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Cellular Structure and Function
Unit 3; Chapter 7 Date Classwork Homework
Notes: History of Cells Read/Questions Chapter 7.1 and 7.2 Venn Diagram
Origins of Eukaryotic Cells Finish Origins Reading/Questions
Notes: Membranes Membrane Lab
Read/Questions Chapter 7.3
Notes: Organelles Color/label Cell Diagrams Cell Flip Book, Day 1 Cell Flip Book, Day 2 Finish Cell Flip Book Cell Lab – Comparing Plant and Animal Cells Finish Cell Lab Cell City Analogy
Review Sheet Finish Review Sheet (page 31)
Notes: Transport Gummi Bear Lab, Day 1
Read/Questions 7.4
Gummi Bear Lab, Day 2 Notes: Transport (finish) Osmotic Solutions Worksheet
Finish Osmotic Solutions Worksheet
Gummi Bear Lab, Day 3 Endocytosis Lab
Finish lab questions
Work on Potato Lab Study for Test Finish Potato lab
Test Review Finish Lab questions Complete packet and study
Test Prepare for next unit
Rubric:
Out of Your Score Reading Questions 40 PowerPoint Notes 20 Venn Diagram 10 Origins of Eukaryotic Cells
10
Membrane Lab 20 Flip Book TBA Comparing Lab 20 Osmotic Solutions 10 Gummy Bear Lab 20 Endocytosis Lab 10 Potato Lab 20
Total
Reading Questions 7.1
Before You Read:
1.
2.
3.
4.
5.
7.2
Before You Read:
1.
2.
3.
4.
5.
7.3
Before You Read:
1.
2.
3.
4.
5.
6.
7.
7.4
Before You Read:
1.
2.
3.
4.
3
What did Robert Hooke call the boxes that he observed in cork?
___________________________________
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___________________________________
___________________________________
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Why should I care?
___________________________________
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So, what is a cell?
Smallest _____________________ that can
support life
A bacterium is ________________ self-
sustaining cell
You are made up of trillions of
_____________________cells
Too small to see without a microscope
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
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4
Problem?
Miss Apgar wants to view a bacterial cell that needs to be magnified 1000 times in order to see it. Her compound light microscope has a 10X ocular lens. Which objective lens should she use to see the bacterium?_____________
Where is the ocular lens?____________________
Where is the objective lens? _________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
What do we remember about microscope history?
Robert Hooke
Named the cell
Cell – Structural and
functional unit of life
Made sketches of the
microscopic world
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Anton van Leeuwenhoek
Perfected a single lens microscope
Examined _____________________ and
__________________________
Called creatures he saw “cavorting wee beasties”
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5
Some More History
Matthias Schleiden Studied plants Determined that all
__________________________________________________________________________________________
Theodor Schwann Studied animals Determined that all
__________________________________________________________________________________________
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Some More History
Rudolf Virchow
German physician
Proposed that cells ______________________
to form new cells
Used his theory to diagnose patients
Father of pathology
___________________________________
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___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Cell Theory - putting their work together
All organisms are made of cells __________________________________________________________
__________________________________________________________
__________________________________________________________
The cell is the basic unit of organization in living organisms __________________________________________________________
__________________________________________________________
__________________________________________________________
All cells come from pre-existing cells __________________________________________________________
__________________________________________________________
__________________________________________________________
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6
How do we know that cells come from other cells?
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Two types of cells…
Prokaryotic cells
Simple interior
Considered to be the
___________________________
Eukaryotic cells
Complex interior
Considered to be the
______________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
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___________________________________
7
Prokaryotes
Simple interior
DNA in central ___________________________
region
Cellular _______________________ happen in open
space
Single cell organisms
Bacteria
Archaea
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Inside a Prokaryote
The _____________________ is where cell life takes place
DNA is concentrated in the nucleoid region
Ribosomes make proteins
The Flagellum provides _____________________
Capsule, cell wall, and cytoplasmic membrane provide __________________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Eukaryotes Complex interior
DNA is neatly packaged and protected by _________________________
___________________________________ perform cellular functions
Single and multiple cell organisms
Amoebas – single celled
_________________________________________________
_________________________________________________
___________________________________
___________________________________
___________________________________
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8
4 Kingdoms Animalia
Ex:_______________________________________ Plantae
Ex:_______________________________________ Fungi
Ex:_______________________________________ Protista
Ex:_______________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Inside a Eukaryote
The ______________________ is where the organelles are located
DNA is housed in the __________________________
Ribosomes make proteins
There are many other organelles each covered by a __________________________
Each organelle has its own function
__________________________ provides protection
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9
More on the Eukaryote cell
Important terminology
DNA –
__________________________________________________
Organelle – _________________________________________
that carry out
__________________________________________________
Means “little organ”
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First up: the plasma membrane
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The Cell Membrane
The cell membrane is selectively permeable
_____________________________________________
_____________________________________________
Cell membranes are made from a
__________________________________________
__________________________________________
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10
Phospholipid Bilayer Structure
Each phospholipid has a ________________________
head and two ____________________________ 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
Allows some things in and not others
Polar molecules do not ___________________pass
H2O is an exception because it is small
Keeps the outside ___________________ and the inside __________
The plasma membrane is always in motion
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Fluid Mosaic Model
Fluid
Membrane is ____________________________________
Membrane is ____________________________________
Mosaic
There are molecules ___________________________________
in the bilayer
The _______________________________________________
looks like a mosaic
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
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11
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
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Animal Cells vs. Plant Cells
Eukaryotic cell which makes up tissues in animals
Lack ______________ and _______________, and have smaller vacuoles.
Appears to be __________________because of the lack of a rigid cell wall.
Eukaryotic cell that makes up plants
__________________
__________________
__________________
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Animal Cell
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12
Plant Cell
___________________________________
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Cell Wall
Mesh of __________________________that
surrounds the
_________________________________________
Protects and supports the cell
Made of carbohydrate -
__________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Cytoplasm
Semi-fluid material inside the plasma membrane
Consists of _______________________and the
cellular organelles (all organelles except the
_________________________________________)
Cytosol - __________________________________
__________________________________________
__________________________________________
_____________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
13
Cytoskeleton
Network of long, thin protein fibers provide an
____________________ for organelles
_____________________________- long hollow cylinders
that assist in
____________________________________________
within the cell
______________________________- thin threads that give
the cell shape and enable the cell to
__________________________________
___________________________________
___________________________________
___________________________________
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___________________________________
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Nucleus
Contains genetic material (DNA)
Nuclear envelope
Nuclear pores allow ___________________________________
___________________________
__________________________________________________
in center
Very dense center
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Ribosomes
Produce ___________________________________
Made of RNA and protein
Made in the ________________________________
Some _________________________in the cytoplasm
Others ________________________ to endoplasmic
reticulum
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
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14
Endoplasmic Reticulum
Interconnected network of tubules
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Two types of Endoplasmic Reticulum
Rough ER Smooth ER
Where
___________________
attach and make proteins
Appear to create bumps
and rough areas on the
membrane
No ribosomes
Produces complex
___________________
and
___________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
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Golgi Apparatus
Modifies, sorts, and packs
proteins in sacs called
___________________
Vesicles fuse with plasma
membrane
They release proteins which
move through membrane to
get outside of the cell
___________________________________
___________________________________
___________________________________
___________________________________
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15
Vacuoles
_____________________storage for materials in the cytoplasm
Store, transport, or digest food and waste
Plant cells – 1 large vacuole Animal cells – several little
vacuoles
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Lysosomes
Vesicles that contain
____________________________________________
to digest excess or worn-out organelles and food particles
They also digest bacteria and viruses that enter the cell
They are _____________________________________
in the Golgi apparatus.
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
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Centrioles
Made of Microtubules
Found near nucleus
__________________________________________
only
Assembled right before replication
Aid in cell ____________________
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___________________________________
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16
Mitochondria Powerhouse Converts organic materials into ____________________ ATP
Outer and inner membranes with lots of folds
Provides large surface area to break
__________________________________________________
(produce energy)
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Chloroplasts- Plant only
Capture
______________________
and convert it to
______________________
through photosynthesis
___________________________________
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Photosynthetic Animals
2010 - found an animal that makes proteins essential
for photosynthesis
Elysia chlorotica – sea slug that looks like a giant swimming leaf
Stole _____________________________________from algae it eats
can live up to 9 months without eating
Appears __________________________because of stolen chlorophyll
Lives - Eastern coast of the United States and Canada
___________________________________
___________________________________
___________________________________
___________________________________
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17
Cilia and Flagella
Cilia- _______________________, hair-like projections Move back and forth like oars on a rowboat Move substances along surface of the cell
Flagella- rather ________________hair-like projections Whip-like motion
Both are composed of microtubules _________________ cells through
watery environment
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18
Cell Transport
Passive Transport Active Transport
Does not use energy Goes
_____________________ the concentration gradient
3 types diffusion facilitated diffusion osmosis
____________________________________
Goes ___________________ the concentration gradient Endocytosis Exocytosis
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Cell Transport
Diffusion -net movement of particles from
________________concentration to
_________________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
__________________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
What affects the rate of diffusion?
What makes molecules move faster? High _________________________________ High _________________________________ High _________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
19
Facilitated Diffusion
Some ions and molecules can’t ____________________ across the cell membrane
Facilitated diffusion – uses ___________________________________________to help move some molecules across the plasma membrane
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Osmosis
Osmosis – diffusion of ___________________ Most cells undergo osmosis because they are
surrounded by water
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
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Hyper—Hypo– Iso tonic Solutions These are comparing words Hypertonic -____________________________________ Hypotonic- _____________________________________ Isotonic- _______________________________________
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?
___________________________________
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20
What happens to a red blood cell when…?
___________________________________
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___________________________________
Active Transport
Goes from ____________ to __________________ concentration
Requires Energy ATP
Moves __________________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Endocytosis
Endocytosis- moving large substances into the cell
___________________________________
___________________________________
___________________________________
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21
Exocytosis
Exocytosis- moving large substances out of the cell
___________________________________
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25
Reading Questions:
1. Who proposed the endosymbiont hypothesis?
2. Billions of years ago chloroplasts and mitochondria were ____________________
_____________________________________________________.
3. What is symbiosis? Give a detailed description.
4. What does the prefix endo- mean?
5. Explain what an endosymbiont is.
6. What is a common example of an endosymbiont?
7. Explain in detail the beneficial relationship between hydra and algae. (Must be 3 or more sentences)
26
8. What evidence suggests that algae are beneficial to the hydra?
9. How do the mollusks harvest the energy from the algae?
10. What is the benefit to the mollusk with the algae compared to mollusks without algae?
11. What happens when the chloroplasts in the mollusk stop functioning?
12. How does this relate to the endosymbiont theory?
When you are finished work on your homework reading and questions
27
Cell Membrane Lab Problem: Is the cell membrane a selective barrier?
Hypothesis:
Materials:
• Microscope • Microscope slides and cover slips • Yeast • Methylene blue stain (Be careful!!) • Water
• Heated water • Eye droppers/pipettes • 2 - 500mL beakers • Stirring rods
Procedure:
1. Done for you: Place a packet of dry active yeast in a beaker. Add 400mL of water and stir. a. One per class.
2. Done for you: Boil 400mL of water and one packet of yeast for 10 minutes and let cool. a. One per class.
3. Prepare a slide of the yeast in the warm water: a. Place a drop of the solution on a clean slide. b. Place a drop of Methylene blue onto the drop of yeast solution. c. Carefully cover it with your cover slip, remembering to drop it at an angle.
4. Look at the slide under the microscope, remembering to start focusing with low power first. 5. Find a good example of the yeast under high power and draw what you see in the data section below. 6. Repeat steps 3-5 for the yeast that has been boiled.
Data:
___________x ___________x Yeast Cells in Warm Water Boiled Yeast Water Mixture Conclusion:
1. Explain how boiling affected the yeast cells.
2. Why does the color of the two groups of cells differ? (remember to consider the role of the plasma membrane)
3. Are the plasma membranes selective barriers? Explain your answer.
28
Cell Flip Book Assignment Your task is to create a cell flip book that you can use to study for this chapter. This is an INDIVIDUAL assignment. You must include all of the organelles listed below and the following for each organelle:
• Colored hand drawing • Organelle function • Where it is found (Prokaryotes: Bacteria and Archaea, Eukaryotes: Plantae, Animalia, Fungi, and
Protista)
Organelles:
1. Cell Membrane 2. Cell Wall 3. Nucleus 4. Nucleolus 5. Cytoplasm 6. Ribosome 7. Smooth Endoplasmic Reticulum 8. Rough Endoplasmic Reticulum
9. Golgi body 10. Chloroplast 11. Mitochondria 12. Centriole 13. Lysosome 14. Peroxisome 15. Vacuole 16. Cilia/Flagella
Rubric
Organelle Drawing Function Where Found Good (1) Poor (0) Good (1) Poor (0) All (1) Missing (0)
Cell Membrane Cell Wall Nucleus Nucleolus Cytoplasm Ribosome SER RER Golgi Body Chloroplast Mitochondria Centriole Lysosome Peroxisome Vacuole Cilia/flagella
Total Points: ___________ (out of 48)
34
Lab Comparing Plant and Animal Cells
Objective
In this investigation, you will compare the structure of a typical plant cell (elodea) and a typical animal cell (human).
Materials:
• Elodea leaf • Microscope slide • Toothpick • Compound Light Microscope • Methylene blue (be careful!!)
Procedure Part A: Examining Plant Cells
1. Place a drop of water in the center of a clean microscope slide.
2. Remove a leaf from the elodea plant and place it on the drop of water on the slide
a. Make sure the leaf is flat, if it is folded unfold it 3. Carefully place a coverslip over the elodea 4. LOW POWER- locate the leaf 5. Switch to medium or high power objective lens. 6. Observe the cells of the Elodea leaf. Draw and label what
you see
Part B: Examining Animal Cells
1. Place a drop of methylene blue on your slide a. The less the better.
2. Gently rub a clean toothpick along the inside of your cheek. 3. Rub the same toothpick on the methylene blue. 4. Carefully place a coverslip over the cheek cells 5. LOW POWER- locate the cells 6. Switch to medium or high power objective lens. 7. Observe the cells of the cheek cell. Draw and label what you
see
_________x
_________x
35
Observations
1. What is the shape of an elodea cell?
2. What is the general location of the nucleus in an elodea cell?
3. What is the shape of a human skin cell?
4. What is the general location of the nucleus in a human skin cell?
5. How are plant and animal cells similar in structure?
6. How are plant and animal cells different in structure?
7. Explain why you cannot use an oak leaf in this investigation?
8. In general, the surface of a tree has a harder feel than the surface of a dog. What characteristics of each organism can be used to explain the difference?
9. If you were given a slide containing cells of an unknown organism, how would you identify the cells as either plant or animal?
36
Cell City Analogy In a faraway city called Grant City, the main export and production product is the steel widget. Everyone in the town has something to do with the steel widget making and the entire town is designed to build and export widgets. The town hall has the instructions for widget making; widgets come in all shapes and sizes and any citizen of Grant can get the instructions and begin making their own widgets. Widgets are generally produced in small shops around the city; theses small shops can be built by the carpenters’ union (whose headquarters are in the town hall).
After the widget is constructed, they are placed on special carts which can deliver the widget anywhere in the city. In order for a widget to be exported the carts take the widget to the postal office, where the widgets are packaged and labeled for export. Sometimes widgets don’t turn out right and the “rejects” are sent to the scrap yard where they are broken down for parts or destroyed altogether. The town powers the widget shops and carts from a hydraulic dam that is in the city. The entire city is enclosed by a large wooden fence, only the postal trucks (and citizens with proper passports) are allowed outside the city.
Match the parts of the city (underlined) with the parts of the cell.
Organelle City Analogy
Mitochondria
Ribosomes
Nucleus
Endoplasmic reticulum
Golgi apparatus
Protein
Cell membrane
Lysosomes
Nucleolus
37
Cell Organelle Review Sheet
Fill in Check Boxes Part of the Cell Structure Function Bacteria Plant Animal
Cell Membrane
Cell Wall
Nucleus
Nuclear Membrane
Nucleolus
DNA
Cytoplasm
RER/SER
Ribosomes
Golgi Apparatus
Mitochondria
Chloroplast
Vacuole
Lysosome
38
Flow Chart – Identify organelles found in each
All Organisms
Domain Prokayote
Bacteria
Domain Eukaryote
Animalia Plantae Fungi Protista
39
Osmotic Solution
1. Osmotic Solution: __________________________
Direction of the Movement of Water __________________________
What will happen to the cell? __________________________
2. Osmotic Solution: __________________________
Direction of the Movement of Water __________________________
What will happen to the cell? __________________________
3. Osmotic Solution: __________________________
Direction of the Movement of Water __________________________
What will happen to the cell? __________________________
4. Osmotic Solution: __________________________
Direction of the Movement of Water __________________________
What will happen to the cell? __________________________
RBC
100% H2O
RBC
40% H2O
RBC
80% H2O
RBC
85% H2O
Note: A RBC is 85% H2O and15% Solutes.
40
5. Osmotic Solution: __________________________
Direction of the Movement of Water __________________________
What will happen to the cell? __________________________
6. Osmotic Solution: __________________________
Direction of the Movement of Water __________________________
What will happen to the cell? __________________________
7. Osmotic Solution: __________________________
Direction of the Movement of Water __________________________
What will happen to the cell? __________________________
8. Osmotic Solution: __________________________
Direction of the Movement of Water __________________________
What will happen to the cell? __________________________
RBC
90% H2O
RBC
75% H2O
90% H2O
80% H2O
70% H2O
70% H2O
41
9. Osmotic Solution: __________________________
Direction of the Movement of Water __________________________
What will happen to the cell? __________________________
For 10-12: = water molecule
10.
Osmotic Solution: __________________________
Direction of the Movement of Water __________________________
What will happen to the cell? __________________________
11.
Osmotic Solution: __________________________
Direction of the Movement of Water __________________________
What will happen to the cell? __________________________
12.
Osmotic Solution: __________________________
Direction of the Movement of Water __________________________
What will happen to the cell? __________________________
30% H2O
40% H2O
42
Gummi Bear Osmosis
Background Information:
Molecules are in constant motion, and tend to move from areas of higher concentrations to lesser concentrations. Diffusion is defined as the movement of molecules from an area of high concentration to an area of low concentration. The diffusion of water molecules through a selectively permeable membrane is known as OSMOSIS; water molecules move from an area of high concentration to an area of low concentration.
Question: How will soaking Gummy Bear candies in distilled water affect the size of the candy? Hypothesis: Materials:
• Plastic cup • Tap water • Saturated salt solution
• 1 Gummy bear • Ruler • Permanent marker
• Balance • 1 aluminum screen
Procedure:
Day 1: 1. Label your plastic with your names and mods, using the permanent marker. 2. Find the mass of your bear using the balance and record your data. 3. Use the ruler to measure your bear top to bottom (length), side to side (width) and front to
back. Calculate volume (L x W x H) and record your data. 4. Fill your plastic cup ½ way full with tap water. 5. Put your candy bear in the water. 6. Set the cup aside for one day.
Day 2
1. After the candy bear has been in the tap water overnight, pour the water with your gummi bear over an aluminum screen into the sink. Be very careful because the candy is now extremely breakable.
2. Blot the screen dry by placing it on a paper towel. 3. While the bear is on the screen, measure your bear top to bottom (length), side to side (width)
and front to back. Calculate volume (L x W x H) and record your data. 4. Find the mass of the bear. Do this by placing the entire screen with the bear on the balance.
Record the total mass. Then carefully slide the bear back into the empty cup. a. Find the mass of the screen alone and calculate the mass of the bear. Record your data.
5. Cover the bears with the saturated salt solution. Set aside overnight.
Day 3
1. Find the mass and dimensions of the bear using the same procedure as noted on Day 2. 2. Record all data. Calculate volumes.
43
Data: Data Table for Mass
Mass (g) Before Soaking (Day 1)
After Tap Water (Day 2)
After Salt Water (Day 3)
Mass of screen and gummi bear
Mass of screen
Mass of gummi bear
Data Table for Volume
Dimensions Before Soaking (Day 1)
After Tap Water (Day 2)
After Salt Water (Day 3)
Length (cm)
Width (cm)
Depth (cm)
Volume (cm3)
44
Questions & Analysis: 1. What happened to the candy after soaking in tap water overnight? Why?
2. Do you think you would get different results if you used distilled water instead of tap water? (Distilled water has fewer solutes than tap water).
3. What happened to the candy after soaking it in salt water overnight? Why?
4. What do you think would have happened to the bears if, after the last day, they were placed again in tap water?
5. Calculate the percent change in volume after each step of the experiment. a. % change in volume = (final volume – initial volume) / initial volume x 100 b. Record calculates below
% Change in Water % Change in Salt Water
Bear 1
45
Endocytosis Lab Objective: Using the materials available you will demonstrate how a cell performs a type of endocytosis.
Materials:
• Paper bag • String
• One piece of candy • Scissors
Procedure: The paper bag represents your cell membrane. The air inside the bag is the cytoplasm. Your cell needs to “eat” a large molecule, like a protein or starch. You, working as an extension of your paper bag cell, need to get the large molecule (your candy) into the cell without exposing the inside of your cell to the outside air.
You may not put the molecule in through the bag opening. You MAY put your hand into the cytoplasm through the top of the bag to help with the procedure.
Analysis:
1. What organelle did you create in your paper bag cell during endocytosis?
2. Describe the difference between endocytosis and exocytosis.
3. Draw a detailed, labeled sketch of the process you used to show endocytosis in this lab. You should include a least three steps/stages and explain what is happening in each. Be sure to label the parts of the cell/bag involved
46
Potato Lab Objective:
• Understand Diffusion and Osmosis • Be able to determine the solute concentration of a potato
Part A: Diffusion of Iodine and Starch
1. Obtain a 30cm piece of dialysis tubing, tie one end off 2. Add 15ml of Starch solution to the tubing and tie the other end off 3. Fill a 250mL beaker 2/3rd full of tap water. 4. Add 4 mL of Lugol’s solution to the beaker 5. Allow to sit for 30 minutes
1. What does iodine test for? ____________________________________________________________
2. Which substances are entering the bag? Which substances are leaving the bag? How do you know this?
_______________________________________________________________________________________
_______________________________________________________________________________________
____________________________________________________________
3. Based on your observations rank the following by relative size, beginning with the smallest: Iodine (IKI),
starch, Water (H2O)
______________________________________________________________________________
Initial Contents
Solution Color Initial Final
Bag Starch Water
Beaker Water Iodine
47
Part B: Determine the Molarity of a Potato
Materials:
• 50mL Water • 50mL 0.2M sucrose • 50mL 0.4 M sucrose • 50mL 0.6M sucrose
• 50mL 0.8M sucrose • 5 small plastic cups • Plastic wrap
Procedure:
1. Pour 50mL of each solution in a small plastic cup 2. Use a Number 2 cork borer to cut 3 potato cylinders into 3cm sections. Remove all of the skin 3. Determine the mass of the three cylinders and record the mass in table 1.2 4. Put the 3 cylinders in the cup with water, cover with plastic wrap and let stand overnight. 5. Repeat procedure 2-4 for each remaining cup (0.2M, 0.4M, 0.6M, and 0.8M) 6. Remove the cores from the beaker, blot them gently on a paper towel, and determine their total
mass. 7. Record the final mass in the table below. 8. Graph your data on graph on the next page.
Data:
Contents in Beaker Initial Mass Final Mass Mass Difference
(initial mass – final mass)
Percent change in mass (mass difference/initial mass)X
100 0.0 M Water
0.2 M sucrose
0.4 M sucrose
0.6 M sucrose
0.8 M sucrose
Lab Station #7
50
9. Determine the molar concentration of the potato core. This would be the sucrose molarity in which the mass of the potato core does not change. To find this, add a line of best fit to your graph. Then, the point at which your line crosses 0% change.
Molar concentration of sucrose __________________M.
10. Your friend asks you to determine the molar concentration of Gatorade. Design an experiment to test this.