Cells Summative Assessment

During the past weeks, I have been working on a cell summative assessment.  Its purpose was to give our science teacher a tool that could be used with the students. The project could be a comic book, storybook, newspaper, game, song, talk show, etc. I decided to write a song.

  My initial plan was to create a website, which didn´t work at all due to a few technical problems. I gave up with 6 days remaining!! I couldn´t decide which project was more suitable for me until the weekend was left. So, I thought writing a song wouldn´t take me much time. Though, I was wrong. Writing the lyrics took me a whole day. Still, I hadn´t finish the entire project. My teacher requested a video which explained my work. Yet, what would I explain if it was a simple song about cell division? Ms. took this into consideration and told me to record it!?! I almost passed out but I had no choice. Despite the fact of my voice, practicing the song helped me remember each step of the cell division process without studying!

At the end comes my self-evaluation. Since I only worked on my project during the last weekend, the quality of it isn´t the most favorable. At least, it became a more interacting and fun way of learning science. The lyrics are provided below so feel free to check it out.

Lyrics:

How do Cells Divide

Ohh

How do cells divide, over and over again

A message to the man ohhh

The sequence of events, preparing to divide

Into two new cells

Let’s Go!!

Yeah, you listening now

 At interphase the cell grows to its mature size

 The cell makes an exact copy of the DNA

 At the end it has two equal sets of DNA

 Preparation in cell division beginns ahaa

 Produces structures that will be used ahaaa

 The next event of the cell cycle is prophase

 Chromatin in the nucleus condenses to form chromosomes

 The pairs of centrioles, move to opposed sides

 Spindle fibers form, a bridge from the end- sides

 The nuclear envelope breaks down

 Then is metaphase, chromosomes line up in the center of the cell

 Each attaches to spindle fibers at its centromere

 Stop making this so hard for me, damn

 I used to be a kid that couldn´t solve this out

 That’s why you have to keep singing till you understand

Ohh

How do cells divide, over and over again

A message to the man ohhh

The sequence of events, preparing to divide

Into two new cells

Yeah, anaphase is next

Two chromatids split becoming two new chromosomes

The new chromosomes

Begin moving to the opposed ends of the cell

It stretches out as the opposite ends are pushed apart

At the end, each pole has a complete pile of chromosomes

 At telophase, chromosomes begin to stretch out and lose

 Mate, now my song would leave them amazed

Great, it feels like a hard time fading out

Since the day I thought of that cunning plan

But I´m missing something I try to remember

Which belong to this song, the final stage!

It’s Cytokinesis, where the cell splits in half

Each ending with alike sets of chromosomes

 Everyone’s a kid that couldn´t solve this out

 You just gotta keep singing till you understand

How do cells divide, over and over again

A message to the man ohhh

The sequence of events, preparing to divide

Into two new cells

Ohh (4x) Interphase

Ohh (4x) Prophase

Ohh (4x) Metaphase

Ohh (4x) Anaphase

Ohh (4x) Telophase

Ohh (4x) Cytokinesis

I know how cells divide, over and over again

A message to the man ohhh

The sequence of events, preparing to divide

Into two new cells 

Egg Lab

Since it is difficult to see when osmosis is happening in cells due to the small size, in my science class we simulated what happens in a cell by using an egg. The egg may not be a single cell though; its membrane is selectively permeable, being a good model to show some basic osmotic effects in animal tissue.  Our aim was to investigate the effect of different solutions on an egg´s mass and volume.  For this experiment the class was split into groups of three. My group chose to use alcohol and salty water 20% solution. The goal of our experiment is to investigate the effect of different solutions on an egg´s mass and volume. At the beginning of the investigation, my group was asked to predict the possible effect. We predicted both eggs, either submerged in salty water 20% solution or alcohol, were going to dehydrate.

Before even starting the egg lab, all eggs spent two days in vinegar in order for the shells to dissolve. After the egg had no shell, my group was free to start the experiment. We measure each of the eggs mass, circumference, and solution filling each cup where the eggs were going to be submerged. Though, how were we going to differ each the second day? We named both eggs! The one in alcohol was named Stuart and the egg in salty water 20% solution, Steven. On the second and third day, we performed the same procedure: measuring the mass, circumference, and solution that was left inside cup from each egg. The average from my results and another group are recorded below. 

Average of Alcohol Solution Effects

Average of Salty Water 20%  Effects

Observations:

- the egg in alcohol got more yellow and lighter each day

- the egg in salty water 20% solution got whiter and heavier each day

- remaining solution decreased in both cups 

-when the egg in alcohol was opened, it looked like a boiled egg

- when the egg in salty water was opened, it exploded and scattered with a single touch

Conclusion and Analysis:

At the end of the experiment, my group had to summarize and analyze the experiment with our knowledge of osmosis. For the egg submerged in alcohol we concluded that there was a larger amount of water inside the egg than outside. This is when osmosis shows up. Since there was a higher concentration of water inside the egg, some H2O molecules went outside to keep balance. The reason the egg got smaller because it lost liquid. Though, how could the remaining solution in the cup be less if water was added to the total of 80ml (already outside the egg). Actually, alcohol evaporates really fast, a possible reason the remaining amount of alcohol reduced from 80ml to 68.5 and eventually until 59ml. At the end, our prediction was right, the egg did dehydrate since it got small and had a dry texture. 

On the other hand, the egg in salty water 20% solution, didn´t meet our expectations. My group thought it was going to dehydrate, supposed to decrease in mass and circumference. Though, the results were totally the opposite: the egg got heavier and larger. As a whole, my group concluded this happened due to the possible lower amount of water inside the cell, which lets the outside environment to send water particles to the inside of the cell. This reflects the enlargement of the egg since it was full of water. The most noticeable part where this effect happened is from the abrupt reduction of solution outside the egg between day 1 and day 2. It decreased from 80ml (what we started with) to 67ml. 

Possible Sources of Errors:


-Procedure: Pouring different amounts of the chosen solution. This may have been one of the causes why results varied a lot. Some groups submerged their eggs in a total of 100ml from their solution. Though, the cups where the eggs were being placed had a small space for the egg to fit. This didn´t let enough space for the primarily requested 100ml of solution. As a result, some of the liquid spilled due to the lack of room. The reason groups ended with various amounts of liquid, affecting the average. 
-Equipment:

String used to measure the eggs´ circumference could be easily stretched. Instead, a retractable tape measure could´ve been used. While you surround the tape around the egg, at the same time you are measuring the circumference. Helping you save some time. 

What have I learned?

Sincerely, the experiment was not a way of studying osmosis yet to review it. Osmosis is the movement of water molecules from a high concentrated area to low. This reflects what happened in the experiment. The center of the egg (yolk) contains protein and water. While, let´s say salty water contains salt and water. Osmosis may happen due to the fact that there are more water molecules in the yolk than in the solution (salty water). So, eventually water molecules move from the inside to the outside to keep balance. 

Team Evaluation:


In my opinion, my team worked efficiently all classes. While one member measured the circumference from one of the eggs, the other measured the mass from the other egg, while I placed the remaining liquid from the cup in the graduated cylinder to measure the solution that was left. We never got distracted by others. I very much appreciated the help from my group since it contributed in my understanding of osmosis. 

Cell Membrane

The simple facts students normally study about the cell membrane is that it´s made of fat and used for protection. If we were to see from a molecules´ point of view, what would happen inside the cell membrane? Actually, if we get through the cell membrane since it is selectively permeable, we could go through by either passive or active transport.   Through passive transport, substance can cross the cell membrane without using cellular energy. In other words, the cell doesn´t need to use its own energy.  On the other hand, active transport requires the cell to use its own energy in order to get through the cell membrane. Below, there´s an informative video I found which explains more clearly what I roughly explained. 

Lifeboat Dilemma

Imagine yourself in a ship which just struck an iceberg and the captain is lead to choose who will be thrown out. Now every passenger needs to convince the captain the reasons they shouldn´t be thrown out. This is basically the task given by my teacher but instead of being humans, each student was given an assigned cell part. The class was divided in two main cells, prokaryotic and eukaryotic. This represents the ships.  The passengers are the different cell parts present in either a prokaryotic or eukaryotic cell. 
My assigned part was the endoplasmic reticulum. The speech I presented was the following: 

The endoplasmic reticulum is a network of membranes, classified in two types: rough and smooth. The main functions of the rough endoplasmic reticulum are synthesis and storage of proteins which are made by the ribosome’s attached to it. The smooth endoplasmic reticulum plays a role in the lipid synthesis and, in muscle cells, in the conduction of the contraction stimulus.

Proteins are needed in the cell for numerous functions and the RER (rough endoplasmic reticulum) is responsible for synthesizing proteins. They can either produce a protein to reproduce or to replace a degraded one. Their procedure is to first transcribe DNA into RNA. The RNA will translate into chains of amino acids, then, the amino acid chain will fold into specific proteins.

The same as the nucleus acts as the brain of the cell, the endoplasmic reticulum acts as the transport system by sending protein to the golgi apparatus. 

What kind of cell I would like to be and why

Throughout the week, my class and I have been studying the difference between prokaryotic and eukaryotic cells.  Based on what I researched, I came with the conclusion of choosing to be a eukaryotic plant cell. 

These cells are surrounded by a cell wall made of cellulose important for producing numerous products. Such as textile, paper, pharmaceuticals, and explosives! The cell wall allows very high pressures to build up inside them because of osmosis (diffusion of a solvent).  In other words, it prevents over-expansion when water enters the cell.  It avoids plant cells from exploding when put in distillate water. This is one of the main reasons I´d like to be a plant cell.  Since animal cells lack a cell wall, they need to excrete excess of water. Otherwise, your kidney will stop working causing your blood to get very dilute each time you drank water. Then water would start to go into your cells by osmosis and they might burst: the end of you! 

Plants cells also contain chloroplasts which contain chlorophyll, necessary for photosynthesis. This contains DNA which controls how other chloroplasts work. The information in the DNA is needed to make enzymes and eventually used for photosynthesis.  

At last, plant cells have a large vacuole which occupies most of the space in it. It can hold many substances from organic molecules to simple excess of water. The central vacuole is important in maintaining plant turgidity (the state of being turgid or swollen). Turgidity is very important for plants for keeping them rigid and upright. 

Project "Meals on Wheels"

Everything started when the owner of “Meals on Wheels”, Sarah Jones, decided to hire us, nutritionists. A task was given to my group; team violet. We needed to choose from the three given menus; a healthy and balanced menu for a long-term period and for one week quick weight loss. It was asked to evaluate each menu and decide which fits on the company list.  The group was supposed to research the consequences from the lack or excess of nutrients in each menu. Not only did we have to evaluate the menus but to explain the directors´ board the reasons for our choices.

Our team´s first goals were to list the things we needed to research and assign a role to each member. However, the plan didn´t work properly because the work wasn´t divided evenly among the group. Hopefully, a sign of optimism appeared- the teacher´s clarification of the task. So, we created a new plan divided in four parts: introduction, menu 1, menu 2, and menu 3 evaluation and research. While working on the third menu, I discovered some of the consequences of lacking vitamins and minerals: scurvy, myxedema, blindness, etc.

Though, which was our final decision? We chose menu #1 as a short term diet since it lacks proteins and fat. This is a fine way of losing weight, though, not a long term period due to the health problems it will cause you. Inadequate levels of proteins during a long time will you’re your body´s ability to regulate blood sugar. Lacking fat for a long period will affect the protection of vital organs such as the heart. On the other hand, my group chose menu #2 as long term diet because it includes small amounts of all nutrients and provides you with snacks throughout the day. 

Overall, this project did contribute on my science knowledge by providing me with information about the lack or excess of each nutrient. This was done by either my own research or/and by the oral presentations.  Also, it let me work on different skills such as leadership, organizational, teamwork, and time management. It was complicated to express my opinion in my group since I´m quiet by nature. Yet, I felt confident about my own knowledge and could solve my groups’ doubts and make decisions to improve the projects quality more easily.

Science project 9

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What was the purpose of these first two days of school and what are my plans for this year?

I entered the Science with a fresh mind. Came in as a 9^th grader for the first time and the teacher directed us with a brand new assignment; the marshmallow challenge. Using 2o sticks of spaghetti, tape, string, and one marshmallow; teams had to build the tallest free-standing structure in eighteen minutes. The task sounds simple however when the marshmallow is placed on the top, everything may come down.

The next day, the class watched a video about the physics of skateboarding. This showed a professor trying to make a new trick on his skateboard. He failed many times until he finally got it right. However, I still didn´t understand the reason of doing the marshmallow challenge and watching the video. At that moment, the teacher gave us the connection or lesson: to be good at something you need MANY hours of practice. In other words, you´ll fail several times.

My expectations for this year are just a few. First, I´d like to interact with different people on group work. Last year, I normally worked with the same person which got me bored. It doesn´t mean I hate that person it´s the way this person works. By interacting with different people I can learn many different ways of working. At the end of the year I´ll chose the most efficient one. Second, I´d like the class to be entertaining. Sometimes the class could do activities which require movement instead of sitting down the whole period. This can change the students’ daily mood related to Science.