Tag: cell-the basic unit of life

• A karyotype is the number and appearance of chromosomes in the nucleus of a eukaryotic cell. The term is also used for the complete set of chromosomes in a species or in an individual organism. The study of whole sets of chromosomes is sometimes known as karyology. Hence, the karyology is the study of the nucleus.
  
• So, the correct answer is 'nucleus'.
  

Answer is option (A) Acetabularia by Hammerling.

• A nucleus is a membrane-bound organelle containing the genetic material in the form of DNA molecule coiled to form the chromosomes.
  
• It is also known as the control centre of the cell.
• Within the nucleus, the DNA molecule gets transcribed into an mRNA template which is translated into a variety of proteins. 
  
• These translated proteins help in performing all the important functions within the cell.
• It was discovered by Robert Brown in the year 1831.
• So, the correct answer is 'Robert Brown'.

• Nucleus is a membrane-bound organelle containing the genetic material in the form of DNA molecule coiled to form the chromosomes.
  
• It is also known as the control centre of the cell.
• The DNA molecule gets transcribed into an mRNA template which is translated into a variety of proteins. 
  
• These translated proteins help in performing all the important functions within the cell.
• So, the answer is 'Nucleus'.

• The nuclear membrane or karyotheca is a double membrane having pores at intervals.
• The nuclear membrane on its inside has a supporting membrane called the nuclear lamina or the fibrous lamina having a uniform thickness.
• It is a dense network of fibres present inside the nucleus of cells and are made up of intermediate filaments and membrane-associated proteins.
• It provides mechanical support to the nucleus and also regulates DNA replication and cell division 
• So, the correct answer is 'Both B and C.'

• A nucleus is a membrane-bound organelle containing the genetic material in the form of DNA molecule coiled to form the chromosomes.
  
• The nuclear membrane or the nuclear envelope is a lipid bilayer membrane (porous double-membrane) that encloses the nucleus.
  
• Nuclear membranes have protein-based channels known as nuclear pores which allow the transport of molecules across the nuclear envelope.
• So, the correct answer is 'Porous double membrane'.

• Hammerling's nucleocytoplasmic experiments state that the cytoplasm is the centre for all the metabolic activities in the cell and the nucleus is the controlling centre. 

• This experiment was conducted using Acetabularia.

• Acetabularia is a genus unicellular or single-celled green algae belonging to the family Polyphysaceae which are found in subtropical waters.

• They are gigantic in size and complex in form, therefore, used in experiments in cell biology.

• So, the correct answer is 'Acetabularia'.

• Chromatin material which remains condensed during interphase is called heterochromatin.
  
• Heterochromatin refers to the certain regions of DNA found on the chromosomes of a eukaryotic cell.
  
• The heterochromatin gets darkly stained due to the highly condensed nature of the DNA in these regions and has higher ribonucleic acid content.
• This heterochromatin is made up of high copy number tandem repeats (repetitive nucleotides).
• So, the correct answer is 'Heterochromatin'.

• The DNA present in the nucleus undergoes transcription to form the messenger RNA or mRNA.
  
• The mRNA formed within the nucleus is transported out of the nucleus and into the cytoplasm of the cell and gets attached to the ribosomes. 
• It then synthesis proteins in the cytoplasm which is required by the cell for various cellular activities.
• So, the correct answer is 'RNAs'.