Module 2 - All cells arise from other cells Flashcards
What is the cell cycle?
A series of events hat occur during cell division as one parent cell divides to make 2 daughter cells
What is mitosis?
The mechanism of cell division that occurs in cells called somatic cells diving one parent cell into 2 daughter cells
What is the longest stage of the cell cycle and explain its function
Interphase. It has a gap 1 phase where the cell grows and makes a new set of organelles and proteins for the daughter cell. Synthesis stage where cellular DNA is replicated and daughter cells get one each. Finally gap2 phase where cell growth continues and there’s synthesis of special proteins
What is the order of mitosis?
Interphase, prophase, metaphase, anaphase and telophase
What happens in prophase?
Chromosomes condense as they become shorter and thicker therefore making the visually visible. Cells contain 2 organelles called centrioles that move to each pole. These contain spindle fibres that span across the cell forming a spindle apparatus. The nuclear envelope and nucleolus breaks down realising chromosomes into cytoplasm.
What happens in Metaphase?
This is when chromosomes are now seen as 2 chromatids one of each containing DNA from each parent cell. This is when the spindle fibres attach to the centromere of the cell and pulls them along the spindle apparatus to form a line along the equator.
What happens in Anaphase?
This is when the spindle fibres pull the 2 chromatids apart and pull them back to each pole of the cell. The energy is supplied from the mitochondria.
What happens in Telophase?
Chromosomes now reach their receptive poles and appear as longer and thinner until they disappear completely. Nuclear envelope reforms so the cell now has 2 nucleus.
What happens in cytokinesis?
Cytokinesis is where the cytoplasm splits forming 2 daughter cells. Each daughter cell is identical to the parent.
What is mitosis important for?
Growth, repair and asexual reproduction
What does it mean that plants don’t have centriole?
This means that spindle fibres will come straight from the cytoplasm.
What is the process called that prokaryotes divide by?
Binary fussion
How does the process of binary fusion work?
Circular DNA molecules replicate and attach to the cell membrane. Plasmids also replicate. Cell membrane grows between the 2 DNA molecules and begins to pinch inwards, dividing the cytoplasm into 2 dividing original cell into 2 identical daughter cells.
What type of organisms are prokaryotes?
Unicellular organisms
How do viruses replicate?
Attach to the host cell using the proteins on their surface. They inject host cells with nucleic acid containing ‘instructions’ on metabolic processes to start producing the viral components. These are then assembled into new proteins
What are examples of viral components?
Nucleic acid, enzymes, structural proteins
What is cancer?
Uncontrolled growth and the division of cells from a result of damage to genes that regulate mitosis and the cell cycle
Where is a tumour most commonly found?
Breast (female), prostate gland (male) and lungs
How does a tumour become cancerous?
If it changes from benign to malignant forming secondary tumours that travel through the blood stream.
Malignant vs benign tumours
Malignant grow rapidly, are less compact and are more likely to be life-threatening. Benign is the opposite
One treatment for cancer
Chemotherapy
What happens in chemotherapy?
They disrupt the cell by preventing DNA from replicating and inhibiting the metaphase stage of mitosis by interfering with spindle formation.
Why does chemotherapy cause hair loss?
Chemo targets cells that divide rapidly. Similar to other cells like hair-producing cells that divide rapidly, this will cause these cells to die meaning hair is likely to fall out.
Mitosis required practical.
Heat 1mol dm^-3 HCL at 60 degrees in a water bath. Then use a scalpel to cut the root tip. Transfer sample to HCL and incubate for 5 mins then remove and wash in distilled water. Remove tip using scalpel. Place tip on microscope slide and use mounted needle to break open tip and add a few drops of stain. Carefully place down cover slip on slide. Place onto a microscope and set objective lens on lowest magnification. Use coarse adjustment lens to move lens down slid and use fine adjustment knob to re-adjust focus until image clear.
What is the purpose of using stain?
Stain makes chromosomes visible therefore showing which cells are undergoing mitosis.
What is the purpose of carefully placing the coverslip onto the slide?
Prevents air bubbles so no distortion to the image.
What is the purpose of ensuring the cover slip doesn’t slide sideways?
This is to ensure that their is no damage to the chromosomes.
How do we calculate mitotic index?
Number of cells undergoing mitosis/number of cells in total
Risk assessment of HCL and using scalpel.
HCL = can cause irritation to eyes and skin. Wear googles and avoid skin contact. If contact then rinse/wash immediately. Low risk Scalpel = can cause cuts. Use away from fingers and keep away from edge of desk. If cut apply pressure, seek medical assistance and evaluate cut. Low risk
