Stem cells and cancer

Define genome and proteome

• Genome - entire set of genes in an organism

• Proteome - Full range of proteins a cell can produce

Why is the genetic code degenerate?

Each amino acid is coded for by more than 1 codon

When do mutations occur and how (give examples)?

• Occur randomly

• From mutagenic agents like ionising radition, carcinogen and carcinogenic chemicals like tobacoo

What is a weakness of mutations?

Can be passed onto next generation and may change the codon which can change the amino acid leading to faulty protein which leads to disease

What effct can mutations have?

• No effect

• Positive effect - may change phenotype which help organism adapt to environment which increase survival.

What are the 6 types of mutations and define them

• Substitution - One or more bases are exchanges for another

• Deletion - One or more bases are removed from DNA sequence

• Addition - One or more bases are added to the DNA base sequence

• Duplication - One or more bases are duplicated

• Inversion - Sequence of bases is reversed

• Translocation - Sequence of bases is moved from one location to another

What 2 types of mutations are likelt to result in no amino acid change and why?

• Inversion and subsitiuion

• Bc only one base is changed and genetic code is degenerate

What 2 mutations are likley to result in change in amino acid and wht can it lead to ?

• Deletion and Addition

• Bc they can cause frame shift mutation

What is frame shift mutation and what is it caused by?

• Change in number of bases in the DNA code causing a shift to all base triplets that follows so all codons change and DNA code will be transcribed differently which results in diff protein structure

• Caused by addition or duplication mutation

What are stem cells?

Unspecialised cells that can differentiate into a range of types of cells

What are the 4 types of stem cells in order of differentiating ability?

• Totipotent

• Pluripotent

• Multipotent

• Unipotent

What is totipotent and give soem features?

• Cells that can differentiate into any type of cell and extra embryionic cells

• Found early embryo stage (day 3-4)

• Most unspecialised type of stem cell

What are pluripotent stem cells and give features?

• Cell that can differentiate into any tissue in the body but not extra embryonic cell

• occur in early embryo

• can be used to treat human disorders

What are multipotent stem cells and give features

• Differentiate into a limited number of cells

• Found in mature animals

What are unipotent stem cells and give some features and an example of cardiac stem cells

• Cells that can differentiate into one type of cell

• Found in mature animals

• cardiac stem cells divide to dorm cardiomyocytes

What is a use of pluripotent stem cells and give an example?

• Repair damaged tissue

• B cells in pancreas can treat type 1 diabted

What can pluripotent stem cells be created from

unipotent

What are 2 characteristics of stem cells?

• Keep dividing

• Undifferentiated

Suggest how growth of new blood vessels into damaged heart tissue can increase rate of tissue repair [3]

• greater blood supply

• More oxygen for respiration

• brings amino acids for protein syntheisis

How does substitution mutation change the structure of polypeptitde? [3]

• change in sequence of amino acids

• change in hydrogen bonds

• alter tertiary structure

What are 3 uses of stem cells?

• Medical therapies like bone marrow transplant

• Drug testtign

• Research

Give 3 differences and 2 similarities of malignant and benign tumours

Differences:

• Malignant: cancerous, spreads to other tissue, grow faster

• Benign: non- cancerous, doesn’t spread, grows slower

Similarities:

• Both have mistakes in DNA

• Have irregular shaped cells

What are tumour supressor genes?

Genes hat slwo division, repair mistakes in DNA

Explain how increase in methylation can lead to cancer? [3]

• Methyl group added to both copied of tumour supressor genes

• Transcription of tumour suppressor gene is inhibited

• Leading to uncontrolled cell division

WHat is increased methylation and decreased acetylation and how can it affect the genome?

• Increased Methylation = adding methyl groups to DNA , this attracts proteins transcription factors cant access DNA

• Decreased Acetylation = removing acetyl groups, increases positive charges on histone so they bind to DNA more tightly transcription factors cant access DNA

What are induced pluripotent stem cells?

Turning unipotent cells into pluripotent cells by activating deactivated genes using transcription factors

Describe how alterations to tumour suppressor genes can lead to the development of tumours. [3]

• Methylation of TSG

• Mutation in TSG

• TSG are not expressed

• uncontrollable cell division;

How can oestrogen increase risk of cancer?

Can stimulate some breast cells to divide and replicate so more cell divisions, increase mutations so increased change of becoming cancerous

How does oestrogen initiate transcription?

• Oestrogen enters cell by facilitated diffuson and binds to receptor on transcription factor

• TF change shape slightly and this changes in shape makes it complementary and able to bind to the DNA to initiate transcription