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Question 1
Incorrect
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Normal parents have a child with a recessive condition, Tay Sachs. The chance of them having a normal child is?
Your Answer: 25%
Correct Answer: 75%
Explanation:The chance for normal parents having a child with a recessive disease is 1:4 or 25%. As both the parents are heterozygous for this condition. They have a 3:4 chance of having a normal child or 75%.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 2
Incorrect
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With regards to P53, which statement is NOT true?
Your Answer: P53’s own expression is induced by broken DNA
Correct Answer: P53 is a RNA binding protein
Explanation:P53 is a tumour suppressor gene. It is not an RNA binding protein. It has been implicated in almost all tumours. It regulates the progression from G1 to the S phase of the cell cycle and is activated in response to damaged DNA.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 3
Incorrect
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Which of the following is an incorrect statement regarding the structure of DNA?
Your Answer: The two strands twist to form a double helix with major and minor grooves.
Correct Answer: The two strands of DNA are held together by cysteine bonds.
Explanation:The two strands of DNA are held together by hydrogen bonds formed between the nucleotide bases.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 4
Correct
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Mutation in RB can lead to the formation of which cancer?
Your Answer: Retinoblastoma
Explanation:Patients with a history of autosomal dominant familial retinoblastoma have at least one mutated copy of the RB gene. This predisposes the patient to develop retinoblastoma in one or both the eyes. Patients with a family history should be screened properly so that it can be detected and treated as early as possible.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 5
Correct
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The process by which DNA fragments are separated by gel and transferred onto a membrane sheet is called:
Your Answer: Southern blotting
Explanation:A Southern blot is a method used in molecular biology for detection of a specific DNA sequence in DNA samples. Southern blotting combines transfer of electrophoresis-separated DNA fragments to a filter membrane and subsequent fragment detection by probe hybridization. The other forms of blotting involve the use of RNA and proteins.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 6
Correct
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When one of the two copies of the autosomes has a mutation and the protein produced by the normal form of the gene cannot compensate. The affected individual has an:
Your Answer: Autosomal dominant disorder
Explanation:An autosomal dominant trait will be expressed no matter the consequence. If one chromosome has a mutation the other will not be able to compensate for the mutation hence the protein formed will be mutated and will not function properly.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 7
Correct
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When 2 nucleotide chains of DNA bind together, thymine is bound to:
Your Answer: Adenine
Explanation:As a general rule in the structure of DNA, thymine always binds to adenine with two hydrogen bonds, cytosine always binds to guanine with three hydrogen bonds and vice versa. However In the structure of RNA the only difference is that adenine binds to uracil instead of thymine. But thymine will always bind to adenine.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 8
Incorrect
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Regarding DNA cloning and sequencing, all of the following are true, except:
Your Answer: Ligase inserts DNA fragments into vector DNA sequences
Correct Answer: Yeast artificial chromosomes ( yacs) are vectors
Explanation:Yeast chromosomes cannot be used as a vector. All the rest are true. Vectors can be bacteria, viruses and plasmids. DNA ligase binds the DNA fragment to the host DNA after insertion. Fluorescence can be used to visualize them.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 9
Correct
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The process by which RNA fragments are separated by gel electrophoresis and transferred onto a membrane sheet is called:
Your Answer: Northern blotting
Explanation:Blots of the gel can be made from using nitrocellulose paper. Northern blots are produced when a fragment of radioactive DNA hybridize with RNA on a nitrocellulose blot of a gel and southern blots are produced when DNA hybrize with DNA on a nitrocellulose blot of the gel.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 10
Correct
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With regard to X-linked disorders which of the following are true:
Your Answer: X linked recessive disorders usually present in males and only very rarely present in homozygous females
Explanation:X linked disorders are more common in males as they only need one mutated copy of the X chromosome to manifest the disease with full severity while the females need two X chromosomes to manifest the disease, even with one defected X chromosome the severity is less than that seen in males.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 11
Incorrect
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When during the cell cycle do the centrioles replicate?
Your Answer: S phase
Correct Answer: G1 phase
Explanation:During G1 phase the cell will prepare for cell division. All the organelles will start to duplicate in this phase and the cell will begin to grow whilst proteins are also synthesized.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 12
Incorrect
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The length of DNA is generally measured in terms of the number of:
Your Answer: Amino acids
Correct Answer: Base pairs
Explanation:As DNA is made up of nucleotides, its length is measured by the number of base pairs in the DNA molecules.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 13
Incorrect
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Which of the following statements is true about chromosomes?
Your Answer: Diploid human cells have 46 chromosomes, 23 inherited from each parent
Correct Answer: All of the above
Explanation:All of the above mentioned statements are true regarding chromosomes.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 14
Correct
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Consanguinity shows a strong association with which pattern of inheritance?
Your Answer: Autosomal recessive
Explanation:Consanguinity involves being from the same kinship as another person. It is a common feature of an autosomal recessive mode of inheritance
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This question is part of the following fields:
- Genetics
- Medicine
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Question 15
Incorrect
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Which statement is incorrect?
Your Answer: RNA polymerase creates an RNA copy of the DNA gene sequence.
Correct Answer: Translation begins when the triplet (UGA) encoding for methionine is encountered.
Explanation:Translation being when the codon for methionine is encountered which is AUG not UGA. This process is known as initiation. All the other options are correct.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 16
Correct
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Which statement is incorrect regarding transcription of DNA?
Your Answer: A gene is always read in the 3’-5’ orientation and at 3’ promoter sites.
Explanation:In both prokaryotes and eukaryotes RNA polymerase acts in the 5′-3′ direction and hence the RNA is transcribed in this direction. The mRNA produced is immature as it has introns as well as exons presents. It undergoes a process known as splicing to remove the exons and then interacts with the ribosomes to form proteins.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 17
Correct
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Carcinogens found in cigarette smoke can transform proto-oncogenes to oncogenes through:
Your Answer: Point mutations in genomic DNA
Explanation:80% of the pancreatic cancers are environmentally influenced by smoking which increases the risk by 50%. Mutation can occur in the KRAS, p16, SMAD4, and TP53 genes among other tumour suppression genes. Smoking can be implicated in transformation of all these genes. Apart from KRAS all the genes are inactivated in pancreatic cancer. As KRAS is the most commonly altered gene, mutation occurs as point mutation. As smoking is the most common aetiology in pancreatic cancer, and KRAS is the most important gene that is altered. Most commonly cigarette smoke causes point mutation.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 18
Correct
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Question 19
Correct
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Question 20
Incorrect
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Which of the following is not true regarding mitochondrial chromosome disorders?
Your Answer: Most mitochondrial diseases are myopathies and neuropathies with a maternal pattern of inheritance
Correct Answer: Because mitochondrial chromosomes have no introns in their genes, any point mutation has a low likelihood of having an effect.
Explanation:Any point mutation in any part of the mitochondrial DNA will lead to a mutated mitochondria and will likewise have its ill effect on the body.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 21
Correct
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The following cells replicate without shortening their telomeres because they express telomerase.
Your Answer: Germ cells
Explanation:Telomerase activity is seen in germ cells and is absent in somatic cells. Telomeres prevent the chromosomes from shortening and prevent the coding portion of the DNA from being lost, thus allowing the cell to replicate indefinitely. During replication telomeres may be lost resulting in cell death.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 22
Incorrect
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Regarding Southern Blotting and DNA probes, which answer is FALSE
Your Answer: Gene probes can consist of DNA or RNA
Correct Answer: RNA fragments are separated by gel electrophoresis and transferred onto membrane sheets in southern blotting
Explanation:Restriction enzymes always cut at different positions. There are different restriction endonucleases for different nucleotide sequences.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 23
Correct
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During which stage does the mitotic apparatus dissolute?
Your Answer: Telophase
Explanation:In telophase the nuclear envelope along with the nucleolus will reappear. The daughter nuclei will enlarge as the chromosome will decondense again. Along with this, cytokinesis will occur. At the end of cytokinesis the daughter centrioles will move from the poles to the intercellular bridge where they will be disassembled and complete the separation of the daughter cells
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This question is part of the following fields:
- Genetics
- Medicine
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Question 24
Incorrect
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Which statement is correct?
Your Answer: Mitochondrial genes contain both introns and exons.
Correct Answer: MtDNA principally encodes for proteins that are involved in oxidative phosphorylation for the production of ATP in the cell.
Explanation:Mitochondria have no nucleus instead they contain their own free floating circular genome (MtDNA), which encodes 13 different subunits of proteins involved in oxidative phosphorylation. The remainder of the mitochondrial proteins are nuclear encoded, synthesized in the cytoplasm, and transported into the mitochondria.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 25
Incorrect
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Which of the following statements is not true about mitochondrial chromosomes?
Your Answer: Encode proteins involved in mitochondrial function i.e. ATP production from oxidative phosphorylation
Correct Answer: Mitochondrial chromosomes play no role in the transmission of disease from generation to generation.
Explanation:All the above mentioned statements are true except that mitochondrial DNA is passed from the mother to the child. If the child inherits the defective mitochondrial gene it will manifest some form of the disease. Commonly inherited diseases related to mitochondrial abnormality are Leber hereditary optic neuropathy and myoclonic epilepsy with ragged red fibers (MERRF).
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This question is part of the following fields:
- Genetics
- Medicine
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Question 26
Incorrect
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The process of DNA amplification and quantification is called:
Your Answer: Southern blotting
Correct Answer: PCR
Explanation:PCR/polymerase chain reaction is a procedure carried out in a test tube that can be used on the smallest amount of DNA to amplify it, allowing for millions of copies of specific nucleotides to be made.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 27
Correct
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Which of the following conditions results from chromosomal ‘non-disjunction’?
Your Answer: All of the options
Explanation:Non-disjunction can result in aneuploidy i.e. abnormal number of chromosomes in a cell. It results due to uneven division of chromosomes in the meiosis 1 or 2 phase. All the above mentioned examples are of non-disjunction.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 28
Incorrect
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Which of the following is not true regarding mitochondrial chromosome disorders?
Your Answer: Most mitochondrial diseases are myopathies and neuropathies with a maternal pattern of inheritance.
Correct Answer: Because mitochondrial chromosomes have no introns in their genes, any point mutation has a low likelihood of having an effect.
Explanation:Mitochondrial DNA (mtDNA) does indeed lack introns, meaning that its genes are closely packed with coding sequences. This actually means that any point mutation in the mtDNA is more likely to have an effect, not less. The lack of introns means there are fewer non-coding regions where mutations can occur without affecting gene function. Thus, mutations in mtDNA often have significant consequences because they are more likely to alter essential coding sequences.
The other statements are true:
- Most mitochondrial diseases are myopathies and neuropathies with a maternal pattern of inheritance: This is correct because mtDNA is inherited maternally, and many mitochondrial disorders affect muscle and nerve function.
- Retinal degeneration, diabetes mellitus, and some forms of hearing loss are some of the other diseases attributed to mitochondrial chromosome defects: These are indeed conditions associated with mitochondrial defects.
- Mitochondrial chromosome defects are inherited from one’s mother: This is correct, as mtDNA is passed from mother to offspring.
- Leber’s hereditary optic neuropathy (LHON), the commonest cause of blindness in young men, is an example of a mitochondrial chromosome defect: This is true; LHON is a well-known mitochondrial disorder.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 29
Correct
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During which phase are the 2 chromatids pulled apart at the centromere?
Your Answer: Anaphase
Explanation:During the prometaphase the microtubule organizing centre completely develops. The spindle fibers attach to the chromosome and the centriole. It is in the Anaphase however that the spindle fibers contract pulling the sister chromatids apart. Later in the anaphase a cleave furrow beings to forms.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 30
Incorrect
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In which phase do chromosomes in the nucleus become completely condensed into well-defined chromosomes?
Your Answer: Prophase
Correct Answer: Metaphase
Explanation:Prophase begins when the nucleus envelope disintegrates and the chromosomes start to condense. The chromosomes consist of two sister chromatids that are joined at a constriction known as centromere. When the cell reaches the metaphase the chromosomes are completely condensed and ready to align on the equatorial plate
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This question is part of the following fields:
- Genetics
- Medicine
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SESSION STATS - PERFORMANCE PER SPECIALTY
