Download Biology Notes for Test #2: Cell Structures and Functions, Microscopy

Biology Unit 3: Cell Structures, Functions, & Membrane Transport
Name
____________________ Hr. ___
I. A Brief Cell History
 In 1665, Robert Hooke was the 1st to see and name the cell from cork found in plants using a ____________________.
 In 1676 Anton Von Leeuwenhoek was the 1st to view a ___________________________________.
 Robert Brown in 1831 was the 1st to see and name the _____________________ of a cell.
Why did it take more than 160 years for Brown to view the nucleus after Leeuwenhoek’s discovery?
A. __________________________________________________________
B. __________________________________________________________
II. Types of Cells
A) Prokaryote - Cells lacking membranes around organelles (no nucleus).
Kingdoms: ______________________ , ___________________ (Monera)
B) Eukaryote – Cells having membranes around their organelles (with nucleus).
Kingdoms: _____________, ______________, ____________, ______________
III. Cell Theory (data gathered over a 200 year period by several scientists)
 All living things are made up of at least one cell.
 The cell is the basic/smallest unit of structure and function in living things.
 __________________________________________________________
IV. Cell Shape, Size & Function
A. Shape & Function - The cell is the smallest living portion of any organism,
unicellular (one-celled) or multicellular (many-celled).
In a multicelled organism, like a human, there can be
over 200 different types of cells, trillions in all.
3 characteristics determine a cell’s function:
1) ______________________________________
2) ______________________________________
3) ______________________________________________________

In multi-celled organisms, individual cells may specialize. Specialized cells perform a limited amount of jobs.
Advantage of Cell Specialization – Increased ____________________ (perform functions quickly with few mistakes)
Disadvantage of Cell Specialization – Increased __________________________ (cells need each other to survive)
B. Size Limitations
1. If a cell gets too large, the distance between the nucleus (directs the making of proteins which determine an
organisms traits) and other organelles becomes too great for effective control and communication.
2. As a cell grows, its surface area (outside of the cell - cell membrane) grows at a slower rate than its volume
(inside of the cell – cytoplasm, organelles, & nucleus), eventually the cell would burst (like an over-filled balloon).
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For simplicity, in this surface area:volume ratio example, let’s assume that a particular cell type is cube-shaped. If this
cube-shaped cell has 1cm sides, its surface area (# of sides [length x width]) = 6, and its volume (L x W x H) = 1. The SA/V
ratio is 6/1 = 6. Complete the data table below and compare the surface area to volume ratio of cells of varying size. Use a
calculator to give a decimal answer. An example of a round cell is just below the data table you are completing.
Cube Side Size (cm)
Surface Area (cm2)
Volume (cm3)
Surface/Volume Ratio
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sides (6) x cube side size (1x1) = 6
L (1) x W (1) x H (1) = 1
6/1 = 6.0
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3
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Q: Why is the surface area of a cell so important?
a) ________________________________________________________________________
b) __________________________________________________________
Diameter (cm)
Surface Area
(cm2)
Volume (cm3)
Surface to
volume ratio
1.5
0.5
1.0
0.79
3.14
7.07
0.06
0.52
1.77
13.17 : 1
6.04 : 1
3.99 : 1
V. Parts of a Cell and Their Generalized Functions (3 general areas – cell membrane, cytoplasm w/organelles, and the nucleus)
1.
Cell Membrane – A bilipid structure that is the outermost portion of the cell (see picture below). Functions include:
(a) A boundary between the cells contents (ICF) and its environment (ECF), which regulates what enters and exits the cell.
(b) Communicates with other cells within an organism or between unicellular organisms.
(c) Contains proteins that ____________________ the cell. Examples: antigen proteins for red blood cells & harmful bacteria
(d) Serves as an attachment site for some organelles (spindle apparatus) and near-by cells (heart cells connected to heart cells)
Hydrophilic
Head
ECF
(e)
Hydrophobic
Tail
ECF
Membrane Transport (Active and Passive)
ICF
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Q: How do cells get important nutrients needed for life like… amino acids to build proteins, nucleotides to
build DNA & RNA, reactants for photosynthesis, Sugars and fats for energy, vitamins, and minerals?

Plants acquire __________________________________________________________________________________

Animals acquire ________________________________________________________________________________
Once inside the organism, how do these nutrients get inside individual cells?
Just like unicellular organisms (bacteria, yeast, amoeba, etc.) nutrients and gasses must pass through each cell’s
membrane for it to survive. Let’s look at humans for example.

We ingest/eat some food, digest it (break down big food molecules into small molecules or monomers) using teeth,
saliva, stomach, enzymes, etc. until it gets to the intestines.

Once the broken molecules (water, nucleotides, amino acids, monosaccharides, fatty acids, etc.) reach the intestines,
these small molecules will then travel through the walls of the intestine and into our bloodstream.

After the small molecules have been absorbed into our bloodstream, they will be delivered to every living cell in our
bodies through blood vessels called _________________ carrying blood away from the heart, ______________ carry
blood toward the heart and ___________________ which are only one cell layer thick and connect the arteries & veins.

Once the blood (carrying water & nutrients) has entered the very thin (1 cell layer thick) capillaries, the digested
molecules will travel through the capillary membrane into the area around cells. Water and nutrients that leave the
capillaries and move into the area surrounding the cells becomes part of the ECF or ExtraCellular Fluid.

If a cell needs water, glucose, calcium, etc. to carry out its life activities (making proteins, photosynthesis, etc.) it can get
them from the ECF just outside the cell’s membrane.
ECF
ICF
Sequence of Digestive System (once food has been chewed and moistened with saliva in the mouth)
_______________
(throat)
→ ____________________
→ stomach → ____________________ → blood → _________ → ICF (cells)
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 What gets across a cell’s membrane? How do molecules get in? How does the cell rid itself of waste? Is
energy needed for membrane transport (the movement of molecules across a cell’s membrane)?
 Homeostasis – Homeostasis is an organism’s way of maintaining normal function (see unit #1 notes).
 Homeostasis is maintained by negative and positive feedback mechanisms (see unit #1 notes).
 Because cells are the basic unit of structure and function, if they die, the tissues they make may die. If tissues die,
organs may fail. If organs fail, the organism can die. Maintaining the cells’ ExtraCellular Fluid (the fluid found inside the
body, but not inside cells) so the cell has all the raw materials needed to function properly is vital to survival.
Q: What raw materials do cells need for DNA replication, protein synthesis, cell respiration and photosynthesis?
_____________________________________________________________________________________________

Homeostasis must be maintained even under times of stress. Stress includes _____________________, malnutrition,
physical exertion, pathogen __________________ (bacteria, viruses, etc.), and temperature ___________________.

The ________________of molecules (hormones transported to other cells, excess water & waste products) from the
ICF/IntraCellular Fluid or Cytoplasm to the ECF outside the cell is as essential to maintaining homeostasis as the
entrance into the cell of molecules that provide the raw materials and energy needed for biochemical processes.
 The cell’s membrane structure allows it to be semi- or selectively ____________________, allowing some, but not all
molecules through. Permeability fluctuates according to the ever changing needs of the cell. For example, if the cell
needs more glucose/sugar, the cell membrane will be more permeable to sugar, allowing more sugar to enter the cell.
A. Passive Transport - The movement of molecules (H20 or solutes) across a cell’s membrane (in or out) without the use
of _________________ to achieve equilibrium. A cell at equilibrium has the same concentration
of a particular molecule inside the cell (ICF) as outside the cell (ECF).
 Simple Diffusion – The movement of molecules or ___________________ (small molecules dissolved by water to form
a solution) from an area of greater to lesser concentration. The cell’s membrane acts as a boundary between areas of
differing concentrations, creating a concentration gradient, or a difference in concentration of solutes.
Molecules that move by simple
diffusion through cell membranes: __________________________________________________________________
 Facilitated Diffusion – The movement of molecules across a cell membrane through specific channels made of
proteins. Molecules may enter or exit its specific channel (100’s in all), but only traveling down a gradient (from high to
low concentration). As with simple diffusion, facilitated diffusion occurs with no energy being used. See diagram below.
 Osmosis – The movement of ____________ molecules across a cell’s membrane from an area of higher to lower
concentration without using energy. The force of water on the cell membrane is termed turgor pressure. When
turgor pressure is too low the cell wilts (plasmolysis), when turgor pressure is too high the cell bursts (cytolysis).
Facilitated Diffusion (example: solute = glucose)
Q: What determines whether or not a molecule will cross a membrane?
____________________, ___________________, ____________________, _________________________________________
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* Terminology associated with the movement of molecules across a cell’s membrane *
Hypertonic– The area (ICF or ECF) that possesses a higher concentration of a solute & a lower concentration of water.
Hypotonic – The area (ICF or ECF) that possesses a lower concentration of a solute & a higher concentration of water.
Isotonic– A condition in which the ICF and the ECF are in equilibrium, or have equal solute concentration.
Solute concentration in
area “A” (ICF)
Solute concentration in
Area “B” (ECF)
Concentration Gradient
Non-water
diffusion (solute)
Water diffusion
(solvent)
to
to
to
to
A  B
A  B
Hypertonic to
Greater
Hypotonic to
Hypertonic to
Less
Hypotonic to
Equal
A
_________tonic ICF
62% solute
=
B
_________tonic ICF
ECF = 42% solute
22% solute
_________tonic
ECF = 42% solute
42% solute
Use red arrows to indicate the direction solute molecules are moving (diffusion) in each of the cells above.
Use blue arrows to indicate the direction water molecules are moving (osmosis) in each of the cells above.
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B. Active Transport – Movement of molecules from an area of lower concentration to an area of higher concentration.
To move molecules against the concentration gradient, cellular energy is needed (ATP).
a) Endocytosis – The movement of substances into a cell by being surrounded/engulfed by the cell’s membrane.
b) Exocytosis – Movement of large molecules or quantities of fluids/dissolved substances out of the cell.
Diagram comparison of Passive vs. Active membrane transport
Q: Do all cells need the same kind and amount of nutrients? _________ Explain: ___________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
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2. Cytoplasm and its Organelles – cytoplasm may also be called the Intracellular Fluid/ ICF/Cytosol
1) Cytoplasm is a viscous fluid made of water, minerals, organic molecules, and organelles. It is located between
the cell membrane and nuclear membrane.
2) Organelles, or “little organs,” each perform specific functions for the cell (division of labor).
_________________________________________________________________________________________________
a) Ribosome
Site of _______________ _______________
where amino acids are assembled into proteins
using directions from DNA.
________________________________________________________________________________________________
b) Endoplamic Reticulum

Smooth ER

Rough ER
Pathways/tunnels for molecules to travel
through cytoplasm and out of the cell.
Makes new membranes for both the cell and its
organelles using lipids, carbohydrates, and
proteins. SER also detoxifies drugs & poisons.
Holds ribosomes (protein maker) on its outer
membranes. RER along with the Golgi make
new lysosomes for the cell.
________________________________________________________________________________________________
c) Golgi Body/Apparatus
Combines small glucose molecules into larger
starch (plants) or glycogen (animal & fungi)
molecules. The Golgi packages various
combinations of macromolecules into specific
shapes to be used or stored by the cell. Golgi
helps RER make membranes and lysosomes.
________________________________________________________________________________________________
d) Mitochondria
Site of ________________ ________________
(using energy for cellular functions – movement,
chemical reactions, active transport, etc.)
Mitochondria have their own ______________.
_________________________________________________________________________________________________
e) Lysosome
Holds digestive enzymes that break down old cell
parts, nutrients, and foreign substances (toxins,
bacteria, viruses, etc.). Found in animal cells but
not plant cells.
_________________________________________________________________________________________________
f) Cytoskeleton
An arrangement of structural proteins giving the
cell shape and support. The cytoskeleton is
made of many proteins. You will only be
responsible for microfilaments and microtubules.
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
Microfilament

Microtubules
Long, thin protein fibers that give a cell it shape
and enables the cell to move (muscles, amoeba).
Microfilaments also aids in cell division (mitosis)
and maintaining cell shape (tension resistance).
Hollow tubes of protein that move chromosomes
(spindle apparatus – mitosis), moves the cell (cilia &
flagella), maintains cell shape (from compression).
_________________________________________________________________________________________________
g) Centrioles
Pair(s) of bundled microtubules located in the
cytoplasm that will assemble the spindle
apparatus in most eukaryotes. Not found in plant
cells.
___________________________________________________________________________________________________________
h) Cilia
Small, numerous microtubules on the outside of
cell membranes that function in the movement of
some single-celled organisms or the movement
of substances near a cell.
i) Flagella
Large, usually singular microtubule on the outside
of the cell membrane that functions to move the
entire cell (sperm tail).
_________________________________________________________________________________________________
j) Cell Wall
A tough, supportive and protective covering of
plant cells (made of cellulose), fungal cells (made
of chitin), most bacteria, and some protists. The
cell wall is located outside the cell membrane
and allows most molecules to pass. Not found in
animal cells.
_________________________________________________________________________________________________
k) Vacuole
Large storage sacs (proteins, lipids, carbohydrates,
water, colored pigments, and waste). Vacuoles aid
structural support to cells by providing turgor
pressure (water pushing on the cell membrane).
Found in plant cells but not animal cells.
_________________________________________________________________________________________________
l) Chloroplast
Holds the green pigment chlorophyll that absorbs
light allowing it to make glucose (photosynthesis).
Chloroplasts have their own DNA. Found in plant
cells, many bacterial cells, many protist cells, but
not in animal or fungal cells.
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3. Nucleus – Contains genetic information in the form of
DNA that codes for biological functions.

Surrounded by the ______________________________
which envelops nucleoplasm that protects DNA. DNA
makes __________. RNA then travels to the cytoplasm to
make ___________________. Proteins determine an
organism’s characteristics.

Contains the ____________________ which makes
ribosomes. Ribosomes (made up mostly of RNA) then
travel to the cytoplasm where most will attach themselves
to _______________ ER.
Cell Structure/Organelle
Nucleus
Give the function of each cell part as if it were part of a city
(write neatly please!)
The nucleus would represent the city government. Because the nucleus contains DNA and DNA
controls the cell through protein synthesis, like the government making laws that control the city.
Nucleolus
Ribosomes
Smooth Endoplasmic Reticulum
Rough Endoplasmic Reticulum
Golgi Apparatus
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Cell Structure/Organelle
Give the function of each cell part as if it were part of a city
(write neatly please!)
Mitochondrion
Lysosome
Cytoskeleton
Centrioles
Cell Wall
Cell Membrane
Vacuole
Chloroplast
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Unit 3 Test Format:
Test Date: ____________________
50 Flash Cards: Students who turn in at least 50 study cards covering material relevant to this exam (based on
this review sheet) will earn up to 3% bonus on their exam.
I. Multiple Choice
Transport (types, concentration gradient – Notes pages 3- 6)
o Distinguish between three types of passive transport (similarities & differences)? (4)
o What direction do molecules move without requiring energy? (4)
o When is ATP/energy required for movement of molecules? (6)
o Which cell structure is involved in transport? (2, 4, 6)
o What is the result when a cell is placed in a hypotonic environment? Hypertonic? Isotonic? (5)
o Exocytosis v. Endocytosis (6)







Characteristics that determine the function(s) of a cell (1)
Distinguish between prokaryotic and eukaryotic cells and which type of cell in each kingdom (1,9)
What is the pathway that nutrients follow to get from your food to your cells? (3)
What are the functions of the cell membrane? (2)
What are the characteristics of the cell membrane (structure, macromolecules)? (2)
What are the points of the cell theory? (1)
What is the main function of a mitochondrion? (7) Chloroplast? (8) Ribosome? (7) Lysosome? (7)
II. Matching
 Cell Organelles (2, 7-9) - cell membrane, cytoplasm/ICF, ribosome, endoplasmic reticulum (smooth ER
& rough ER), Golgi body/apparatus, mitochondria, lysosome, cytoskeleton, centrioles, flagella, cilia, cell
wall, vacuole, chloroplast, nuclear membrane, nucleoplasm, nucleus, & nucleolus
III. Constructed Response – Write your answers in complete sentences on the test.


Identify at least two conditions that determine whether or not a molecule can enter a cell (pass through the
cell membrane)? Explain your answer. (4-6)
Compare and contrast a plant cell and an animal cell. (7-9) Which cell parts are found in both? Only in
plant cells? Only in animal cells? How does each obtain energy?

Discuss the advantages and disadvantages of cell specialization. (1)

What instrument did Hooke use when he discovered the cell? Give 2 reasons that it was over 160 years
later before Brown was able to see the nucleus. (1)

State two ways that active transport is different from diffusion. (4-6)

Do all cells have the same number of each type of organelle? Explain your answer. (1, 7-9)

Draw a segment of a cell/plasma membrane. Include and label a protein channel, the hydrophobic and
hydrophilic ends of the lipids, the extracellular fluid (ECF), and the intracellular fluid (ICF). (2)

Explain why cells are limited in how large they can become. (1-2)
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