The Mitotic Cell Cycle Flashcards
Define mitosis
The division of the nucleus of a cell.
What is chromatin made of?
DNA + histone protein
Define chromatins
A combination of DNA wound around histone proteins.
Define sister chromatins.
They are short and thick structures.
Why do chromatins super coil?
Because of the histone proteins.
Define chromosome.
Thread like structure containing DNA and genes.
Define chromatid.
one of two identical parts of a chromosome, held together by a centromere, formed during interphase by the replication of the DNA strand.
Define telomere.
Repeated short base sequence at the end of the chromosome.
What happens during G1 phase?
- number of organelles increase
- size of cell increases
- volume of cytoplasm increases
Explain why chromosomes condense?
Because when DNA is tightly packed, it makes it easier to separate the chromatids at the centromere into daughter cells.
Define centromere.
The region where chromatids are held together.
Outline the roles of telomere.
- prevents loss of gene
- permits continued replication
- protect ends of chromosomes
What are the three phases during interphase?
1- G1 phase
2- S-phase
3- G2 phase
What happens during G1 phase of the cell cycle?
There is a gap after cytokinesis and before S-phase. 46 chromosomes and chromatids at this phase and producing RNA, proteins and enzymes prepare for growth and DNA synthesis.
What happens during the S-phase?
During this phase DNA synthesis will occur so that each chromosome has two identical chromatids. At this stage there will 46 chromosomes and 92 chromatids.
What happens during G2 phase?
The new DNA will be checked and if there are any error it will be repaired. Also an increase in tubulin production makes microtubules for the formation of a mitotic spindle
The importances of mitosis
- replacement of cells
- repair of tissue
- increase in cell numbers
- asexual reproduction
- maintains the number of chromosomes
- genetically identical to parents
- produces genetically identical daughter cells
- cloning of B and T-lymphocytes during immune response
What happens during prophase?
- chromosomes condense
- nuclear envelope breaks down
- nucleolus disappears
What happens during metaphase?
- chromosomes are lined up at the metaphase plate.
- each sister chromatid is attached to a spindle fiber originating from opposite poles.
What happens during anaphase?
- sister chromatids are pulled apart.
What happens during telophase?
- chromosomes arrive at opposite poles and begin to decondense
- the mitotic spindle breaks down
What happens during cytokinesis?
- in Animal cells: a cleavage furrow separates the daughter cells.
- in plant cells: a cell plate separates the daughter cells.
Define cytokinesis
Division of cytoplasm between daughter cells.
Define stem cells.
Cells that divide repeatedly by mitosis and differentiate into specialized cells or remain as stem cells.
