Genetics final
Which of the following is true regarding chromosomal abnormalities?
- A reciprocal translocation swaps genes between non-homologous chromosomes - Robertsonian translocations complicate recombination during gametogenesis by generating chromosomes with DNA from 2 different chromosome types.
The Crispr-Cas 9 system allows investigators to
- Disable dominant disease alleles - Insert functional alleles - Control gene expression by eliminating Cas 9 nuclease activity and attaching it to transcriptional activators or repressors
Successful matching of donor and recipient tissue in an organ transplant involves
- Identifying the HLA haplotype of donor and recipient - determining the identity of linked alleles for 4 genes on chromosome 6
Electronic cigarettes are believed to be healthier than cigarette smoke due to the elimination of multiple carcinogens. However, studies indicate exposure to nicotine alone can be potentially carcinogenic as binding to the nAChR receptor results in:
- Inactivation of Rb - Transcription of cell survival genes - Cell cycle progression
When vaccination against HPV (human papilloma virus) was first available it was recommended only for girls not boys. This could be viewed as appropriate / inappropriate because _____________________.
- Inappropriate, because HPV infection can cause penile, anal and oropharyngeal cancers in addition to cervical and vaginal - Inappropriate, because high risk HPV strains inactivate RB and p53 proteins increasing cancer risk
The ABO blood group gene locus has 3 alleles that specify for type A, B, AB and O blood. The H gene locus has two alleles (H,h). Expression of the dominant allele at the H locus is required for generating a precursor molecule needed for ABO blood group expression. An individual with B blood is born to parents with O blood. A genetic explanation for this event is:
- One parent has O blood due to epistasis - One of the parents was homozygous recessive for the 'H' locus.
what does STR stand for
- Short tandem repeats - Used to compare specific loci on DNA from two or more samples. - A short tandem repeat is a microsatellite, consisting of a unit of two to thirteen nucleotides repeated hundreds of times in a row on the DNA strand.
what does SNP stand for?
- Single Nucleotide Polymorphism. - Some people, will have one base at a certain position, in a sequence of bases, and other people will have a different base at that position. - The two forms of SNP are called "alleles."
In a monohybrid cross, the ratio 1:2:1 is consistent with
- The genotypic ratio with independent assortment of alleles subject to complete dominance - the genotypic ratio and phenotypic ratio with codominant alleles - the genotypic ratio and phenotypic ratio with incomplete dominance
Recombinant DNA molecules
- contain DNA combined from two different organisms - are made using restriction endonucleases to generate 'sticky ends' or 5' overhangs - are made using enzymes that recognize sequence palindromes - need ligase activity during their construction to seal the sugar-phosphate backbone
Microarrays
- could be used in personalized medicine to identify candidate targets for treatment of complex diseases - are used to compare the relative amount of mRNA produced for different genes in a cell
what is GWAS?
- genome-wide association study - it is an observational study of a genome-wide set of genetic variants in different individuals to see if any variant is associated with a trait.
Pairs of homologous autosomes do not have
- have 100% identical DNA sequences in their genes - are found in gametes - separate in meiosis II
what does VNTR stand for?
- variable number of tandem repeats - short sequence of DNA that is repeated in a head-to-tail fashion at a specific chromosomal locus
Deafness is a relatively rare characteristic. A deaf man is homozygous for a recessive deafness allele on chromosome 17. He marries a deaf woman who is homozygous for a different recessive deafness allele on chromosome 3. Excluding the possibility of gene interaction, what is the probability that their children will be deaf due to either of these mutated genes?
0% probability
Two normal parents produce a child with PKU (an autosomal recessive disorder). What is the probability that their next child will be a daughter who has PKU?
1/4 chance of PKU x 1/2 chance of being a girl = 1/8 chance of having a daughter who has PKU
Red-green color blindness is X-linked recessive. A woman with normal color vision has a father who is color-blind. The woman has a child with a man with normal color vision. What is the probability they will have a color-blind son?
1/4 probability
Building block for a RNA polynucleotide strand
2'OH
A hypothetical diploid somatic cell has a total of 10 chromosomes What is the total number of chromatids in each cell during prophase I of meiosis I?
20
If the sequence of one strand of a DNA molecule is 5'ATGGCAT3', the sequence of the complementary strand is:
3'TACCGTA5'
HER2 positive breast cancers are particularly aggressive. These tumor cells have many extra receptors for epidermal growth factor (HER2), and so they receive too many signals to divide. Which of the following could cause an excess in HER2 receptors? A - Translocation of the HER2 gene next to a highly expressed gene B - Deletion of the HER2 termination sequence C - Nonsense mutation halfway through the coding sequence D - A loss of function mutation E - Loss of function mutation in both copies of HER2
A - Translocation of the HER2 gene next to a highly expressed gene
inversions
A chromosome rearrangement in which a segment of a chromosome is reversed end to end. Occurs when a single chromosome undergoes breakage and rearrangement within itself. There are two types: paracentric and pericentric
One year later you identify the disease gene - "adneomatous polyposis coli" or APC- and perform an analysis to find the mutations causing colon cancer in this affected family. Using PCR followed by sequencing techniques, a nonsense mutation in the APC gene of Don is found. How does this mutation affect the protein produced?
A nonsense mutation = A codon specifying an amino acids is changed to a stop codon
Non-reciprocal translocations
A one-way transfer of a chromosomal segment to another chromosome.
what is a DNA fingerprint
A technique used especially for identification (as for forensic purposes) by extracting and identifying the base-pair pattern of an individual's DNA
Because cancers are clonal, when tumor cell DNA is examined from people at different stages of the same cancer type, mutations that are common to all tumor cells examined
Act early in the disease
Which of the following depicts the correct types of nucleotides required for each process? A - PCR requires ddNTPs B - Sanger sequencing requires dNTPs and ddNTPs C - Next generation sequencing requires dNTPs and ddNTPs D - In vivo DNA replication requires dNTPs and rNTPs
B - Sanger sequencing requires dNTPs and ddNTPs D - In vivo DNA replication requires dNTPs and rNTPs
A disorder in which blood clots when it is not needed is caused by a mutation in the promoter of a gene. How does this mutation lead to excessive blood clotting?
By increasing the transcription of a particular clotting factor gene
Gene A has 2 alleles (A,a) and 'A' is completely dominant to 'a'. Which of the following crosses would be categorized as a test cross? A - Aa x AA B - Aa x Aa C - Aa x aa D - AA x AA E - aa x aa
C - Aa x aa could be a test cross... so could AA x aa
5'-GTG ATG *TAC* GTA AAC CGT GAG GAC TGG ACT-3' Affected patients have a C to G mutation in the last base of the codon stared. Which of the following statements is FALSE? A - The mutation represents a transversion B - The mutation results in a truncated protein C - Diagnosis can be made by PCR with the primer pair 5'-GTGAT-3' and 5'-TCAGG-3' D - This disease gene is caused by the results of a SNP E - This disease gene is caused by a point mutation (base substitution)
C - Diagnosis can be made by PCR with the primer pair 5'-GTGAT-3' and 5'-TCAGG-3'
Which of the following is true regarding STRs? A - STR is the abbreviation for Single Trinucleotide Repeats B - An STR expansion is responsible for causing Huntington disease C - Alleles with STRs vary by length, whereas alleles with SNPs vary by nucleotide base changes D - B and C E - A, B and C
D - An STR expansion is responsible for causing Huntington disease AND Alleles with STRs vary by length, whereas alleles with SNPs vary by nucleotide base changes
Which of the following is true regarding primers? A - DNA replication in-vivo requires a single primer for each origin of replication B. DNA replication in-vivo could not begin without a DNA primer C - RNA transcription requires a single primer for each transcription unit D - PCR requires 2 primers—either of which could be used in a subsequent Sanger sequencing reaction. E - PCR primers serve to target a region for amplification but they are not incorporated into the corresponding DNA amplicon.
D. PCR requires 2 primers—either of which could be used in a subsequent Sanger sequencing reaction.
16. XDMD Xdmd x Xdmd Y ---> XDMD Xdmd Y
From the information provided you cannot determine which parent's gamete was subject to a nondisjunction event.
In an effort to identify the gene responsible for detecting asparagus urine, the personal genomics company 23andMe completed a study on a collection of phenotype and genotype data for 22 different traits among nearly 10,000 participants. (e) This type of examination is known as a:
GWAS
Loss of a tumor suppressor protein's activity in a cell results from
Heavy CpG methylation of one allele and a loss of functions missense mutation in the other allele
In the diagram of a replication bubble below, lagging strands would be found in quadrants ______ and Okazaki fragments would be found in quadrants_______.
I & III / I & III
An individual with an XXY genotype is
Is a male with Klinefelter's syndrome and 1 Barr body per somatic cell.
Sister chromatids segregate during ___________.
Meiosis II anaphase
Upon successful completion of meiosis, a diploid cell would produce gametes with how many chromosomes written in n-notation?
N and N+1
Frederick Griffith observed that
Nonvirulent bacteria become virulent when mixed with heat-killed virulent bacteria
What is a test cross?
The crossing of an organism, with an unkown genotype, to a homozygous recessive organism (tester). A cross between an individual of unknown genotype or a heterozygote (or a multiple heterozygote) to a homozygous recessive individual
A DNA molecule consisting of 10 base pairs consists of 30% Cytosisne
The molecule has 6 C-G base pairs and 4 A-T base pairs
Individuals with Xeroderma Pigmentosum cannot repair thymine dimers generated by covalently joined adjacent thymine bases in a DNA sequence following exposure to UV light.
These individuals have a defect in their nucleotide excision repair pathway
Which of the following is true regarding the mRNA transcript below? 5' -GGCAAUAUGGaguacggaACUUCUGAGAACUUAG-3'
This transcript could be targeted for degradation by a microRNA with the sequence: 3'CCGUUAUACCUC5'
Chromatin remodeling can act as an on/off switch for ___________, while RNAi can block _________.
Transcription; translation
autosomal recessive
Two copies of an abnormal gene must be present in order for the disease or trait to develop
The Crispr-Cas 9 system for genome editing relies upon ________________ to specifically target locations in the genome.
a RNA guide strand
The nitrogeneous bases adenine and thymine are:
a purine and a pyrimidine, respectively.
robertsonian translocations
a rare form of chromosomal rearrangement where the participating chromosomes break at their centromeres and the long arms fuse to form a single, large chromosome with a single centromere
Blood pressure in humans is a quantitative trait. Let's assume the systolic blood pressure (top number) ranges in a population from 80 mm Hg (homozygous recessive genotype) to 220 mm Hg (homozygous dominant genotype) and is controlled by 7 unlinked genes. The alleles of each gene are additive and equal in their effects. Considering genotype alone, an individual with 5 dominant additive alleles will have:
a systolic blood pressure of 130 mmHg
polyploidy
contains more than two paired (homologous) sets of chromosomes.
Pairs of homologous autosomes do have
have genes for the same characteristics at the same loci
Blood pressure in humans is a quantitative trait. Let's assume the systolic blood pressure (top number) ranges in a population from 80 mm Hg (homozygous recessive genotype) to 220 mm Hg (homozygous dominant genotype) and is controlled by 7 unlinked genes. The alleles of each gene are additive and equal in their effects. The number of additive alleles associated with the minimum (base) phenotype is ________ and the total number of phenotypes possible based solely on genetic influence is _________.
minimum - 0 total - 15
reciprocal translocation
occur when chromosomal segments are exchanged between two non- homologous chromosomes and is the most typical type of translocation
The RB gene
stops cell division at the G1:S checkpoint
