EC: LA Arboretum

The LA Arboretum is a botanical garden and historical sit. Within the Los Angeles County Arboretum and Botanic Garden, there is a cultivation of our natural, horticultural and historic resources for education and enjoyment. The LA Arboretum allowed me to discover new plants and trees from all over the world. For instance, the arboretum's plants are grouped by geography with gardens for South American, Mediterranean, South African, Australian and North American plants. Due this experience, I gained new knowledge about more plant species and learn about the differences of plants’ anatomy. Also, I mainly toured the Tule Pond, where there are many species of resident and migratory birds, aquatic creatures, as well as numerous small reptiles and mammals. This allowed me to understand the lifestyle of these creatures. In addition, the arboretum shelters nearly 200 peafowl, which are descendants of original birds imported by Baldwin from India. These birds was a clear example of the results of evolution and natural selection. Ultimately, I was able to learn about California history after my tour of the place.

Evernote Evolution: Maybe This Is The Reason Neanderthals Went Extinct

Many researchers come to believe that our prehistoric rivals did not decline from epidemics or climate change, but rather due to their limited culture, making competition with the modern humans extremely disadvantageous. When two groups are competing with one another, the more advanced species can "invade and overwhelm" the other. Some instance include hunting skill, communication ability, or adaptations. Generally, the arrival of modern humans meant doom for the underdeveloped Neanderthals.

As I read this article, the information that I learned about evolution served as evidence towards the extinction of the Neanderthals. For instance, as we see from Darwin’s theory of evolution, the Neanderthals eventually adapted to new environmental conditions, leading to advanced, modern humans. As a result of the modern humans, social Darwinism was supported as the Neanderthals were soon replaced by modern humans.

However, despite losing in the game of evolution, the Neanderthals continue to remain as their genes are passed along generations. In fact, research has shown that everyone alive today whose ancestry is from outside of Africa has a bit of Neanderthal DNA. Consequently, I believe that evolution played an essential role towards the extinction of the Neanderthals.

Fluid Mosaic Model of the Cell Plasma Membrane

The fluid mosaic model was first proposed by S.J. Singer and Garth L. Nicolson in 1972 to explain the structure of the plasma membrane. The model has evolved somewhat over time, but it still best accounts for the structure and functions of the plasma membrane as we now understand them. The fluid mosaic model describes the structure of the plasma membrane as a mosaic of components —including phospholipids, cholesterol, proteins, and carbohydrates—that gives the membrane a fluid character . Plasma membranes range from 5 to 10 nm in thickness. For comparison, human red blood cells, visible via light microscopy, are approximately 8 µm wide, or approximately 1,000 times wider than a plasma membrane. The proportions of proteins, lipids, and carbohydrates in the plasma membrane vary with cell type. For example, myelin contains 18% protein and 76% lipid. The mitochondrial inner membrane contains 76% protein and 24% lipid. The principal components of a plasma membrane are lipids (phospholipids and cholesterol), proteins, and carbohydrates attached to some of the lipids and some of the proteins. The fluid mosaic model of the plasma membrane describes the plasma membrane as a fluid combination of phospholipids, cholesterol, and proteins. Carbohydrates attached to lipids (glycolipids) and to proteins (glycoproteins) extend from the outward-facing surface of the membrane. The main fabric of the membrane is composed of amphiphilic or dual-loving, phospholipid molecules. The hydrophilic or water-loving areas of these molecules are in contact with the aqueous fluid both inside and outside the cell. Hydrophobic, or water-hating molecules, tend to be non-polar. A phospholipid molecule consists of a three-carbon glycerol backbone with two fatty acid molecules attached to carbons 1 and 2, and a phosphate-containing group attached to the third carbon. This arrangement gives the overall molecule an area described as its head (the phosphate-containing group), which has a polar character or negative charge, and an area called the tail (the fatty acids), which has no charge . They interact with other non-polar molecules in chemical reactions, but generally do not interact with polar molecules. When placed in water , hydrophobic molecules tend to form a ball or cluster. The hydrophilic regions of the phospholipids tend to form hydrogen bonds with water and other polar molecules on both the exterior and interior of the cell. Thus, the membrane surfaces that face the interior and exterior of the cell are hydrophilic. In contrast, the middle of the cell membrane is hydrophobic and will not interact with water. Therefore, phospholipids form an excellent lipid bilayer cell membrane that separates fluid within the cell from the fluid outside of the cell.

Amazing Cells

INSIDE A CELL

Nucleus

The nucleus safely stores the cell’s DNA blueprint. It also separates the cell’s DNA from the activity of the cytoplasm, keeping it safe from interference. Proteins work together to copy segments of DNA into RNA during transcription.

Cytoskeleton

The cytoskeleton functions as a system of roads for the transport of cargo by motor proteins. It also acts as a springy skeleton that gives the cell it’s shape as well as organize the events of cell division.

Endoplasmic Reticulum

The ER makes up roughly half the membrane in a cell. So there’s a lot of surface area to perform chemical reactions and store important enzymes in the smooth ER. Freshly made proteins and fats are packed into vesicles and sent from the ER to the Golgi apparatus.

Mitochondria

Mitochondria have their own set of unique proteins embedded in their membrane folds enabling them to participate in a variety of cellular activities. Mitochondria are responsible for generating the cell’s energy. Using sugar and oxygen, protein complexes in the inner membrane manufacture energy molecules that are used throughout the cell.

Golgi Apparatus

Vesicles filled with proteins and other macromolecules fuse with the Golgi apparatus. Here these molecules are tagged with specific labels that transport proteins will use to deliver them to the proper place in the cell.

Lysosomes and Other Specialized Vesicles

When proteins have reached the end of their usefulness, they are transported to the lysosome to be degraded. Specialized motor proteins carry tethered proteins along microtubules to their destination.

DIRECTING TRAFFIC: HOW VESICLES TRANSPORT CARGO

Generally, molecules, such as proteins, are too big in order to pass through membranes. Instead, large molecules are loaded into vesicles. Vesicles are constantly forming, usually at the plasma membrane, the ER, and the Golgi. Once formed, vesicles deliver their contents to locations within or outside of the cell. A vesicle forms when the membrane bulges out and pinches off. It travels to its destination then merges with another membrane to release its cargo. In this way proteins and other large molecules are transported without having to cross a membrane. When the coat proteins assemble at the membrane, they force the lipid bilayer to begin to blend. As they gather at the membrane, coat proteins, may also select the cargo that is packaged into the forming vesicle. As more oat proteins are added, they shape the surrounding molecule into a sphere. Once a coated vesicle pinches off, the coats falls off, and the cargo-filled vesicle is ready to travel to its’ destination.

THE EVOLUTION OF THE CELL

Some of the oldest cells on Earth are single-cell organisms called bacteria. Fossil records indicate that mounds of bacteria once covered young Earth. Some began making their own food using carbon dioxide in the atmosphere and energy they harvested from the sun. This process (called photosynthesis) produced enough oxygen to change Earth's atmosphere. Soon afterward, new oxygen-breathing lifeforms came onto the scene. With a population of increasingly diverse bacterial life, the stage was set for some amazing things to happen. Mitochondria and chloroplasts have striking similarities to bacteria cells. They have their own DNA, which is separate from the DNA found in the nucleus of the cell. And both organelles use their DNA to produce many proteins and enzymes required for their function. A double membrane surrounds both mitochondria and chloroplasts, further evidence that each was ingested by a primitive host. The two organelles also reproduce like bacteria, replicating their own DNA and directing their own division. Mitochondrial DNA (mtDNA) has a unique pattern of inheritance. It is passed down directly from mother to child, and it accumulates changes much more slowly than other types of DNA. Because of its unique characteristics, mtDNA has provided important clues about evolutionary history. For example, differences in mtDNA are examined to estimate how closely related one species is to another.

CELL SIZE AND SCALE

The smallest objects that the unaided human eye can see are about 0.1 mm long. That means that under the right conditions, you might be able to see an amoeba proteus, a human egg, and a paramecium without using magnification. A magnifying glass can help you to see them more clearly, but they will still look tiny. Smaller cells are easily visible under a light microscope. It's even possible to make out structures within the cell, such as the nucleus, mitochondria and chloroplasts. Light microscopes use a system of lenses to magnify an image. The power of a light microscope is limited by the wavelength of visible light, which is about 500 nm. The most powerful light microscopes can resolve bacteria but not viruses. To see anything smaller than 500 nm, you will need an electron microscope. Electron microscopes shoot a high-voltage beam of electrons onto or through an object, which deflects and absorbs some of the electrons. Resolution is still limited by the wavelength of the electron beam, but this wavelength is much smaller than that of visible light. The most powerful electron microscopes can resolve molecules and even individual atoms.

MEMBRANES ORGANIZE CELLULAR COMPLEXITY

Membranes organize proteins and other molecules enabling the cell to run much more efficiently than if everything were floating freely. Mitochondrial membranes, for example, keep protein assembly lines together for efficient energy production. And the lysosome safely holds enzymes that would destroy essential proteins if released into the cytoplasm. Membrane-enclosed vesicles form packages for cargo so that they may quickly and efficiently reach their destinations. In this way, membranes divide the cell into specialized compartments, each carrying out a specific function inside the cell. Phospholipids provide the framework for all membranes in the cell. Phospholipids are made up of a phosphate head region and a lipid tail region. The two ends of a phospholipid have very different chemical properties. The head end is attracted to water, while the tail end moves away from water. Phospholipids with their embedded proteins form a dynamic, fluid environment. Individual proteins and phospholipids flow freely. Complexes of proteins and specific subtypes of phospholipids form "rafts" that move through the membrane. Organelles stretch and bend and even flow through the cell. Fluid membranes allow cells to be dynamic and responsive to their environment.

PhotoLab

PROBLEM

Will changing the temperature of the plant’s environment affect its rate of photosynthesis?

HYPOTHESIS

If the temperature of the plant’s environment is increased, then the rate of photosynthesis will also increase and result in a faster production of bubbles.

INDEPENDENT: temperature of water

DEPENDENT: rate of photosynthesis/production of bubbles

CONTROL: light intensity, amount of carbon dioxide, amount of water, color of light

DATA

Temperature	Bubble Production (1 min)
10	60
25	43
40	22

RESULTS/CONCLUSION

In conclusion, my hypothesis was proven incorrect because my data showed that the lower the temperature was, the faster the production of bubbles. This means that the rate of photosynthesis will be more efficient in an environment of low temperature. Whereas, in the case of high temperature, the bubble production has a significant decrease, showing that the rate of photosynthesis is not as effective in an environment of high temperature. Thus, we can see that changing the temperature low can increase the rate of photosynthesis whereas changing the temperature high can decrease the rate of photosynthesis.

Photosynthesis Virtual Lab

BACKGROUND INFORMATION
Photosynthesis is the process in which plants use light energy, water, and carbon dioxide to produce food. Plants use the food they make for growth and carrying out other life processes. Sunlight is the natural energy source for photosynthesis. White light from the sin is a mixture of all colors of the light spectrum: red, orange, yellow, green, blue and violet. Light can either be absorbed or reflected by substances called pigments. Most plants are green because the pigment chlorophyll reflects green and yellow light and absorbs the other colors of the spectrum.

PROBLEM

Which colors of the light spectrum are the most important for plant growth?

HYPOTHESIS

If each plant were to grow under a blue light source, then the height of the plants will be taller in comparison to other light colors.

If each plant were to grow under a green light source, then the height of the plants will be shorter in comparison to other light colors.

INDEPENDENT: color of light

DEPENDENT: height of each plant

CONTROL: soil, moisture, water, temperature

PROCEDURE

1. Click the “Video” button. Watch the animation to learn about how light affects photosynthesis.
2. Make a hypothesis about which part of the light spectrum causes the most plant growth and which part of the light spectrum causes the least plant growth. Assume that all conditions except the color of the light are the same for the seed as it grows.
3. Test your hypothesis by choosing different plant seeds and observing how the plants grow under different colors of light.
4. Choose the type of seed that you want to test and click its seed packet.
5. Click the arrow on the color display to select a color light filter for each set of three plants.
6. Start the experiment by clicking the light switch to the “ON” position.
7. Observe the plant growth.
8. Click the ruler and drag it to each plant to measure the height. Use the calculator to average the heights of the three plants under each color light filter. Record your calculation in the Table.
9. Click the “Reset” button. Repeat the experiment using a different color light filter and same type of seed.
10. After all the color filter have been tested on one seed, conduct the experiment again with another type of seed to verify your conclusions.

DATA/GRAPH

Filter Color	Spinach Avg. Height (cm)	Radish Avg. Height (cm)	Lettuce Avg. Height (cm)
Red	18	12.6	11
Orange	14	8	6
Green	3	1	3
Blue	19	14	12
Violet	16.3	10	8.3

RESULTS/CONCLUSION

In conclusion, my first hypothesis was proven incorrect whereas my second hypothesis was supported. In fact, my results showed that the color blue rather than the color violet would be more efficient towards faster plant growth in terms of photosynthesis. On the other hand, my results also showed that the color green has the least effective plant growth in comparison to the other colors of light. Thus, we can conclude that the color blue from the light spectrum is the most significant for plant growth.

JOURNAL QUESTIONS

Human Biology/Karyotypes Summary

BLOODTYPES

An allele is one of several different forms of genetic information that is present in our DNA at a specific location on a specific chromosome. Human blood type can determined through co-dominant alleles. In fact, human possess three different alleles for human blood type, which include A, B, and O. Now everyone of us possess two ABO blood type alleles, since we each inherited one blood type allele from our biological mother and one from our biological father. Since there are three different alleles, there are a total of six different genotypes at the human ABO genetic locus.

COLOR BLINDNESS

Color blindness is generally a X-linked recessive trait. In fact, red-green color perception defect is the result of a mutation on the X-chromosome, yet the defect manifest itself only upon females when both X-chromosomes are mutant. Males, in comparison, would inherit red-green color blindness if they inherited only one mutant X-chromosome with the defect. Essentially, color blindness is a sex-linked trait.