed within lysosomes

• 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

• 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

• Vesicles generated by the Golgi apparatus
• Enzymes
• 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)

• Vesicles smaller than lysosomes
• Use O2 and an enzyme (catalase) to detoxify harmful molecules taken into the cell

• 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

• 1. Ribosomes
• 2. Cytoskeleton
• 3. Centrosomes and centrioles
• 4. Cilia and flagella
• 5. Microvilli

• 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

• 1. Microfilaments
• 2. Intermediate filaments
• 3. Microtubules

• • Maintain and change cell shape
• • Participate in muscle contraction and cell division

• Provide structural support and stabilize junctions between apposed cells

• • 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

• 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

• 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

• • 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

• • 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

• 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

• 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

• 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 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

• 1. Harmful agents or mechanical damage
• 2. Programmed cell death or apoptosis