Which of the following statements regarding Meiosis is true
Meiosis I is reduction in which separation of homologous chromosomes occur, while Meiosis II is equational division, just like mitosis in which separation of sister chromatids occur.
When secreting cell acting on nearby targeting cell by discharging a ligand and receptor of this ligand present of targeting cell, then this type of signaling is called-
In paracrine signaling, signaling cell and target cell both differ.
Transport of proteins from Golgi to ER
Measurements of amount of DNA per nucleus were taken from a large no. of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picogram per nucleus. In which state of the cell cycle did the nucleus contain 6 picogram of DNA, firstly observed.
In the S-phase of the cell cycle, the amount of DNA doubles but the number of chromosomes remain same. So, DNA level here ranges from 3 picogram to 6 picogram, so amount is doubling.
The gamma tubulin ring complex is-
Tubulin is the basic monomer of the microtubule.
Firstly, tubulin units are polymerised to give a protofilament and then proto filaments are arranged to form a microtubule.
So steps are
Nucleation → Polymerisation → Steady state
So in nucleation step gamma tubulins are required.
A C-terminal KDEL sequence in the protein will most often ensure-NA
KDEL sequence is retention signal or retrieval sequence for ER-retention of the protein
K = Lysine
D = Aspartic acid
E = Glutamic acid
L = Leucine
Find out the correct match-
Vinblastin is microtubule polymerisation inhibitor
Quabain is inhibitor of Na+ – K+ pump
Tunicamycin blocks first step of N-linked glycosylation
A young college student had nausea, vomiting, visual disorders, and muscular paralysis after eating canned tuna fish. The probable diagnosis is botulism, caused by ingestion of the Clostridium botulinum toxin. The physiological effect of this toxin is to
The toxin from Clostridium botulinum inhibits the release of acetylcholine, the neurotransmitter at myoneural junctions. As a result, motor nerve impulses cannot be transmitted across the junction, and muscle cells are not stimulated to contract.
Which one of the following is true in breast cancer cells that involve the BRCA 1 gene?
Mutations in the BRCA 1 gene, a breast tumor supressor gene, are the major cause of breast cancer. In most breast cancers involving this gene, deoxyribonucleic acid synthesis proceeds, indicating that the G1-S checkpoint is not affected; however, the mutated cells cannot control the transition between G2 and M. Moreover, the mutated cells have abnormal centrosome numbers, and their nuclear division does not proceed normally, leading to aneuploidy and genetic instability of the daughter cells.
Which of the following is a carbohydrate containing covering associated with the outer leaflet of the plasma membrane?
The glycocalyx (cell coat) is associated with the outer leaflet of the plasma membrane. It is composed primarily of proteoglycans, which possess polysaccharide side chains.
Which of the following organelles possesses mixed-function oxidases that detoxify phenobarbital and other drugs?
Smooth endoplasmic reticulum possesses mixed-function oxidases. Drugs detoxification occurs in hepatocytes following proliferation of the SER in response to the drug phenobarbital; the oxidases that metabolize this drug are located in the SER.
Which of the following has a rigid wall composed of 13 protofilament strands?
A microtubule consists of α - and β-tubulin dimers polymerized into a spiral around a hollow lumen to form a fairly rigid tubule. When cross-sectioned, the microtubule reveals 13 protofilament strands, which represent the tubulin dimers present in one complete turn of the spiral.
Find out the right statement
In the G-protein coupled receptor signaling if effector molecule is Adenylate cyclase then it forms cAMP from ATP. cAMP then activates protein-Kinase A.
If effector molecule will be
Which of the following amino acids of a membrane protein are not most likely to be buried in the interior of protein structure?
Non-polar amino acids are present in α -helix region of the integral proteins.
Find out the correct statement-
In the G0 phase the cell is metabolically active
cdc-25 is a phosphatase and it is involved in the last step of formation of active MPF. For G1 to S transition cyclin -E is required.
Human cells maintained concentration gradients across their plasma membranes, such that there is high sodium concentration outside the cell and a high potassium concentration inside the cell. Suppose that within the cell membrane are sodium leak channels. Which of the following statements are wrong regarding sodium transport.
Ions move from high concentration to low concentration. Here the sodium concentration gradient is established. So Na+ movement occurs from outside to inside with transported proteins thats why facilitated diffusion.
There are mentioned some properties. Out of these, find out the properties of cancerous cells
Cancerous cells have the following properties
(i) Loss of contact inhibition
(ii) Growth factor independent
(iii) Autocrine growth stimulation
(iv) Less adhesive than normal cells (loss of E-Cadherin, the principal adhesion molecule of epithelical cells)
(vi) Failure to undergo apoptosis
(vii) Expression of high level of telomerase
(ix) Cell cycle check points abnormal
A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. The amount of DNA (in picograms) found at the end of S and G2 phase would be __________
In the S-phase of cell cycle, the amount of DNA doubles. So in S-phase, 8 picogram will double as 16 picogram. And then G2 phase will occur.
Consider an epithelial cell which is perfect cube of side 24 with a nucleus in the centre. The surface area to volume ratio of this cell is _________
In a proliferating cell system, the number of mitotic divisions required to produce 1024 cells from a single parent cell are _______________
If there are total 14 chromosomes in the cell after completion of meiosis-I, then the number of chromosomes present on that cell after completion of meiosis-II would be ___________
Meiosis-I is a reductional division, hence after meiosis-I, chromosome numbers are reduced to half. Here the reduced chromosomes are 14 and meiosis-II is an equational division, so 14 chromosomes will be there after meiosis-II.