Chap. 10: Molecular Diagnostics Flashcards
Compacted into chromosomes and bound to basic proteins.
Helical human DNA
Bound to basic proteins
histones
DNA + histone complex is called?
chromatin
The human nucleus contains ___ chromosomes.
46
Humans have two copies of each chromosome, a condition called?
Diploid
Two types of chromosomes are:
Somatic
Sex
Somatic: ___ pairs
Sex: ___, ___
22 pairs
X or Y, XX (F), XY (Male)
Coding parts of a gene.
Exons
Exons are ________ sequences.
expressed
Noncoding regions of a gene are called?
Introns
Introns are _______ sequences.
intervening
They can contain regulatory/transcriptional elements and have other functions.
Introns
Approximately ___% of all human genes have multiple allelic forms called ___________?
25
polymorphisms
Refers to a different version or form of a gene or noncoding region.
Allele
Highly polymorphic which codes for peptides that establish self-identity of the immune system.
Human Leukocyte Antigen (HLA)
Physical locations or positions of a gene or noncoding region on a chromosome.
Loci
Lack a nucleus and nuclear membrane.
Procaryotes
___% coding sequence.
___% noncoding sequence.
95
5
Extrachromosomal DNA containing nonessential genetic information.
Plasmids
Circular genome of approx. _______ base pairs, inherited _________.
16,600
maternally
mtRNA contains:
___ tRNA
___ rRNA
___ genes coding for oxidation-phosphorylation components.
22
2
12
Mutations in genes coding for oxidation-phosphorylation are responsible for ___________ and ___________.
neuropathies
myopathies
noncoding regions: ___ bp
hypervariable I regions: ___ bp
hypervariable II regions: ___ bp
610
342
268
Noncoding, hypervariable I, & hypervariable II are routinely sequenced for _________?
Forensics
Normal conformation of DNA is _______ stranded.
double stranded (ds)
Distrupted form of DNA is known as _________ (or ________) DNA, is ________ stranded.
denatured (melted)
single stranded (ss)
Denaturation can be accomplished through ___________ or ___________.
heating
chemicals
Assays requiring denaturation of human DNA are conducted at about ___ degrees celcius.
94
Is the association of denatured DNA to native dsDNA.
Renaturation (annealing)
Reassociation of complementary base sequences.
Hybridization
Two requirements for annealing:
High salt concentration
High temperature
Why is high salt concentration a must for annealing?
To overcome electrostatic repulsion between negatively charged phosphate group in two strands.
Why is high temperature is required for annealing?
To disrupt the random, nonspecific intrastrand hydrogen bonds.
Annealing of human DNA will occur around what temperature?
52 degree celcius
Is a process in which genetic information is transferred from parent to daughter cells. It requires energy to unwind the helix and distrupts H-bonds.
DNA Replication
This exist to minimize the replication errors.
Proofreading, repair systems
Base changes occur resulting in _________; sometimes it doesn’t have an effect, producing polymorphisms.
mutations
The synthesis of each nucleotide chain only occurs in the _______ direction.
5’ –> 3’
One strand is synthesized continuously, whereas the other strand is synthesized discontinuously, resulting in _____________ that must be ligated together by the enzyme _________.
Okazaki fragments
ligase
As replication proceeds, the parental double helix unwinds by the action of enzymes called __________ in procaryotes and ______________ in eucaryotes.
helicase
topoisomerase
Polymerization of DNA is catalyzed by enzymes called ____________.
DNA polymerases
Most RNA molecules are __________ stranded.
single
Environmentally labile and easily degraded.
RNA
Ribosomal RNA (rRNA) makes up ___% to ___% of total RNA in a cell.
80-90
It is part of ribosomes and involved in translation of mRNA into proteins.
Ribosomal RNA (rRNA)
Messenger RNA (mRNA) makes up ___% to ___% of total RNA in the cell.
2.5-5
It is an intermediate between the genetic code in DNA and the total protein product. It is read by ribosomes to produce proteins.
Messenger RNA (mRNA)
In eucaryotes, transcription of DNA forms a pre-mRNA molecule with both introns and exon. This molecule is referred to as _____________.
heteronuclear RNA (hnRNA)
In heteronuclear RNA (hnRNA), the introns are ________, and the exons are ______________.
removed
joined together
Further processing into mature mRNA inclues addition of ________________ cup and _____________ tail of up to ___ adenylate nucleotides at the _________ terminus.
5’ methylguanine
polyadenylate (poly A)
200
3’-OH
Reads mRNA triplets and brings the appropriate amino acid to the ribosome for polypeptide synthesis.
Transfer RNA (tRNA)
There are at least one ______ for each amino acid.
tRNA
Involved in removal of introns.
Small nuclear RNA (snRNA)
Other RNAs that involved in cellular processes.
Small and micro RNAs
A variety of enzymes called _______ break phosphodiester bonds in nucleic acids.
nucleases
Ubiquitous, very high concentrations on hands; thus it is necessary to wear gloves when working.
Ribonucleases (RNases)
Cut only at the end of a nucleic acid, removing a single nucleotide at a time.
Exonucleases
RNases act at a wide range of temperatures:
below -20 to >100 degree celcius
Recognize a specific base sequence in a DNA molecule and cut near or within the sequence.
Restriction enzyme/endonucleases
Endonucleases make two cuts, one in each strand, generating a ____ and ____ terminus.
3’-OH
5’-P
