Tag: introduction to eukaryotic cell

Questions Related to introduction to eukaryotic cell

Consider the following statements regarding characters of Archaebacteria that they share with eukaryotes:
I. The cell wall does not contain peptidoglycan.
II. DNA associated with histones.
III. Translation initiated with formylated methionine.
IV. RNA polymerase similar to eukaryotic RNA polymerase II
V. ATPase similarity
VI. Similar DNA replication and repair
How many of the above characters Archaebacteria share with eukaryotes?

bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

  1. 3

  2. 4

  3. 5

  4. 6

Show answer
Correct Option: A
Explanation:

Following characteristics of Archaebacteria that they share with eukaryotes:

The cell wall does not contain peptidoglycan, DNA associated with histones, ATPase similarity.
So the correct option is '3.'

Which of the following is not true for a eukaryotic cell?

bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

  1. Cell wall is made up of peptidoglycans

  2. It has 80S type of ribosome present in the cytoplasm

  3. Mitochondria contain circular DNA

  4. Membrane bound organelles are present

Show answer
Correct Option: A
Explanation:
  • Inside the cell wall, if present, do not contain muramic acid (therefore, no peptidoglycan). 
  • A eukaryotic cell has 80S ribosomes present in the cytoplasm. 
  • Membrane-bound organelles are present, like, mitochondria, ER, Golgi apparatus, chloroplasts, etc. 
  • Mitochondria are semi-autonomous organelles, which are double membrane-bound and have their own ribosomes (70S) and DNA (circular).
  • So, (A) statement is not true for the eukaryotic cells.

Choose the incorrect statement 

bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

  1. RNAi silencing takes place in all eukaryotic cells for cellular defence

  2. RNAi involves binding of  dsRNA molecules with mRNA for silencing to occur.

  3. Complementary nucleic acid could be from mobile genetic elements (transposons).

  4. Ti plasmid with nematode specific genes have been used in RNAi

Show answer
Correct Option: A
Explanation:

Gene silencing by dsRNA makes use of the naturally occurring cell machinery that is involved in the processing of miRNA in eukaryotic cells. It does not provide any defense mechanism. So the correct answer is ' RNAi silencing takes place in all eukaryotic cells for cellular defense'.

Which of the following statements is correct?

bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

  1. Prokaryotic cells are surrounded by a cell membrane.

  2. Prokaryotic cells have a nucleus.

  3. Eukaryotic cells have genetic information.

  4. Eukaryotic cells have membrane bound organelles.

Show answer
Correct Option: D
Explanation:
Organelles are the specialised and organised structures in a living cell. These may be bound by a single or double membrane (Exception is ribosomes which are non-membranous cell organelles present in both prokaryotes and eukaryotes). Membrane-bound cell organelles include nucleus, vacuole, endoplasmic reticulum, chloroplasts, mitochondria, lysosomes, Golgi apparatus and are present only in eukaryotes.
Hence D is the correct option.

Select the correct sequence of molecules in cell on the basis of molecular size from the smallest to the largest.

bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

  1. Carbon dioxide$-$phospholipid$-$DNA polymerase$-$ribosome

  2. Phospholipid$-$DNA polymerase$-$ribosome$-$carbon dioxide

  3. Phospholipid$-$carbon dioxide$-$ribosome$-$DNA polymerase

  4. Carbon dioxide$-$DNA polymerase$-$phospholipid$-$ribosome

  5. DNA polymerase$-$ribosome$-$carbon dioxide$-$phospholipid

Show answer
Correct Option: A
Explanation:

Carbon dioxide, has two atoms of oxygen and one atom of carbon, making it the smallest one among the given options. Phospholipids are amphipathic molecules, having phosphate head group and fatty acid tails. DNA polymerase is polypeptide enzyme while ribosomes are the assemblage of rRNA and proteins. 
The correct answer is option A.

Cell organelles are embedded in

bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

  1. Cytoplasmic membrane

  2. Protoplasm

  3. Cytoplasm

  4. None of the above

Show answer
Correct Option: C
Explanation:
  • Cytoplasm is a semifluid matrix present within a cell surrounding the nucleus (i.e without the nucleoplasm) which is enclosed by a cell membrane.
  • They are the nonnuclear content of protoplasm in which all of the cell organelles are embedded.
  • A cytoplasmic membrane or cell membrane is a phospholipid bilayer that separates the cell from the external environment.
  • Protoplasm is the living substance of a cell that is enclosed by a plasma membrane and includes the nucleoplasm.
  • So, the correct answer is 'Cytoplasm'.


Which of the following is not characteristic of a eukaryotic plant cell?

bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

  1. Ribosomes associated with endoplasmic reticulum

  2. Dictyosomes associated with Golgi bodies

  3. Cristae inside of mitochondria

  4. Thylakoids inside of chloroplasts

Show answer
Correct Option: B
Explanation:

The characteristics of a eukaryotic plant cell are

1. A membrane-bound nucleus.
2. Ribosomes associated with the endoplasmic reticulum.
3.Thylakoids inside of chloroplasts.
4. Dictyosomes are not associated with Golgi bodies. These are discrete tubules of the Golgi Apparatus.
Hence, the correct answer is 'Dictyosomes associated with Golgi bodies'.


Organelles 

bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

  1. Are typical of eukaryotic cells, not prokaryotic cells

  2. Separate chemical reactions in time and space

  3. Are membrane bound compartments

  4. All of the above are features of the organelles

Show answer
Correct Option: D
Explanation:

Organelles are small, specialised structures which perform a specific function within the cell. Organelles are enclosed by their own membrane.  They are found in eukaryotic cells. Their function is from generating energy to the cell to controlling of cell's growth and reproduction.

Hence, the correct answer is 'All of the above are features of the organelles'.

Which cellular organelle would be concentrated at the top of the centrifuged mixture after centrifugation of cells containing solution?

bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

  1. Nuclei

  2. Endoplasmic reticulum

  3. Mitochondria

  4. Ribosomes

  5. Membrane-bound proteins

Show answer
Correct Option: C
Explanation:

Centrifugation of cells is a sedimentation process used to separate certain organelles for analysis of specific parts of cells. a sample of tissue is lysed to break the cell membranes and mix up the contents of the cell. However, while the procedures may break many of the membranes of the cell including the plasma membrane and endoplasmic reticulum, it leaves certain  organelles such as mitochondria, nuclei, Golgi apparatus, peroxisomes and lysosomes intact in a homogeneous extract. During the process, particles of different densities or size sediment at different rates. The largest and most dense particle sediments first followed by less dense and smaller particles. Hence the cellular organelle concentrated on the top of the centrifuged mixture will be the mitochondria due to its less density and small size. Thus, the correct answer is option C.

Mesokaryotic condition was distinguished by

bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

  1. Whittaker

  2. Dodge

  3. Copeland

  4. Haeckel

Show answer
Correct Option: B
Explanation:
  • A mesokaryotic (meso= in between, karyon= nucleus) cell shows intermediate resemblance to both eukaryotic and prokaryotic cell.
  • It contains well-developed nucleus but it undergoes cell division by amitosis (because the mitotic spindle is not formed).
  • This condition in a cell was first distinguished by Dodge in the year 1966.
  • So, the correct answer is 'Dodge'.