Cell Membrane Structure / Function and Cell Transport Ms. Kim Honors Biology
Cell Biology: The Cell, its Structure and History
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Transcript of Cell Biology: The Cell, its Structure and History
The Cell:Its History, Structure, & FormsEarshad B. Banjal
Instructor
University of Mindanao
Cell BiologyThe Invention of the Microscope
A microscope produces an enlarged image of something very small.
In the 1600s, a Dutch lens maker, Zacharias Jansen, invented one of the microscope’s earliest prototypes.
Today, microscopes are available in varieties:
Compound Microscopes
Stereomicroscopes
Electron Microscopes
Cell Biology
The Discovery of the CellIn 1665, Robert Hooke used anearly compound microscope tolook at a nonliving thin slice ofcork, a plant material; termedthem as cells.
In Holland, Anton van Leeuwenhoek used a single-lens microscope to observe pond water and other things; termed them as animalcules.
Cell Biology
The Discovery of the Cell
Felix Dujardin termed allsubstances found inside thecell as sarcode.
Later, Jan EvangelistaPurkinje, called it asprotoplasm.
Robert Brown discovered thenucleus.
Prokaryotes & Eukaryotes
ProkaryotesDo not contain a nucleus
Do not have membrane-bound organelles
Small in size
Examples are Bacteria and Archaea
EukaryotesCells contain a nucleus
Have membrane-bound organelles
Mostly larger than a prokaryote
Examples are Plants, Animals, Fungi and Protists
Prokaryotes
•First cell type on earth
•Cell type of Bacteria and Archaea
Eukaryotes
Plant Cell Animal Cell
Prokaryotes & Eukaryotes
The human eye can see objects larger than about 0.5 mm. Most of what interests cell biologists, however, is much smaller than that. Microscopes make seeing the cellular and subcellular world possible.
Cell Theory
1. Cells are the basic unit of life.
2. Every organism is made up of cells. (Schwann & Schleiden)
3. Every cell comes from pre-existing cells. (Virchow)
What do cells do?
Basically,
1. Cells acquire and synthesize energy
2. Cells synthesize proteins
3. A cell makes more copies of itself
ATP
What are the basic structures of
a Eukaryotic cell?
1. Cell Membrane – controls what gets
in and out of the cell
2. Cytoplasm – where organelles float
& chemical reactions occur
3. Nucleus – control center of the cell
Cell Parts & Organelles
Organelles are cell parts that have specificfunctions. Organelles do the work of cells.Each structure has a job to do. Organelleskeep the cell alive. Functions are the ff:
1. Organelles that store, clean-up, & support
2. Organelles that build proteins
3. Organelles that capture & release energy
4. Cellular boundaries
Organelles that store, clean-up, & support
1. Vacuoles – storage tanks
2. Vesicles – smaller than a vacuole,transports substances
3. Lysosomes – suicidal bags/ recyclebins
4. Centrioles – for cell division
5. Cytoskeleton – skeletal system of thecell
Plant Cells
contractile
vacuole
Animal Cells
central vacuole food vacuole
Protist Cells
Vacuoles & Vesicles• Function
• moving material around cell
• storage
• Structure
• membrane sacsmall food
particle
vesicl
e
vacuole filled w/
digestive enzymes
vesicle filled w/
digested nutrients
Lysosomes
small food
particle
vacuole
digesting food
lysosomes
• Function• digest food
• used to make energy
• clean up & recycle• digest broken
organelles
• Structure• membrane sac of
digestive enzymes
digesting brokenorganelles
A Job for Lysosomes
15 weeks
6 weeks
Centrioles
•Function• help coordinate cell
division• only in animal cells
•Structure• one pair in each
cell
Cytoskeleton• Filaments & fibers
• Made of 3 fiber types• Microfilaments
• Microtubules
• Intermediate filaments
• 3 functions:• mechanical support
• anchor organelles
• help move substances
A = actin, IF = intermediate filament, MT = microtubule
Cilia & Flagella• Provide motility
• Cilia • Short
• Used to move substances outside human cells
• Flagella• Whip-like extensions
• Found on sperm cells
• Basal bodies like centrioles
Cilia & Flagella Structure• Bundles of microtubules
• With plasma membrane
Organelles that build proteins
1. Ribosomes – protein factories
2. Endoplasmic Reticulum – passageway/ roadways
A. Rough ER
B. Smooth ER
3. Golgi bodies – transport/ vehicles
Ribosomes on ER
Ribosomes & ER
• Function
• protein factories
• read instructions to build proteins from DNA
• Structure
• some free in cytoplasm
• some attached to ER
• Function• works on proteins
• helps complete the proteins after ribosome builds them
• makes membranes
• Structure• rough ER
• ribosomes attached
• works on proteins
• smooth ER• makes membranes
Endoplasmic Reticulum
transport vesicles
vesiclescarrying proteins
• Function• finishes, sorts, labels &
ships proteins• Like a logistics service
• shipping & receiving department
• ships proteins in vesicles• “logistics trucks”
• Structure• membrane sacs
Golgi Apparatus
Organelles that capture & release energy
1. Chloroplasts – convert solar energy into chemical energy; found only in autotrophs; “solar power plant”
2. Mitochondria – powerhouse of the cell; “power plant”
•Function• make ATP energy
from cellular respiration• sugar + O2 ATP
• fuels the work of life
•Structure• double membrane
Mitochondria
ATP
Chloroplasts•Derived form photosynthetic bacteria
•Solar energy-capturing organelle
•Structure:•double membrane
•Thylakoid
•Stroma
Colored organelles (plastids)a) Chromoplast – red
b) Leucoplast – colorless
c) Chloroplast – green
Cellular boundaries
1. Cell Membrane (Plasma Membrane) –regulates the entrance & exit of substance
2. Cell Wall – shapes, supports, protects
Plasma Membrane
•Contains cell contents
•Double layer of phospholipids & proteins
Fluid-Mosaic ModelIt explains the structure of the cell membrane (Singer and Nicholson, 1980s).
Polar heads
love water
& dissolve.
Non-polar
tails hide
from water.Proteins
Carbohydrate
cell markers
Phospholipids
Nature:
Amphipathic
Structure:• Hydrophilic head
• Hydrophobic tail
Movement Across the Plasma Membrane
A few molecules move freely:• Water, Carbon dioxide, Ammonia, Oxygen
Carrier proteins transport some molecules• Proteins embedded in lipid bilayer
• Fluid mosaic model – describes fluid nature of alipid bilayer with proteins
Membrane Proteins
1. Channels or transporters• Move molecules in one direction
2. Receptors • Recognize certain chemicals
Membrane Proteins
3. Glycoproteins
• Identify cell type
4. Enzymes
• Catalyze production of substances
Cell Walls
• Found in plants, fungi, & many protists
• Surrounds plasma membrane
• Plants – cellulose
• Fungi – contain chitin
• Bacteria – peptidoglycan
• Protists – cellulose & pectin