Causes And Effects Of Mutations Flashcards
How is variation classified
- large or small
- common or rare
- pathogenic or nonpathogenic
What is an mutation
An alteration in the genetic material that gives harm
What is polymorphism
Non harmful
Sequence changes that has no impact
Common type of polymorphism
Single nucleotide polymorphism
What is single nucleotide polymorphism
When only one nucleotide changes but has no impact
How do we examine bases of dna
DNA sequencing
How do examine large blocks of dna
FISH
Microarray analysis
How do we examine chromosome
Light microscope by karyotypes
How do mutation occur
- cell division
- from intrinsic and extrinsic attack on DNA
How does cell division cause mutation
- during S PHASE of dna replication
- non-disjunction
- crossing over
Mitotic cells give mutation
- dna replication : new mutation
- Anaomlies of chromosome number by non-disjunction
What is the difference between somatic and germline mutation
Somatic only the individual is affected
Germ line can affect offspring
What are the endogenous attacks to cause mutation
- depurination
- deamination
- reactive oxygen
- methylation of cytosine
What is depurination
Spontaneous link between purine base and sugar
What is deamination
Cytosine deaminates to uracil
What does reactive oxygen do
Attack Purine or pyrimidine rings
What is methylation of cytosine
Deamination of 5methylcytosine to thymine
What are extracellular agents that cause dna damage
- uv
- environmental chemical
- ionizing radiation
How does uv cause dna damage
Cross link adjacent thymine to form a dimer
How does environmental chemical cause dna damage
Dna breaks
How does ionizing radiation cause dna damage
Breaks dna
How does the cell cycle prevent mutation
By checkpoints
What occurs in dna replication to prevent replication errors
DNA polymerase proofread the strand and correct it’s wrong
How is thymine diners corrected
DNA mismatch repair proteins remove the dna strand
The gap of removed dna is made again by DNA polymerase
Joined back by ligase
How do you correct damage do ionizing radiation and reactive oxygen species
The DNA is broken
Repaired by homologous dna pairs
What is end joining broken ends
When dna damage is repaired as a result of ionisation and oxygen species bu ends up with deletion of nucleotide at repair site
What are the types of mutation affecting the coding sequence of a protein
Missense Nonsense Framshift Duplication Deletion Insertion
What is a silent mutation
When the mutation results in the same amino acid due to genetic code being redundant
What is missense mutation
Change of an amino acid
What is nonsense mutation
A stop codon is introduced so a protein does not form
What happens when there is a splice-site mutation
Extrons may be spliced out to give an altered protein
What type of disorder does triplet repeats give
Dominant inherited disease if it’s above the upper limits
