MODEL OF A HUMAN CELL

I made a model of a human cell with all of its internal parts. This was no easy task. The cell is highly organized. I used all sorts of interesting things around my house. I will list the parts and what their function is inside the cell…….

NUCLEUS – I used a fishing bobber, bright orange. The nucleus is in the center of a cell and houses the cell’s genetic material; DNA (deoxyribonucleic acid)

THE CELL - The whole cell is made of Styrofoam colored with crayon. We have millions of them in our bodies.

ROUGH ENDOPLASMIC RETICULUM – I used green yarn. Even though this particular organelle has tunnels, I think it is a good representation. The RER is studded with ribosomes’s given it is rough look. It is associated with the ribosome for protein synthesis.

LYSOSOME- I used a fuzzy yellow ball. These organelles are responsible for intercellular digestive system. They contain powerful hydrolytic enzymes which catalyze hydrolysis reaction. They take up the debris and foreign materials; like bacteria.

ENDOCYTOSIS VESICLE – I used a bottle cap with a marker. The endocytosis occurs when the plasma membrane dips outward and brings in a droplet of extracellular fluid. The lysosomes work very closely with these vesicles. Endo= within

PLASMA MEMBRANE – I used a large freezer bag. The plasma membrane surrounds and protects the cell. It is a protein studded lipid bilayer. It is separated from the extracellular fluid.

SMOOTH ENOPLASMIC RETICULUM – I used red paper. The SER does not contain ribosomes and that is why it is “smooth.” It serves as a central packaging and discharge site for molecules that are to be transported from the Endoplasmic Reticulum.

GOLGI COMPLEX (APPARATUS) – I used a pink pipe cleaner. The vesicles that bud off the Endoplasmic reticulum go to this organelle for processing the raw material into finished products. MITOCHONDRIA – I used green clay and magic marker. The magic marker was to draw the compartments within the mitochondria. It has 2 parts; the cristae, and the matrix. The mitochondria are the energy producing organelle they extract energy from the nutrients in food and transforms it into a usable form for cell activities. Generates ATP (adenosine diphosphate) with cellular respiration.
CILIA – I used green strands from a decorative straw I had. Cilia are the motile, hair like protrusions from the surface of the cell. The are responsible for sweeping away debris. Ie., in lungs it brings up sputum so we can spit it out.
RIBOSOMES – I used large black seeds. These are very important when it comes to protein synthesis because they are referred to as the “work benches.”
VAULT – I used a tip of a crayon. Serves as cellular trunks for transport from nucleus to cytoplasm.
PEROXISOME – I used a red berry (not real). They perform detoxification activities.
EXOCYTOTIC VESICLE – I used green clay with black seeds. These vesicles are opposite of the endocytotic vesicle in whereas they spill out of the cell.

CENTERIOLE – I used a bright orange crayon. They form the mitotic spindle during cell division.

Here is a picture of my completed cell model. I must say, at first I was stressed out about what to use, but I think it came together nicely. It is amazing how all the components or organelles inside the cell work together. The cell is the smallest unit that displays the properties of life.

Unfortunately, I did not get to include the inside of the nucleus, but I did take a picture of what I made. It is a piece of green Styrofoam with the middle cut out. I added water and lots of string to indicate the CHROMATIN; which are the strands of DNA when they are condensed and when they package themselves they are chromosomes.
supplies used for my mitosis or cell division model. Orange fuzzy ball for the nucleolus, straws , glue, large and small shells for the the cell and centromeres, the decorative things on the straws are used for the spindle fibers, paper plates and red and blue yarn for the chromosomes.
I also made a model of how mitosis works. Mitosis is cell division in which the chromosomes replicate before nuclear division, so that each of the two daughter cells receives a full set of chromosomes. There are four phases of mitosis. The picture of the chromatin shows the interphase of mitosis. The four stages are……. I also included the early prophase which is when the centrosomes have duplicated. Chromatin is condensing into chromosomes, and the nuclear envelop is fragmented.

Early Prophase- the picture shows in the shell the nucleolus disappeared, chromatin condensed.

1. PROPHASE – the chromatin condenses and becomes chromosomes. The condensed duplicate strand of DNA, or sister chromatids, remain joined together with the chromosome at the point call the centromere. Cells contain a pair the centromeres. The centromere forms the mitotic spindle during cell division. They divide and the daughter cells move to opposite ends of the cell.

In this picture I am showing the spindle fibers, and in the center of the yarn, the shells, are the centromeres.

2. METAPHASE- The nuclear membrane disappears. The 46 chromosomes each consisting of a pair of sister chromatin's align themselves at the equator of the cell. Each chromosome becomes attached to the spindle by several spindle fibers that extend from the centeriole to the centromere of the chromosomes.

In this picture you can see that for the Metahase all the chromosomes lined up at the equator.

3. ANAPHASE – The centromeres split converting each pair of sister chromatin's into two identical chromosomes, which separate and move towards opposite poles of the spindle. At the end of this phase, an identical set of 46 chromosomes is present in each of the poles, for a total of 92 chromosomes.

In this picture it shows the chromatin's part and become daughter cells.

4. TELOPHASE – The cytoplasm divides through formation and gradual tightening of the actin contractile ring at the midline of the cell. Form two separate daughter cell each with a full set of chromosomes. Spindles fibers disassemble, chromosomes uncoil to chromatin and the nuclear membrane reforms in each new cell.

Daughter cells are formed.

supplies used for DNA protein synthesis
I used clay for my tRNA, pipe cleaners for base pairing the helix of DNA and a poster board to put it on.

The pipe cleaners where not easy to put together, but I managed. In this photo you can see the DNA helix which is starting to unravel to make a mRNA. Also in this picture is the tRNA which translates amino acids to make proteins. I will go into further detail. First here is a better pic of my helix of DNA...................................................................................

In this picture I actually wrote that this is a DNA helix with base pairing. The different color pipe cleaners represent the bases These are the bases in DNA.........

C=Cytosine

G=Guanine

A=Adenine

T=Thymine

Transcription is what happens first. A strand of DNA is used as a template by the enzyme RNA polymerase to synthesis the mRNA (messenger RNA) which in turn leaves the nucleus and goes to the cytoplasm. The coding mRNA sequence can be described as a unit of 3 nucleotides called CODONS, which cause the insertion of a particular amino acid into a protein or termination of translation. Next is TRANSLATION. While the mRNA is in the cytoplasm the ribosomes, which contains the rRNA (ribosomal RNA) binds to it at the start codon, AUG, that is recognized only by the imitator tRNA (transferRNA). Amino acids are linked to the tRNA and bind to the appropriate codon in mRNA by forming complementary base pairing with the tRNA anticodon. In my picture of the model of tRNA and the ribosomes you can see that the ribosomes has two binding sites where codons bind to anticodons. The top of the ribosome is where codons bind to anticodons and the middle where the letters are is a tRNA amino acid is approaching.

The ribosome moves from codon to condon along the mRNA. Amino acids are added one by one translated into polypeptidic sequences dictated by DNA and represented by RNA. At the end a release factor binds to the stop codon terminating translation and releasing the complete polypeptide from the ribosome. RNA has one different base then DNA, which is urasil. Urasil replaces thymine.

I tried to make my explanation short and sweet by not going into much detail. Its hard to believe that all this is happening in our bodies while we are walking around, sleeping, or doing this report!!