3 lecture 2 Flashcards
do cells make mistakes
yep
what is an example of a mistake a cell makes
lagging chromosomes
why do chromosomes lag behind
some just take longer than others to separate
what is a euploid cell
have correct number of chromosomes
do lagging chromosomes cause problems
they can
how do lagging chromosomes cause problems
the lagging chromosome will be trapped in the spindles mid zone during anaphase
the trapped chromosome will be trapped and damaged in the process of the cell splitting
is it quick to fix mistakes int he cell
nope
is cell division a controlled process
Cell division is a tightly controlled process
what ensures that there are no mistakes in a cell
Proteins survey the condition of the cell at each step
If a mistake is detected, what happens
normal cells halt at checkpoints and make repairs
what must happen in order for cells to proceed with division
Cell must pass the survey to proceed with cell division
what are the 3 major checkpoints
3 major checkpoints: G1,G2, and metaphase
do the checkpoints have a fixed amount of time that they go on for
checkpoints monitor the processes and impose a delay as needed
what is checked in the g1 checkpoint
is cell division necessary
are growth factors present
is the cell large enough
are suficient nutrients available
what is checked in the s checkpoint
nothing really
what is checked in the g2 checkpoint
what DNA replicated correctly
is the cell large enough
what is checked in the metaphase checkpoint
are all the chromosomes attached to microtubules
what happens if the daughter cells are not the exact same size
daughter cells may not be exactly the same size, so the smaller one will take longer to reach the cell size threshold and and will be in G1 phase for longer
what does Mitosis do
produces two genetically-identical nuclei
what happens if even one chromosome is wrong
chromosome attachment is monitored if even one is wrong, anaphase is delayed
can mistakes happen in healthy cells
yep
what is disease, if mistakes also happen in healthy cells
it is the failure to detect and correct mistakes that lead to disease
what are the 2 origins of cancer
oncogenes
tumour suppressors
what is oncogene
losing control
what are tumour suppressors
losing a checkpoint
cancer is the result of what
defects in checkpoint or repair systems
what typically are the ones that turn into oncogenes
growth factors
what are growth factors
stimulate cells to divide
how do growth factors work
Growth factors bind to receptors to trigger a response from a cell
what is a Mutation:
a change in the sequence of DNA
Changes to DNA can change what
Changes to DNA can change the structure and function of the protein coded by the DNA
what causes mutations
Mutations may be inherited or caused by carcinogens
what are Proto-oncogenes
genes that code for cell cycle control proteins
what happens When proto-oncogenes mutate
When proto-oncogenes mutate, they become oncogenes
Their proteins no longer properly regulate cell division
They usually overstimulate cell division
what are the 3 paths to cancer (oncogenes)
1– translocation or transportation: gene move to new locus, under new controls… this leads to normal growth-stimulating protein in excess
2– gene amplification: multiple copies of the genes…. normal growth-stimulating protein in excess
3– point mutation within the gene: oncogene: hyperactive or degradation-resistant protein: excess growth
what are Tumor suppressor genes:
genes for proteins that stop cell division if conditions are not favorable
what happens when Tumor suppressor genes are mutated
When mutated, can allow cells to override checkpoints
what happens when oncogene and tumour suppressor mutations occur
= bad
Depending on the number of mutations and whether the tumor suppressor protein is functional will determine whether it is a benign or malignant tumor that is formed
what is the Multiple hit model
process of cancer development requires multiple mutations
what is the 2 hit hypothesis
Some mutations may be inherited (familial risk)
Most are probably acquired during a person’s lifetime
progression from a benign tumor to cancer requires many mutations and results in what
a constellation of defects
what are the 2 types of results that can happen from mutation (on a cellular function level)
Loss of contact inhibition:
Loss of anchorage dependence:
what is Loss of contact inhibition
cells will now pile up on each other
what is Loss of anchorage dependence
enables a cancer cell to move to another location
is Loss of contact inhibition definitely cancerous
can be part of benign
is Loss of anchorage dependence definitely cancerous
big indicator of cancerous
what is Immortalized:
cells no longer have a fixed number of cell divisions due to an enzyme called telomerase
what is the difference between malignant and benign tumours
malignant– (cancer) cells invade neighbouring tissues, enter blood vessels, and metastasize to different sites
benign– (not cancer) tumour cells grow only locally and cannot spread by invasion or metastasis
give a detailed process of metastasis
primary tumour vascularization detachment intravasion circulating tumour cell adhesion to blood vessel wall extravasation growth of secondary tumour
animal cells need what to divide
telomeres
what is the the relationship between telomere length and age
the relationship between telomere length and age is not understood
Early detection increases odds of survival true or false
true
is there just one way to detect cancer
There are different detection methods for different cancers
what is a Biomarker
Some cancers produce increased amount of a characteristic protein (non-functional or altered)
what is Biopsy
surgical removal of cells or fluid for analysis
what are the ways to detect cancer
Biomarker
biopsy
what are the types of biopsyq
Needle biopsy:
Laparascope:
what is Needle biopsy:
removal is made using a needle
what is Laparascope:
surgical instrument with a light, camera, and small scalpel
what are the types of cancer treatment
Chemotherapy:
Radiation therapy:
what is chemotherapy
drugs that selectively kill dividing cells
Combination of different drugs used (“cocktail”)
Interrupt cell division in different ways
Helps prevent resistance to the drugs from arising
Normal dividing cells are also killed (hair follicles, bone marrow, stomach lining)
what is radiation
use of high-energy particles to destroy cancer cells
Damages their DNA so they can’t continue to divide or grow
Usually used on cancers close to the surface Typically performed after surgical removal of tumor
If a person remains cancer free after treatment for 5 years they are in remission and after 10 years they are considered to be cured
true or false
true
how tough is a tardigrade
the water bear is almost impossible to kill
when dehydrated can go more than than 10 years without food or water;
when hydrated it:
can survive unprotected in space;
extreme temperatures
• A few minutes at 151 °C (304 °F)
• A few days at −200 °C (−328 °F)
• A few minutes at −272 °C (~1 K, −458 °F)
can withstand vaccum and high pressure (>1,200 x);
can survive ionizing and UV radiation that would kill a human
why are they so tough (the tardigrade)
its complicated…
extra copies of genes required to repair DNA
loss of genes that stimulate autophagy in the presence of stress
tardigrade-specific genes that protect DNA (Dsup)
many tardigrade genes function still unknown
