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AP Bio Unit 2 Part 1 Cheat Sheet by

Basic Cell Intro, Organelles, Origin of Life and Origin of Eukaryotic Cells

All Cells have ......

Plasma Membrane
Bound by selective barrier that allows passage of enough O, nutrients, and wastes for the entire cell
Semi-f­luid, jelly-like substance, where organelles are suspended
Gene ares carried in from of DNA
Tiny complexes that make proteins according to instru­ctions from DNA
place of Cytosol

Pro vs Eu

DNA is in nucleus, which is bound in nuclear envelope
DNA is concen­trated in a region called nucl­eoid
Evolved before Eu
Evolved after Pro
Very low amounts of Organelles
Many complex organelles
Much Smaller than Pro
Much Larger than Pro
Size relates to Func­tion

Plant vs Animal Organelles

Nucleus - nuclear envelope, nucleolus, chromatin
Nucleus - nuclear envelope, nucleolus, chromatin
Plasma Membrane
Plasma Membrane
Golgi Apparatus
Golgi Apparatus
No Lyosome
Endopl­asmic Reticulum - rough ER, smooth ER
Endopl­asmic Reticulum - rough ER, smooth ER
No Flaggellum
No Centrosome
Cytosk­eleton - microf­ila­ments, microt­ubules
Cytosk­eleton - microf­ila­ments, interm­ediate filaments, microt­ubules
No Microvilli
No Chloro­plast
Central Vacuole
No Central Vacuole
No Plasmo­desmata
Cell Wall
No CEll Wall
Eukaryotic Cells - extensive, elabor­ately arranged internal membranes that divide the cell into compar­tments
Compar­tments provide different local enviro­nments that support specific metabolic functions, so incom­patible functions can take place simult­ane­ously

Function of Organelles in Eukaryotes

Plant vs Animal
Contains most genes of eukaryotic cells
Nuclear Envelope
Encloses the nucleus, separating its content from the cytoplasm. Is a double membrane made of a lipid bilayer
associated with many proteins
DNA's discrete units taht c arry genetic inform­ation, Each one contains one long DNA molecules soociate
complex of DNA and proteins making up chromo­somes
Plasma Membrane
membrane enclosing teh cell
complexes that make proteins: free in cystosol or bound to rough ER or nuclear envelope
Golgi Apparatus
organelle active in synthesis, modifi­cation and secretion of cell products
digesive organelle where macrom­ole­cules are hydrolyzed
Endopl­asmic reticulum
network of membranous sacs and tubes: active in membrane synthesis and other synthetic and metabolic processes
Rough ER
is studded with ribosomes: Involved in the synthesis of proteins and also a membrane factory for the cell
Smooth ER
not studded ribosomes: functions are the synthesis of lipids, steroid hormones, the detoxi­fic­ation of harmful metabolic byproducts and the storage and metabolism of calcium ions within the cell
motility structure composed of cluster of microt­ubules w/i an extension of the plasma membrane
region where the cell's microt­ubules are initiated; contains a pair of centrioles
reinfores cell's shape: functions in a cell movement: components are made of proteins: includes microf­ila­ments, interm­ediate microf­ila­ments, and microt­ubules mainte­nance
made of actin protein subunits: mainte­nnance of cell shape: changes in cell shape: muscle contra­dic­tion: cell motility: division of animal cells
Interm­ediate Microf­ila­ments
mainte­nance of cell shape: anchorage of nucleus and certain other organe­lles: formation of nuclear lamina
mainte­nance of cell shape: cell motility like cilia or flagella: chromo­somes movements in cell division: organelle movements
projec­tions that increase the cell's surface area
organelle with various specia­lized metabolic functions: produces hydrogen peroxide as a by-product and then converts it to water
organelle where cellur respir­ation occurs and most ATP is generated
Central Vacuole
prominent organelle in older plant cells: functions include storage, breakdown of waste products, and hrdrolysis of macrom­ole­cules: enlarg­ement of the vacuole is a major mechanism of plant growth
photos­ynt­hetic organelle: converts energy of sunlight to chemical energy stored in sugar molecules
cytopl­asmic channels through cell walls that connect the cytoplasms of adjacent cells
Cell Wall
outer layer that maintains cell's shape and protects cell from mechanical damage, made of cellulose, other polysa­cch­arides, and proteins
Endome­mbrane System
Nuclear Envelope, ENdopl­asmic Reticulum, Golgi Apparatus, Lysosomes, various vesicles and vacuoles, Plasma Membrane
Not all parts are in both types
small sac or cyst containing fluid or gas
a small cavity or space in the tissues of an organism containing air or fluid

Origins of Life

Theory Name
life evolved from nonliving chemical systems
Oparin­-Ha­ldane hypothesis and Miller­-Urey Experiment
Oparin­-Ha­ldane hypothesis
life arose gradually from inorganic molecules, with “building blocks” like amino acids forming first and then combining to make complex polymers.
Miller­-Urey Experiment
Miller­-Urey experiment
organic molecules needed for life could be formed from inorganic components
Used a sparking device to mimic a lightning storm on early Earth. Their experiment produced a brown broth rich in amino acid
RNA world hypothesis
that the first life was self-r­epl­icating RNA
Scientists think RNA building blocks (nucle­otides) emerged in a chaotic soup of molecules on early Earth. These nucleo­tides bonded together to make the first RNAs. RNA store of genetic inform­ation, self-r­epl­icate, and act as a cellular catalyst
Metabo­lis­m-first hypothesis
metabolic networks before DNA or RNA
origin of life is triggered by the accumu­lation of very simple organic molecules in thermo­dyn­ami­cally favorable circum­sta­nces. Simple organic molecules can then be combined in various ways that result in simple amino acids, lipids, etc. These, in turn, could act as catalysts for the formation of more organic molecules. This is the beginning of metabo­lism.
Organic compounds came on meteorites
Simple organic compounds might have come to early Earth on meteor­ites.
One scientist tested this - used guns - samples had main organic acids - gun will stimulate pressures of comets - results = the amino acids had survived and transf­ormed into a compound - peptide molecules were formed. § One scientist tested this - used guns - samples had main organic acids - gun will stimulate pressures of comets - results = the amino acids had survived and transf­ormed into a compound - peptide molecules were formed. ○ Don Brownley - designed experiment to know of space had building blacks of life - commis­sioned former spy plane to collect space dust - discovered that these particles had seeds of life - but not only possible source of life - asteroids and meteoroids have building blocks for life - had amino acids (blocks of life) § Enough meteoroids - 70 kinds of amino acids found on them - delivered by comets - comments size of mountains that could have contained organic compounds
Life in Sea
life could have started in the oceans.
Yes - life is there despite scalding temper­atures and no sunlight, many typed of creatures are surviving here § Yes - life is there despite scalding temper­atures and no sunlight, many typed of creatures are surviving here

Origins of Eukaryotes

Theory Name
Endosy­mbiotic theory
Eukaryotic cells are believed to have evolved from early prokar­yotes that were engulfed by phagoc­ytosis
Mitoch­ondrion and Chloro­plast have double meb=mb­arnecs, can reprodece in a fissio­n-like process, have their own DNA which is similar to prokar­yotic DNA, and has ribisomes similiar to prokar­yotes.

SA; V Ratio

Why are Cells So Small?
The higher the difference between SA:V ratio, the more amount of diffusion takes place
What could a cell do in response to a shrinking SA/V ratio?
A cell could slow down its processes in response to shrinking SA: V because a smaller ratio of SA: V could mean more space available inside the cell. The cell could also start to divide or evolve
Justify “Numerous small cells are evolut­ion­arily advant­ageous in regard to mainta­ining homeos­tasis in multic­ellular organisms”
This is true because having smaller cells maximize the surface area to volume ratio, helping the diffusion rate go up.
As the mitoch­ondria metabolize the glucose, they produce carbon dioxide waste. Would the CO2 be able to leave the cell faster if the cell had a smaller volume or larger volume?
CO2 would be able to leave the cell with a smaller volume faster than a cell with a larger volume due to there being less surface area to journey.
Is bigger always better for a cell?
Bigger is not always better for the cell because cell’s with a larger surface area would have waste and other unwanted objects in their cell for a longer time. This additional time traveling could also create more time objects to travel that a cell might need immedi­ately.
Is it more desirable for a cell to have a small surfac­e-a­rea­-to­-volume ratio or a large surfac­e-a­rea­-to­-volume function of a cell?
It would not be desirable for cells to have a small surfac­e-a­rea­-to­-volume because as seen above a lower surfac­e-a­rea­-to­-volume ratio would guarantee a larger cell that has more processes occuring and having a lower rate of diffusion (so waste would leave the cell slower).
What might be some reasons why these unicel­lular organisms have larger cells than cells with similar traits (heter­otr­ophic, lacking cell walls) that are found in multic­ellular organisms?
Unicel­lular organisms have larger cells because they depend on only themselves for protection and nutrients. That one cell has to be specia­lized in different jobs, unlike multic­ellular cells that can work with each other.

Plasma membrane structure and function

How are phosph­olipids arranged in the cell membrane?
Heads facing out toward the water and the tail face each other.
Rememb­ering the charac­ter­istics of a lipid, why must one of the fatty acid chains be replaced with a phosphate group?
So the lipid can become hydrop­hilic. Lipids are naturally hydrop­hobic, so adding a phosphate group will change the lipid and give it a hydrop­hilic part.
What do you have to put into the membrane to help stabilize it?
Choles­terol will help stabilize the membrane.
What does Choles­terol do for the membrane?
Choles­terol acts as a Buffer for the membrane, it will dampen the effects of temper­ature
What is select­ively permeable?
That the membrane allows some substance to pass through, but not others.
What 2 molecules easily pass through the membrane?
Simple Diffusion - O2 moves high concen­tration (outside the cell) to lower concen­tration (inside the cell) and Simple Diffusion - CO2 moves high concen­tration (outside the cell) to lower concen­tration (inside the cell
What does polar mean?
Molecules that have areas where there is a partial positive or negative charge.
Why are CHANNEL PROTEINS part of the cell membrane?
TO help transp­ort­ation of substances that couldn’t pass easily through the membrane
Compare and contrast diffusion and facili­tated diffusion.
DIffusion happens naturally, but facili­tated diffusion happens with help from channel proteins. Both do not require energy.
Why is energy (ATP) sometimes required for the transport of materials?
ATP is needed for active transport, this is when the substance needs to go against its concen­tration gradient. This type of transport is called active transport. What type of materials are moved via this transport mechanism? Negative charges substances
What do Carboh­ydrates do in plasma membranes?
Carboh­ydrates are like identi­fic­ation badges. Cells that have different membrane carboh­ydrates do different jobs/f­unc­tions. The immune system uses the carboh­ydrates to recognize that your cells belong to you and are not viruses, bacteria, or other foreign cells.
What is dynamic equili­brium?
Dynamic equili­brium is a state where no change is occurring but individual molecules still react contin­uously.
Why can’t sugar diffuse across the membrane?
Because it is polar and too large.
Why did diffusion stop after a certain period of time? .
Because there was nothing left to diffuse
What is Osmosis?
Water moves into and out of the cell by osmosis. This is when the diffusion of water across the membrane from an area of high concen­tration to an area of low concen­tra­tion.
What are solutes?
Solutes are the substances that are dissolved in water.
What is Hypotonic?
When there is a low amount of solutes in water.
What is Hypert­onic?
When there is a high amount of solutes in water.
What is Isotonic?
When there is an equal amount of solutes in water
What is Water Potenial?
This measures the concen­tration of free water molecules. It is a measure of the tendency of these molecules to diffuse to another area. The more free water molecules, the higher the Water Potential.
Define Toncity
The ability of an extrac­ellular solution to make water move into or out of a cell by osmosis
What will happen when a cell is placed in a hypertonic solution?
There will be a net flow of water out of the cell, and the cell will lose volume. A plasmo­lyzed plant cell has gaps between the cell wall and the cell membrane. This occurs when a plant cell is placed in a hypotonic solution. Water molecules move out of the cell resulting in the loss of turgor pressure
What will happen when a cell is placed in a hypotonic solution?
There will be a net flow of water into the cell, and the cell will gain volume. . A turgid cell is a cell that has turgor pressure. A plant cell that is placed in a hypotonic solution would cause the water to move into the cell by osmosis, resulting in large turgor pressure being exerted against the plant cell wall.
What will happen when a cell is placed in a isotonic solution?
There will be no net flow of water into or out of the cell, and the cell’s volume will remain stable. A flaccid plant cell is not swollen and the cell membrane does not press against the cell wall tightly.


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