gene mutation Flashcards
true or false:
mutation can affect any part of the genome
true
it refers to the process of altering a DNA sequence
mutate
- substitution of a single dna bases
- deletion or duplication of tens, hundreds, thousands bases/ of entire chromosomes
what are the effects of a mutation
“loss-of-function”
gene’s product is reduced or absent
recessive
“gain-of-function”
gene’s activity changes
dominant and toxic
people who have loss of function mutations but are healthy
knockout mutations
- genetic alterations that completely inactivate of a specific gene
a variant present in more that one percent of a population
polymorphism
variant refers to polymorphism and mutations
example:
A polymorphism is just a common change in DNA that lots of people have. It’s so common that at least 1 in every 100 people has it.
Think of it like hair color - having brown or black or blonde hair are all common variations.
this term refers to the
mutation:
mutant:
mutation:
refers to genotype
change at dna or chromosomes level
mutant:
phenotype and also describes and allele
what does the phenotype in the context of diseases describe?
it describes the observable sign and symptoms
this is a major structural protein in connective tissues, skins, bones and tendons
collagen
- provide strength and elasticity
what happens if there is mutations affecting collagen
lead to various connective tissue disorders
mutations in COL7A1 gene that encodes type VII collagen breaks down fibrosis that attach epidermis to dermis
dystrophic epidermolysis buliosa
osteogenesis imperfecta type I signs and symptoms (phenotype)
easily broken bones
blue eye whites
deafness
it is the inactivation of a1 collagen gene (COL1A1 or COL1A2) reduces number of collagen triple helices by 50%
osteogenesis imperfecta type I
difference between germline and somatic mutations
change occurs during dna replication before
meiosis: germline
mitosis: somatic
occur in
reproductive cells: germline
non-reproductive cells: somatic (other than the sperms/ exons)
passed to offspring
can: germline (heritable)
cannot: somatic
*germline affects all cells of an indiv while somatic is limited to specific cells
a person has 2 or more sets of dna in their body rather than just one so this happens when the mutation occurs in some cells but not others and creates patches of genetically diff cells in the body
somatic mosaicism
[The key things to remember are:
Normally all cells have the same DNA
But sometimes a mutation happens in just some cells
That creates patches of cells with slightly different DNA
It’s like having multiple “sets” of DNA in your body]
it is the subset of genetic disorders that arise from mutations in the same gene but can lead to different clinical manifestations or phenotypes
allelic diseases
- diff clinical phenotype caused by mutations in the same gene
[Imagine there’s a gene that controls how your muscles work. A mutation in that gene could lead to one type of muscle disease, but a slightly different mutation in the same gene could cause a different muscle disease.]
[So in simple terms, allelic diseases are genetic disorders tied to the same gene, but with flexibility in how they actually impact a person’s health and body functions. The gene is the same, but the effects can differ.]
how can the mutation occur
spontaneously
induced by exposure to a chemical or radiation
an agent that causes mutation
mutagen
naturally occurring mutations due to errors in DNA replication or repair mechanisms
Spontaneous Mutations
- DNA polymerase errors during replication
- can manifest gonadal mosaicism [a parent has a mutation in some sperm or oocyte bcs spontaneous mutations occurred in the developing testis or ovary and was transmitted only to the cells descended from the original cell burning the mutation]
