Cell: The Unit of Life

Questions and Answers

What is the characteristic of the genetic material in prokaryotes?

It is basically naked, not enveloped by a nuclear membrane. (correct)

It is divided into multiple chromosomes.

It is found in the cytoplasm.

It is enveloped by a nuclear membrane.

What is the function of plasmid DNA in bacteria?

It helps in the destruction of foreign DNA.

It confers certain unique phenotypic characters to bacteria. (correct)

It regulates the expression of genomic DNA.

It helps in the replication of genomic DNA.

Which of the following organelles are found in prokaryotic cells?

Ribosomes (correct)

Mitochondria

Golgi apparatus

Lysosomes

What is the size of typical bacteria?

1-2 μm Signup and view all the answers

Which of the following is NOT a characteristic of prokaryotic cells?

Genomic DNA is enveloped by a nuclear membrane Signup and view all the answers

What is the function of the cytoplasm in prokaryotic cells?

It is the fluid matrix filling the cell. Signup and view all the answers

Which of the following bacteria is an exception to having a cell wall?

PPLO Signup and view all the answers

What is the significance of plasmid DNA in higher classes?

It is used to monitor bacterial transformation with foreign DNA. Signup and view all the answers

What is the approximate length of Mycoplasmas, the smallest cells?

0.3 µm Signup and view all the answers

What is a unique feature of prokaryotes?

Inclusions and infoldings of cell membrane Signup and view all the answers

What is the typical shape of the bacterium Coccus?

Spherical Signup and view all the answers

What is the outermost layer of the cell envelope in prokaryotes?

Glycocalyx Signup and view all the answers

What is the general size range of bacteria?

0.3 to 5.0 µm Signup and view all the answers

What is the main function of the cell wall in prokaryotes?

To maintain the cell's shape and provide structural support Signup and view all the answers

Which of the following is a characteristic of the plasma membrane in prokaryotes?

It is selectively permeable in nature Signup and view all the answers

Which of the following is a characteristic of prokaryotic cells?

They multiply more rapidly than eukaryotic cells Signup and view all the answers

What is the name of the smallest isolated single cell?

Ostrich egg Signup and view all the answers

What is the term for the process of staining cells to distinguish between Gram-positive and Gram-negative bacteria?

Gram staining Signup and view all the answers

Which of the following is an example of a prokaryotic cell?

Mycoplasma Signup and view all the answers

What is the function of glycocalyx in prokaryotes?

To protect the cell from the environment Signup and view all the answers

What is the shape of the bacterium Vibrio?

Comma-shaped Signup and view all the answers

What is the term for the infoldings of cell membrane in prokaryotes?

Mesosomes Signup and view all the answers

Which of the following is a characteristic of Gram-positive bacteria?

They take up the Gram stain Signup and view all the answers

What is the fundamental organization of prokaryotic cells?

Fundamentally similar to eukaryotic cells Signup and view all the answers

Study Notes

Cell Size and Shape

Mycoplasmas, the smallest cells, are only 0.3 µm in length.
Bacteria can be 3 to 5 µm in length.
The largest isolated single cell is the egg of an ostrich.
Red blood cells are about 7.0 µm in diameter.
Cells vary greatly in shape, including disc-like, polygonal, columnar, cuboid, thread-like, or irregular shapes.

Prokaryotic Cells

Prokaryotic cells include bacteria, blue-green algae, mycoplasma, and PPLO.
They are generally smaller and multiply more rapidly than eukaryotic cells.
Prokaryotes exhibit a wide variety of shapes and functions.
They have a cell wall surrounding the cell membrane, except in mycoplasma.
The fluid matrix filling the cell is the cytoplasm.
There is no well-defined nucleus in prokaryotes.
Genetic material is basically naked, not enveloped by a nuclear membrane.
Prokaryotes have plasmids, which are small circular DNA outside the genomic DNA, conferring unique phenotypic characters to bacteria.

Cell Envelope and Modifications

The cell envelope consists of a tightly bound three-layered structure: glycocalyx, cell wall, and plasma membrane.
Each layer of the envelope performs distinct functions, but they act together as a single protective unit.
Bacteria can be classified into two groups based on the differences in the cell envelopes and the manner in which they respond to the staining procedure developed by Gram.
Gram-positive bacteria take up the gram stain, while Gram-negative bacteria do not.

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Description

This quiz covers the basic structure and types of cells, including red blood cells, white blood cells, and epithelial cells.