Lecture 6: The cell cycle Flashcards
what can effect the length of a cycle?
cell division in eukaryotic cells
regulated by the cell cycle (interphase, mitosis and cytokinesis)
cell division in prokaryotic cells
binary fission
what happens if not everything is in order in the cell ?
it will get aborted or stay in a particular phase
stem cells
Unspecialised (undifferentiated)
Has the ability to differentiate into any type of cell
Found in bone marrow (adult), umbilical cord blood and embryos (ethics)
stem cells in bone marrow
stem cell -> cell division (some are specialised) ->cell specialisation -> specialised cells e.g. nerve cells / muscle cells
cell cycle
Interphase – longest part
Cell growth and DNA replication
Interphase divided into G1, S and G2
Cell division -M phase (Mitosis & Cytokinesis)
Mitosis = nuclear division
Cytokinesis = cytoplasm division
Regulated by check points
what occurs in interphase
the cell grows in preparation for cell division, chromosomes are duplicated with the genetic material (DNA) copied precisely.
what occurs in prophase
chromosomes condense (shorter and fatter) nuclear envelope breaks down
what occurs in metaphase
chromosomes (each 2 chromatids) line up along the middle
checkpoints checks chromosomes are attached to spindle -> G1 phase
what occurs in anaphase
Centromeres divide, separating each pair of sister chromatids.
Spindle contract, pulling chromatids to opposite ends of the cell
what occurs in telophase
Nuclear envelope forms around each set of chromosomes
what occurs in mitosis
the chromosome copies and are separated from each other (moved to opposite ends of the cell)
what occurs in cytokinesis
the cell divides into two daughter cells genetically identical to each other to the parent cell (splitting of the cell)
why do we have check points in the cell cycle
to make sure it is ok for the process to continue.
where do the checkpoints occur
in the G1 check point & Metaphase check point
how to calculate the length of time in phase
observed number of cells at that stage / total number of cells observed x total length of time of cell cycle
mitosis in plant cells
Mitosis can be observed in any tissue that is actively dividing.
A tissue in which it is easy to observe mitosis is the growing tip of a plant root
In plants, mitosis takes place in tissues called meristems (found at the growing tips of shoots and roots) undifferentiated.
Mitotic index
Calculate the mitotic index for your chosen field of view, using the formula
MITOTIC INDEX = NUMBER OF CELLS IN THE FIELD OF VIEW UNDERGOING CELL DIVISION / TOTAL NUMBER OF CELLS IN THE FIELD OF VIEW
(if u can see the nucleus count it)
Cancer
Mitosis is a controlled process (genes)
Mutations
Uncontrolled cell division can lead to the formation of tumours and cancers
Blood/lymphatic system
primary cancer
is where the cancer begins
secondary cancer
is where cancer spreads and grows in other areas
(they are named by where they first began developing)
how many types of tumors are there
x2
what are the types of tumour cells
benign and malignant
