Mutations 2 Flashcards
What are the types of mutations in terms of cell type?
Germ line/hereditary
Somatic
What type of cells are affected by germ line mutations?
Sperm
Eggs
What type of cells are affected by somatic mutations?
Body cells
Are germ line mutations or somatic mutations passed on to offspring?
Germ line mutations
Germ line mutations that have passed on to the offspring affect which cells of the offspring?
All of them!
Are DNA replication errors or transcription errors more common? Why?
Transcription errors
RNA polymerase doesn’t proof-read like DNA polymerase does
Do DNA replication errors or transcription errors have shorter-term effects? Why?
Transcription errors
- Not all copies of RNA will contain errors
- RNA molecules not inherited
- RNA molecules quickly degraded
Germ line mutations in mitochondrial DNA that have passed on to the offspring affect which organs the most? Why?
Brain
Heart
Muscles
Because require most energy
What are the symptoms and signs of mitochondrial disease?
Dementia
Heart disease
Muscle weakness, wasting
Hearing loss
Abnormalities of vision
What type of mutation builds up in mitochondrial DNA? Why?
Somatic mutations
because mitochondrial DNA has limited ability to repair itself
What is a build up of somatic mutations in mitochondrial DNA associated with?
Ageing
Age-related disorders
What are some examples of age-related disorders?
Neurodegenerative diseases
Heart disease
What are the types of mutations in terms of heridity?
Spontaneous
Inherited
What are spontaneous mutations?
Newly arising mutation
What is an inherited mutation?
Mutation carried from parents to offspring
If a cell has trisomy for a chromosome that contains genes which slow down growth, what may this lead to?
Cell death
If a cell has trisomy for a chromosome that contains genes which increase growth, what may this lead to?
Uncontrollable cell growth and division
leading to cancer
What is a primordial follicle?
Primary oocyte surrounded by squamous epithelium
How do numbers of primary oocytes change with age?
Decrease signifiantly from birth to puberty
By what process are primary oocytes decreased in number from birth to puberty?
Apoptosis
How does the mutation rate change with age? Why?
Increases with age
- Spermatogonium been exposed to mutagens for longer
- Primary oocytes spent longer in meiosis arrest
Is the mutation rate in male or female gametes higher? Why?
Male gametes
- More mitotic divisions in spermatogenesis than oogenesis
- Spermatogonium continue dividing by mitosis throughout life
The IVF embryo mutation rate is higher or lower than in vivo rate? Why?
Higher
No selection of fittest sperm to fertilise egg as occurs in vivo
Why do primary oocytes decrease in number from birth to puberty?
Have defective genomes
Dying primary oocytes act as nurse cells for surviving primary oocytes
What would happen to an embryo if it was exposed to mutagens?
Teratogenesis
Death
What are the conditions of a germ line mutation to be inheritable?
Must not impair fertilisation
Must not impair gamete function
Allows production of adult who can reproduce as normal
What do recessive mutations generally cause?
Loss of function
What do recessive mutations generally affect?
Biochemical pathways
What do dominant mutations generally cause?
Increased function
What do dominnt mutations generally affect?
Structure - give structural abnormalities
Are most mutations more likely to deactivate a protein or activate it? Why?
Deactivate protein
many more ways to do this than to do activate one
Why do recessive alleles require the individual to be homozygous to be expressed in phenotype?
Because loss of function can be compensated by other allele being normal
no overall effect
Why are dominant alleles expressed in phenotype in heterozygous individuals?
Increased function cannot be compensated for by other allele being normal
will have an effect
What are miscarriages commonly caused by?
Chromosomal abnormalities
- structural
- numerical
