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AP Bio Unit 2 Cheat Sheet (DRAFT) by

ap bio review for class

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Cell Structure and Organelles

Nucleus:
Double­-me­mbrane organelle that contains and organizes the DNA. It has pores that allow for the exchange between the nucleo­plasm and cytoplasm.
Nucleolus:
A region of condensed chromatin where rRNA is synthe­sized and ribosomes are assembled.
Cytoplasm:
The region of the cell from the nuclear membrane to the plasma membrane.
Rough ER:
Extension of the outer nuclear membrane that has ribosomes attached to its membrane. The ribosomes synthesize proteins destined for transport through the endome­mbrane system­(also synthe­sizes phosph­oli­pids).
Smooth ER:
Has no ribosomes attached to its membrane and synthe­sizes many compounds such as carboh­ydr­ates, lipids, and steroids. Stores calcium ions and detoxifies medica­tions and toxins
Ribosomes:
Macrom­ole­cules composed of proteins associated with ribosomal RNA(rRNA). Translate genetic material by reading the messenger RNA(mRNA) and performing dehydr­ation reactions between amino acids.
Golgi Apparatus:
Lipids and proteins that add short chains of carboh­ydrates to proteins to ensure the proteins travel to their target destin­ation, usually through vesicles. This plays a part in cell wall synthesis for plant cells.
Vesicles:
Phosph­olipid bubbles that are formed when the ER and Golgi pinch a part of their membrane off. Vesicles can also be formed when the cell membrane itself pinches off(en­doc­yto­sis).
Lysosomes:
Specia­lized vesicles that come from the Golgi and stay in the cytoplasm. Enviro­nment of a lysosome is very acidic and it fuses with organelles to break down the contents of the organelle. The contents are broken down to simple building blocks and the cell can use these for its own purpose.
Peroxi­somes:
Respon­sible for lipid metabo­lism. Peroxi­somes break down fatty acid tails into smaller components and send them to the mitoch­ondria for further oxidation. They destroy reactive oxygen species such as hydrogen peroxide and is important for the synthesis of choles­terol.
Mitoch­ondria:
Extracts energy from organic molecules, primarily carboh­ydrates and lipids, to generate ATP.
Cell Membrane:
Select­ively permeable membrane that regulates the movement of substances into and out of the cell. The more surface area a cell has relative to its volume, the more efficient the cell is at exchanging material with its enviro­nment.
Vacuoles:
There are three types of vacuoles; the central, the food, and the contra­ctile. The central vacuole takes up the majority of space in the cytoplasm. It helps the plant cell maintain high water pressure. A contra­ctile vacuole collects excess water in the cytoplasm. The cytosk­eleton squeezes the contra­ctile vacuole, expelling the excess water out of the cell. This is important for single­-celled organisms that live in freshwater enviro­nments. A food vacuole is essent­ially a vesicle formed through phagoc­ytosis (cellular eating). The membrane folds inward around the food partic­le(s) and pinches off to form a vesicle.
 

Prokar­yotic and Eukaryotic Cells

Simila­rities:
Both enclosed by a plasma membrane, has a cytoplasm, has ribosomes, and has genetic materi­al(DNA)
Differ­ences:
Eukaryotes are much larger and have membra­ne-­bound organelles that compar­tme­ntalize their cytoplasm. They have a membra­ne-­bound nucleus where genetic material is found. Eukaryotes can be single­-celled or multic­ellular and its genetic material is fragmented into linear chromo­somes Prokar­yotes are single­-celled organisms that contain one single circular chromosome in the nucleoid region.

Function

Organelles work together in a coordi­nated manner to exchange materials, signals, and energy through membrane transport and other processes. This maintains cellular function and support the survival of the cell.

Cell Wall

Structure and Function: The cell wall provides strength and protection against pressure and stress on the cell. It provides the framework for the cell to prevent expansion and regulates diffusion by allowing some substances in and our of the cell.

Diffusion

Simple Diffusion:
The movement of molecules through a cell membrane without the help from any transport proteins.
Facili­tated Diffusion:
The movement of molecules through a cell membrane with the help of transport proteins.
Passive Transport:
Diffusion of molecules along their concen­tration gradie­nt(from high to low concen­tra­tion).
Active Transport:
Movement of molecules against their concen­tration gradie­nt(from low to high concen­tra­tion) by using ATP.
Endocy­tosis:
A process where cells absorb external materials by engulfing it with their cell membrane into a vesicle.
Exocyt­osis:
A process where cells move large material from inside the cell to the outside through vesicles.

Evolution

Endosy­mbi­osis:
Mitoch­ondria and classic membra­ne-­bound organelles of eukaryotic cells used to once be its own cell that was then engulfed by another cell to make eukaryotic cells.
Cell Theory:
Cell is the most fundam­ental unit of life, all living things are made up of one ore more cells, and cells come from cells.
What makes something alive?:
It can reproduce, respond, has metabo­lism, does homeos­tasis, can evolve, and has organi­zation
 

Cell Size

Surface Area to Volume Ratio:
Cells need to transport molecules through their cytoplasm effici­ently and surface area and volume play a role in this. Cells can only grow to a certain size due to their surafec area to volume ratio. Surface area us the area of the outside of the cell and volume is how much space is inside the cell. The ratio measures the efficiency of a cell with the larger the ratio being more effcient and the smaller the ratio being less efficient.
Specia­lized Structures and Strate­gies:
Cells have developed strategies to effici­ently exchnage materials in a cell. An example of this could be active transport, osmosis, and facili­tated diffusion.

Structure of Plasma Membrane

Plasma Membrane: Made up of a phosph­ilipid bilayer with hyrophbic tails facing the interior of the membrane and hydrop­hilic heads facing the outside of the membrane. Channel proteins and choles­terol can be found on the membrane as well.
Result: The structure of the plasma membrane results in selective permea­bility. Selective permea­bility is the movement of molecules across the membrane through osmosis, active transport, and facili­tated diffusion. This maintains homeos­tasis in the cell as the cell determines what leaves and enters the cell.
Molecules: Due to the structure of the plasma membrane only certain molecules can pass through it. Small hydrop­hobic molecu­les(no bigger than a water molecule) can pass through the membrane. No charged molecules can pass through the plasma membrane at all

Osmosis and Tonicity

Tonicity:
The capability of a solution to modify the volume of cells by altering their water content.
Osmosis:
The net movement of water across a plasma membrane. Water will tend to move from an areas of low concen­tration of solute to areas of high concen­tration of solute.
Water Potential:
A measure of the difference in potential energy between water with solutes and pure water. Water moves from area of high water potential to areas of lower water potential.