Hereditary Disorders + Molecular Diagnosis of Genetic Disorders (P) Flashcards
During cell division, what is the form of chromosome?
The chromosome during cell division is in its condensed form
What is DNA?
It is a NA in the form of a double-stranded helix
Each strand of DNA is composed of 4 types of what?
Nitrogen bases
What are the nitrogen bases that composes each strand of DNA?
1) Adenine
2) Guanine
3) Cytosine
4) Thymine
What is the most energetically favorable state of DNA?
The double stranded helix
The double stranded helix of DNA is so stable, what are the factors that can lose its conformation?
1) Extreme heat
2) Extreme pH
3) By use of destabilizing agents
What is RNA?
It is a NA that has 3 types
What are the 3 types of RNA?
1) Messenger RNA (mRNA)
2) Ribosomal RNA (rRNA)
3) Transfer RNA (tRNA)
What is mRNA?
It is the transcribed copy of DNA
Where is rRNA found?
It is found in the ribosomes
What is the function of rRNA?
It is involved in the translation of mRNA to protein
What is the function of tRNA?
It carries AAs to ribosome for translation of mRNA to protein
In terms of characteristic, what is the comparison bet DNA and RNA?
RNA is less stable than DNA
What are the reasons why RNA is less stable than DNA?
1) Because it is single stranded
2) The hydroxyl grp (-OH) predisposes susceptibility from alkaline hydrolysis
What does DNA contain?
It contains our genetic info
What is the process (or steps) from DNA to proteins?
1) DNA is transcribed to RNA
2) Then translated to proteins
What is the purpose of reverse transcriptase?
It allows reverse transcription of DNA from RNA
True or False
Some viruses have reverse transcriptase
True
What is the percentage of the human genome that encodes proteins?
< 2%
What is the amt of genes that code for proteins?
20,000 - 25,000 genes
In connection to DNA discovery (or developments w/ regards to DNA), what happened during the ff timelines:
1) 1953
2) 1975
3) 1985
4) 1987
1) Double-stranded DNA
- > beginning of molecular medicine
2) DNA can be sequenced
- > “Book of Life” (human genome) can be read base by base
3) DNA can be amplified w/ PCR
- > DNA diagnostics - unlimited potential
4) Automated DNA sequencing becomes available
- > Critical development for Human Genome Project
In connection w/ Human Genome Project, what happened during the ff timelines:
1) 1990
2) 1991
3) 1995
4) 1996
1) Human Genome Project starts, and first successful gene therapy
- > Modern molecular medicine era
2) Controversy - NIH pts anonymous DNA sequences
- > Commercialization increasingly prominent
3) DNA sequence for 1st model organism (H. influenzae) published
- > Success w/ model organisms fuels enthusiasm for completing human genome
4) NIH policy that human genome sequences are freely available
- > 2 models: public (free) & commercial (user pay)
In connection w/ omics, what happened during the ff timelines:
1) 2000
2) 2003
3) 2007
4) 2010
1) 1st draft of human genome sequence publicly announced
- > complete sequences for fruit fly and a plant are published
2) Annotated final version of human genome sequence are now available
- > beginning of genomics era
3) 1st diploid human genome published
- > beginning of next generation DNA sequencing
4) Alternative fuels & artificial bacterium
- > synthetic biology on the march
What are the 2 most common forms of DNA variations in the human genome?
1) Single-nucleotide polymorphisms (SNPs)
2) Copy number variations (CNVs)
What is the purpose of SNPs?
They represent variation at single nucleotide positions
What are CNVs?
These are form of genetic variation consisting of diff #s of large contiguous stretches of DNA
Approx 50% of CNVs are involve in what?
Gene-coding sequences
Since approx 50% of CNVs involve gene-coding sequences, what is the result of this?
CNVs may underlie a large portion of human phenotypic diversity
What are the characteristics of SNPs?
1) Disease-causing mutations
2) Susceptibility variants
3) Disease modifiers
4) Determinants of response to therapy
5) Neutral variants
How many SNPs are present across humankind?
30M
How many SNPs are present bet any 2 people?
3M
What is epigenetics?
It is defined as heritable changes in gene expression that are not caused by alterations in DNA sequence
What is proteomics?
It concerns itself w/ the measurement of all proteins expressed in a cell or tissue
What is bioinformatics?
It is computer-based techniques that can manage vast collections of data
*What is the function of microRNA and gene silencing?
*Modulate the translation of target mRNAs into their corresponding proteins
Who discovered microRNA?
Andrew Fire and Craig Mello
What is the award of Andrew Fire and Craig Mello?
Nobel prize in Physiology and Medicine
When did Andrew Fire and Craig Mello received their prize?
2006
True or False
A large # of genes do not encode proteins but rather functions in gene regulation
True
*What is the function of the most recently discovered genes?
Code for microRNA
What is the characteristic (in terms of structure) of microRNA?
It is 21 - 30 nucleotides long
What is the function of microRNA?
It do not code for protein but it inhibits gene expression
What are hereditary disorders?
These are derived from one’s parents and are transmitted in the germ line through the generations therefore are familial
What does congenital imply?
It simply implies “born with”
True or False
Genetic disorders are far more common than is widely appreciated
True
What is the estimated frequency of genetic diseases?
670 per 1,000
50% of spontaneous abortuses during the early mos of gestation have a what?
Demonstrable chromosomal abnormality
What are mutations?
These are defined as a permanent change in the DNA
What are the characteristics of mutations?
1) In germ cells, these are transmitted to the progeny
2) In somatic cells, these do not cause hereditary diseases but are important in the genetics of cancers and some congenital malformations
Since in the germ cells, mutations are transmitted to the progeny, hence, mutations can give rise to what?
Inherited diseases
Mutations can result in what?
In partial or complete deletion of a gene or, more often, affect a single base
What are the diff types of mutations?
1) Point mutations within coding sequences
2) Mutations within noncoding sequences
3) Deletions and insertions
4) Trinucleotide-repeat mutations
What are the diff types of point mutations within coding sequences?
1) Missense mutations
2) Nonsense mutations
What are the diff types of missense mutations?
1) Concervative missense mutations
2) Nonconcervative missense mutations
Both deletions and insertions can cause what?
Occurrence of frameshift mutations
What is the characteristic of trinucleotide-repeat mutations?
These mutations are characterized by amplification of a sequence of 3 nucleotides
What are the categories of genetic disorders?
1) Disorders related to mutations in single gene w/ large effects
2) Chromosomal disorders
3) Complex multigenic disorders (polymorphisms)
Mutations and their associated disorders are what?
Highly penetrant