cell structure and function - mrs. tran's biology portal · •in 1665, robert hooke was the...
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Cell Structure and Function
Definition of CellA cell is the smallest unit that is capable of
performing life functions.
RECALL... Levels of Organization!
Why do we call them cells?
• In 1665, Robert Hooke was the first to view cells from cork (dead plant material).
• He called them “cells” because they looked like tiny rooms.
What is the Cell Theory?1. All living things are composed of
cells
2. Cells are the basic units of structure and function in living things.
3. New cells are produced from existing cells.
Why Cells are Important?• What happens inside cells causes us to
be who we are.
What is it that is found inside of all cells???
• All diseases start at the level of the cell.
• All growth and life starts from a single cell.
• Cell specialization: allows cells to perform different functions in multicellular organisms
GENES!! (DNA/RNA)
2 main types of cells
1. Prokaryote:
ex. Bacteria
2. Eukaryote: ex. Plant, Animal, Fungi, Protist
HOW DO PROKARYOTES DIFFER FROM
EUKARYOTES?
1.) No Nucleus
2.) DNA floats in cytoplasm
3.) Flagella
Flagella
As we discuss the differences between Eukaryotic and Prokaryotes fill in your venn diagram.
Eukaryotes Prokaryotes
both
What Makes Prokaryotic Cells Different?
ONLY WRITE THE UNDERLINED WORDS
• Much smaller
• Less complex (SIMPLE)
• No nucleus
• Circular DNA that is found free floating in the cytoplasm
• NO membrane bound organelles found in the cytoplasm
• Always has a cell wall
What Makes Eukaryotic Cells Different?
ONLY WRITE THE UNDERLINED WORDS
• Much larger
• Much more complex• Contain a nucleus to house the genetic material (DNA)
• Linear DNA packaged into chromatin found inside the nucleus
• Contains MEMBRANE BOUND organelles-specialized structures in the cytoplasm
• Not all have a cell wall
Examples of MBOs
• Nucleus
• Smooth endoplasmic reticulum
• Rough endoplasmic reticulum
• Golgi apparatus
• Lysosome
• Mitochondria
• Centrioles
• Vacuole
• Chloroplast
*Ribosomes are NOT membrane bound so can be found in both types of cells*
Characteristics Shared (BOTH)
ONLY WRITE THE UDNERLINED WORDS IN VENN DIAGRAM
• same basic functions
• Plasma membrane to control what enters and leaves the cell
• “Filled” with cytoplasm
• Contain ribosomes to make protein
• Contain Nucleic Acids (DNA/RNA)
Eukaryotic Cells
What does size have to do with it?• Prokaryotic cells are much smaller than
eukaryotic cells. Why?– Smaller surface area to volume allows nutrients to
easily and quickly reach inner parts of the cell.
– No specialization because they are UNICELL ; one cell must be able to do all life functions
– Eukaryotic cells are larger and can not pass nutrients as quickly. They require specialized organelles to:
• carry out metabolism
• provides energy
• transport chemicals throughout the cell
About Cell Membranes
1.All cells have a cell membrane
2.Functions:
a.Controls what enters and exits the cell to maintain an internal balance called homeostasis
b.Provides protection and support for the cell
TEM picture of a
real cell membrane.
3.Structure of cell membrane
Lipid Bilayer -2 layers of phospholipidsa.Phosphate head is polar
(water loving)
b.Fatty acid tails non-polar(water fearing)
c.Proteins embedded in membrane
Phospholipid
Lipid Bilayer
4. Cell membranes have pores (holes) in ita.Selectively permeable: Allows some molecules in
and keeps other molecules outb.The structure helps it be selective!c. The plasma membrane is describe as a Fluid Mosaic
Model because of how it is arrange and there are PORES in between the phospholipids.
Pores
Proteins
Membrane
movement
animation
Polar heads
love water
& dissolve.
Non-polar
tails hide
from water.
Carbohydrate cell
markers
Fluid Mosaic
Model of the
cell membrane
Purpose of Cell TransportCells must move materials across the membrane in
order to maintain homeostasis
– Nutrients/ Oxygen must be able to easily move into the cell– Wastes/ Carbon dioxidemust be able to easily
move out of the cell
Molecular Movement
• All the substances important to life are
almost always part of a solution.
• Solute: The substance dissolved in the
solvent
Ex. Sugar, salt, starch
• Solvent: dissolves the solutes
Ex. Water is the universal solvent of most
solutions involved in cellular activities.
Molecular MovementFactors that affect the rate of diffusion:
1. concentration (higher=faster)
2. temperature (warmer=faster,
colder=slower)
3. pressure (high pressure=faster)
Concentration = amount of material in an areaDraw a higher concentration of solutes inside the cell than outside the cell.
Draw a lower concentration of solutes inside the cell than inside the cell.
How would these cells go back into homeostasis?
Types of Cellular Transport
Passive Transport
cell does NOT use energy1. Diffusion
2. Facilitated Diffusion
3. Osmosis
Active Transport
cell DOES use energy1. Protein Pumps
2. Endocytosis
3. Exocytosis high
low
This is
gonna
be hard
work!!
high
low
Weeee!!
!
•Animations of Active
Transport & Passive
Transport
Passive Transport• cell uses no energy
• molecules move randomly
• Molecules spread out from an area of highconcentration to an area of low concentration.
• (HighLow)• Moves with the concentration
gradient
Passive Transport:1. Diffusion
1. Diffusion: random movement of particles from an area of high concentration to an area of low
concentration.
(High to Low)
• Diffusion continues until all molecules are evenly spaced (equilibrium is reached)-Note:molecules will still move around but stay spread out.
http://bio.winona.edu/berg/Free.htm
Simple Diffusion
Animation
2. Facilitated diffusion: diffusion of specific particles through transport proteins found in the membrane
a. Transport Proteins are specific – they “select” only certain molecules to cross the membrane
b.Transports larger or charged molecules
Facilitated
diffusion
(Channel
Protein)
Diffusion
(Lipid
Bilayer)
Passive Transport:
2. Facilitated Diffusion
Carrier Protein
A B
• http://bio.winona.edu/berg/Free.htm
3.Osmosis: diffusion of water through a selectively permeable membrane
• Water moves from high to low concentrations
•Water moves freely
through pores.
•Solute (green) too
large to move across.
Osmosis
animation
Passive Transport:
3. Osmosis
Hypotonic Solution
Hypotonic: The solution (environment) has a lower
concentration of solutes and a higher concentration of
water than inside the cell. (Low solute; High water)
Result: Water moves into the cell from solution: Cell
swells and bursts open (cytolysis)!
• OsmosisAnimations for
isotonic, hypertonic, and hypotonic
solutions
Hypotonic: freshen that lettuce!
Hypertonic Solution
Hypertonic: The solution has a higher concentration
of solutes and a lower concentration of water than
inside the cell. (High solute; Low water)
Result: Water moves out of the cell into the solution:
Cell shrinks (Plasmolysis)!
• OsmosisAnimations for
isotonic, hypertonic, and hypotonic
solutions
shrinks
Isotonic Solution
Isotonic: The concentration of solutes in the solution
is equal to the concentration of solutes inside the cell.
Result: Water moves equally in both directions and
the cell remains same size! (Dynamic Equilibrium)
• OsmosisAnimations for
isotonic, hypertonic, and hypotonic
solutions
What type of solution are these cells in?
A CB
Hypertonic Isotonic Hypotonic
Osmosis Video Osmosis Rap
Active Transport
•cell uses energy
•actively moves molecules to where they are
needed
•Movement from an area of low concentration
to an area of high concentration (Low High)
•Molecules go against the concentration
gradient
3 Types of Active Tranport
1. Protein Pumps
2. Endocytosis
3. Exocytosis
Types of Active Transport
1. Protein Pumps -
transport proteins that
require energy to do
work
•Example: Sodium /
Potassium Pumps
are important in nerve
responses.
Sodium
Potassium Pumps
(Active Transport
using proteins)
Protein changes
shape to move
molecules: this
requires energy!
Types of Active Transport
• 2. Endocytosis: taking bulky
material into a cell
• Uses energy
• Cell membrane in-folds around food particle
• “cell eating”
• forms food vacuole & digests food
Ex. This is how white blood cells eat bacteria!
Endocytosis by white blood cell
Types of Active Transport
3. Exocytosis: Forces material out of cell in bulk• membrane surrounding the
material fuses with cell membrane
• Cell changes shape –requires energy
• EX: Hormones or wastes released from cell
Endocytosis &
Exocytosis
animations
Endo and Exocytosis (~at 1:13 mark)
Exocytosis and Endocytosis
Exocytosis – process of a cell releasing materials (exiting)
Endocytosis – process of cell taking materials in (entering)Exocytosis
How Organisms Deal with Osmotic Pressure
• Paramecium (protist) removing excess water video
•Bacteria and plants have cell walls that prevent them
from over-expanding. In plants the pressure exerted on
the cell wall is called turgor pressure.
•A protest, like paramecium, has contractile vacuoles
that collect water flowing in and pump it out to prevent
them from over-expanding.
•Salt water fish pump salt out of their specialized gills so
they do not dehydrate.
•Animal cells are bathed in blood. Kidneys keep the
blood isotonic by remove excess salt and water.
The process in which the movement of materials across a membrane from low to high concentration requiring energy is ____.A. passive transportB. diffusionC. active transportD. facilitated diffusion
A. B.
C. D.
• Which one is different?
• How is it different?
• Does ACTIVE transport require ENERGY?
• Does passivetransport require energy?
Cell Transport Concept Map Name Date
Cell transport involves the
exchange of molecules
through the
Against the
concentration gradient
(low to high)
Down the
concentration gradient
(high to low)
requires small molecules move
through
examples
moved by
Small molecules
move through
Larger molecules
move through
of water
also called
large molecules
transported by
in out
Example: Example:
Word Bank: Facilitated Diffusion Cell Membrane (2X) Osmosis
Active Transport ATP Energy Food/Bacteria Proteins (2X)
Passive Transport Glucose/Amino Acids/Ions Endocytosis
Diffusion Wastes/Secretions Exocytosis
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