Chapter 5- Mitotic cell cycle Flashcards
what is the cell cycle
A sequence of events that takes place between one cell division and the next
the combination of DNA and protein Is called a
chromatin
What are chromosomes
these are structures made up of one very long condensed DNA molecule
what is the role of histone proteins
These condense and organise DNA tightly so as to to fit into the nucleus
describe the structure of a full chromosome from DNA
1-DNA
2-Histone proteins
3-chromatin
4-chromatid
5-chromosome
why is it important to ensure the 2 chromatid sisters are identical
-these is so that the 2 daughter cells formed are genetically identical as they contain the same DNA
the ends of chromatids are sealed with protective structures called
_________________
telomeres
chromatin exists in 2 forms
euchromatin- loosely coiled
heterochromatin- tightly coiled
what is mitosis
A nuclear division that produces 2 genetically identical daughter nuclei each containing the same number of chromosomes as the parent
the mitotic cell cycle consists of
-Interphase
-Mitosis division
-cytokinesis
what takes place in the S phase for interphase
-the synthesis phase involves DNA replication so that each chromosome consists of 2 identical chromatids
What takes place in the G1 phase
GROWTH: Here the production RNA, enzymes and proteins are made.
What takes place in the G2 phase
-This phase checks if there were any errors in DNA before going to mitosis. These errors are fixed at this stage
what are the 4 main stages in order of mitosis
1-prophase
2-metaphase
3-anaphase
4-telophase
what takes place in early and late prophase
EARLY- the chromosomes start to be visible and coil and shorten up
>nucleus wall is still intact
>centrosomes duplicate
LATE-the chromosomes consist of paired chromatids
>nucleus begins to break down
>centrosomes begin to move opposite sides of the cell.
what takes place in metaphase
-spindles attach to the centromeres
-Centrosomes are at opposite poles chromosomes line up across the equator
-chromosomes split from their centromeres and the chromatids start to be pulled apart.
What takes place in anaphase
-the now chromatids move from the equator to the opposite poles pulled by microtubules
What takes place in telophase
-Nucleus and nucleus envelope reform
-The chromatids uncoil and thin up
-remains of the spindle fibres will break down
-cytokinesis occurs and the cell spilts into two.
Describe the roles and function of the centromeres
-centromeres is needed for the splitting of the chromatids during mitosis
-acts as a site for attachment of spindle microtubules
-there are 2 kinetochores
What are the biological significance of mitosis
-Growth
-repair of damaged tissues
-replacement of cells
-asexual reproduction
-immune response (clonal expansion)
What is the main function of telomeres
To ensure that when DNA is replicated the ends of the molecule are included in the replication and not left out. Therefore to prevent loss of genes during cell division and to allow continued replication.
What is a stem cell
Stem cells are cells that can divide multiple times by mitosis
What is potency of a stem cell
Refers to the extent of the power of a stem cell to produce different cell types
what are totipotent, pluripotent and multipotent stem cells
Totipotent- stem cells that can form any type of cell in a body
Pluripotent- Stem cells that form any type of cell that make up the body
Multipotent- stem cells that can develop into more than one cell type
what is cancer a result of
the uncontrolled cell division of mitosis forming a tumour
any agent that causes cancer is called a
carcinogen
What do tumours do to the body
-Damage and invade the body tissue
-interfere with the normal functioning of the area they have started to grow
-block the intestines lungs or blood vessels
What are second growths referred to as
metastasis
