cell biology - what can go wrong

What does transcription of a gene involve?

RNA polymerase making a single stranded copy of DNA

What is a mutation?

Permanent and heritable change or disruption in he base sequence of the genome

What is the difference between spontaneous and induced mutation?

Spontaneous: occur in the natural environment without the addition of mutagens - occur at a low rate

Induced: created by the addition of mutagens

What is a change in the DNA sequence ?

Mutation

What are the types of sequence mutations?

Substitution

Insertion

Deletion

What type of mutation is A?

Substitution

What type of mutation is B?

Insertion

What type of mutation is C?

Deletion

What is substitution?

One base in the DNA sequence changed to another base

Transcript affected too

What is silent mutation?

Amino acid sequence not affected

Due to redundancy of code

What is missense mutation?

Mutated codon calls for incorrect amino acid

What is nonsense mutation?

Mutated codon is now a stop codon

What can be said about insertion/deletion?

Inappropriate number of bases in a DNA sequence following mutation

Affects entire reading frame of 3-letter codons after the point of change

• frame shift mutation

• Potential catastrophic change in functionality of protein

Mistakes are made during DNA replication, how often is this ?

Every 1 in 10^5 pairings

Must be repaired

Mistakes are also made during transcription, how is this solved?

Mini smiled by repair mechanisms

What is A?

Teratogens

What is B?

Carcinogens

What is C?

Clastogens

What is D?

Non-specific

What is a mutation?

Permanent and heritable change or disruption in the base sequence of the genome

What is factor VII deficiency (FVIID)?

Clotting disorder resulting from a lack of proconvertin (clotting factor VII) in the blood , which typically results in mild bleeding and bruising

What makes up the cell cycle?

G1- growth in cell size and preparation for DNA replication

S- replication of DNA

G2- continuation of growth and preparation of other cell components for division

M- growth stops and division takes place:

• prophase

• Metaphase

• Anaphase

• Telophase

What does the green dot represent?

Stimulating proteins (encoded by proto-oncogenes)

What does the red dot represent?

Inhibitory proteins (encoded by tumour suppressor genes)

What is a p53 tumour suppressor ?

Stops progression through G1 if DNA is damaged

Allow cell time to repair DNA

If irreparable, triggers apoptosis

What are CDK-cyclins?

• Enzymes that activate or inhibit other proteins via phosphorylation

• Can activate proteins that stimulate cell cycle progression

Uncontrolled cell division results in what?

Cancer

Mutations in these genes lad to what?

Unregulated cell division and avoidance of preventative strategies such as apoptosis

What is the role of a lysosome ?

• break down cellular waste

• Contain hydrologic enzymes

• Acidic environment

• Can be transported into, out of and around the cell

What can cause a lysosome to look this way?

Accumulation of unprocessed material due to lack of certain metabolic enzymes

What are clinical signs of lysosome storage diseases?

• failure to thrive

• Incoordination and balance issues

• Exercise intolerance

• Abnormal vision

• Fainting

• Seizures

What is ceroid lipofuscinosis ?

• missing enzyme that breaks don lipofuscin

• Accumulates in nerve cells, liver, kidneys and spleen

• Progressive permanent loss of motor function

• Decreased vision, dementia, seizures, balance problems

• Affects border collies, daschunds etc