-
Question 1
Incorrect
-
With regard to X linked disorders which of the following are true
Your Answer: None of the above
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 2
Incorrect
-
During which stage does the mitotic apparatus dissolute?
Your Answer: Metaphase
Correct 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
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 3
Incorrect
-
The following cells replicate without shortening their telomeres because they express telomerase.
Your Answer: Somatic cells
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 4
Incorrect
-
The process where by DNA fragments are separated by size and charge is called:
Your Answer: PCR
Correct Answer: Gel electrophoresis
Explanation:Fragments of DNA of varying length can be separated on the basis of their charge and their size by a process called gel electrophoresis. Because DNA contains negatively charged phosphate groups, it will migrate in an electric field toward the positive electrode. Shorter chains migrate more rapidly through the pores of the gel, and thus separation depends on length. DNA bands in the gel can be visualized by various techniques including staining with dyes and autoradiography.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 5
Incorrect
-
What is the structure of nucleosomes?
Your Answer: Strands of double strand DNA + telomeres
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 6
Correct
-
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.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 7
Correct
-
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.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 8
Correct
-
Question 9
Incorrect
-
Which statement is correct regarding mRNA?
Your Answer: mRNAs are polymers of nucleosides containing a ribose-phosphate unit attached to a base.
Correct Answer: mRNAs are mainly found in the nucleus and cytoplasm of a cell.
Explanation:mRNA is transcribed from DNA and is carried to the cytosol to be translated. Hence it is mainly found in the cytosol and the nucleus of a cell. It is single stranded and contains the base uracil instead of thymine.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 10
Incorrect
-
In meiosis, the period of prophase 1 involves:
Your Answer: Chromosomes aligning themselves on the microtubules at the centre of the cell
Correct Answer: Replicated DNA condensing to form visible chromosomes
Explanation:Prophase 1 has been divided into five different stages (laptotene, zygotene, pachytene, diplotene and diakinesis). In prophase 1, chromosomes are going to condense to become visible, each chromosome will contain two chromatids that are joined at the centromere.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 11
Correct
-
Critical shortening of Telomeres result in:
Your Answer: Activation of p53 and prb and cell crisis
Explanation:Telomeres are repetitive nucleotide sequences at the ends of chromosomes that protect them from deterioration or from fusion with neighboring chromosomes. Each time a cell divides, its telomeres shorten. When they become critically short, they can no longer protect the chromosome ends, triggering a DNA damage response.
This response leads to the activation of tumor suppressor proteins p53 and pRb (retinoblastoma protein). Activated p53 can induce cell cycle arrest, allowing time for DNA repair or triggering apoptosis if the damage is irreparable. Similarly, pRb helps regulate cell cycle progression and can halt the cell cycle to prevent the proliferation of cells with damaged DNA.
As a result, the cell enters a state of crisis, characterized by widespread cell death and genomic instability, which ultimately prevents the propagation of cells with critically shortened telomeres.
Therefore, the correct answer is:
Activation of p53 and pRb and cell crisis
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 12
Incorrect
-
What is the role of cyclin and cyklin-dependent kinases in mitosis:
Your Answer: Causes breakdown of the nuclear envelope
Correct 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 13
Incorrect
-
What is the protective hexametric sequence at the ends of chromosomes called?
Your Answer: Intron
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 14
Incorrect
-
Telomerase is active in all of the following cells, except:
Your Answer: Germ cells
Correct Answer: Certain liver cells
Explanation:Telomerase is an enzyme that adds repetitive nucleotide sequences to the ends of chromosomes (telomeres), preventing their shortening during cell division. Telomerase activity is crucial for cells that divide frequently and need to maintain their telomere length for continued proliferation. These include:
- Stem cells: They have high telomerase activity to maintain their long-term proliferative capacity.
- Germ cells: These cells also have active telomerase to ensure the stability of genetic material across generations.
- Certain white blood cells: Some immune cells, particularly those that need to proliferate in response to infection, show telomerase activity.
- Certain cancer cells: Many cancer cells reactivate telomerase, which contributes to their uncontrolled growth and immortality.
However, most somatic cells, including certain liver cells, do not exhibit significant telomerase activity. While some liver cells might show low levels of telomerase activity during regeneration, it is not generally active in normal, differentiated liver cells.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 15
Incorrect
-
Which of the following with regard to autosomal dominant disorders are true:
Your Answer: The offspring of a heterozygous individual has a 25% chance of inheriting the chromosome carrying the disease allele
Correct Answer: The offspring of a heterozygous individual has a 50% chance of inheriting the chromosome carrying the disease allele
Explanation:50% of the children will be effected from parents who are heterozygous for an autosomal dominant disorder. An allele can be dominant or recessive. Individuals, meanwhile, can be homozygous or heterozygous: individuals who are homozygous for a certain gene carry two copies of the same allele. individuals who are heterozygous for a certain gene carry two different alleles.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 16
Correct
-
Which statement is incorrect?
Your 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 17
Incorrect
-
Which of the following statements is true regarding chromosomes?
Your Answer: During mitosis, division of the chromosome takes place along its long axis
Correct Answer: All are true
Explanation:All of the above mentioned statements are true regarding chromosomes.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 18
Correct
-
In DNA cloning and sequencing, the bases in nucleotides chains are bound together by:
Your 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 19
Incorrect
-
During which phase of the cell cycle does DNA synthesis occur?
Your Answer: G2
Correct Answer: S
Explanation:DNA synthesis occurs in the S phase of the cell cycle. In the G1 phase the cell prepares to divide. In G2 the cellular organelles divide and in the M phase mitosis occur. In the G0 phase the cell becomes quiescent and does not divide further
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 20
Incorrect
-
Mutation in RB can lead to the formation of which cancer?
Your Answer: Osteosarcoma
Correct 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.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 21
Incorrect
-
Which of the following is false with regard to the following statement: Proto- oncogenes can be transformed to oncogenes in the following ways.
Your Answer: Chromosomal translocation
Correct Answer: Inhibition of P53
Explanation:Proto oncogenes cannot be transformed into oncogenes due to inhibition of P53 gene. There has to be a mutation in the proto oncogene. All the other options are true.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 22
Incorrect
-
In Restriction Fragment Length Polymorphism (RFLP), the DNA fragments are separated by length through a process known as:
Your Answer: Insertion
Correct Answer: Gel electrophoresis
Explanation:Samples of DNA from individuals are broken into pieces by restriction enzymes and the fragments are separated according to their lengths via gel electrophoresis. Although now largely obsolete due to the rise of inexpensive DNA sequencing technologies, RFLP analysis was the first DNA profiling technique inexpensive enough to see widespread application.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 23
Incorrect
-
When during the cell cycle does DNA replication occur?
Your Answer: Cytokinesis
Correct Answer: S phase
Explanation:The S phase is known as the synthesis phase. During this phase DNA will begin to replicated, as well as the synthesis of the centrosomes and associated proteins.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 24
Incorrect
-
The enzyme responsible for telomeres maintaining their length after cell division is called:
Your Answer: Telomere reconstructing enzyme
Correct Answer: Telomerase
Explanation:Telomerase is the enzyme responsible for maintenance of the length of telomeres by addition of guanine-rich repetitive sequences. Telomerase activity is exhibited in gametes and stem and tumor cells.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 25
Incorrect
-
Which of the following are true when it comes to tumour suppressor genes:
Your Answer: Viruses can inactivate tumour suppressor genes
Correct Answer: All of the options are true
Explanation:All of the above mentioned statements are true regarding tumour suppressor genes. Tumour suppressor genes generally follow the two-hit hypothesis, which implies that both alleles that code for a particular protein must be affected before an effect is manifested.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 26
Incorrect
-
Telomerase is active in the following cells except:
Your Answer: Certain liver cells
Correct Answer: Certain osteoblasts
Explanation:Some cells have the ability to reverse telomere shortening by expressing telomerase, an enzyme that extends the telomeres of chromosomes. Telomerase is an RNA-dependent DNA polymerase, meaning an enzyme that can make DNA using RNA as a template.
Telomerase is not usually active in most somatic cells (cells of the body), but it’s active in germ cells (the cells that make sperm and eggs) and some adult stem cells. These are cell types that need to undergo many divisions, or, in the case of germ cells, give rise to a new organism with its telomeric “clock” reset.Interestingly, many cancer cells have shortened telomeres, and telomerase is active in these cells. If telomerase could be inhibited by drugs as part of cancer therapy, their excess division (and thus, the growth of the cancerous tumor) could potentially be stopped.A subset of liver cells with high levels of telomerase renews the organ during normal cell turnover and after injury. -
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 27
Incorrect
-
Which of the following conditions is NOT X-linked recessive?
Your Answer: Haemophilia B
Correct Answer: Cystic fibrosis
Explanation:Cystic fibrosis is a autosomal recessive disease with an incidence of about 1 in 2500 live births. The most common mutation occurs in the long arm of chromosome 7 which codes for the chloride channel (cystic fibrosis transmembrane conductance regulator) gene.
To have CF, a child must inherit two abnormal genes—one from each parent. The recessive CF gene can occur in both boys and girls because it is located on non-sex-linked chromosomes called autosomal chromosomes.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 28
Incorrect
-
Carcinogens found in cigarette smoke can transform proto-oncogenes to oncogenes through:
Your Answer: Chromosomal translocation
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
-
-
Question 29
Incorrect
-
When 2 nucleotide chains of DNA bind together, thymine is bound to:
Your Answer:
Correct 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.
-
This question is part of the following fields:
- Genetics
- Medicine
-
-
Question 30
Incorrect
-
In RFLP (restriction fragment length polymorphism), the DNA fragments are separated by length through a process known as:
Your Answer:
Correct Answer: Agarose gel electrophoresis
Explanation:Samples of DNA from individuals are broken into pieces by restriction enzymes and the fragments are separated according to their lengths via gel electrophoresis. Although now largely obsolete due to the rise of inexpensive DNA sequencing technologies, RFLP analysis was the first DNA profiling technique inexpensive enough to see widespread application.
-
This question is part of the following fields:
- Genetics
- Medicine
-
SESSION STATS - PERFORMANCE PER SPECIALTY
