mitosis Flashcards
eukaryotic cell cycle
– Cell grows.
– DNA is replicated.
– Mitotic cell division produces daughter cells identical to the parent.
– Repeat.
The timing of replication and cell division is highly regulated.
what is cell division
Cell Division — process by which a cell divides into 2 new cells
why do cells need to divide
Living things grow by producing more cells, NOT because each cell increases in size
Repair of damaged tissue
If cell gets too big, it cannot get enough nutrients into the cell and wastes out of the cell
what happens before cell division
Before cell division occurs , the cell replicates (copies) all of its DNA, so each daughter cell gets complete set of genetic information from parent cell
Each daughter cell is exactly like the parent cell – same kind and number of chromosomes as the original cell
how do unicellular organisms reproduce
Many organisms, especially unicellular organisms, reproduce by means of cell division – called asexual reproduction – Ex: bacteria
DNA
DNA is located in the nucleus and controls all cell activities including cell division
Long and thread-like DNA in a non-dividing cell is called chromatin
Doubled, coiled, short DNA in a dividing cell is called chromosome
Consists of 2 parts: chromatid and centromere
chromosome structure
2 identical “sister” chromatids attached at an area in the middle called a centromere
When cells divide, “sister” chromatids separate and 1 goes to each new cell
2 major phases of eukaryotic cell cycle
Interphase (3 stages)
– DNA is not condensed
Mitosis (4 stages + cytokinesis)
– Nuclear division & division of cytoplasm
– DNA condensed
cell cycle
Cell Cycle – series of events cells go through as they grow and divide
Cell grows, prepares for division, then divides to form 2 daughter cells – each of which then begins the cycle again
interphase
Interphase—period of cell growth and development
DNA replication (copying) occurs during Interphase
During Interphase the cell also grows, carries out normal cell activities, replicates all other organelles
The cell spends most of its life cycle in Interphase
three sub-stages of interphase
Gap 1 – cell grows in size
– organelles replicated
Synthesis – replication of DNA
– synthesis of proteins
associated with DNA
Gap 2 – synthesis of proteins
associated with mitosis
What is mitosis
Division of somatic cells (non-reproductive cells) in eukaryotic organisms.
A single cell divides into two identical daughter cells.
Daughter cells have same number of chromosomes as does parent cell.
why does mitosis occur
So each new daughter cell has nucleus with a complete set of chromosomes
When the cell is not dividing…
DNA molecules are in extended, uncondensed form = chromatin
Cell can only replicate and transcribe DNA when it is in the extended state.
When the cell is preparing for division…
DNA molecules condense to form chromosomes prior to division.
each chromosome is a single molecule of DNA
easier to sort and organize the replicated DNA into daughter cells
