Cell lab Unit 1

Model of Cell
I made a model of a living animal cell. To show what the different parts look like and do. The materials that I used are as follows; play dough, skittles, a plum, a grape, nuddles, walnuts, rope candy.

The Nucleus is composed of three parts the nuclear envelope, chromatin, and nucleolus. The Nuclear envelope is the outer shell of the nucleus. The chromatin consists of DNA, RNA and proteins that form chromosomes during cell division. The nucleolus is in ribosomal RNA sythesis and the formation of ribosomes.

Endoplasmic Reticulum (ER) is composed of rough ER and smooth ER. Rough ERis studded with ribosomes and in involved in the transportation of materials. While smooth ER does not have ribosomes and synthesizes lipid molecules.

Ribosomes are where protein synthesis takes place.

Mitochondrion are organelles that carry out cellular respiration which produces ATP molecules. Mitochondrion is responsible for producing energy.

Polyribosome are a cluster of ribosomes that simultaneously synthesize protein. Polyribosmoes are connected by a strand of messenger RNA.

Golgi apparatus processes, packages and secretes secretory and synthetic products from the endoplasmic reticulum. The finished product is released into the cell cytoplasm or to the outside of the cell.

Vesicle is a small sac that stores and transports substances.

A lysosome is a vesicle that contains enzymes that digest macromolecules and even cell parts.

Actin filaments are protein fibers that help the movement of the cell and organelles.

Centrioles are cylindrical structures that have microtubules. These form asters during mitosis.

Centrosome is the same region in the cell cytoplasm that contains two centrioles.

Intermediate filaments are also protein fibers but they provide support and strength to the cell.

Cytoplasm a semifluid clearish substance that contains the cytosol, organelles, cytoskeleton, and other particles.

Plasma membrane is the out shell of the cell that allows the entrance and exit of molecules. It is composed of protein and phosholipid.

Microtubules are a tube-shaped protein structure. They help to maintain the shape of a cell and also assist in forming the cell spindle fibers during cell division. They are present in the cytoplasm, centrioles, cillia, and flagella.

Cell Division

The following show the stages of Mitosis, cell division, and what takes place during each stage. For simplicity reasons only four chromosomes are shown in diagrams.

During early prophase the nuclear envelope starts to fall apart and the centrosomes have duplicated and the chromatin in the nucleus starts to change into chromosomes.

By now the nucleolus has completely disappeared and the chromosomes are now visible. The centrosomes start moving away from each other and spindle fibers start forming.

The chromatids are attached to spindle fibers that stretch out from each spindle ploe and overlap.

Sister chromatids represented by the red and blue x's are duplicated chromosomes each one is attached to a spindle fiber by the centromeres and are aligned at the center of the cell. The spindle poles are now at opposite sides of the cell.

Thes sister chromatids part from each other and move in opposite direction towards the spindle poles. This insures that each side receives the same number and kind of daughter chromosomes.

Daughter cells that are exact copies of the parent cell start forming and the nuclear envelopes and nucleoli start to reappear. The chromosomes will become chromatin.

Each chromosome is made up of a double stranded DNA refered to as a double helix. DNA is a nucleic acid and is the genetic material of all organism. Below showns how when the DNA double helix is unwound it resembles a latter. The verticle supports are made up of sugar (S) and phospate (P) molecules and the horizontal steps are complementary bases.

The following is a demonstration of DNA replication which takes place during cell division.

This is the parent DNA molecule (above) which contains "old strands" of hydrogen-bonds by complementary bases if you will. The DNA strand "unzips" allowing new strands to be bonded with the old. Resulting in two final identical strands.

These two diagrams above are showing new complementary DNA nucleotides fit into place by complementary base pairing. For example G's always with C's and T's always with A's. So basically the old strangs in blue combining with the new strands in purple.

To complete the process an enzyme seals any breaks in the sugar-phosphate leaving two identical DNA molecules. Each one has an old strand from the parent and a new strand from the daughter. The replication is complete.

I hope with these diagrams you better understand the parts of a cell, the stages of cell division and how DNA replicates.