Introduction to Cell Structures and Functions

Questions and Answers

What are bacteria?

Single-celled organisms that lack a nucleus or any membrane-bound organelle.

Which of the following statements is true regarding prokaryotic cells?

Their DNA is not enclosed in a nucleus. (correct)

They are always larger than eukaryotic cells.

They are multicellular organisms.

They have a nucleus.

Eukaryotic cells have a more complex structure than prokaryotic cells.

True

Bacterial cell walls are composed of ______.

peptidoglycan Signup and view all the answers

What is the function of the capsule in bacteria?

Keep the bacterium from drying out and protect from phagocytosis Signup and view all the answers

What is the function of ribosomes in bacterial cells?

For protein synthesis Signup and view all the answers

Match the bacterial structures with their functions:

Cell Wall = Provides support and rigidity Plasma Membrane = Transportation of substances Flagella = Means of locomotion Pili = Gene transfer mechanism Signup and view all the answers

Plasmids are small cellular DNA used to exchange DNA between bacterial cells.

True Signup and view all the answers

What shape is the DNA in prokaryotic cells?

Circular Signup and view all the answers

Study Notes

Introduction to Bacteria

Bacteria are single-celled organisms classified as prokaryotic cells, lacking a nucleus and membrane-bound organelles.
Recognized for their potential to cause diseases and infections in various living organisms.

Prokaryotic vs. Eukaryotic Cells

Prokaryotic Cells:
- Simple structure with DNA floating freely in the cytoplasm.
- Generally smaller than eukaryotic cells.
Eukaryotic Cells:
- Can be single-celled or multicellular with a defined nucleus.
- More complex structure and generally larger than prokaryotic cells.

Bacterial Cell Structure

Bacterial cells contain various structures that provide functionality similar to those in plant and animal cells.

Cell Wall

Composed of peptidoglycan, unlike plant cell walls made of cellulose.
Provides structural support, mechanical strength, and protection against bursting in hypotonic conditions.

Capsule

A polysaccharide protective layer that prevents dehydration and shields against phagocytosis.

Cytoplasm

Acts as a storehouse for chemicals and cellular components necessary for growth, metabolism, and replication of genetic material.

Plasma Membrane

Semi-permeable membrane regulating the movement of substances in and out of the cell, including waste removal.

Ribosomes

Responsible for protein synthesis; unique in that antibiotics can selectively inhibit bacterial ribosomes without affecting eukaryotic counterparts.

Flagella

Hair-like structures enabling locomotion; assist in moving bacteria in various directions and may be found at the cell's ends or surface.

Pili

Small hair-like projections that aid in adhesion to surfaces or hosts; involved in gene transfer through a mechanism known as conjugation via a fertility pill.

Plasmid

Small circular DNA molecules that facilitate the exchange of genetic material between bacterial cells.

Characteristics of Prokaryotes

Lack a nucleus, containing circular DNA structured like a twisted rubber band.
Do not possess membrane-bound organelles.
Have a protective cell wall external to the cell membrane.
May feature flagella for movement.

Microscopy of Bacterial Cells

Observation through light and electron microscopes reveals the intricate structure of bacteria, including external features like the cell wall and flagella.

Description

This quiz explores the fundamental structures and functions of bacteria, which are prokaryotic, single-celled organisms. You'll learn about their unique cellular components and how their shapes classify them. Perfect for anyone studying microbiology or cellular biology.