the cell cycle and its regulation Flashcards
define cytokinesis
cytoplasmic division following the nuclear division , resulting in 2 new daughter cells
define interphase
phase of the cell cycle where the cell is not dividing ; it is subdivided into growth and synthesis phases
define mitosis
type of nuclear division that produces daughter cells genetically identical to each other and the parent cell
how do cells reproduce ?
by duplicating their contents and then splitting into 2 daughter cells
what can researchers observe under the microscope to with cell division ?
- they can easily see the behaviour of chromosomes during mitosis ( nuclear division )
- followed by cytokinesis (cytoplasmic division) resulting in 2 daughter cells
what is the M phases ?
when both nuclear division and cytoplasmic phase which only occupies a small part of the cell cycle
what is the purpose of interphase ?
- elaborate preparations are being made for cell division –> in a carefully ordered and controlled sequence with checkpoints
what is the order of the cell cycle ?
interphase
(G0–> G1 –> S –> G2)
m phase
(mitosis –> cytokinesis )
what is interphase ?
when the cell grows and prepares to divide
what are the 2 main checkpoints of the cell cycle ?
-G1/S checkpoint and G2/M checkpoint
where else are there checkpoints ?
one halfway through mitosis and one in early G1
what is the purpose of the checkpoint ?
- to prevent uncontrolled division that would lead to tumours (cancers)
- to detect and repair damage to DNA (damaged caused by UV light
what does the molecular events that occur in a specific sequence ensure that ?
- the cycle cannot be reversed
- the DNA is only replicated once during each cell cycle
how many cycles should the cell normally undergo ?
- about 50
- known as the Hayflick constant
what happens if the cell division becomes uncontrolled ?
it can be become a tumor
what is the difference between benign and malignant tumors ?
benign - non-cancerous , they grow slowly and don’t spread to other parts of the body
malignant - cancerous tumors , they grow uncontrollably and can spread to other parts of the body through a process called metastasis
why are malignant tumors dangerous ?
as they invade healthy tissues and can cause damage to organs
what are proto-oncogenes
- they are normal genes within our cells that help to control cell growth and division
what happens if proto-oncogenes mutate ?
they can become oncogenes (cancer -causing genes ) due to a mutation and if they are overactive
why does the division phase in cancer cells take the same amount of time as in non-cancerous cells ?
- they go through the same process but in cancer cells they divide more often but their M phase isn’t happening faster, they just tend to have a shorter interphase
- they have a shorter interphase as they skip some checkpoints and have faulty DNA repair
what is apoptosis ?
a natural process of programmed cell death
why is apoptosis important ?
- to remove damaged or unnecessary cells
-during development it helps to shape the body - to prevent disease can stop the growth of cancer cells. if ti has damaged DNA could lead to cancer
how does apoptosis work ?
it goes through several steps
- signal to die
- cell shrinks
- cell membrane changes
- breaks into fragments - called apoptotic bodies and then engulfed
why does apoptosis matter for cancer ?
- if it doesn’t happen properly damaged cells might keep dividing
–> can lead to cancer
–> cancer cells can sometimes escape apoptosis –> reason for why they keep growing and dividing uncontrollably
