Cell Structure and Function
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Transcript of Cell Structure and Function
CELL STRUCTURE AND FUNCTION
Cell Discovery and
Theory
The Cell
A cell is the basic unit of structure and function Humans have trillions and trillions of cells You can’t see cells with the naked eye
Cell Dudes Robert Hooke- 1665
Looked at cork, saw little box-shaped structures and called it cellulae
Anton van Leeuwenhoek- late 1600s Looked at pond water and milk and saw
“beasties”
Cell Dudes Matthias Schleiden- 1838-botanist
Studied plants and concluded that all plants are made of cells
Theodor Schwann- zoologist Concluded that all animal tissues were made
of cells
Rudolph Virchow- Suggested that cells come from cells
Hooke’s Microscope Hooke’s Drawing of
Cork
Back when… Had to draw images
No cameras! First images of nervous system
Maid (Harriet) willed her body to Dr. Rufus Weaver (1888)
He meticulously dissected her body to analyze nervous system
The Human Nervous System, 1888 Dr. Weaver took 5
months to carefully dissect Harriet and then remove and draw the nerves!
Still on display at Hahnemann Medical College, Philadelphia, PA
Nerve tissue is real and coated; eyes are models
More history Understanding blood flow
Criminals sentenced to death had option to be dissected while alive – 16th century
William Harvey 1628 – dissect live and dead animals Heart pumps blood and then it is returned –
continuous flow
The Cell TheoryPrinciple Explanation
1. All living organisms are made up of one or more cells.
An organism can have one or many cells. Most plants andanimals have many cells.
2. The cell is the basic unit of organization in living organisms.
Even in complex organisms such as humans, the cell is the basic unit of life.
3. All cells come from cells. Cells pass copies of their genetic material on to their daughter cells.
Cells contain hereditaryinformation that passes fromcell to cell during cell division.
How do we know cells come from other cells?
Problem? A compound light microscope has a 10X
ocular lens and a 46X objective lens. Where is the ocular lens?
____________________ Where is the objective lens?
_________________ What is the total magnification ___________X
Prokaryotes
2 Kingdoms Eubackteria Archeabacteria
No nucleus DNA in a central nucleoid
region Contains ribosomes First organisms on earth
Eukaryotic Cells
4 Kingdoms Protist (single celled) Plants (cell wall/chloroplasts) Animals (lack cell wall/lack chloroplasts) Fungi (cell wall/lack chloroplasts)
Contain membrane bound organelles Organelles are specialized structures that
carry out functions
Venn Diagram Time… turn to page 10!
Prokaryotic Cells
Eukaryotic Cells
Your task now…
Look on page 11 in your packet Read “The Origin of the Eukaryotic Cell” Answer questions pages 13 and 14
Homework if you do not finish!!
Let’s focus on the plasma membrane
The Cell Membrane
The cell membrane is selectively permeable Some things can pass but others can’t
Cell membranes are made from a phospholipid bilayer
Phospholipid Bilayer Structure Each phospholipid has a polar head and
two nonpolar tails Polar head is attracted to water Nonpolar tails are repelled by water
Outsideof cell
Insideof cell(cytoplasm)
Cellmembrane
Proteins
Proteinchannel Lipid bilayer
Carbohydratechains
Phospholipid Bilayer Function The function is to let some things in and
not others Polar molecules do not easily pass
H2O is an exception because it is small Allows membrane to separate environment
inside from outside the cell The plasma membrane is always in
motion Fluid mosaic model
Animal Cells vs. Plant Cells Eukaryotic cell which
makes up tissues in animals
Lack cell walls and chloroplasts, and have smaller vacuoles.
Appears to be circular because of the lack of a rigid cell wall.
Eukaryotic cell that makes up plants
Cell Wall Chloroplast Large Vacuoles
Animal Cell
Plant Cell
Cytoplasm
Semi-fluid material inside the plasma membrane
Consists of cytosol and the cellular organelles (all organelles except the cell nucleus)
Cytosol - fluid in which the cellular organelles are suspended
Cytoskeleton
Network of long, thin protein fibers provide an anchor for organelles
Microtubules-long hollow cylinders that assist in moving substances within the cell
Microfilaments-thin threads that give the cell shape and enable the cell to move
Cytoskeleton in Red and Green
Nucleus
Contains genetic material (DNA)
Nuclear envelope Nuclear pores
allow substances in and out
Nucleolus in center Very dense center
Ribosomes
Produce proteins Made of RNA and protein Made in the nucleolus Some float freely in the cytoplasm Others attach to endoplasmic reticulum
Endoplasmic Reticulum
Interconnected network of tubules
Rough ER Where ribosomes attach
and make proteins Appear to create bumps
and rough areas on the membrane
Smooth ER No ribosomes Produces complex
carbohydrates and lipids
Golgi Apparatus
Modifies, sorts, and packs proteins in sacs called vesicles
Vesicles fuse with plasma membrane
They release proteins which move through membrane to get outside of the cell
Vacuoles
Act as temporary storage unit for materials in the cytoplasm
Store, transport, or digest food and waste
Plant cells have one large one
Animal cells have little ones
Lysosomes
Vesicles that contain digestive enzymes to digest excess or worn-out organelles and food particles
They also digest bacteria and viruses that enter the cell
They are built in the Golgi apparatus.
Centrioles
Microtubules Found near nucleus Animal Cells only Aid in cell
replication
Mitochondria
Powerhouse Converts organic
materials into energy ATP
Outer and inner membranes with lots of folds Provides large surface
area to break sugar molecule bonds (produce energy)
Chloroplasts- Plant only
Capture light energy and convert it to chemical energy through photosynthesis
Photosynthetic Animals Elysia chlorotica- a sea slug
appearing here as a giant swimming leaf
2010 - found to be the first known animal to make proteins essential for photosynthesis Stole the chloroplasts from algae it eats – can live up to 9
months without eating Appears green because of stolen chlorophyll
Lives - Eastern coast of the United States and Canada
Cell Wall
Mesh of fibers that surrounds the plasma membrane
Protects and supports the cell Made of carbohydrate, cellulose
Cilia and Flagella Cilia- short projections that look like
hairs Move back and forth like oars on a rowboat Move substances along surface of the cell
Flagella- longer projections that move in a whip-like motion
Both are composed of microtubules Move cells through watery environment
Cell Transport
Diffusion -net movement of particles from high concentration to low concentration Doesn’t require energy
because the particle are in motion passive transport
Dynamic equilibrium- the overall concentration does not change, but molecules are still moving randomly
What affects the rate of diffusion?
What makes molecules move faster High
temperature High Pressure High
concentration
Facilitated Diffusion
Some ions and molecules can’t diffuse across the cell membrane
Facilitated diffusion – uses transport proteins to help move some molecules across the plasma membrane
Osmosis
Osmosis – diffusion of water Most cells undergo osmosis because
they are surrounded by water
Hyper—Hypo– Iso tonic Solutions
These are comparing words Hypertonic -more solute Hypotonic- less solute Isotonic- same solute as
What would happen if you Put a red blood cell in a hypertonic solution Put a red blood cell in a hypotonic solution Put a red blood cell in an isotonic solution
Active Transport
Goes from low to high concentration Requires Energy
ATP Moves large substances
Endocytosis
Endocytosis- moving large substances into the cell
Exocytosis
Exocytosis- moving large substances out of the cell