Assessment Statement 10: Draw and label a diagram of the ultrastructure of Escherichia coli (E. coli) as an example of a prokaryote.

external image prokaryotic_cell.jpg

You can tell this is a prokaryotic cell because of the lack of a nucleus, and basically a lack of any membrane covered organelles at all. By the way I got that image from, which is a website all about IB bio. Check it out, it's mucholy helpful!

Assessment Statement 11: Annotate the diagram of E. Coli with the functions of each structure.
The cell wall maintains the cell's shape, protects the cell, and allows it to hold more water than an animal cell could. The plasma membrane maintains the cell's homeostasis because it is semi-permeable, only allowing in certain things, and through the help of membrane proteins which transfer particles in and out of the cell by facilitated diffusion. The pili allows the cell to stick to other cells and to other surfaces. The flagella propel the cell, usually through water. The nucleoid is where most of the DNA is located, as well as a few messanger RNA and proteins. Ribosomes synthesize proteins that have been coded by the DNA. Like the pili, the capsule allows the cell to stick to other cells and surfaces. It also keeps out viruses and toxic materials. The cytoplasm is the part of the cell within the cell membrane.

Assessment Statement 12: Identify structures from above in an electron micrograph of E. Coli

external image bacteriatem.gif
I have no idea why there are no pili or flagellum in this picture, I couldn't find a good one that did. But you get the point. The capsule is probably the outermost line surrounding the cell, the cell wall is the next one in, then the plasma membrane. Flagella should be at the end, and pili all over it. Based on the labelling already there, the nucleoid is the white areas and the ribosomes are the black. If anyone has a different interpretation please correct me!

Assessment Statement 13: Draw and label a diagram of the ultrastructure of a liver cell as an example of an animal cell.
Cell Diagram; Image ONLY
Cell Diagram; Image ONLY

This isn't a liver cell per se, but it is the basic animal cell.

Assessment Statement 22: Explain the role of protein pumps and ATP in active transport across membranes.
Active transport is defined as the transportation of particles across a cell membrane, from an area of low concentration to an area of high concentration, through the use of a protein pump. Because the particles are going against the concentration gradient, energy is required in the form of ATP. An ATP molecule decomposes into ADP, releasing a phosphate group and a whole lot of energy as it does so. The phosphate group attatches to the protein pump, causing it to change its shape so that it can take in a sodium ion, for example. The protein then changes shape again so that the sodium ions can be released on the other side. In the case of this pump, the sodium-potassium pump, potatssium ions then enter the protein pump. The protein changes back to its previous shape, allowing the potassium to be released on the other side. This whole cycle takes one phosphate group to occur. Thjere are many other protein pumps as well, not just the sodium-potassium one, because the proteins have specificity. The sodium-potassium pump, for example, wouldn't be able to transport hydrogen across the membrane.

external image 0645.jpg

Assessment Statement 23: Explain how vescicles are used to transport materials withing a cell between the rough endoplasmic reticulum, golgi apparatus, and plasma membrane.
​The rough ER has a "rough" apperance because it is studded with ribosomes. These ribosomes make proteins, with the help of the DNA's codes, which are then placed in a vacuole that the ER forms. The vescicle might then carry the protein to the golgi apparatus where the membranes fuse and the contents dumped. Here, other molecules might be added to the protein, to make it a glycoprotein for example. It is then placed in a new vacuole made from the golgi apparatus. If its next destination is the cell membrane so that the protein can leave the cell, the vacuole fuses with the membrane, dumping its contents outside of the cell. Vesicles can carry other materials too, but if the vesicle is made from the ER it is likely to be carrying a protein.

Assesment statement # 6 Calculate the linear magnification of drawings and the actual size of specimens in images of known magnification.

The actual size of an object is found by dividing the size of the drawing by the magnification factor that is stated. This will tell you what the actual size of the object is, and the formula can be applied to different situations. For example, drawing size is the magnification multiplied by the specimen size.

Assessment statement # 7 Explain the importance of the surface to volume ratio as a factor limiting cell size.

The surface to volume ratio is an incredibly important factor for the limiting of cell sizes, because in order to maintain the maximum absorption efficiency for cells, they must remain smaller. When objects are smaller in size yet greater in number, they have much more surface area, and therefore a much larger surface to volume ratio. This large surface area allow the many small cells to absorb more water than one large one, as discovered through our sponge lab. When more surface area is present, the smaller sponges were able to absorb larger amounts of water. This is the reason that cells only grow to a certain maximum size and the split, because if the cells were to get too large, their surface to volume ratio would grow smaller, and they would not have as much surface area. This lack of surface area could greatly diminish the water absorption capacity of the cell, so naturally it would remain smaller.

Assessment statement # 8 State that multicellular organisms show emergent properties.

Multicellular organisms posses emergent properties, because emergent properties are properties that result from the interaction of components, such as amino acids forming together to make proteins. These protiens then interact and fold, which makes new structures and so on. All multicellular organisms will have these properties, as they result from biological interactions between cells.

Assessment statement # 9 Explain that cells in multicellular organisms differentiate to carry out specialized functions by expressing some of their genes but not others.

When cells are in their developmental stage, the only way that they are able to differentiate and become specific cells is to express their specific genes. For skin cells as an example, when they form, the genes that are important in skin cells will be activated. This is really the only way that stem cell will become other cells to form a complete organism.

Assessment statement # 21 Define diffusion and osmosis
Diffusion- The movement of particles in a high concentration to a lower concentration. This is one method of passive transport, as the substances on one side of the membrane diffuse to the other side without the use of energy. An example of diffusion is if someone sprays perfume in one location, it is initially concentrated where it was sprayed. Over time though, the particles will diffuse to other locations in the room, which explains why you can smell it from a distance.

Osmosis- The diffusion of water through a semi permeable membrane This is how water is absorbed and used by cells.
Osmosis also uses a concentration gradient like diffusion, as it will move to an area of lower concentration from one of higher concentration. This is how it diffuse into the cell.

Assessment Statement 15: Compare prokaryotic and Eukaryotic Cells


Assessment Statement 16: State three differences between plant and animal cells

Animal cell
-Contains Centrioles
-Shape is flexible, but is usually rounded.
- chloroplasts and cell wall not present. Skeleton is used to hold the structure.
Plant cell
-Chloroplasts, and cell wall present.
-Does not contain Centrioles

Assessment Statement 17: Outline two roles of Extracellular components: are things that help the cell do its job, but are outside the cell
  1. One role is structural help to the cell itself. For example, the ECM (Extracellular Matrix), in animal cells, holds the cell structure in place while acting as a communication agent with other tissues. The Cell Wall in plant cells helps to keep its structure in place as well.
  2. Another role would be to act as a connecter for cell-cell interactions. Such as Glycoproteins that attach cells to other cells for communication purposes.
Assessment Statement 18: Draw and label a diagram to show the structure of membranes

external image CellMembraneComplex.gif
Assessment Statement 25: Describe how the fluidity of the membrane allows it to change shape, break, and re-form.

The fluidity of the membrane allows it to be flexible and conform to different shapes. For example, during endocytosis, the membrane pushes inward, engulfing the substance and breaks into a vesicle. The membrane is allowed to break because of the flexibility of the membrane. Once one side attaches to the other, it breaks. For example, during exocytosis, The membrane and the vesicle fuse together and the vesicle part of the membrane pushes outward moving the waste. The phospholipids are attracted to one another, so when they do break they immediately want to rejoin.

Assessment Statement 1: Outline the cell theory.

1. All organisms are composed of one or more cells.
2. All cells come from pre-existing cells.
3. Cells are the smallest unit of life.

Assessment Statement 2: Discuss the evidence for the cell theory.

All vital functions of an organism occur within cells. Cells contain the hereditary information necessary for regulating cell functions and for transmitting information to the next generation of cells.

Assessmnet Statement 3: State that unicellular organisms carry out all of the functions of life.

Unicellular organisms carry out all functions of life, such as metabolism, homeostasis, reproduction, growth, and nutrition.

Assessment Statement 4:

Molecules = 1 nm
Cell Membrane Thickness = 10 nm
Viruses = 100 nm
Bacteria = 1 um
Organelles = 10 um
Cells =100 um

Assessment Statement 19: Explain how the hydrophobic and the hydrophillic properties of phospholipids help to maintain the structure of cell membranes.

Hydrophilic molecules are attracted to water. Hydrophobic molecules are not attracted to water, but are attracted to each other. The phosphate head is hydrophilic and the two hydrocarbon tails are hydrophobic. In water, phospholipids form double layers with the hydrophilic heads in contact with water on both sides and the hydrophobic tails away from the centre. The attraction between the heads and the surrounding water makes membranes very stable.

Assessment Satement 20: List the functions of membrane proteins.

The functions of membrane proteins are it is a binding site, a pump for active transport, channels for passive transport, and it recognizes other cells.