cell structure a. there are three basic structures of all types of cells: 1. cell membrane a....
TRANSCRIPT
Cell Structure
A. There are three basic structures of all types of cells:
1. Cell membrane
a. Contains a bilayer of lipids
b. Is selectively permeable (allows only certain molecules through protein carriers)
2. Nucleus
3. Cytoplasm
Plasma Membrane
Separates intracellular fluids from extracellular fluids
Allows certain substances in and out
Glycocalyx is a glycoprotein are biological markers by which cells recognize one another
Cell walls and membranes video
Fluid Mosaic Model
Double bilayer of lipids with imbedded, dispersed proteins
Bilayer consists of phospholipids, cholesterol, and glycolipids
Glycolipids are lipids with bound carbohydrate
Phospholipids have hydrophobic and hydrophilic bipoles
Functions of Membrane Proteins
Functions of Membrane Proteins
Transport
Enzymatic activity
Receptors for signal transduction
Functions of Membrane Proteins
Intercellular adhesion
Cell-cell recognition
Attachment to cytoskeleton and extracellular matrix
Membrane Junctions
Tight junction – impermeable junction that encircles the cell
Desmosome – anchoring junction scattered along the sides of cells
Gap junction – a nexus that allows chemical substances to pass between cells
Membrane Junctions: Tight Junction
Membrane Junctions: Desmosome
Membrane Junctions: Gap Junction
Diffusion
Facilitated Diffusion
Osmosis
Isotonic – solutions with the same solute concentration as that of the cytosol
Hypertonic – solutions having greater solute concentration than that of the cytosol
Hypotonic – solutions having lesser solute concentration than that of the cytosol
Sodium Potassium Pump
Active Transport
Transport of large particles and macromolecules across plasma membranes
Exocytosis – moves substance from the cell interior to the extracellular space
Endocytosis – enables large particles and macromolecules to enter the cell
Phagocytosis – pseudopods engulf solids and bring them into the cell’s interior
Ex. Of Endocytosis
Generation and Maintenance of Membrane Potential
B. Differences between animal and plant cells, plant cells have:
1. Chloroplasts a. Contain pigments that absorb sunlight.
2. Vacuoles a. Large containers that store water. 3. Cell walls a. Rigid structure(contain cellulose)
surrounding the cell.
1. Nucleus
a. “Boss” of the cell. b. Contains the genetic material of an organism=chromosomes. c. Surrounded by a nuclear envelope with pores (openings). d. Contains the nucleolus which makes ribosomes.
e. Cells or organisms with a nucleus (area that contains the DNA with a surrounding nuclear envelope) are called eukaryotic. f. Cells or organisms without a nucleus (DNA not contained within a nuclear envelope) are called prokaryotic. 1. Ex. bacteria
Nuclear Envelope
Selectively permeable double membrane barrier containing pores
Outer membrane is continuous with the rough ER and is studded with ribosomes
Pores regulate transport of large molecules into and out of the nucleus
The Nucleus Video
Nucleoli
Dark-staining spherical bodies within the nucleus
Site of ribosome production
Acts like the “assistant to the boss”
Chromatin
Threadlike strands of DNA and histonesArranged in fundamental units called nucleosomesForm condensed, barlike bodies of chromosomes when the nucleus starts to divide
Cell Cycle
InterphaseGrowth (G1), synthesis (S), growth (G2)
Mitotic phaseMitosis and cytokinesis
Interphase
G1 (gap 1) – metabolic activity and vigorous growth
G0 – cells that permanently cease dividing
S (synthetic) – DNA replication
G2 (gap 2) – preparation for division
2. Cytoplasm
a. The area between the nucleus and the cell membrane.
b. Holds all the organelles in place.
c. Gives shape to the cell.
3. Centrioles
a. Structures that aid in cell division.
b. Found in the nucleus.
Centrioles Video
4. Mitochondria
a. Known as the “power house” of the cell.
b. Converts food into ATP to be used as energy.
c. ATP= Adenosine Triphosphate
(Adenine plus three phosphate molecules.)
5. Ribosomes
a. Sites of protein synthesis (making).
6. Endoplasmic Reticulum=E.R.
a. Passageway that transports materials throughout the cell.
b. Rough E.R. is studded with ribosomes.
c. Smooth E.R. is not studded with ribosomes.
7. Golgi apparatus
a. Passageway that modifies and packages proteins as they pass through.b. Stacked and flattened membranous sacs (stack of pancakes)c. Functions in modification, concentration, and packaging of proteins
8. Lysosome
a. Round organelle that rids the cell of unwanted waste.
b. Digest ingested bacteria, viruses, and toxins
c. Degrade nonfunctional organelles
Lysosomes video
9. Peroxisomes
a. Detoxify harmful or toxic substances
b. Neutralize dangerous free radicals
10. Vacuole
a. Containers that hold water and food for the cell.
Vacuole video
11. Cytoskeleton
a. Contain microtubules and filaments to add structure to the cell.
Cytoskeleton
Microtubules
Dynamic, hollow tubes made of the spherical protein tubulin
Determine the overall shape of the cell and distribution of organelles
Microfilaments
Dynamic strands of the protein actin
Attached to the cytoplasmic side of the plasma membrane
Braces and strengthens the cell surface
Attach to CAMs and function in endocytosis and exocytosis
Intermediate Filaments
Tough, insoluble protein fibers with high tensile strength
Resist pulling forces on the cell and help form desmosomes
Motor Molecules
Protein complexes that function in motility
Powered by ATP
Attach to receptors on organelles
Motor Molecules
12. Cilia and flagella
a. Hair-like projections that help move some types of cells.
Cilia act like oars
Flagella act like a whip to move the cell:
Ciliary Action