B1.1 What makes a cancer Flashcards
What is cancer ?
The uncontrollable growth of abnormal cells in the body
What does malignant cells mean/ refer to ?
Cancerous cells
What is meant by the uncontrollable growth of cells ?
Where regulation of cell proliferation is compromised, allowing cells to grow free from their usual constraints.
What is meant by abnormal cells ?
Differ in behaviour to normal cells
True or false?
Cancers are simply too many cells.
False.
Cancer aren’t simply too many cells, but too many badly behaved cells.
What are the defining features of cancer cells ?
Accumulation of abnormal cells due to:
- Increase in division
- Decrease in cell death
This can be one or the other but most like to be both of these factors at the same time
What are the three states that cells can be in within a tissue ?
- Dividing
- Dying
- Quiescent
What is the meaning of quiescent ?
Cells which just do their job without dying or dividing but can change their behaviour to divide or die in response to a stimuli
What is a gene ?
A bit of DNA that does the job. A functional sequence of DNA
What is meant by gene expression? What does this control in relation to cancer?
How genes are switched on and off, or up and down. This controls whether cells proliferate or apoptoses (or do neither)
What is the language of protein coding genes ?
Triplet genetic code
What organelle carries out protein synthesis ?
Ribosomes
True or false?
The sequence of nucleotides in the double helix spells out the code to direct protein synthesis by ribosome
True
What are errors in the genetic code caused by ?
Mutations-
What is a mutation ?
Changes in genetic information
Give examples of how changes in genetic information occurs
Addition, removal or swapping of nucleotides either individually or as longer sections of DNA
Explain why mutations are not strictly random?
Although we cannot predict when or where mutations can occur within a gene, some genes are more susceptible to mutation than others.
How do cells control mutations ?
Cells can not control whether a mutation will take place or not therefore we cannot predict where or when specific mutations will occur
How many genes do we have ?
Around 20 thousand
Are all genes within cells ?
Yes, all genetic information is in cells however not all genes are expressed within that particular cell
What kinds of MUTATIONS do we need to worry about in terms of cells in cancers?
- Accumulation of small detrimental mutations that change the cells behaviour without killing or disabling the cell
- Mutations that increase the likelihood hood of proliferation and decrease the likelihood of apoptosis
What causes cells to divide ?
Cells sensing and responding to stresses and signals. Nature of the response depends on the gene product
How can mutations promote proliferation ?
Increasing the activity or abundance of gene products that promote proliferation but can also decrease the activity an abundance of gene products that protect against runway proliferation
How can mutations have an effect on the active site of an enzyme ?
- changing shape of active site - substrate binding domaine and change substrate specificity
- disable the catalytic activity and enter the protein inert
- receptors may be constitutively active, meaning they’re permanently detecting their logins and signal constantly to other proteins
- amount of protein
What is transcription (RNA synthesis) ?
The process in which genetic information is converted from DNA into RNA
What is transcription performed by ?
RNA polymerase II or pol II
What is transcription regulated by?
Transcription factors that recognise DNA a sequences near the start of the gene
How is the amount of RNA produced regulated ?
Promotors (or DNA sequence) acts as switches or volume controls to regulate the amount of RNA that is transcribed from each gene.
What is the effect of mutations in promotors ?
Increase or decrease activity. Some mutations can increase promotors activity others will decrease it
What are the two groups that cancer genes are divided into ?
Proto-oncogenes
Tumour suppressor genes
What is a proto-oncogene ?
A gene that has gene products that promote cell proliferation and decrease cell death
What is tumour suppressant genes ?
Genes that reduce cell proliferation and induce cell death
True or false?
The balance of Porto-oncogenes and tumour suppressant genes determine whether or not cells develop into cancer
True
Why are proto-oncogenes not intrinsically harmful ?
We need them as part of out health cell cycle to allow tissue growth and replenishment if old or redundant cells
What is the name if when Porto-oncogenes mutate, becoming over expressed or give rise to over active gene product ?
Oncogene - meaning cancer
True or false?
Tumour supperesor genes are important safeguards against oncogenesis or cancer formation?
True
What happens when tumour suppressor genes mutate ?
They lose their protective abilities and cancers can form
How does mutation phenotype occur?
Genes that encode proteins needed for DNA repair and the removal of mutations. This causes further mutations to accumulate more rapidly and can lead to the vicious cycle of mutation phenotype
What is mutation phenotype ?
Mutated DNA repair genes that allows the accumulation of further mutations which further damages the DNA repair systems
