-
Question 1
Correct
-
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.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 2
Correct
-
With regards to P53, which statement is NOT true?
Your 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.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 3
Correct
-
What is the role of cyclin and cyklin-dependent kinases in mitosis:
Your Answer: Phosphorylation of proteins that make up pre-replication complexes
Explanation:There are certain regulators of the cell cycles that mediate progression through the cell cycle. These are cyclins and cyklin-dependent kinases (CDKs). They form a complex that phosphorylates protein involved in the cell cycle.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 4
Incorrect
-
Three adjacent nucleotides code for a particular amino acid. These are called codons. How many common amino acids are there and how many potential codon combinations make up the genetic code?
Your Answer:
Correct Answer: 20 amino acids, 64 codon combinations
Explanation:There are around 20 amino acids and 61 out of the 64 combinations of codon code for these 20 common amino acids.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 5
Incorrect
-
Question 6
Incorrect
-
Consanguinity shows a strong association with which pattern of inheritance?
Your Answer:
Correct 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
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 7
Incorrect
-
Which of the following with regard to DNA mutations does not fit:
Your Answer:
Correct Answer: All gene mutations cause clinical disease entities
Explanation:All gene mutations do not cause a clinical manifestation of the disease, some gene mutations are silent mutations. They are present but do not cause any disease.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 8
Incorrect
-
When during the cell cycle do the centrioles replicate?
Your Answer:
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.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 9
Incorrect
-
With regard to X linked disorders which of the following are true
Your Answer:
Correct Answer: X linked recessive disorders usually present in males and only very rarely present in homozygous females
Explanation:All are true for autosomal recessive disorders. Dominance rules for sex-linked gene loci are determined by their behaviour in the female: because the male has only one allele (except in the case of certain types of Y chromosome aneuploidy), that allele is always expressed regardless of whether it is dominant or recessive.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 10
Incorrect
-
The mitochondrial chromosome is a circular DNA molecule. They encode for proteins needed for ATP production. These proteins are also essential for:
Your Answer:
Correct Answer: Apoptotic cell death
Explanation:The intrinsic pathway or the mitochondrial pathway of apoptosis is activated due to the loss of BCL-2 and other antiapoptotic proteins. This loss results in the increased membrane permeability and release of cytochrome C which activates caspases downstream resulting in apoptosis.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 11
Incorrect
-
In which phase do chromosomes in the nucleus become condensed into well-defined chromosomes?
Your Answer:
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
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 12
Incorrect
-
The following cells replicate without shortening their telomeres because they express telomerase.
Your Answer:
Correct 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.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 13
Incorrect
-
Which statement is correct?
Your Answer:
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.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 14
Incorrect
-
What is the structure of nucleosomes?
Your Answer:
Correct Answer: Strands of double strand DNA + histones
Explanation:DNA is packed and condensed by binding to histone proteins. The double stranded DNA forms a complex with histone proteins which is called a nucleosome. There are 8 histone proteins contained in one core of nucleosome.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 15
Incorrect
-
Question 16
Incorrect
-
Immortality can result from over expression of which enzyme?
Your Answer:
Correct Answer: Telomerase
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.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 17
Incorrect
-
Which of the following is an incorrect statement regarding the structure of DNA?
Your Answer:
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.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 18
Incorrect
-
Which part of the chromosome plays a role in preserving its integrity and stability?
Your Answer:
Correct Answer: Telomere
Explanation:Telomeres are non coding DNA plus proteins that are found at the end of the linear chromosomes. They maintain the integrity of the chromosomes and prevent their shortening
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 19
Incorrect
-
Which statement is incorrect?
Your Answer:
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.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 20
Incorrect
-
Restriction Enzymes...
Your Answer:
Correct Answer: Cut DNA sequences at specific sites
Explanation:Restriction endonucleases are enzymes that recognise short sequences of double stranded DNA and cut them at specific nucleotide points or sequences. These sequences differ for different restriction endonucleases.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 21
Incorrect
-
Question 22
Incorrect
-
The process by which RNA fragments are separated by gel electrophoresis and transferred onto a membrane sheet is called:
Your Answer:
Correct 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.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 23
Incorrect
-
Question 24
Incorrect
-
In DNA cloning and sequencing, the bases in nucleotides chains are bound together by:
Your Answer:
Correct Answer: Hydrogen bonding.
Explanation:Nucleotides will always bind together via hydrogen bonds. There are two hydrogen bonds present between thymine and adenine and three hydrogen bonds present between guanine and cytosine.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 25
Incorrect
-
In a knockout mouse model the process used to combine the new DNA sequence and the stem cells is known as:
Your Answer:
Correct Answer: Insertion
Explanation:Chimerisation is also known as the formation of recombinant DNA. When a foreign DNA sequence is inserted into a plasmid or other DNA sequence, this process is known as insertion.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 26
Incorrect
-
Which statement about X linked dominant disorders is FALSE?
Your Answer:
Correct Answer: Heterozygous females tend to have the disease more severely than affected males.
Explanation:Women who have the affected X chromosome will be affected, but the severity will be less than that in males as they have a normal X chromosome to counter the effect of the mutated X chromosome. Affected males will pass on the defect to their daughters 100% of the time but not to their sons.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 27
Incorrect
-
The enzyme responsible for Telomeres to maintain their length after cell division is called:
Your Answer:
Correct Answer: Telomerase reverse transcriptase
Explanation:Telomeres are non-coding DNA consisting of repetitive nucleotide sequences plus proteins that are found at the end of the linear chromosomes. They maintain the integrity of the chromosomes and prevent their shortening.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 28
Incorrect
-
Regarding Polymerase Chain Reaction, all are true except:
Your Answer:
Correct Answer: There is a linear rise of DNA copies during amplification.
Explanation:All are true except there is a linear rise of DNA copies during amplification. There is an exponential rise in amplification of DNA.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 29
Incorrect
-
Which of the following is not true regarding mitochondrial chromosome disorders?
Your Answer:
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.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 30
Incorrect
-
Carcinogens found in cigarette smoke can transform proto-oncogenes to oncogenes through:
Your Answer:
Correct 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.
-
This question is part of the following fields:
- Genetics
- Medicine
-
SESSION STATS - PERFORMANCE PER SPECIALTY
