1.1 Cell Organelles ☝🏻

Materials for cell organelles

• 👆🏻 Quick video tips about the topic.
• Website showing the differences between prokaryote and eukaryote ribosomal proteins.
• Download diagrams (high resolution) – FREE!
• BUY notes ⌲ includes phrasing error corrections & review question solutions.
• Purchase notes (including phrasing error corrections & review question solutions) for cell organelles.

Phrasing errors

• The cell membrane is a …
• Nucleolus consists of DNA.
• Lysosomes contain lysozymes.
• The nuclear envelop is a bilayer.
• Mitochondria are sites of respiration and they produce energy.

Exam tips

• Centrioles are not found in most plants.
• Transport vesicles are different from secretory vesicles.
• Cisterna and crista refers to structures in different organelles.
• When asked to label, check arrow # and give appropriate singular or plural forms.
• It is not important to contrast animal and plant cells anymore but one should understand and be able to describe what structures makes plants unique e.g. chloroplasts and cellulose.
• Glycosylation of proteins begin in the RER vs. lipids in GA. What happens to the glycoproteins in GA is further/final chemical modifications as well as packing and sorting.
• Finally, many students do not spend enough time contemplating the concept of cell theory. Make sure you do as the idea of viruses being non-living is built on this very concept.

Calibration of microscopes to measure cell organelles Part 1

• Idea ⌲ You need to measure a structure you are looking at in the microscope to determine the actual length. In order to do so, someone thought why not use a ruler? However, if you use a ruler together with the sample, this presents with a logistical problem. Since every time the sample have to be prepared together with a ruler. After that it has to be washed. As such, a solution is to stick it to the ocular eyepiece instead. That way, you will constantly have a ruler that you can reference and use to measure the size of the structure you are seeing in the microscope. However…
• Problem ⌲ When you stick an ocular ruler into the eye piece, it remains static even though you increase magnification because you want to get a clearer view of the cellular details. As such, if the magnification changes, the unit length represented by the division of the ocular ruler will therefor have to change as well.
• Solution ⌲ Consequently, you need to calibrate what each division of your ocular ruler represents in length under each magnification. In order to do that, you use a stage micrometer that has a known length per division. That way, when you have a certain magnification, you can work out the actual length of a division on the ocular ruler by multiplying the number of divisions the structure occupies with the unit length at a particular magnification.

Calibration of microscopes to measure cell organelles Part 2

• Steps ⌲ Decide on which magnification you want to use. Then try to align the stage micrometer with the ocular micrometer as shown below using the same magnification.

• Calculations ⌲ The stage micrometer total length will be = (unit length*) X (total # of divisions within the 2 meeting points). Once you get the total length (L), then your calculation of what is a unit length of the ocular ruler will be ⌲ (L) / (the total # divisions within the aligned 2 points). This will give you a unit length of the ocular ruler at the particular magnification that you used. * will be made known to you.