cell structure. the cell essential to the study of biology simplest form of life every organism’s...
TRANSCRIPT
![Page 1: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/1.jpg)
Cell Structure
![Page 2: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/2.jpg)
The Cell
ESSENTIAL to the study of biology
Simplest form of life Every organism’s basic
unit of structure and function
Named by Robert Hooke in 1665 after observing cork cells (cell walls) under microscope.
![Page 3: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/3.jpg)
Prokaryotic vs. Eukaryotic Cells
Prokaryote “before” “nucleus”/ NO
NUCLEUS/few organelles Bacteria DNA is concentrated in
nucleoid (non membrane-bound)
Eukaryote “true” “nucleus” / many
membranous organelles Protists, plants, fungi,
animals Nucleus with nuclear
membrane holds DNA
![Page 4: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/4.jpg)
Why so small?
Metabolism requires that cells stay small As a cell grows, its
volume grows proportionately more than its surface area
Cells need a high surface area to volume ratio to exchange materials with their environment through plasma membrane.
![Page 5: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/5.jpg)
Compartmental Organization of Cells
Compartments (ORGANELLES) provide different local environments (pH, etc.)Incompatible but equally important
processes can occur next to each other in different “rooms”
![Page 6: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/6.jpg)
Cytoskeleton & Related Organelles
Cytoskeleton Maintains shape of cell Responsible for
movement of cell and movement of organelles within cell
Made of three types of protein fibers:
Microtubules, microfilaments, & intermediate filaments
![Page 7: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/7.jpg)
Cytoskeleton & Related Organelles
Microtubules Hollow tubes Made up of A- and B-
tubulin Responsible for:
• Cell motility• cilia/flagella
• Chromosome movements (mitosis)
• centrioles
• Movement of organelles
• Maintenance of cell shape
![Page 8: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/8.jpg)
Cytoskeleton & Related Organelles
Components of Cytoskeleton:Microtubules – 25 nm diameterIntermediate Filaments – 8 – 12 nm
diameterMicrofilaments – 7 nm diameter
![Page 9: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/9.jpg)
Cytoskeleton & Related Organelles
Intermediate Filaments Made up of fibrous
proteins Made up of keratin Responsible for:
• Structural support• Maintenance of cell
shape• Anchors nucleus &
certain organelles
![Page 10: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/10.jpg)
Cytoskeleton & Related Organelles
MicrofilamentsMade up of 2 intertwined strands of
actinResponsible for:
• Muscle contraction• Cytoplasmic streaming• Cell motility (pseudopodia)• Cell division (cleavage furrow)• Maintenance of/changes in cell shape
![Page 11: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/11.jpg)
Centrioles Only found in animal
cells Visible only during cell
division 9+0 arrangement of
microtubules May give rise to cilia &
flagella May be involved in
formation of spindle fibers in animal cells, but not plants!
![Page 12: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/12.jpg)
Flagella and Cilia
Structures for cell motility
Flagella (long & few in #)
Cilia (short & numerous)
9 + 2 internal structure
Basal body has 9+0
structure like centrioles
dynein
microtubule
Figure 4.25Page 73
![Page 13: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/13.jpg)
Cellular Organelles
Nucleus: “control center” of the cell Surrounded by a nuclear
envelope Contains DNA Nucleolus: site of ribosome
synthesis
![Page 14: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/14.jpg)
Cellular Organelles
Ribosomes Site of protein assembly Free and bound ribosomes
• Free: float through cytoplasm (make proteins for use inside that cell)
• Bound: attached to Rough ER (make proteins to be transported out of the cell)
![Page 15: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/15.jpg)
Cellular Organelles
Endoplasmic Reticulum:Made up of membranous tubules and
cisternae (sacs)Smooth ER: NO ribosomes attached
• Synthesis and transport of lipids• Controls glucose glycogen conversion in
liver & muscles• Detoxification of drugs and other poisons• Sarcoplasmic reticulum (muscle ER) stores
calcium needed in muscle contraction.Rough ER: ribosomes attached
• Synthesis & transport of proteins
![Page 16: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/16.jpg)
Endomembrane System
Smooth and Rough ER
![Page 17: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/17.jpg)
Endomembrane System
Golgi Apparatus: Products of the
Endoplasmic Reticulum are modified and stored here
Modifies & packages proteins
![Page 18: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/18.jpg)
Endomembrane System
Lysosomes: Used by cells to
digest macromolecules
Sac of hydrolytic enzymes
Apoptosis: • Programmed cell
death Usually found only
in animal cells
![Page 19: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/19.jpg)
Endomembrane System Vacuoles:
Food vacuoles (storage)
Contractile vacuoles (pump extra water out of cells in freshwater protists)
Central vacuole (plant cells)
• Stores organic compounds, inorganic ions (K+, Cl-), and water
• Surrounded by tonoplast
![Page 20: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/20.jpg)
Endomembrane System
Peroxisomes:Contain enzymes that transfer
hydrogen from various substances to oxygen, producing H2O2 as a byproduct
Various functions:• Break fatty acids down into smaller
molecules for cellular respiration• Detoxify alcohol in liver
![Page 21: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/21.jpg)
Energy-related organelles Mitochondria
Site of cellular respiration (Energy from the breakdown of organic molecules is used to phosphorylate ADP to produce ATP)
“powerhouse of the cell”
More metabolic activity = more mitochondria
![Page 22: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/22.jpg)
Energy-related organelles
Mitochondrial Structure: Outer membrane Inner membrane:
• Cristae = large surface area makes more efficient at producing energy
Intermembrane space
Mitochondrial matrix
![Page 23: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/23.jpg)
Energy-related organelles
Chloroplasts: Found in plants and
eukaryotic algae Site of photosynthesis Contain the green
pigment chlorophyll
![Page 24: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/24.jpg)
Energy-related organelles Chloroplast
Structure Thylakoids
• Grana = stacks of thylakoids
• (Light Dependent Phase)
Stroma• Fluid outside the
thylakoids• (Calvin Cycle)
![Page 25: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/25.jpg)
Cellular Organelles
Cell Wall Found only in plant cells Protects the cell Maintains
cell shape Prevents excessive uptake
of water Holds plant up against
gravity Primary Cell Wall-thin;
cellulose Secondary Cell Wall-
thicker; found in woody plants
![Page 26: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/26.jpg)
Cellular Organelles
Extracellular Matrix: Found in animal cells Made up of
glycoproteins (collagen) & proteoglycans
• Proteins + carbohydrates
Provides support and anchorage for cells
Differs from one cell type to another
![Page 27: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/27.jpg)
Intercellular Junctions
Neighboring cells are connected to one another
Plant cells: Plasmodesmata:
• Channels in the cell wall through which strands of cytoplasm pass through and connect the living contents of adjacent cells
![Page 28: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/28.jpg)
Intercellular Junctions (Animal Cells)
Tight junctions-membrane proteins interlock
Desmosomes, (anchoring junction)-intermediate filaments “sew” membranes together
Gap junctions- channels align allowing materials to flow between cells
![Page 29: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/29.jpg)
Intercellular Junctions
Tight junctions: Membranes of
neighboring cells are fused
Form a continuous “belt” around a cell
Example: junction between epidermis of the skin
![Page 30: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/30.jpg)
Intercellular Junctions Desmosomes
Anchoring junctions
Act as rivets Muscle cells
are held together by desmosomes.
What happens when a muscle is torn?
![Page 31: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/31.jpg)
Intercellular Junctions
Gap junctions Communicating
junctions Cytoplasmic
channels between adjacent cells
Salts, sugars, AAs, etc. can pass through
![Page 32: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/32.jpg)
Membrane Structure & Function
![Page 33: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/33.jpg)
Functions of the Cell Membrane
Isolates the cytoplasm from the external environment
Regulates the flow of materials into and out of the cell
Communicates with other cells
![Page 34: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/34.jpg)
The Fluid Mosaic Model Currently accepted model of
the cell membrane Proposed by Singer and
Nicolson in 1972 Phospholipid bilayer
Hydrophilic “head” – exposed to the outside
Hydrophobic “tail” – hides inside
Membrane proteins are randomly dispersed in phospholipid bilayer
![Page 35: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/35.jpg)
Fluid Mosaic Model
![Page 36: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/36.jpg)
Fluidity of the Membrane The lipids and
proteins can drift throughout the membrane
Membrane is NOT stiff/rigid
Cholesterol makes the membrane stronger by limiting the movement of phospholipids
![Page 37: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/37.jpg)
Membrane as a Mosaic Lipid bilayer has
membrane proteins embedded in it
Integral proteins Go through the
membrane (both sides)
Peripheral proteins attached to the
surface of the membrane
![Page 38: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/38.jpg)
Selective Permeability of the Cell Membrane
The cell membrane can “choose” what enters and exits a cell
“Gatekeeper of the Cell”
![Page 39: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/39.jpg)
Passive Transport
Def’n: Diffusion of a substance that does
NOT require the input of energy by the cell
3 types of passive transport:DiffusionOsmosisFacilitated diffusion
![Page 40: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/40.jpg)
Diffusion
Movement of molecules from high to low concentration until equilibrium is reached.
Passive Transport= no energy required
What substances may diffuse across membrane? Nonpolar (non-charged) molecules; small polar molecules
![Page 41: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/41.jpg)
Diffusion Each substance
diffuses down its OWN concentration gradient and is unaffected by concentration gradients of other substances
![Page 42: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/42.jpg)
Diffusion
Does all movement stop once equilibrium is reached?? NO!! Equal rates in all
directions
![Page 43: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/43.jpg)
Osmosis Def’n:
The passive transport of water across a selectively permeable membrane
Hyper-, hypo-, iso- tonic• RELATIVE TERMS!!
• Always referring to solute concentration
Water moves from areas of lower concentration of solutes (hypotonic) to areas of higher solute concentration (hypertonic)
![Page 44: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/44.jpg)
Osmosis in Plant and Animal Cells Animal Cells:
Cell crenate/shrinks Cytolysis
• Occurs when a cell is in a hypotonic solution
• Water goes from solution into cell
Plant Cells: Turgid- vacuole
swells Flaccid-vacuole
shrinks (plasmolysis)
![Page 45: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/45.jpg)
Facilitated Diffusion
Def’n:The diffusion of large molecules
across the cell membrane using transport proteins
Glucose; ions Does NOT require an input of energy
Solute is still moving down its concentration gradient
![Page 46: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/46.jpg)
Facilitated Diffusion
Transport proteins are specific for their solutes
Transport proteins can become saturated
Some are gated channels: Chemical or electrical
stimulus causes them to open
![Page 47: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/47.jpg)
Example
Which direction will sucrose move?
Which direction will glucose move?
Which direction will fructose move?
![Page 48: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/48.jpg)
Pop Quiz – Passive Transport1. What is passive transport across
the cell membrane?
2. Describe 3 types of passive transport discussed yesterday.
3. If a blood cell is placed in a hypotonic solution what would be the result?
4. What type of solution is preferred in plant cells.
![Page 49: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/49.jpg)
Active Transport
Def’n:The pumping of solutes against their
gradientsRequires an input of energy by the cellUsed so cells can “stockpile” extra
supplies (storage of any substance in a very high concentration; i.e. Iodine stored in thyroid; glycogen stored in liver
Sodium/Potassium Pump
![Page 50: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/50.jpg)
Electrogenic Pumps
Voltage across membranes = stored energy that can be used for cellular work
Sodium-Potassium Pump:3 Na+ OUT of the cell for every 2 K+
pumped inNet transfer of one positive charge from
cytoplasm to extracellular fluid Very important for transferring signals
between nerve cells
![Page 51: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/51.jpg)
Sodium-Potassium Pump
![Page 52: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/52.jpg)
Cotransport
Substance that has been pumped across a membrane can do work as it “leaks” back by diffusion
Another substance “hitches a ride”
![Page 53: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/53.jpg)
Endocytosis & Exocytosis
Def’n:The movement of large molecules
(polysaccharides, proteins, etc.) across the membrane using vesicles
Endocytosis = cell takes in macromolecules
Exocytosis = cell secretes macromolecules
![Page 54: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/54.jpg)
Endocytosis Cell takes in macromolecules
by forming vesicles made from the plasma membrane
Phagocytosis = “cell eating” Large molecules
Pinocytosis = “cell drinking” Small molecules & liquids
Receptor-mediated endocytosis = seeks out specific molecules
![Page 55: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/55.jpg)
Exocytosis
The cell secretes macromolecules by the fusion of vesicles with the plasma membrane
Used to release hormones, chemical signals, etc.
![Page 56: Cell Structure. The Cell ESSENTIAL to the study of biology Simplest form of life Every organism’s basic unit of structure and function Named by Robert](https://reader035.vdocuments.us/reader035/viewer/2022062720/56649f1b5503460f94c3024a/html5/thumbnails/56.jpg)
Pop Quiz 2
1. What is Active Transport across the cell membrane?
2. What does it mean when molecules are moving up the concentration gradient?
3. Describe (in detail) how the sodium potassium pump works in nerve cells.
4. What is the difference between phagocytosis and pinocytosis?