Post on 27-Oct-2019
Cell Structure
and Function
Unit 4
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 multicellularorganisms
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
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 nutrientsto 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
Examples of MBOs
Nucleus
Smooth endoplasmic reticulum
Rough endoplasmic reticulum
Golgi apparatus
Lysosome
Mitochondria
Centrioles
Vacuole
Chloroplast
*Ribosomes are NOT membrane bound*
Eukaryote
(Eu – True)
Prokaryote
(Pro – No)
• No
Nucleus• Has TRUE
Nucleus• Genetic
Material
(DNA)
• Cell
Membranes
• Cytoplasm
• Ribosomes
• No
membrane
bound
organelles
• Simple,
small
• Membrane
bound
organelles
• Large,
complex
Pro
kary
otic v
s. E
ukary
ote
sSize does
matter!
Which type
of cell is
bigger?
Watch
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
Amoeba Video
Complete Cell Structure Flip
BookWrite the function for each cell organelle
and label pictures
***Major Test Grade: Cell Comparison
Poster
Day 2 Notes: Cell membrane, transport and solutions
• To be a barrier between a cell and its environment
• Allow nutrients and water to enter while removing waste products
• The membrane is selectively permeable (controls
what molecules come in and keeps other molecules out) Ex. Bouncer at a club
Function of the Cell Membrane
Cell / Plasma membrane Function
• Maintains an internal balance inside the cell: Homeostasis
Parts of the plasma membrane• The phospholipid form 2 layers.
• Each layer contains hydrophilic heads (water-loving) and hydrophobic (water-fearing) tails
Parts of the plasma membrane• Carbohydrate chains are at the surface and are
sites where viruses or chemical messengers can attach.
• Proteins will help transport (move) macromolecules (glucose) in & out of the cell.
Transport Protein
Transport Protein
Carb Chain
PhospholipidBilayer
Hydrophobic
Parts of the Cell (Plasma) Membrane
• Phospholipid bilayer • Transport proteins
INSIDE OF 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?
A B Where is there a higher conc.?
Where is there a lower conc.?
What does “B” represent?
Predict what will happen in the diagram?
CA
C
SELECTIVELY PERMEABLE MEMBRANE
PARTICLES WILL MOVE FROM A TO C TO REACH EQUILIBRIUM
Passive Transport-
Passive Transport
– requires NO energy
– Goes from high to low concentration
– 3 main types: diffusion, facilitated diffusion, osmosis
3 Types of Passive Transport1. Diffusion
• Movement of moleculesthrough the cell membrane from high to low conc.
2. Facilitated Diffusion
• Movement of molecules through the cell membrane using transport proteins from high to low conc.
3. Osmosis
• Movement of water molecules through the cell membrane from high to low conc.
Facilitated diffusionWhy?
Diffusion (any particles) or
Osmosis (water only)Uses a TRANSPORT PROTEIN going from H to L concentration
Assessment
When no energy is required for molecules to move through the membrane it is called
A. Active transport
B. Passive transport
Assessment
What transport moves particles into and out of the cell?
A. Osmosis
B. Diffusion
C. Facilitated Diffusion
D. Both B and C
WATER ONLY!
Passive Transport: Osmosis
Osmosis - Movement of water from high to low concentration through a membrane
Water molecule
Solute moleculeEx. sugar
• Water is so small and can easily pass through the membrane so it REQUIRES NO ENERGY (passive transport).
• Water is ALWAYS flowing.
•Water moves freely through pores.
•Solute (green) too large to move across.
Osmosisanimation
Passive Transport: Osmosis
3 types of Osmotic solutions
Remember!
Solution: Mixture of water (solvent) and particles (solutes)
Ex. The environment of the cell is a solution. Blood is a solution.
3 types of osmotic solutions for cells
a. Isotonic
b. Hypertonic
c. Hypotonic
3 types of Osmotic solutions
Isotonic SolutionCell remains same size
• Water moves?
– In and out equally
Where is there more water, cell or environment?
– Equal conc. of water inside and outside of cell
• When you have balance its called?
Homeostasis
Hypotonic Solution ex. distilled waterCell gets BIG- blows up
(Hypo – Hippo)
• Water moves?– Inside the cell
Where is there more water, cell or environment?
• Solution– has more water
• Cell– has less water
Animal cell may LYSIS or BURST
Hypertonic Solution ex. salt solutionCell Shrinks
• Water moves?– Out of cell
What has more water?
• Solution– has less water
concentration
• Cell– has more water
concentrationVideo
Plant will WILT
Osmosis Across Membranes
Questions
• What type of solution is in side A? Hypotonic Solution
• What type of solution is in side B? Hypertonic Solution
• Which way will water move to balance out the tube? Right to left (There is more water)
• Are the black dots moving through the membrane? Yes or no, explain. No, only water is!
Inside CellOutside Cell Inside Cell Inside CellOutside Cell Outside Cell
A B CIsotonic Hypertonic Hypotonic
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 tugor pressure.
•A protist 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.
Osmotic Solutions: Real Life
• If you put salt onto a slug, it dies. Why? Explain using information about the osmotic solutions.
Water moves in or out of cell?
What happens to the cell?
What solution is this?
80% water
20% water
2.Water moves in or out of cell?
What happens to the cell?
What solution is this?
10% salt
90% salt
3.
Water moves in or out of cell?
What happens to the cell?
What solution is this?
17% water
83% salt
6.
Osmotic Problems
Active Transport•cell uses ATP energy
•actively moves molecules to where
they are needed
•Movement from an area of low
concentration to an area of high
concentration
(Low High)
• Goes against the concentration
gradient
3 Types of Active Transport
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!
Types of Active Transport
3. Exocytosis: Forces bulky material out (exit) of cell in membrane surrounding the material fuses with cell membrane
• Cell changes shape –requires energy
• EX: Hormones or wastesreleased from cell
Exocytosis
Exocytosis and Endocytosis
Exocytosis
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?