Cell Structure and Function, Enzymes,

Cell Structure and Function, Enzymes, Meiosis, And the Ecology of Organisms

Cell function

For each structure identified, do you think its location affects its ability to function? Why or why not?

Each organelle/structure has a specific site of location in the cell that affects its distinctive function. For instance, nucleus that is the control department of the cell is located in the middle so that it can monitor all the activities. Additionally, the plasma membrane surrounds all the cell structures because it has to protect them and also has to regulate the passage of substances (Rastogi 2007).

Furthermore, mitochondria are situated all around the cell as it is the site of respiration so it can easily fuel all metabolic reactions taking place. Moreover, endoplasmic reticulum and Golgi apparatus are situated close to one another so that proteins and lipids from ER can easily be transported for packaging (Rastogi 2007).

Draw a labeled diagram of a small section of the plasma membrane and briefly describe its structure and function.

(Miercoles, 2011)

Plasma membrane consists of two layers of phospholipids that have cholesterol and proteins situated between them. Few carbohydrate molecules are also attached to them forming conjugate molecules. Membrane is responsible for shielding a cell from the external atmosphere and maintaining the internal environment. Moreover, it monitors and directs the transport of substances across it (Rastogi 2007).

3. Describe the differences between animal and plant cells.

Animal cell

Plant cell

Cell wall absent

Cell wall present

Chloroplasts absent

Chloroplasts present

Small vacuoles present

Large vacuole present

Plastids absent

Plastids present

Centrioles present

Centrioles absent

Irregular shape

Regular shape

4. Which of the structures are present in both prokaryotic and eukaryotic cells?

Plasma membrane, ribosome, genetic material (DNA/RNA) and vesicles are present in both types of cells (Rastogi 2007).

5. Where is genetic material found in plant cells?

Genetic material (DNA) is mainly present inside the nucleus of plant cell (Rastogi 2007).

6. Mitochondria are the only organelles that contain their own DNA (circular) and have a double membrane. Why do you think this might be so?

Mitochondria are structures that seek the ancestral links from bacterial cells; therefore, they contain circular DNA and possess a rough natured inner membrane like bacteria. The generation of ATP in mitochondria due to the presence of space between double membranes resembles the energy yielding process in ancient species of bacteria (Rastogi 2007).

7. How is the structure of plant's cellulose-based cell wall related to its function?

Cell wall is made up of cellulose and other molecules whose arrangement provides high flexibility and strength to the structure of the wall. It facilitates the cell wall to perform its role of allowing cells to have definite shape, shielding it from harmful agents and providing overall support to the cell (Rastogi 2007).

8. Defects in structures of the cell can lead to many diseases. Pick one structure of a eukaryotic cell and develop a hypothesis as to what you think the implications would be if that structure did not function properly.

Malfunction of mitochondria can beget to seizure of energy-driven metabolic reactions in the cell, as the supply of energy will be cut short. Additionally, muscular contractions and the nervous system (synapse) will be hampered. Moreover, there will be paramount chances of organ failure. The consequences may prove to be fatal.

9. Using books, articles, the internet, etc. conduct research to determine if your hypothesis was correct.

According to sources, the hypothesis is correct. However, several other implications are also present that depicts that all the senses, processes and systems in an organism will feel the effects of the disease (Fleisher 2006).

Enzymes

1. How does temperature affect enzyme function?

Every enzyme demonstrates maximum activity at a particular temperature known as its optimum temperature. Generally, all enzymes are inactivated at temperatures below 10°C and get denatured (lose its three-dimensional protein nature) above its optimum temperature (Seager & Slabaugh 2010).

Experiments conclude that enzyme activity increases by almost ten percent coupled to each degree rise in temperature until it reaches its optimum state and declines beyond it as they start denaturing (Seager & Slabaugh 2010).

2. Do plants and animals have an enzyme that breaks down hydrogen peroxide? How could you test this?

The process of converting toxic hydrogen peroxide into harmless substances occurs at a very slow rate; therefore, both plants and animals have enzymes to catalyze it. Catalase is an enzyme that is present in animal cells; however, plants possess enzyme peroxidase to carry out this decomposition (Seager & Slabaugh 2010).

It can be tested by mixing hydrogen peroxide and a piece of animal liver (containing catalase) or a piece of potato (source of peroxidase) in a test tube. Bubbles of gas will be observed showing the decomposition of hydrogen peroxide (Seager & Slabaugh 2010).

3. How does the boiling water affect the overall reaction?

Boiling water has a temperature that is much higher than the optimum temperature of catalase and peroxidase, therefore; it will denature the enzymes thus causing a decrease in the rate of reaction (Seager & Slabaugh 2010).

4. How can enzyme activity be increased?

Enzyme activity can primarily be increased by adjusting the surrounding temperature and pH to achieve optimal state for an enzyme-catalyzed reaction (Seager & Slabaugh 2010).

5. Design an experiment to determine the optimal temperature for enzyme function, complete with controls. Where would you find the enzymes for this experiment? What substrate would you use?