Genome - health and disease Flashcards
What are homebox genes?
Large family of similar genes that direct the formation of many body structures during embryonic development.
Present on every human chromosome.
Produce proteins that are transcription factors (about 60 a.a.’s)
Homebox genes were first discovered in what species?
drosophila
With what area of the DNA do homebox genes interact?
Major groove of the DNA via number of H-bonds and hydrophobic interctions
Describe what happened to drosophila when their homebox genes were mutated?
Legs grow from the head where antenna should be
What does MSX stand for?
Muscle Segment Box
What is MSX?
A transcription factor that consists of 3 genes: Msx1, Msx2, and Msx3.
Homebox gene family.
These act as transcriptional PREPRESSORS by interacting directly with the TATA binding protein
What is TATA and what iccurs when it interacts with MSX
TATA binding protein is a component of the general transcription. MSX sequesters TATA and turns it off, thus INHIBITING its activity and causing TRANSCRIPTION REPRESSION.
___ demonstrates greater affinity for DNA while ___ is a more potent repressor
Msx2 demonstrates greater affinity for DNA while Msx1 is a more potent repressor
Mutation of what cuses orofacia clefting and tooth agenesis in humans?
Msx1
Define oligodontia
condition in which multiple teeth fail to develop. Caused by MSX1 gene mutation
What is the PAX family?
- family of 9 genes
- transcription factors for a DNA-binding protein
Which PAX family gene products are expressed in developing teeth?
PAX1 and PAX9
How do the PAX9 gene products function?
They function by binding the enhancer DNA sequences and modifying transcriptional activity of downstream genes
Mutations in PAX 9 gene have been implicated in ___ ___
tooth agenesis
Define missense mutation
Switch one amino acid for another.
May or may not affect the protein function, depending on whether the change is “CONSERVATIVE” or ‘NON-CONSERVATIVE” and what the amino acid does
Define nonsense mutation
a stop codon is generated (due to adding or replacing a single nucleotide).
Insertion mutation
insertion of a single nucleotide
Loss of a single nucleotide is known as a ___ mutation
deletion
Duplication mutation
A piece of DNA is abnormally copied one or more times. May alter the function of the resulting protein
Frameshift mutation
Changes the gene’s reading frame and this changes the code for amino acids. Usually non-functional resulting protein.
Insertion, deletions and duplications can all be considered as frameshift mutation
A mutation which does not change an amino acid but can still have a phenotypic effect in some cases is known as ___ mutation
silent
How can a silent mutation have a phenotypic effect?
by speeding up or slowing down protein synthesis, or by affecting splicing
PAX9 frame shift, deletion and missense termination mutations cause ____ in both the permanent and primary dentition
hypodontia
___ ___ mutations of PAX9 genes affect only the permanent dentistion
missense substitution
T/F: PAX 9 and MSX1 interact duting tooth deveopment at both the gene and protein level
true
What are stem cells?
cells capable of dividing indefinitely and have the ability to produce specialized cells
What are the 3 types of stem cells?
- TOTIPOTENT: cells with capacity to specialize into ALL the cells necessary to form a complete embryo, including placental tissue
- PLURIPOTENT: cells capable of producing most tissues of the body, but not placental tissues
- MULTIPOTENT: give rise to several other cells types (eg. blood stem cells can give rise to various blood cell types, but not brain cells)
Dental stem cells include:
dental pulp stem cells, stem cells from human exfoliated deciduous teeth, periodontal ligament stem cells, stem cells from the apical papilla, and dental follicle stem cells
Technique which uses genes to treat or prevent disease is known as:
gene therapy
In simple terms, describe gene therapy using an adenovirus vector
A new gene is injected into an adenovirus vector and the modified DNA is introduced into a human cell. If this works, the new gene will produce a functional protein
What is exon skipping?
A mechanism for restoring the reading frame within a gene
The molecule that finds a string of DNA and makes a precision cut is known as:
CRISPR
CRISPR consists of a strand of ___ and an enzyme called __
CRISPR consists of a strand of RNA and an enzyme called Cas
What is the purpose of CRISPR?
The RNA in CRISR recognizes and docks onto the VIRUS DNA nad Cas makes a cut in the DNA, DISABLING THE VIRUS.
What type of engineering is being used to prevent browning in mushrooms?
CRISPR edited white mushrooms
How are the effects of growth factor mediated?
through binding to cell surface receptors
Growth factors have been shown to be positive for what?
wound healing
What does exon skipping do?
Exon skipping is a form of RNA splicing that causes cells to skip over faulty or misaligned sections of genetic code, leading to a truncated but still functional protein despite mutation
