Select the incorrect statement about prokaryotic ribosomes.
50S and 30S subunits unite to form 70S ribosomes.
Polysome/polyribosome consists of many ribosomes only.
Ribosome is the site of protein synthesis.
Polysome indicate the synthesis of identical poolypeptide in multiple copies.
Correct Answer :
B. Polysome/polyribosome consists of many ribosomes only.
Prokaryotes have 70S ribosomes, each consisting of a small (30S) and a large (50S) subunit. Polyribosomes (or polysomes) are a cluster of ribosomes, bound to a mRNA molecule in translation during the process of protein synthesis. It was first discovered and characterized by Jonathan Warner, Paul Knopf, and Alex Rich in 1963. Polysomes indicate the synthesis of identical polypeptide in multiple copies.
Related Questions
Read the folowing statements and identify the correct option.
- Contractile vacuole takes part in osmoregulation and excretion.
- Food vacuole is formed by engulfing the food particles.
- The vacuole is bound by a double membrane called tonoplast.
- Vacuole can occupy upto 90 percent of the volume of the cell.
(i) and (ii)
(ii) and (iv)
(i), (ii) and (iv)
None of the above
Which of the following is absent in prokaryotes?
DNA
RNA
Plasma membrane
Mitochondria
Which one of the following organelle given below is correctly matched with its function ?
Golgi apparatus Protein synthesis
Golgi apparatus Formation of glycolipids
Rough endoplasmic reticulum Protein synthesis
Rough endoplasmic reticulum Formation of glycoproteins
Polysome is a chain of
oxysomes
sphaerosomes
ribosomes
dictyosomes
Identify the cell organelle given below. Which is an important site of formation of glyeoproteins & glycolipids
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
Golgi body
mitochondria
Cell sap is a
living content of cytoplasm.
nonliving content of cytoplasm.
nonliving content of vacuole.
living content of vacuole.
Protein synthesis in an animal cell occurs
on ribosomes present in cytoplasm as well as in mitochondria.
on ribosomes present in the nucleolus as well as in cytoplasm.
only on ribosomes attached to the nuclears envelope and endoplasmic reticulum.
only on the ribosomes present in cytosol.
In which method of transport, plasma membrane does not require carrier molecule?
Active transport
Facilitated diffusion
Simple diffusion
Na+ K+ pump
The given diagram shows the sectional view of a mitochondrion.
Identify the parts labelled as A, B, C, D & E
A - Outer membrane, B - Inner membrane, C - Matrix, D - Inter- membrane space, E - Crista
A - Outer membrane, B - Inner membrane, C - Intermembrane space, D - Matrix, E - Crista
A - Outer membrane, B - Inner membrane, C - Matrix, D - Crista, E - Inter - membrane space
A - Outer membrane, B - Inner membrane, C- Crista, D - Matrix, E - Inter-membrane space
Golgi apparatus is concerned with
excretion
secretion
ATP synthesis
RNA synthesis
The figure below shows the structure of a mitochondrion with its four parts labelled (A), (B), (C) and (D).
Select the part correctly matched with its function.
Part (D): Outer membrane Gives rise to inner membrane by splitting.
Part (B): Inner membrane Forms infoldings called cristae.
Part (C): Cristae Possess single circular DNA molecule and ribosomes.
Part (A): Matrix Major site for respiratory chain enzymes.
Golgi apparatus is absent in
higher plants
yeast
bacteria and blue-green algae
None of the above
The diagram given below represent a filuid mosaic model of plasma membrance. Match the components marked as A, B, C, D and E in the diagram below from the list (i) to (vii).
- Sugar
- Protein
- Lipid bilayer
- Integral protein
- Cytoplasm
- Cell wall
- External protein
A - (i), B - (ii), C - (iii), D - (iv), E - (v)
A - (ii), B - (i), C - (iii), D - (iv), E - (v)
A - (i), B - (ii), C - (iii), D - (iv), E - (vi)
A - (i), B - (ii), C - (iii), D - (vii), E - (v)
Active transport across biomembrane involves
production of ATP
requirement of energy
production of toxin
release of energy
A student placed two cells in the same solution in two different containers. The observation was given in the table.
| Container | Observation |
|---|---|
| 1 | Cell burst |
| 2 | Cell does not change its shape |
Which structure maintains the shape of the cell present in container 2 and provides the most significant difference between the two cells?
Nucleus
Cell wall
Chloroplast
Cell membrane
Which of the following statements are correct ?
- In prokaryotic cells, a special membranous structure formed by the extension of the plasma membrane into the cell is known as polysome.
- The smooth endoplasmic reticulum is the major site for synthesis of glycoproteins.
- RuBisCO is the most abundant protein in the whole biosphere.
- Mitochondria, chloroplasts and peroxisomes are not considered as part of endomembrane system. Of the above statements
(iii) and (iv)
(i) and (ii)
(ii) and (iii)
(i) and (iv)
Which of the following pair lack the unit membrane?
Nucleus and E.R.
Mitochondria and chloroplast
Ribosome and nucleolus
Golgi body and lysosome
Extension of plasma membrane in prokaryotic cell is
mesosome
haploid
ribosome
none of these
Function of contractile vacuole in Amoeba is
excretion and osmoregulation.
digestion and respiration.
osmoregulation and transportation.
none of the above.
The given diagram shows the types of chromosomes (labelled as A, B, C & D) based on the position of centromere.
Which one is the correct option for the labelled chromosomes. A, B, C and D ?
A Telocentric chromosome, B Acrocentric chromosome, C Submetacentric chromosome, D Metacentric chromosome
A Acrocentric chromosome, B Telocentric chromosome, C Metacentric chromosome, D Submetacentric chromosome
A Submetacentric chromosome, B Metacentric chromosome, C Telocentric chromosome, D Acrocentric chromosome
A Metacentric chromosome, B Submetacentric chromosome, C Acrocentric chromosome, D Telocentric chromosome.
The following diagram shows some of the missing structures in a plant cell marked as A, B, C, D E. Choose the option with their correct names.
A - Plasmodesmata, B - Rough endoplasmic reticulum, C - Golgi apparatus, D - Mitochondrion, E - Ribosomes
A - Desmosome, B - Rough endoplasmic reticulum, C - Golgi apparatus, D - Mitochondrion, E - Ribosomes
A - Plasmodesmata, B - Smooth endoplasmic reticulum, C - Golgi apparatus, D - Mitochondrion, E - Ribosomes
A - Tight junction, B - Rough endoplasmic reticulum, C - Golgi apparatus, D - Mitochondrion, E -Ribosomes
Match column-I with column-II and select the correct option.
| Column - I | Column - II |
|---|---|
| A. RER | I. Intracellular and extracellular digestion |
| B. Cell wall | II. Provide structural support to the cell |
| C. Flagella | III. Protein synthesis and secretion |
| D. Lysosomes | IV Responsible for cell movement |
A III, B II, C IV, D I
A II, B III, C IV, D I
A I, B III, C II, D IV
A IV, B II, C III, D I
In which of the following the cells are held together by a Ca-pectate layer?
Primary cell wall
Secondary cell wall
Middle lamella
Tertiary cell wall
Microtubules, motor proteins, and actin filaments are all part of the
mechanism of photosynthesis that occurs in chloroplasts.
rough ER in prokaryotic cells.
cytoskeleton of eukaryotic cells.
process that moves small molecules across cell membranes.
Microtubules are absent in
mitochondria
centriole
flagella
spindle fibres
Nucleolus is
rounded structure found in cytoplasm near nucleus.
rounded structure inside nucleus and having rRNA.
rod-shaped structure in cytoplasm near the nucleus.
none of the above.
Which of the following statements are correct?
Na+/K+ pump is an example of active transport.
In plant cells lipid like steroidal hormones are synthesized in SER.
In plant cells, the vacuoles can occupy up to 10% of the volume of the cell.
Chlorophyll and leucoplast are responsible for trapping light energy essential for photosynthesis.
Which of the following lacks cell wall?
Gametes
Amoeba
Mycoplasma
All of these
Match column-I (cell organelle) with column-II membrane and select the correct option from the codes given below.
| Column-I | Column-II |
|---|---|
| A. Mitochondria | I. Without membrane |
| B. Lysosomes | II. Single membrane |
| C. Ribosomes | III. Double membrane |
A - I, B - II, C - III
A - III, B - I, C - II
A - III, B - II, C - I
A - II, B - III, C - I
Identify the components labelled as A, B, C, D and E in the diagram given below from the list (i) to (viii).
- Cristae of mitochondria
- Inner membrane of mitochondria
- Cytoplasm
- Smooth endoplasmic reticulum
- Rough endoplasmic reticulum
- Mitochondrial matrix
- Ribosome
- Nucleus
A - (viii), B - (v), C - (vii), D - (iii), E - (iv)
A - (i), B - (iv), C - (vii), D - (vi), E - (iii)
A - (vi), B - (v), C - (iv), D - (vii), E - (i)
A - (v), B - (i), C - (iii), D - (ii), E - (iv)