Unit 4 genes/genomes part Flashcards
Micro and minisatellites can be used for what? How?
Used for genetic mapping.
If parent 1 has 2 alleles (6 VNTR, 9 VNTR) and parent 2 has 2 alleles (5 VNTR, 7 VNTR) alleles will differ by number of repeats at a mini-satellite locus, so digestion generates restriction fragments that differ in length
progeny will receive 1 allele from each parent. AKA shows that 50% of the bands in an individual are inherited from a particular parent
What is a variable number tandem repeat (VNTR)
very short repeated sequences that include microsatellites and minisaellites
-used in forensic science
When mRNA is expressed at low levels…
mrna will overlap of extensively when different cell types are compared
What is a housekeeping gene? what can it be used for?
a gene that is theoretically expressed in all cells b/c it provides basic functions needed for maintenance of all cell types.
-can be used to determine if a gene is over-expressed
Whaat is a luxury gene ?
a gene encoding a specialized function usually synthesized in large amounts in a particular cell.
What is a satellite DNA?
short sequences repeated several times aka
DNA that consists of many tandem repeats (identical or related) of short basic repeating units
-satellites are not translated and can be polymorphic. They are also found in the heterochromatic region or centromeres possibly has a structural role in chromosome segregation
What is a minisatellite DNA?
DNA that consists of repeated copies of short repeating sequence w/more repeat copies than microsatellite but fewer than satellite DNA
length of repeating units is measured in tens of base pairs
Abundant mRNA
Consists of small number of individual species , each present in large numbers of copies per cell
Scarce mRNA?
mRNA that consists of a large number of individual mRNA sequences, each present in very few copies per cell
How can the proportion of protein coding DNA be measured?
by measuring DNA that hybridizes to mRNA isolated from cell
All all genes essential genes?
NO, only in protein synthesis are 50% of genes essential
What is meant by redundant gene ?
Usually 2 or more genes are redundant when mutation in any one of these genes does not produce a detectable disease - in a way redundancy protects cells from gaining mutations
What are the three regions on the Y chromosome? what is their role?
1) X transposed region - regions is transposed from x chromosome
2) X degenerate region - sequence w/common origin w/X chromosome
3) Amplicons - sequences repeated on Y chromosome
How does Y chromosome differ from X?
60% of Y chromosome is expressed in testes.
Y chromosome is smaller and has less genes than X. It is also haploid b/c there is only 1 copy of chromosome
TRUE OR FALSE: In prokaryotes, the number of genes is proportional to genome size and in eukaryotes the number of genes does not correlate w/genome size or complexity
TRUEEE
In yeast, what are the origin of replication?
The ARS (autonomous replicating sequences), which are short A-T sequences w/11 base pair sequence that is called the A domain
What is the ORC in yeast?
origin recognition complex that is made up of 6 proteins and binds to the ARS in yeast
What is the licensing factor?
proteins that are necessary for replication. Each replicon can only be initiated once!
Prior to replication the nucleus contains an active licensing factor, what happens after replication?
the Licensing factor in the nucleus is inactive and licensing factor in the cytoplasm cannot enter the nucleus.
-dissolution of nuclear membrane during mitosis will allow LF to associate w/nuclear material aka enter the nucleus. after cell division generates daughter cells with LF in nucleus
What are the two licensing factors that bind to the ORC?
cdc6 and cdt1
What is MCM?
replication helicase in orc yeast
How are okazaki fragments made in mammals?
1) okazaki fragment displaces RNA primer
2) flapp is formed
3) FEN1 cleaves flap
4) adjacent fragments are ligated by ligase AMP
what is a linkage map?
a linkage map shows the percent of recombination between two genes and is measured in lmu. linkage maps do not represent physical distance.
equation: #of recombinant offspring/total # offspring x 100% = lmu
What are restriction maps? How are they made?
represents physical distance between genetic markers
1) cut DNA fragments
2) measure length of each fragment
**restriction map is independent of gene function, thus if there is no phenotypic variation, we can still detect RFLPs using restriction maps
What is meant by polymorphism? How are these shown on restriction maps?
variation! When there are multiple alleles at a specific location. alleles can have different mutations that may alter phenotype.
Restriction maps of such alleles would also be polymorphic provided that mutations were at a restriction enzyme target site. Each map/sequence would be different from each other.
***if changes do not affect function then we don’t observe polymorphism at phenotypic level
What are RFLPs?
Restriction fragment length polymorphism (RFLP) results from variation in the DNA sequence recognized by restriction enzymes (point mutation on restriction enzyme). These are bacterial enzymes cut DNA molecules at known locations. They are independent of gene function so we can still identify RFLPs
what does it mean if a restriction map is associated w/a phenotypic trait?
That the restriction site is close to the gene for that specific phenotype.
EX: comparing restriction maps of healthy individual vs single gene disorder individual - you will find a particular restriction site always present or absent in patients. We could say that the restriction marker is closely linked to the disease gene.
What are SNPs?
single nucleotide polymorphism.
SNPs cause a change in one single nucleotide and are responsible for most genetic variations seen w/in populations
TRUE OR FALSE: RFLPs are SNPS
true, they are SNPs located in the restriction enzyme recognition site.
What can SNP and RFLP maps be used for?
used for establishing parent /offspring relationship.
What is a haplotype?
DNA variations or polymorphisms that are inherited together. So it can be the combination of alleles in a region or a set of SNPs on the same chromosome
Following denaturing of a genome, what does measuring kintetics (or renaturing) the same genome allow?
to identify sequences based on the frequencies of repetitions in genomes
Kinetics of DNA reassociation show what two type of frequencies?
1) Non repetitive DNA, appear only once -polypeptides are encoded by non-repetitive DNA
2) Repetitive DNA, which is present more frequently and can be divided into moderately repetitive or highly repetitive.
TRUE OR FALSE: Large genomes contain more genes than small genomes?
FALSE: large genomes do NOT contain more genes, rather they contain large amount of repetitive DNA
What is the difference seen repetitive/nonrepetitive DNA in bacteria vs amphibias/plants ?
Bacteria - 100% nonrepetitive
Amphibians/plants: 80% moderately and highly repetitive
What occurs to the genes as complexity of organism increase?
the number of minimum genes also increases
