What time is it? LAB TIME!

 This week in AP Biology we did the mitosis and meiosis lab. As I previously discussed in my last blogs, mitosis which is when two genetically identical diploid daughter cells are produced and meiosis is the process which produces four genetically different haploid daughter cells. To began this lab we modeled mitosis and meiosis. We then prepared garlic for another activity. After following that we looked at onion root and fish egg cells to locate cells in the various stages of mitosis. We then proceeded to prepare the garlic root tip squash lab. In this part of the lab we took the garlic we had previously prepared by putting it into a sand and water mixture and placing it into a dark drawer, and cut off around 2 mm of the root tip. After that we put the root tip and hydrochloric acid on a slide  and passed it through an open flame for five seconds. Then we put a chemical that was bright pink and fuchsia in the name on the slide and passed it over an open flame for 2 minutes. We then squished the root tip and put it under a microscope to see if we could locate cells in the various stage of mitosis, but unfortunately we were unable to. That then concluded the lab.


(I will publish pictures separately.)

Meiosis

 This week in AP Biology we went over meiosis. Meiosis is divided into 2 different parts, meiosis 1 and meiosis 2. Meiosis 2 is the most similar to mitosis. In meiosis 1 there are four stages prophase 1, metaphase 1, anaphase 1, and telophase 1. In prophase 1 chromosomes condense, homologous chromosomes attach, crossing over between chromosomes, and centrioles move to opposite ends. In metaphase 1 the tetras line up at the metaphase plate. During anaphase 1 the homologous chromosomes are separated and taken to opposite poles. After anaphase 1, telophase occurs and the sister chromosomes continued to be pulled. Cytokinesis then takes place. After that meiosis 2 takes place which is very similar to mitosis. 

 Mitosis and meiosis differ greatly in their end products; mitosis results in 2 genetically identical diploid cell and meiosis results in 4 genetically different haploid cells. 

Message Passing and Reproducing in Cells

 This week in AP Biology we reviewed cell to cell communication and the cell cycle. 

 There are three types of cell to cell communication no distance, short distance, and long distance. In no distance communication the cells are touching and can send messages to one another. Plants have holes in there cell wall that allows the message to pass. When there is a short distance in cell to cell communication a local regulator is used to pass on the message, neurotransmitters are an example. When there is a long distance to pass on a message a hormone is used. The hormone is sent all around but only passes the message on to the right cells. 

After we went over cell to cell communication we then went to the cell cycle. The cell cycle is made up of the G1 phase, S phase, G2 phase, mitosis, and cytokinesis. There is also a G0 phase that some cells go into. G1, S, and G2 phase all make up interphase. In G1 phase the cell is working normally as the cell progresses into G2 it starts copying its DNA. When the cell starts S phase it again goes through its normal process. Then the cell gets to mitosis.  When mitosis and cytokinesis are combined it is called the mitosis (m) cycle the first phase is prophase. In prophase the chromatin becomes more clear and thicker and the centrioles become visible. Metaphase follows prophase in which the chromatin which has turned into sister chromatids are lined up in the middle of the cells with the centrioles at opposite ends and the mitotic spindle is forming. Anaphase which is the third phase is when the sister chromatids are pulled apart by kinectchores and nonkinectchores elongate the cell. The fourth and finall stage of mitosis (m) cycle is telophase and cytokinesis which is when the nucleus splits apart and start to reform the nuclear wall. And the cytoplasm splits thus creating another cell identical to its self. 

 To help control mitosis and prevent uncontrollable division there are checkpoints that the cell must pass before it can proceed into different phases. The are also internal and external  mechanisms that help to control uncontrollable division which can lead to cancer. 

Lab Time!!!

This week in AP Biology we did a photosynthesis lab. The first portion of out lab tested the different pigments in spinach leaves. The next portion of our lab tested the rate of photosynthesis in spinach leaves. 

The first lab where we tested for the different pigments showed four different pigments. There was chlorophyll a, chlorophyll b, xanthophyll, and carotene in the spinach leaves. We then tested for a constant that measured how far the chromatography solvent travelled divided by how far the pigment travelled. 

Part two of the lab tested the rate of photosynthesis in spinach leaves. At the first of the lab we took ten spinach leaf discs and put them in a syringe with a bicarbonate solution with dish soap. We them created a vacuum inside the syringe to compress the mesophyll cells so the leaf discs would sink. We then placed the discs into another bicarbonate solution. Every thirty seconds we checked for leaf discs that we're floating. This would mean the mesophyll cells had  air in them and that photosynthesis was occurring. 

The Food-Making Plant Process

               

 This week in AP Bio we went over Photosynthesis. Photosynthesis is an anabolic and endergonic process that plants use to produce food (glucose). The process is done in two reactions, the light reaction and the Calvin Cycle. The chemical equation of this process is:

6 CO₂ + 6 H₂O à C₆H₁₂O₆ + 6O₂

                The first reaction in Photosynthesis is the light reactions. In this reaction solar energy is converted into chemical energy in the thylakoid membrane. This starts with water being split, and because of this it provides a source of electrons and protons and gives off O₂ as a by-product. Light is then absorbed by chlorophyll which excites the electrons in a domino effect until finally the electrons are accepted by the primary electron acceptor. All of this takes place in photosystem two. The electrons are then passed via electron transport chain to photosystem one. The fall of the electrons to a lower energy level provides enough energy for the synthesis of ATP. As the electrons do through part of the electron transport chain a proton gradient of H⁺ is produced and which is often used in chemiosmosis. Light energy meanwhile is transferred by light harvesting complexes and is used to excite electrons in photosystem one until they are accepted by the primary electron transport. The electrons in photosystem’s one primary electron acceptor are then transferred through redox reactions to another electron transport chain, although this one does not produce a proton gradient. The electrons are then transferred to NADPH.

                The second reaction in Photosynthesis is the Calvin Cycle. The Calvin Cycle performs carbon fixation where it takes CO₂ from the air and it to the enzyme RuBP. Then through a series of reactions the ATP and NADPH produced by the light reactions are used up and recycled back. After all these reactions a sugar called G3P is produced which eventually is used to make glucose.

                 

FINALLY!!!

This week in AP Biology we reran our cellular respiration lab. We had tried to run it last week but unfortunately the lab went wrong. To begin the lab again we put the peas in water so they would germinate. Then, to prevent our lab going wrong from last time we hot glued the respirameters to the rubber cork they were supposed to be attached to. The next day in AP Biology we prepared for the lab even more. In the bottom of each test tube we placed a cotton ball and then put 1 mL of KOH solution on them. After that we placed a rayon ball which is considered a nonabsorbent cotton ball on top of them. The KOH solution attaches to the CO₂ released in cellular respiration that way in the experiment you are only measuring the amount of oxygen consumed. We finally ran our lab the next day after putting 10 germinating peas in test tubes 1 and 4 and then putting dry peas and beads of equal volume in test tubes 2 and 5 and glass beads of equal volume in test tubes 3 and 6. We placed the repirameters on top of the test tubes and put them in water baths of 10 and 25 degrees Celsius. After a five minute resting period we began to take measure on the respirameters of the amount of data consumed. Unfortunately our data was very irregular and did not make sense. We attributed this to the fact that we moved the test tubes while they were in the water baths which caused the red dye at the top of the respirameters to leak out. In the end though the germinating peas consumed the most oxygen in the 25 degree Celsius water bath. The colder temperatures affected the peas because it slowed down the process of cellular respiration. 

Oops!!!

This week in AP Biology we attempted to do two labs. Our first lab involved enzymes. In this lab we used hydrogen peroxide as a substrate and the enzyme in this lab would be peroxidase, an enzyme that is found in potatoes. In this lab we would dilute the hydrogen peroxide with water and add blended potato and water. When putting the two substances together the peroxidase in the potato would catalyze hydrogen peroxide into water and oxygen. We were going to see the rate of reaction of this catabolic reaction in different pHs, but unfortunately we prepared our different pH solutions too early and they began to mold. We now have to make more solutions of different pH and then we will be able to perform the lab. Our second lab dealt with cellular respiration. In this lab we were going to compare the amount of air produced by germinating peas, non-germinating peas and glass beads, and glass beads. We had six vials that we numbered one through six. In vial one we placed ten germinating peas. In vial two we put 10 non-germinating peas and a certain number of glass beads that made the volume of the germinating peas and non-germinating equal. In vial three we put only glass beads that equaled the volume of the germinating peas. We repeated this in vials four through six. After this was finished we placed vials one through three in a room temperature water bath and four through six in cool (10⁰C) water bath. The lab was not successful because the vials had repirometers on top of them and when the vials fell into the water the repirometers did also which screwed up the lab. This upcoming week in AP Biology we will restart the cellular respiration lab and will soon restart the enzyme lab.