53 terms

College Anatomy Chapter 2

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Endocytosis
Materials taken up into the cell packaged into vesicles
Cytology
The study of cells
Microscopy
the use of a microscope to view cells
Light Microscopy (LM)
uses visible light that passes throug the cell
Transmission Electron Microscopy (TEM
uses a beam of electrons that passes through the cell. TEM can magnify about 100X greater than LM.
Scanning Electron Microscopy (SEM)
uses a beam of electrons which is reflected off the surface of a cell to provide a 3D study of the cell surface
Cell Functions
Covering ,Lining ,Storage ,Movement ,Connection ,Defense ,Communication ,Reproduction
Prototypical Cell
A generalized cell, not a real cell in the body
Combines features from many different cells and is used for teaching purposes
Three Basic regions or components of cells in the body
Plasma (cell) membrane
Cytoplasm
Nucleus
Cell membranes
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
components of Membrane
lipids and protein
Membrane Lipids
Two layers: outer and inner
Insoluble in water....prevents cells from dissolving in water
Three types of lipids in membranes
Phospholipids
Cholesterol
Glycolipids
Phospholipids
Represent the majority of lipids in cell membranes
Each phospholipid molecule has a polar (charged) region and non-polar (uncharged) region
When phospholipids are exposed to an aqueous (water) environment, they always form a spontaneous phospholipid bilayer
Cholesterol
Scattered in hydrophobic regions, fills gaps
Strengthens and stabilizes membrane against temperature extremes. Shrimp and Lobster have a lot.
Represents about 20% of all membrane lipids
Glycolipids
Lipids with carbohydrate (sugar) molecules attached facing the outside of the membrane only. forming, in part, the glycocaylx , helps with cell to cell recognition, adhesion and communication
Represents about 5-10% of all membrane lipids
Membrane Proteins
Lipids provide the structure to a membrane but proteins give the individual membrane its own unique personality
Proteins are complex molecules comprised of chains of amino acids
Types of Membrane protein
Integral and peripheral
INTEGRAL MEMBRANE PROTEINS
Embedded within and extend through the phospholipid bilayer. Some have pores or channels so specific molecules can pass. Others are receptors
Span the entire thickness of the membrane
Peripheral
Not embedded in the lipid bilayer
Loosely attached to the external or internal surface of the plasma membrane
Have many varied functions
Float on Surface like beach ball.
General Functions of the Plasma (Cell) Membrane
Communication
Intercellular connection
Physical barrier
Selective permeability
Protein-Specific Functions of the Plasma (Cell) Membrane
Transport
Transport
Intercellular attachment
Anchorage for the cytoskeleton
Enzyme activity
Cell-cell recognition
Signal transduction
Passive Transport
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 of movement is called diffusion.
Active transport
requires energy from the cell. Materials are moved against a concentration gradient (movement up the concentration gradient).
Four types of diffusion:
Simple diffusion
Osmosis
Facilitated diffusion
Bulk filtration
Simple diffusion
Involves small and/or nonpolar (uncharged) molecules
A good example is the movement of O2 out of 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
osmosis
Exclusively applies to the movement of H2O
Same principle as simple diffusion
H2O moves from region of higher concentration to region of lower concentration
Facilitated diffusion
Involves either large and/or polar (charged) molecules
Requires a specific integral membrane protein that will bind to the molecule being "transported". This membrane protein is called a "transport" protein.
Bulk Filtration
Involves diffusion of both liquids (solvents) and dissolved molecules (solutes)
Bulk Transport
Moves large molecules or bulk structures across the plasma membrane
Requires energy from the cell
Can go in either direction:
Exocytosis - secreted out of the cell
Endocytosis - uptake into the cell
Phagocytosis
nonspecific uptake of particles involving the formation of membrane extensions (pseodopodia) that surround particles to be engulfed
Pinocytosis - nonspecific uptake of extracellular fluid
Receptor-mediated endocytosis
engulfing of specific molecules that have bound to receptors on the surface of the plasma membrane
Exocytosis
Materials to be secreted out of cell packaged into vesicles
Vesicles fuse with plasma membrane and materials are secreted
endocytosis
Materials taken up into the cell packaged into vesicles
cytoplasm
Nonspecific term for all materials, both solid and liquid, between the plasma membrane and the nucleus. This includes:
Cytosol
Organelles
Inclusions
cytosol
A viscous, (high water content) syruplike fluid containing many different dissolved substances such as:
Ions
Nutrients
Proteins
Carbohydrates
Amino acids
Inclusions
A large and diverse group of chemical substances that are stored temporarily, include pigments,ie: melanin,protein crystals and nutrients such as glycogen or triglycerides. Found in liver and skeletal muscle cells.
ORGANELLES
Means "little organs"
Many different types of organelles performing different functions
A type of division of labor
The type and number of organelles within a cell is a reflection of the cell's function
Organelles can be classified as one of two types:
Membrane-bound
Non-membrane-bound
Membrane bound
Surrounded by a membrane
Membrane separates contents of organelle from cytosol
Membrane is similar in structure to the plasma membrane. Proteins are different.
Biochemical activity within organelle is isolated from the cytosol and other organelles
Endoplasmic reticulum
A network of intracellular membrane-bound tunnels
The enclosed spaces are called cisternae
Smooth ER
Walls have a smooth appearance
Continuous with RER (touch)
Functions include:
Synthesis, transport and storage of lipids including steroid hormones
Metabolism of carbohydrates
Detoxification of drugs, alcohol and poisons
Rough ER - RER
Walls have roughened appearance due to the attachment of ribosome to the outside of the RER membrane.The function of RER is to synthesize, transport( to Golgi apparatus) and store proteins destined to be:
Secreted by the cell
GOLGI APPARATUS
Composed of stacked cisternae whose lateral edges bulge, pinch off and give rise to small transport and secretory vesicles
Function is to receive proteins and lipids from the RER in vesicles: and modify, sort and package these molecules. Has a disctinct polarity Has 2 poles: receiving region and packaging region.
LYSOSOMES
Vesicles
Membrane sacs generated by the Golgi apparatus
Contain enzymes used to digest and remove waste products and damaged organelles within the cell (autophagy) cell garbage men.
mitochondria
Bean-shaped organelles that has a double membrane Contain a small amount of DNA so can self replicate in cells that need a lot of energy like muscles.
The main function of a is to produce a high energy containing molecule called ATP which is produced on the cristae
NoN membrane bound
Ribosomes
Cytoskeleton
Centrosomes and centrioles
Cilia and flagella
Microvilli
Ribosomes
Comprised of a large and small subunit, subunits formed in nucleus, once formed, some float freely in cell.
Responsible for all protein synthesis within the cell
Cytoskeleton
Comprised of protein subunits organized throughout the cytosol in either filaments or hollow tubes
Centrosome and Centrioles
Centrosome - consists of a pair of centrioles at right angles to each other
Centriole - Paired. Cylndrical. consists of nine sets of three closely aligned microtubules "Triplets" (in circles)
Replicate immediately prior to cell division.Involved in organizing microtubules of mitotic spindle.
attached to chromosomes during cell division causing chromosomal migration
Cilia and Flagella
Projections extending from the cell containing cytoplasm and microtubules
Both are capable of movement
Cilia - found on cells whose function is to move objects across the surface of those cells i.e. cells of the respiratory tree and oviduct
Flagella - longer and usually appear alone, help to propel a cell e.g., sperm
NUCLEOUS
Core or Control center for cellular activity
Has 3 basic structures. Nuclear envelope, Nucleoli, Chromatin
Contains DNA (deoxyribonucleic acid), a complex molecule in which genes are embedded
When a cell is not dividing, the nuclear DNA is unwound into fine filaments called chromatin
When the cell is in the process of dividing, the chromatin coils tightly to form observable structures called chromosomes
NUCLEAR ENVELOPE
Double membrane structure
Controls entry and exit of molecules from nucleus and cytoplasm
Outer membrane is continuous with endoplasmic reticulum
Nuclear pores are selectively permeable channels that allow molecules in or out of the nucleus
NUCLEOLI
Dark staining bodies within the nucleus
Responsible for making the components of the small and large units of the ribosome