I have come across this website about overview of two different plant Cells namely . The article gives me a holistic view of the Plant Cell.

Two types of different Plant Cells.

The eukaryotic cell is composed of 4 main parts:

cell membrane - outer boundary of the cell
cytoplasm - jelly-like fluid interior of the cell
nucleus - the "control center" of the cell, contains the cell's DNA (chromosomes)
organelles - "little organs" that carry out cell functions





Prokaryotes are very simple cells, probably first to inhabit the earth.
Prokaryotic cells do not contain a membrane bound nucleus.
Bacteria are prokaryotes.
DNA of bacteria is circular.

The word "prokaryote" means "before the nucleus"

Different cells and their functions

There are many different cells in the body, and all of them are created to perform a specific duty or function. Here are some of the more commonly know cells:

The red blood cell. These are cells that are shaped like biconcave disks and they lack a nucleus and other common cell parts. Their duty is to deliver oxygen to other body parts via the blood flow in the circulatory system. They will pick up the oxygen from the lungs and then will release it while sqeezing through the capillaries. The cytoplasm of a red blood cell is rich in a chemical known as haemoglobin, which gives the blood its red colour and can bind oxygen to the cell.

Red blood cells are usually about six to eight microns in diameter.

The nerve cell, or neuron, is a cell that is electrically excitable and its function is to process and transmit information to the brain via electrical and chemical signalling. A typical nerve cell comprises a body, dendrites (filaments that arise from the cell body) and an axon (a special filament that also arises from the cell's body). Neurons are highly variable in size, and range from 4 microns to 100 microns.

The human egg cell is a gamete, or reproductive cell, that is produced by women in the ovaries. It is the largest cell in the human body, with a diameter of up to 120 microns and can be seen with the naked eye. When a sperm cell fuses with it, fertilisation occurs, and the fertilised egg becomes a zygote. It then starts to develop into a human foetus.

The sperm cell's name is derived from the Greek word sperma, meaning seed. It is an appropriate name, as the sperm is the seed that decides the sex of a baby after fertilasation of the egg cell. A sperm cell has a head, which contains a nucleus and chromosomes; many mitochondria, to aid in movement; and a tail that enables it to mive independently. Sperm cells have a head 5 microns by 3 microns, and a tail 41 microns long.

Cells (further info) (contd.)

A eukaryotic cell is at least 15 times larger than a prokaryotic cell. It is also up to 1000 times greater in volume. The eukaryotic cell is more complex, and contains specific parts that carry out specific functions. One thing that a eukaryotic cell has that a prokaryotic cell doesn't have is a nucleus that contains genetic material and DNA, and this is how the eukaryotic cell gets its name, as eukaryotic stands for "true nucleus".

Cells (further info)

There are actually not one, but two different types of cells: prokaryotic and eukaryotic.

A prokaryotic cell is simpler than the other type of animal cell, and is therefore smaller. It lacks a nucleus and other characteristics that are usually present in eukaryotic cells. Bacteria and archaea are two examples of prokaryotic cells.

As afore mentioned, a prokaryotic cell has a simpler architecture structure than its counterpart, with flagella and pili protruding from the cell's surface. Surrounding the cell is a cell envelope consisting of a cell wall and a plasma membrane. Inside this outer covering is the cell's cytoplasmic region, with DNA, ribosomes, and other inclusions.

Reflection on my Science Lessons (up to date)

These days, I find that I can remember facts better, and I can do my work without much trouble at all. So, I have high hopes for the next science test.

At the moment, I'm now starting on a new chapter in biology - cells. Originally, I always had problems trying to absorb facts and the lesson in general, as I was half asleep and could barely stay awake to listen to the lesson. So, it was no suprise when I failed my chemistry test.

However, now I am able to stay awake better, as I get sufficient sleep and can stay awake during lessons, even if they're boring. Therefore, I expect myself to be able to think better, and I should be able to score better for the coming tests.

Singapore's new aquatic science centre

I read up in the paper that the Straits Times sent reporters to the Aquatic Science Centre to see some of the state-of-the-art equipment that they use to develop eco-friendly and sustainable water management soutions.

This building, which is two-thirds the size of a soccer field, has many research facilities and structures, such as a 37.5 metre-long bio-flume that replicates near-natural conditions for scientists to study how organisms interact in a natural aquatic environment.

Even the structure contributes to the research of the scientists who work in the facility: the roof is built for collecting rainwater for analysis and research.

Through this article, I realise that there are actually people who care about the world's growing water crisis and are researching day and night to save it.

My Reflection on Science Lab sessions

So far, I'm quite enjoying my Science Lab sessions on Mondays. Though some of my experiments and practicals were a failure, such as the time when I tried to view cells under a microscope, or the time when I attempted chromatography of black ink.

However, some experiments went well, especially our first experiment for chemistry.

Therefore, I'd like to say that my science lessons have been fun, and, though my science results have been terrible, I'd like to continue doing such fun experiments during Monday lab sessions.