Importance of Cell Division Cell division allows organisms to reproduce, to grow, and to repair damage. Osmosis- the movement of a fluid, usually water, across a membrane toward an area of high solute concentration. Diffusion- a transport mechanism for moving chemicals into and out of the cell, from an area of higher concentration to an area of lower concentration. Active transport- requires chemical energy Passive transport- requires no energy because the molecules move from an area of high concentration to one of low concentration. Hypertonic environment- there’s a net movement out of the cell.
Isotonic environment- there’s no net movement Hypertonic environment- there’s a net movement into the cell. Asexual reproduction- the process of producing offspring from only one parent; the production of offspring that are genetically identical to the parent. Sexual Reproduction- the process of producing offspring by the fusion of two gametes; the production offspring that have genetic information from each parent. The Cell Cycle G1 phase lasts about 10 hours S phase usually takes 5-6 hours to complete G2 phase usually lasts 2-3 hours Mitosis takes about 2 hours The Cell Cycle takes about 18-20 hours.
Mitosis 1. Interphase- Chromosomes are copied Chromosomes appear as threadlike coils (chromatin) at the start, but each chromosome and its copy (sister chromosome) change to sistr chromatids at the end of this phase. 2. Prophase- Mitosis begins (cell begins to divide) Centrioles (or poles) appear and begin to move to the opposite ends of the cell Spindle fibers form between the poles 3. Metaphase- Chromatids (or pairs of chromosomes) attach to the spindle fibers 4. Anaphase- Chromatids (or pairs of chromosomes) separate and begin to move to the opposite ends of the cell.
5. Telophase-Two new nuclei form Chromosomes appear as chromatin (threads rather than rods) Mitosis ends 6. Cytokinesis Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes. Chromosome- thread like structures found in nucleus carrying genetics information inform of genes. Chromatid- one of the two identical stands of DNA that make up a chromosome Parent Cell- the original cell before cell division Daughter Cell- the cell formed after cell division Centromere- each pair of organelles near nucleus involved in the spindle fibers in cell division.
Spindle Fibers- One of a network of achromatic filaments that extend inward from the poles of a dividing cell, forming a spindle-shaped figure. Interphase- the phase of the cell cycle during which the cell performs its normal functions and its genetic material is copied in preparation for cell division. Mitosis- the stage of the cell cycle in which the DNA in the nucleus is divided; the first part of cell division. Cytokinesis- the stage in the cell cycle when the cytoplasm divides to form two identical cells; the final part of cell division.
Cytokinesis in plant cells: Plant cells under-go cell plant information Cytokinesis in animal cells: Animal cells under-go cell furrowing. Cell Division Gone Wrong: Cancer Metastasis- the process of cancer cells breaking away from the original (primary) tumour and establishing another (secondary) tumour elsewhere in the body. Mutation- a random change in DNA Carcinogen- any environmental factor that causes cancer Teratoma- a tumour composed of tissues not normally present at the site (the site being typically in the gonads). Benign tumour- a tumour that does not affect surrounding tissues other than by physically crowding them.
Non- cancerous Malignant tumour- a tumour that interferes with the functioning of surrounding cells; a cancerous tumour. Cancer Treatments Surgery- physically removing the cancerous tissue Chemotherapy- treating cancer using drugs Radiation- using a focused beam or by implanting a radioactive source into the tumour Causes of Cancer Some mutations are caused by carcinogens: environmental factors that cause cancer. Well-known carcinogens include tobacco smoke; radiation, such as X-rays and UV rays from tanning beds and sunlight; some viruses, such as HPV and hepatitis B; certain chemicals in plastics; and many organic solvents.
Imaging techniques may include endoscopy, X-ray, ultrasound, CT scanning, and MRI. Specialized Cells Red blood cells contain hemoglobin that carries oxygen in the blood. The cells are smooth so that they can easily pass through the blood vessels. White blood cells can move like an amoeba to engulf bacteria and fight infection. Skin cells fit together tightly to cover the outside of the body. Protect the cells inside and reduces water loss. Bone cells collect calcium from food. Allow the growth and repair of bones.
Muscle cells are arranged in bundles called muscle fibres. Can contract which makes the fibres shorter and causes bones to move. Sperm cells are able to move independently. They carry DNA from the male parent to join an egg from the female parent. Fat cells have a large vacuole in which to store fat molecules. How cells store chemical energy. Nerve cells are long, thin, and have many branches. Conduct electrical impulses to coordinate body activity. Photophore cells can emit light and are used by animals that are active at night or live deep in the ocean.