Wk. 1 | Applications + Nucleic Acids Flashcards
Molecular Diagnostics is a combination of these three things
Lab medicine
Knowledge of molecular genetics
Technology
5 uses for nucleic acid testing
- Establish dx
- Classification
- Prognosis
- Monitor therapy
- Assess drug sensitivity/resistance
Applications of molecular dx in the clinical lab
Genetic disorders/inheritance
Mutations + cancer
Infectious diseases
Endocrine disorders
Cardio disorders
Neuro disorders
Cancer examples
B and T cell lymphomas
Chronic Myelogenous leukemia
Ewings sarcoma
Rhabdomyosarcoma
Infectious disease examples
Viruses
- EBV
- CMV
- HIV
Bacteria
- M. tuberculosis
- Chlamydia
- Neisseria
Inherited diseases examples
Fragile X
Leiden Factor V
Hereditary hemochromatosis
DNA ID examples
Organ transplant
Paternity testing
Family analysis of pedigrees
Forensics
All infectious agents contain ___
nucleic acids
Advantages of molecular diagnostics
- Enhanced specificity and sensitivity
- Detects single cells
- Viral Load: can detect as few as 50 copies of DNA/RNA
Limitations of molecular dx
- High cost, low reimbursement
- Contamination causes false positives
- Space, equipment and training
Appropriate samples for mol. dx
- Peripheral blood (50 uL WBCs)
- Sperm
- Urine
- Saliva
- Hair follicle
- Bone
- Teeth
_____ has as much DNA in 5 uL as 50 uL of blood
Sperm
Mol dx needs samples containing
any cell with a nucleus
What cell does not have a nucleus
RBCs
Three types of genetic disorders
Chromosomal
Monogenic
Polygenic
Chromosomal Disorders are
a loss, gain, or abnormal arrangement resulting in too much/little of genetic material
Monogenic Disorders are the result of
a single mutant gene
What genetic disorder follows traditional Mendelian inheritance
monogenic disorders (10/1000 births)
Polygenic disorders
- result of multiple genetic factors
- does NOT follow mendelian inheritance
- examples include chronic adult diseases and congenital malformations
Common mutations are referred to as
polymorphisms
Fragment length variations
Part of a mutation
- Analyzed by endonuclease digestion
Hyper variable regions of DNA are
Many copies of same DNA sequence
- Mini and microsatellites
Minisatellite
Variable number tandem repeats
- 10-100 bp in length
Microsatellite
Di, tri, or tetra nucleotide repeat sequences
Tri-nucleotide Repeat
Common in everyone, expansion of repeat beyond normal results in disease such as Fragile X or Huntington’s
Three types of mutations
Germline (inheritable)
Acquired
Point mutations (single nucleotide)
Point mutations can either be _____ or _______
Transition: purine -> purine
Transversion: purine -> pyrimidine
Direct tests depend on and are useful for
depend mutation or gene being known
- good for detecting mutations or foreign DNA sequences
Indirect molecular tests
sequence is unknown
- good for tracking inheritance and gene mapping
Disorders that can be analyzed with mol dx
- Endocrine disorders
- Cardiovascular disease
- Human neoplastic disease (accumulation of several somatic mutations)
- Oncogenes
- Antioncogenes
- DNA damage
- Familial cancer
Oncogenes
normally expressed in prolif. cells but associated with tumor formation
- activated = proto-oncogene
Anti-oncogenes
Tumor supressor genes
- results in loss of function
Cell Elements involved in growth
Nucleus
Ribosomes
ER
Golgi
Vacuoles
Centrioles
Cell Elements involved in metabolism or energy
Membrane
Vacuoles
Mitochondrion
Chlorplast
Cytoplasm
Function of the nucleus
- Genetic info storage system (where DNA is located)
- Ribosome synthesis
Subcomponents of nucleus
- Chromatin and chromosomes
- Nucleolus
- Nucleoplasm
Nucleic acid structure
Sugar
Phosphate
Nucleotide base
Each nucleic acid has millions of
nucleic acids bonded to it
___________ is the coding information
order of the nucleotide bases
What did Chargaff discover
the number of purines is not equal to the number of pyrimidines
Nucleosides
Deoxyribose sugar + Base
Nucleotides
Phosphate + Deoxyribose sugar + Base
The building blocks of nucleic acids
Deoxynucleotides
________ are used to store and transfer chemical energy like ATP
Deoxynucleotides
A gene is
a segment of DNA that codes for a protein which codes for a trait
A _____ codes for traits such as skin tone or eye color
gene
A chromosome is
a highly ordered structure of a single dsDNA molecule wound very tightly around histones
Purines
Adenine
Guanine
Pyrimidines
Thymine
Cytosine
DNA strands have polarity based on
the phosphodiester backbone
Nucleotide bases form complementary pairs via
hydrogen bonds
Chargaff discovered that the number of ___ = ____ and the number of ____ = _____
of A = # of T
# of G = # of C
the nucleotide building blocks are
triphosphate
a polynucleotide is read from the
5’ to 3’
DNA replication begins with
hydrogen bonds breaking
RNA differs from DNA in these 3 ways
- single stranded
- ribose sugar
- uracil instead of thymine
3 important types of RNA in humans
messenger RNA (mRNA)
ribosomal RNA (rRNA)
transfer RNA (tRNA)
Qualities of RNA replication
- No priming required
- Slower (50-100 bp/sec vs. 1000/sec)
- More initiation sites
- Lower fidelity
RNA replication process
- Begins at the promotor
- RNA polymerase and accessory proteins assemble on DNA
- First base of synthesized RNA is +1
Combos of chemical modification of histones result in
varying responses such as:
- acetylation
- phosphorylation
- methylation, etc.
RNA structure
- Not linear, folds on itself forming hairpin loops
- Extensive regions of complementary AU/GC pairs
Adopts a helical dtructure in base-paired regions
RNA Function(s)
- relays info stored in cellular DNA from the nucleus to other parts of the cell
- protein production
RNA involved in protein synthesis is found in
the cytoplasm
RNA is synthesized in
the nucleus
mRNA function
carries genetic info out of the nucleus for protein synthesis
tRNA function
decodes info, transports aminos to the site of protein synthesis
This type of RNA constitutes 50% of a ribosome
ribosomal RNA
catalytic RNA is involved in
many reactions in cell cytoplasm
the smallest RNA is
tRNA
Diploid means
you have two full complements of the human genome organized into 23 chromosomes
- 1 maternal
- 1 paternal
Chromatin is
Nuclear DNA and associated structural proteins such as histone
___ condensation changes with the cell cycle
chromatin
Euchromatin
- rich in genes
- less compact
Heterochromatin
- poor in genes
- tightly compact