Mitosis Flashcards
How many cells are produced in mitosis?
Two daughter cells with the same number of chromosomes
How many chromosomes are found in eukaryotic cells?
Diploid
How many chromosomes are found in prokaryotic cells?
Haploid
What is mitosis?
Division of cells where the daughter cells have an exact copy of the DNA of the parent cell
What proceeds mitosis?
Interphase
What occurs in interphase?
Replication of DNA
Replication of organelles
What is the structure of a chromosome?
Two chromatids joined at a centromere
Said to be tightly packed DNA
What are the stages of mitosis?
Prophase
Metaphase
Anaphase
Telophase
What occurs immediately after mitosis?
Cytokinesis
What step in mitosis and what occurs in prophase?
DNA condenses, chromosomes form
Breakdown of nuclear membrane
Centrioles move to opposite ends (animal)
From which spindle fibers develop (called spindle apparatus)
Nucleolus and nuclear envelope disappears
Chromatids drawn towards equator by spindle fibers which are attached to centrometers
Why are the centrioles not essential for the spindle apparatus?
They aren’t present in plant cells but spindle fibers still form
What happens in metaphase?
Chromatids visible
Align on the metophase plate
Caused by microtubules
What happens in anaphase?
Centromeres divide
Sister chromatids move to opposite poles
Energy provided by mitochondria
What happens in telophase?
Nuclear membrane reforms
Chromosomes decondense to chromatin
Spindle fibers disappear
Nuclear envelope reforms
What happens in cytokinesis?
Cytoplasm divides
Parent cell becomes 2 daughter cells with identical genetic information
Actin ring divides
What is the difference when plant cells undergo mitosis?
Plant cells don’t change shape before division
Cell plate forms to divide cells (lamella)
Eytokinin causes process
What causes mitosis in animals?
Many different hormones
What is a centriole?
Organelle which forms the spindle fibers in animal cells
Go to poles in prophase
Not found in plant cells
Where does mitosis occur in animals?
Bone marrow and many epithelia
Where does mitosis occur in plants?
Meristems (roots and shoots)
What cell division occurs in prokaryotic cells?
Binary fission
What is binary fission?
The circular DNA replicates and attach to cell membrane
Plasmids replicate
Cell membrane grows between DNA and begins to split
New cell wall forms between DNA
What is the replication of viruses?
Virus attaches to cell surface DNA injected into the cell (virus outside) Replication in nucleic acid New protein coats synthesized by cell Mature cells form and ruptures
Why can viruses not undergo cell division?
They are non-living
When does mitosis occur?
Growth
Repair
Reproduction (single-celled)
What is the mitotic index?
Proportion of cells in each stage of the cell cycle
Proportion of time each cell takes to go through the stage
Average % of cells dividing
What is the mitotic index equation?
Number of cells dividing / total cells x 100
What is cancer?
Group of diseases caused by a growth disorder in cells
How are cancer cells formed?
Damage of genes that regulate mitosis and cell cycle
What is a tumour?
Uncontrolled growth to form a growth of abnormal cells
What are the three stages of the cell cycle?
Interphase
Nuclear division
Cytokinesis
When does a tumour become cancerous?
When it changes from benign to malignant
What can cause uncontrolled mitosis?
Environmental factors
Mutation in genes
What is the treatment of cancer?
Killing divining cells by blocking the part of the cell cycle
Prevents DNA from replicating
Inhibiting metaphase by interfering with spindle formation
What is the problem with cancer treatment?
Kills other cells that are dividing (hair cells)
