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4.1 The Cell
4.11 Cell Size
4.12 Cell Basics
4.13 Organelles

4.2 Cell Types

4.3 The Cell Membrane
4.31 Membrane transport

4.32 Concentration differentials

4.32.1 water balance in animal cells
4.32.1 water balance in plant cells

4.33 The cytomembrane system

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LECTURE OBJECTIVES:

1. List and differentiate between the various organelles in eukaryotic cells.
2. Contrast the general features of prokaryotic and eukaryotic cells.
3. Describe the essential structure and function of the cell membrane.
4. Know the forces that cause substances to move across membranes ‘passively’ (from high to low concentration without expending energy).
5. Know the forces that cause substances to move across membranes ‘actively’ (from low to high concentration, against a concentration gradient, expending energy).
6. Contrast between hypotonic, isotonic, and hypertonic solutions.
7. Recognize that animal cells -- unless adapted to hypo- or hypertonic environments, are dependent on relatively constant, isotonic environments.
8. Recognize the interconnections among membranous organelles of the cytomembrane (endomembrane) system.
9. Define selected key terms

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Key Terms

The terms have been separated into the three chapter sub units 4.1, 4.2, and 4.3.

In submit 4.1 the the names of the organelles have been listed in blue for your convenience.

4.1 The Cell

def. Cell membrane (Plasma membrane): The outermost membranous semi-permeable boundary between cytoplasm and external fluid bathing the cell (membrane that surrounds the cytoplasm of cells and regulates the passage of molecules in and out of cells).
def. Cell wall: A semi-rigid, permeable structure outside the plasma membrane in a bacterium, a fungal cell, an algae cell, or a plants cell, that helps a cell hold its shape, resist rupturing if internal fluid pressure rises, and provide mechanical protection
def. Cell: The basic structural unit of all living things (the smallest living unit, the basic unit of life)
def. Centriole: Cell organelle, a cylinder of triplet microtubules that gives rise to microtubules of cilia and flagella, and that organizes o mitotic spindle for chromosome movement during cell division.
def. Chlorophyll: Green pigment located in the chloroplasts associated with trapping light energy.
def. Chloroplast: An sac-like membranous energy transforming organelle in plants and certain protistans, containing chlorophyll, that serves as the site of photosynthesis.
def. Chromatin: Non-condensed structures of DNA and protein in the nucleus of eukaryotic cells, containing the hereditary units, the genes, observed within a nucleus that is not dividing.


def. Chromosome: Condensed structures of DNA and protein in the nucleus of eukaryotic cells, containing the hereditary units, the genes, visible only during cell division.
def. Cilium (pl. cilia): A short, hair like projection with an internal, regular array of microtubules. (Can serve as motile or sensory structures or help create currents of fluids).
def. Cytomembrane system (endomembrane system): Organelles functioning as a system to modify, package, and distribute newly formed proteins and lipids. (Endoplasmic reticulum, Golgi bodies, lysosomes, and various vesicles are its components.)
def. Cytoplasm: All parts -- semi-fluid, organelles, and particles, of a cell located between the nucleus and the cell membrane (Cytosol: semi-fluid parts of the cytoplasm.)
def. Cytoskeleton: The internal "skeleton" (framework) of a eukaryotic cell.
def. Endoplasmic reticulum: Membranous organelle that begins at the nucleus and curves through the cytoplasm and provide a large surface upon which chemical activities take place.
def. Flagellum (pl. flagella): Tail-like motile structure of many free-living eukaryotic cells.
def. Golgi apparatus (Golgi body): Membranous organelle of lipid assembly, polypeptide chain modification, and packaging of both in vesicles for export outside of the cell or for transport to locations in the cytoplasm.
def. Lysosome: Membranous organelle (vesicle) that contains enzymes specialized for digesting macromolecules (hydrolytic enzymes).
def. Microtubule: Small, hollow tubes of protein that function throughout the cytoplasm to provide structural support and enable movements.
def. Mitochondrion: Membranous organelle resembling a small bag with a larger bag inside that is folded; site of aerobic cellular respiration.
def. Nucleolus (pl. nucleoli): Spherical body in the nucleus that produces ribosomal sub units.
def. Nucleus: Organelle in eukaryotic cells containing the chromosomes.
def. Organelles: Specialized structures within cells.
def. Photosynthesis: A series of reactions in chloroplasts and result in the storage of sunlight in the form of chemical-bond energy.
def. Ribosome: Non-membranous organelle, RNA and protein in two sub units, site of protein synthesis in the cytoplasm.
def. Rough ER: Rough endoplasmic reticulum (have ribosomes on the surface)
def. Smooth ER: Smooth endoplasmic reticulum (do not have ribosomes on the surface)
def. Vacuole: A large sac within the cytoplasm of a cell.

4.2 Cell Types

def. Eukaryotic cell: A cell that possesses a nucleus and other membrane-bound organelles.
def. Prokaryotic cell: Cell lacking the organelles found in eukaryotic cells
- - - - - - - -
def. Multicellular: Many-celled (most members of the kingdom Fungi, Plantae, and Animalia), with intimate cooperation among cells.
def. Unicellular: Single-celled (members of the Monera, and most members of the kingdom Protista) without intimate cooperation among cells.
- - - - - - - -
def. Nucleus: Organelle in eukaryotic cells containing the chromosomes.
def. Nucleoid region: Area in prokaryotic cells where DNA is found.

4.3 The Cell Membrane

def. Active transport: Net movement of molecules from a place of lower concentration to a place of higher concentration (movement up a concentration gradient).
def. Diffusion: Net movement of molecules from a place of higher concentration to a place of lower concentration (movement down a concentration gradient).
def. DNA: Deoxyribonucleic acid, for all living organisms the molecule of inheritance.
def. Dynamic equilibrium: The condition in which molecules are equally dispersed, movement is equal in all directions.
def. Fluid mosaic model of the cell membrane: Name given to the idea that the cell membrane has a "fluid mosaic" structure.
- - - - - - - -
def. Hypertonic solution: When comparing two solutions, the solution with greater solute concentration than the other hypotonic solution.
def. Hypotonic solution: When comparing two solutions, the solution with a lesser solute concentration than the other hypertonic solution.
def. Isotonic solution: When comparing two solutions, solutions of equal solute concentration.
- - - - - - - -
def. Lipid bilayer: Structural basis of all cell membranes, with two layers of mostly phospholipid molecules.
def. Membrane protein: Protein in or on the cell membrane of eukaryotic cells (e.g., transport protein, cell recognition protein, receptor protein, and enzymatic protein)
def. Osmoregulation: The maintenance of an optimal and constant water balance (osmotic pressure) in the body of organisms living in hypertonic, hypotonic and terrestrial environments.
def. Osmosis: Diffusion (net movement of molecules from a place of higher concentration to a place of lower concentration) of water through a semi-permable membrane.
def. Osmotic Pressure: A measure of the tendency of a solution to take up water when separated from pure water by a semi-permeable membrane.
def. Passive transport: Net movement of molecules from a place of higher concentration to a place of lower concentration (movement up a concentration gradient).
def. Phospholipid: A type of lipid that is the main structural component of cell membranes, a hydrophobic tail of two fatty acids and a hydrophilic head that incorporates glycerol and a phosphate group.)
def. Semi-permeable: Selectively permeable.
def. Solute: Substance dissolved in a solvent (forming a solution)
def. Solution: A liquid mixture of at least two substances.
def. Solvent: The dissolving agent of a solution (e.g. water)

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4.1 THE CELL
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• 4.11 Cell Size
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• Lower limits on cell size -- DNA
The cells must have enough DNA -- to provide enough instructions to carry out necessary functions.

• Upper limits on cell size -- metabolic requirements (surface to volume area problems)
The cells must have enough surface area to be able to obtain oxygen and nutrients, and get rid of carbon dioxide and other waste products. If the cell is too large this becomes difficult due to surface to volume area problems (to small surface area).

-- transportation problems across the cell membrane
-- diffusion problems inside the cell

• Multicellular organisms consist of many small cells.

Same problems to solve -- transportation across the cell membrane, and diffusion.
Many are located far from the surface and the surrounding environment. These organisms have solved this by having distribution systems supplying nutrients etc., and removing waste.

Dr. Thinkwell

../Thinkwell_f/04_GiantAmoebas_2692_2715.mov

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• 4.12 Cell Basics (Overview of Eukaryotic cells)
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def. Cell: The basic structural unit of all living things (the smallest living unit, the basic unit of life)

• All cells have:

1. Plasma membrane (Cell membrane).
2. Cytoplasm
3. DNA
4. Organelles


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• 4.13 Organelles (Compartmentalization of Eukaryotic cells)
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• Structures of Eukaryotic cells:
• NON-MEMBRANOUS ORGANELLES

1. Ribosomes
Site for protein synthesis

• MEMBRANOUS ORGANELLES

1. Nucleus
Location of DNA

2. Endoplasmic Reticulum (ER)
Synthesis of organic compounds

3. Golgi Apparatus
Modify and store products from the ER.

4. Lysosomes
Contain digestive enzymes used by the cell to digest macromolecules.

5. Vacuoles
Various cell maintenance functions

6. Energy transformers
Transform energy acquired from the surrounding
-- mitochondria
-- chloroplasts

7. Cytoskeleton & Centrioles
Structural support and cell movement
-- microtubules

8. Cell Wall
Protection

9. Cell Membrane
Semi-permeable barrier & various functions related to membrane proteins


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4.2 CELL TYPE
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• Two cell types

def. Prokaryotic cell: Cell lacking the organelles found in eukaryotic cells.
def. Eukaryotic cell: A cell that possesses a nucleus and other organelles.

Because Monera (bacteria) is so different from us, we can use antibiotics against many diseases caused by these organisms, without hurting our own body.

Streptomycin – combines with prokaryotic ribosomes and prevents them from producing proteins. Does not hurt our ribosomes.

Penicillin – cell wall in eukaryotic cells: cellulose cell wall in prokaryotic cells: not cellulose

Dr. Thinkwell

../Thinkwell_f/04_Nucl_WhyVocab_2694_2717.mov

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4.3 CELL MEMBRANE
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• Living organisms are separated from the environment by a flexible sheet called the cell membrane.

Encloses the cell from its surrounding -- different composition compared to the surrounding
yet
The cell can eliminate waste
The cell can take up nutrients (& toxins & pollutants)


• Fluid and Mosaic Quality of the plasma membrane

Fluid in texture
Mosaic in composition

PhospholipidStruct

Dr. Thinkwell

../Thinkwell_f/04_CellMembr_2693_2716.mov

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• 4.31 Membrane transport
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--- Passive transport (does NOT require energy)
--- Active transport (requires energy)

Diffusion

Membrane transport

Membrane permeability

• Diffusion
-- passive transport

def. Diffusion: Net movement of molecules from a place of higher concentration, to a place of lower concentration (movement DOWN a concentration gradient)
def. Dynamic equilibrium: The condition in which molecules are equally dispersed, movement is equal in all directions.
def. Osmoregulation: The maintenance of an optimal and constant water balance (osmotic pressure) in the body of organisms living in hypertonic, hypotonic and terrestrial environments.
def. Osmosis: Diffusion (net movement of molecules from a place of higher concentration to a place of lower concentration) of water through a semi-permable membrane.
def. Osmotic Pressure: A measure of the tendency of a solution to take up water when separated from pure water by a semi-permeable membrane.


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• 4.32 Concentration Differentials
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def. Osmoregulation: The maintenance of an optimal and constant water balance (osmotic pressure) in the body of organisms living in hypertonic, hypotonic and terrestrial environments.
def. Osmosis: Diffusion (net movement of molecules from a place of higher concentration to a place of lower concentration) of water through a semi-permable membrane.
def. Osmotic Pressure: A measure of the tendency of a solution to take up water when separated from pure water by a semi-permeable membrane.

--- Isotonic solutions
--- Hypertonic solutions
--- Hypotonic solutions

• 4.31.1 WATER BALANCE (Osmosis) IN ANIMAL CELLS

example: RBCs

• ISOTONIC water solution (e.g., blood compared to human cells)
‡ water flows across the membrane at the same rate
(NORMAL, STABLE)

• HYPERTONIC water solution (e.g. ocean salt water comp. to human cells)
‡ water flows out of the cell at a faster rate
(LOSE WATER, SHRIVEL, DIE)

• HYPOTONIC water solution (e.g. pond fresh water comp. to human cells)
‡ water flows into the cell at a faster rate
(GAIN WATER, SWELL, BURST)

• Isotonic solutions can vary between different animals
e.g., Isotonic Salt Concentration in Humans -- 0.7% salt
Isotonic Salt Concentration in Jellyfish -- 3.5% salt
(same as the sea water)

• Animals must live in an environment ISOTONIC to their cells, unless they have
a method to balance water gain or water loss

-- OSMOREGULATION


• An isotonic condition is the stable state in animal cells.

HypotIsotHypert_AnimPlant

• 4.31.2 WATER BALANCE (Osmosis) IN PLANT CELLS

• An hypotonic condition is the stable state in plant cells.

HypotIsotHypert_AnimPlant

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• 4.33 The Cytomembrane System

(Endomembrane System)

• The plasma membrane is a movable “fluid mosaic” structure

Endomembrane_System 1

Endomembrane_System 2