Scribe Post for Wednesday, 10/5

What we did in class today:

• Egg Osmosis Demo
  
• Normal and Plasmolyzed Cells Lab
• Osmosis Worksheet
• Mitosis Video

Homework for tonight:

• Fill in your mitosis notes from Moodle
• Read Chapter 8
  
• Read mitosis lab- UP p. 53-60

Egg Osmosis Demo

This was the second day of our Egg osmosis demo, the first day we were just to observe a raw egg. Today, we observed a raw egg that had soaked in vinegar for 24 hrs. During the time it was soaking, the egg cracked. This was not part of the demonstration, so it was a little bit wacky, but there was still evident differences from the raw egg to the egg soaked in vinegar.

Some observations of the egg soaked in vinegar:

• Pieces of shell are missing
• Outside of what is left of the shell is soft
• Rubbery to the touch
• A few bubbles on the egg itself
• No difference in size

Since I drew a diagram of the egg in vinegar, I found a picture of one.

As you can see here. The egg looks like it has lost some pieces of shell, also you can see some bubbles on it.

Normal and Plasmolyzed Cells Lab

Purpose: This lab was to show the effects osmosis can have on a cell, and to show the before and after of a cell when its surroundings are changed from an isotonic solution to a hypertonic solution.

Materials:

• microscope
• microscope slides/cover slip
• Elodea leaf
• tap water
• salt water

Procedure:

1. Prepare two separate slides, one with an Edolea leaf and a wet mound with 3 drops of tap water ( 1 percent salt, 99 percent water), another one with an Edolea leaf and a wet mound with 3 drops of salt water ( 6 percent salt, 94 percent water)
2. Wait 2 or 3 minutes for the reaction, if any, to happen.
3. Under a microscope, carefully observe both slides and look at the position of the chloroplasts, cell wall, vacuole, and cell membrane
4. Fill it what is seen on a diagram

Since I drew my own diagrams on the unit packet, I found pictures of what cells looked like in tap water and salt water on the internet.


This is an elodea leaf in tap water, the evident structures that are visible are the cell wall, and chloroplasts. But the clear spot in the middle is the central vacuole, it looks like there is a lot of water stored inside it. There is also a nucleous, and the cell membrane is surrounding everything. The cell looks turgid and happy.


This is the Elodea leaf in salt water ( 6 percent salt) As you can see, the cell wall maintained its shape and didn't move. The cell membrane, however, looks like it has contracted in a smaller shape. This is because the vacuole had let out too much water, and shrunk. It is still there, but much smaller. The chloroplasts and nucleous are there also, but much more compact and closer together.

Analysis

1. Describe the location of chloroplasts in a normal Elodea cell ( in tap water).
A: Spread out evenly around the vacuole in the cell membrane.
2. Describe the location of chloroplasts in a plasmolyzed cell (in salt water).
A:Very close together in the membrane
3. Answer the following q's about the cell in tap water

[a] What is the percentage of water outside the cell?
A:99 percent
[b] What is the percentage of water inside the cell?
A: 99 percent
[c] How do the percentages compare
A: They are the same
[d] Did the cell change shape? Explain.
A: No, it was in a surrounding environment that was the same as the cell. It was an isotonic solution.
4. Answer the following q's about the cell in salt water
[a] What is the percentage of water outside the cell at the investigations start?
A: 94 percent
[b] What is the percentageof water inside the cell at the investigation's start
A:99 percent
[c] Is the percentage of water [concentration] inside higher or lower than the percentage outside?
A: It is higher than the outside cell
[d] When will water move across the cell's membrane?
A: When there's a difference of concentration
[e] The water should move from?
A: High tolow
[f] Did the inside of the cell change shape due to water loss? Explain.
A: Yes, the central vacuole lost it's water and the inside contracted.
5. What is plasmolysis?
A: Plasmolysis is cell water loss.

Osmosis Worksheet

Effects of water concentrations on cells.

Red Blood Cell Elodea cell
a. Equal water concentrations- Cell - Isotonic Cell- Isotonic

b.Great water concentration- Cell- Hypertonic Cell-Hypertonic
outside cell-pure water

c.Great water concentration- Cell-Hypotonic Cell-Hypotonic
inside cell- salt water

Mitosis Video

Here are some bulleted notes that recaps the main points of the video!

• Mitosis-forming of two identical cells from one cell

• Chromosomes- A threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes
• Humans have 26 chromosomes. Every animal has a specific number.
• Split chromosomes are called chromatids (Also called sister chromatids)
• When chromatids separate they make two new cells

Four Phases of Mitosis

1. Prophase: The genetic material in the nucleus condenses and the duplicated chromosomes become visible. The nucleolus disappears and the nuclear envelope begins to break down, spindle fibers also start extending from both poles of the cell.


2.Metaphase: The duplicated chromosomes form a line in the center of the cell, spindle fibers attach themselves to the centromere of the chromosomes


3.Anaphase: This is when the duplicated sets of chromosomes separate and two identical groups move to opposite poles of the cell.


4.Telophase: The cell divides into two new cells!


Don't forget to read and fill in your notes!

Sincerely,

Minji

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