Ap Biology Unit 9 Study Guide

Biology

Major substances:

Organic compounds – are compounds that contain carbon and were originally made by living things e.g. carbohydrates, lipids, proteins, nucleic acids
Inorganic compounds – are compounds do not contain carbon as a main element

Organic compounds | Composition | Function | Proteins | Carbon, hydrogen, oxygen and nitrogen | Used in the structure, storage, movement and transport of cells for growth and repair. | Lipids | Carbon, hydrogen and oxygen | Stores energy but is more difficult to release than carbohydrates. It breaks down into fatty acids and glycerol. Used as stores of energy | Lignin | Composed of a complex polymer | Provided support for stems and leaves of cells to prevent them from collapsing |
Starch | Consists of glucose units joined together | Made by plants to store excess sugar | Glucose | Comes from digesting the sugar and starch in carbohydrates. | Provides energy to the cell |

Cell chemical | Test Reagent | Negative result | Positive result | Glucose | Benedict’s solution | Pale blue or no colour change | Yellow or orange | Starch | Iodine solution | Yellow brown or no colour change | Dark blue or black | Protein | Biuret | Blue or no colour change | Purple | Lignin | Toluidine blue | Blue or green or no colour change | Pale blue | Chloride ions | Silver nitrate | No precipitate | White precipitate |

 Protein can be identified by Biuret reagent, and if starch is present iodine solution will turn from yellow/brown to black/dark blue

 If Benedict’s solution turns from blue to yellow, this proves that glucose is present.

Cell Organelles

Key terms
Light microscopes: an instrument that uses light and lenses to magnify very small specimens
Electron microscopes: an instrument that uses electron beams to enlarge images more than 200 times
Organelle: specialised part of the cell
DNA: deoxyribonucleic acid contains hereditary information that can be passed on through reproduction
Cytoplasm: gel material that makes up a living cell, not including the nucleus
Cellulose: inorganic complex carbohydrate
Chlorophyll: green pigment used in photosynthesis
Photosynthesis: the process of how plants make glucose and the by product oxygen from the reaction water and carbon dioxide in the presence of sunlight and chlorophyll.
Stroma: the fluid in the chloroplast holding the grana and starch
Granum: a stack of membranes that photosynthesis in the chloroplasts
Electron micrographs: pictures that have been taken by an electron microscope
Cellular respiration: the process of creating energy using glucose and oxygen in mitochondria
Crista: the folding of the inner membrane in a mitochondrion which increases the surface area for reactions
Matrix: the fluid in the mitochondria that contains enzymes for respiration
Vesicle: small fluid filled sacs
Chromatin: material that makes up nucleus and DNA which holds hereditary information
Pores: holes
Protein: macro molecule made of aminoacids used for structure and function
Lipids: are fats, they are high in energy

Identify cell organelles seen with current light and electron microscopes
Organelles and Structures that can be seen with light microscopes Organelle or Structure | Description | Function | Nucleus | Large circular membrane bound organelle in the cytoplasm that contains DNA. | Controls all cell activity. | Cell Membrane | Semi permeable structure made of phospholipids that surrounds the contents of the cell. | Control what substances enter and leave the cell. | Vacuole | Membrane bound sac of dissolved ions in water. | Stores water and ions and provides support stopping it from becoming flaccid. | Chloroplast | Double membrane bound green organelle containing chlorophyll. | Photosynthesis which involves the creation of glucose using sunlight. | Cell Wall | Rigid membrane of cellulose that surrounds a plant cell. | Provides support and structure. |

Organelles and Structures that can be seen with electron microscopes
All of the above are seen and the organelles below Organelles or Structures | Description | Function | Nucleolus | Dense spherical area in the nucleoplasm that contains some DNA and RNA. | Produces the organelle called ribosomes. | Ribosomes | Small round dense granules | Performs the tasks that are coded in the DNA. Produces proteins which are needed for functioning and structure. | Golgi Bodies | Curved shaped surface called forming face with vesicles coming off. | They place different membranes around cell products sorting and packaging them. | Rough Endoplasmic Reticulum | System of membranes with ribosomes connecting the nucleus cell membrane. | Transport system and is the site of protein production . | Smooth Endoplasmic Reticulum | System of membranes connecting the nucleus cell membrane. | Transport system and is the site of lipid production. | Lysosome | Small membrane bound round sac of fluid | Breakdown of cell organelles that are no longer needed, so that they can be used to create new ones. | Mitochondria | Bean shaped organelle with an inner and outer membrane | Cellular respiration, which provides energy for cell functions.
| Centrioles | A dense granular cylindrical structure made of microtubules | Produces spindles which separates the cell during cell division. |

The organelles that can be seen under a light microscrope are Cell Wall, Cell membrane, Cytoplasm, Mitochondria (with staining), Nucleus, Vacuole, Nucleolus and Cytoskeleton. The rest need a higher resolution to be visible to the naked eye, thus the electron microscope is used.
KEY WORDS AND DEFINITIONS - Key Word | Definition | Molecule | A group of atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction | Permeable | (of a material or membrane) Allowing liquids or gases to pass through it | Concentration | The amount of substance present. | High concentration | There is a lot of that particular substance in one area | Low concentration | There is not a lot of that particular substance in one area | Cell membrane | The semipermeable membrane surrounding the cytoplasm of a cell | Substance | A particular kind of matter with uniform properties | Solute | The minor component in a solution, dissolved in the solvent
| Osmosis | Osmosis is the diffusion of molecules across a semi-permeable membrane. | Diffusion | Process where liquid or gas particles spread from where they are numerous (high concentration) to where they are scarce (low concentration) until they are evenly distributed | Particle | A minute portion of matter |

SUMMARY OF IMPORTANT POINTS -

What is diffusion –
Diffusion is the process where liquid or gas particles spread from where they are numerous (high concentration) to where they are scarce (low concentration) until they are evenly distributed.

The green particles are moving from the area of high concentration to the area of low concentration. They are moving down a concentration level.

What is osmosis –
Osmosis is the diffusion of molecules across a semi-permeable membrane. A semi-permeable membrane allows some substances to pass through (water) but not others (starch). In osmosis, water moves in such a way as to even out the molecules on either sides of the membrane.

The red particles represent water molecules. The red particles can pass through the membrane but the blue cannot. The concentration of blue particles is higher on the left of the membrane but since these particles cannot move to the right side the only way that the concentration can be evened out between the two sides is for the water particles to move to the left.
Key Terms:
Cell membrane: a boundary that controls what enters and leaves a cell
Molecules: atoms that are bonded together
Selectively permeable: only some substances can pass through
Permeable: allows all substances to pass through
Impermeable: does not allow any substances to pass through
Pores: holes
Fluid: unfixed shape that can flow
Hydrophobic: water hating
Hydrophilic: water loving
Phospholipid: a lipid attached to a phosphate

Identify that there is movement of molecules into and out of cells
The cell membrane is the passage where substances enter and leave the cells. Molecules can enter the cell because the cell membrane is selectively permeable. The pores allow some substance in and not others.

Substances that enter cell:
- Gases such as carbon dioxide and oxygen
- Water
- Sugars
- Amino acids
- Glycerol
- Fatty acids
Substances that leave cells:
- Urea
- Uric acid
- Gases such as carbon dioxide
- Mucus
- Hormones

Robert Hookes contribution to cell theory:
He looked at thin slices of cork through his microscope and discovered little "cells," which he named because he described the plant cells as resembling the cells where monks lived. He then developed this discovery into cell theory.
In 1663 an English scientist, Robert Hooke, discovered cells in a piece of cork, which he examined under his primitive microscope. Actually, Hooke only observed cell walls because cork cells are dead and without cytoplasmic contents. Hooke drew the cells he saw and also coined the word CELL. The word cell is derived from the Latin word 'cellula' which means small compartment. Hooke published his findings in his famous work, micrographia:Physiological Descriptions of Minute Bodies made by Magnifying Glasses (1665).

Robert Brown’s contribution to cell theory:
As time passed, microscopes were improved and the biological knowledge base grew. In the 1830's, almost two centuries after Hooke's observations, Robert Brown observed a small and dark-staining sphere inside plant cells. He called this structure a nucleus. Brown's discovery was a key step in the development of the basic cell theory.

Cell theory:
Cell theory is based upon the following evidence:

-The use of an early microscope by Robert Hooke to look at a piece of cork and called what he saw (dead cells) as Cells (1663)
-In 1673, Anton van Leeuwenhoek saw bacteria and protoza through his microscope
-In 1833, Robert Brown discovered the nucleus
-In 1838, Dr. Schleiden published a paper stating that the nucleus was the most important part of the cell and the basic structure from which the rest of the cell developped.
-In 1939, Dr Theodor Schwann published a book in which he stated that there was a link between animal and plant cells: the nucleus. This spawned what is now known as the cell theory
-The final addition was from Rudolph Virchow. he stated that all cells come from other cells.

Advances in technology:

* 1665 Robert Hooke invented the compound microscope where he was able to observe cork cells. This became the first cellular organism to be observed * Improvements were made to in the light microscope in the 1870’s when Zeiss and Abbe introduced oil-immersion lenses, which gave a magnification of 1500x * In the 19th century compound microscopes advanced and were no longer limited the lenses quality. The limiting factor now was the wave length of light. * 1928 Ernst Ruska and supervisor Max Kroll created the Electron microscope which on reached to a magnification of 15x * Ruska later continued the work and in 1933 built the first transmission electron microscope which reached a magnification of 12 000x * Through WWII Ruska and his team continued the work on the microscope and reached a magnification of one million times * The Transmission Electron microscope has electrons pass through the specimen * Later the invention of the Scanning electron microscope was made in 1955, which gave a high magnification and resolution to cells in much greater detail * Through the electron microscope scientists see more detail in cells such as sub-cellular structures (organelles) in great detail which provides evidence of their functions in the cell * Phase contrast Microscope was later invented and it doesn’t alter a specimen when being looked * With the invention of computers, light microscopes are now linked with computers to make images more detailed. * Confocal Microscopes use a laser light which makes the specimen have a 3 dimensional view * Synchrotrons are the most very recent microscope which can be used the study the structure at an atomic level. Similar to the electron microscope it controls the movement of electron within a vacuum A Synchrotro * Advances in technology have also helped biologists add 3 more statements to the cell theory:
4. Cells contain hereditary information which is passed on during cell division
5. All cells have the same basic chemical composition
6. All energy flow of life occurs within cells