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.