39 Questions
What types of cell forms can bacteria exhibit?
Spheres, rods, and spirals
Which diagram represents a bacterial cell in its typical form?
The top diagram
How do bacteria reproduce?
Both sexually and asexually
When observing the transition between diagrams, what cellular process is depicted in the bottom diagram?
Binary fission
Which feature is not a typical form or shape for bacteria?
Cube
What type of bacteria are rod shaped?
Filamentous
Which type of bacteria lacks cell walls?
Mycoplasma genus
What is one way bacteria reproduce?
Binary fission
Which of the following bacteria are gram-positive?
Staphylococcus
What function do flagella serve in bacteria?
Movement
Which of the following bacteria forms cubic packets?
Sarcinae
Which of the following structures is present in bacteria for fixation and DNA transfer?
Pili
Bacteria are classified into Gram-Positive and Gram-Negative based on which structural component?
Cell wall
Which type of bacteria produces its food through photosynthesis?
Phototrophic
What is the primary molecule that makes up the bacterial cell wall?
Peptidoglycan
Which cellular structure in bacteria is responsible for motility?
Flagella
What is the form of the genetic material within bacterial cells?
Single circular DNA
Which of the following is NOT a characteristic of bacterial cytoplasm?
Contains multiple complex organelles
Which of these components is found in the outer membrane of some bacteria?
Lipopolysaccharide
Which bacterial cell arrangement forms chains of spherical cells?
Streptococci
What is the function of the bacterial cell membrane?
Surrounding the cytoplasm and regulating substance passage
Which structure in bacterial cells is responsible for protein synthesis?
Ribosomes
Which bacterial arrangement describes rod-shaped cells in pairs?
Diplobacilli
Which of the following is a characteristic of Coccus bacteria?
Spherical-shaped
What is the arrangement of cocci in a cube-shaped group of eight called?
Sarcina
What is the purpose of flagella in bacterial cells?
Helping with movement
Which statement is true about bacterial capsules?
They help bacteria evade the immune system
Which type of bacteria is rod-shaped?
Bacillus
Which bacterial morphology represents Treponema pallidum?
Spirillum
What describes spiral-shaped bacterial cells?
Spirilla
What structure in bacterial cells contains their DNA?
Nucleoid
What enables bacteria to change their shape and size?
External stresses
Which of the following bacteria is an example of a Vibrio?
Vibrio cholerae
Which term describes cocci that appear in chains?
Streptococci
What is the color of gram-negative bacteria after gram staining?
Red
Which types of bacteria are known to produce endospores?
Bacilli
What feature allows some bacteria to move?
Flagella
Which structure protects some bacteria from the immune system?
Capsule
Why do gram-positive bacteria stain purple?
Because they have a thick layer of peptidoglycan
Study Notes
What is Bacteria?
- Bacteria are single-celled prokaryotic organisms, lacking a nucleus and other membrane-bound organelles, and are ubiquitously found in all habitats.
- They can be pathogens or beneficial and can be classified as parasites or producers, playing a crucial role in biogeochemical cycles.
Structure of Bacteria
- Bacterial cells are composed of peptidoglycan, lacking a true cell wall, and a smooth membrane.
- They contain 80% water and a cytoplasm without a true envelope.
- The cytoplasm lacks organelles like mitochondria and has a central core of protein surrounding the nucleus aspect from nucleoid DNA.
- They possess microscopic inclusions for storing fats and minerals extracted from outside.
Locomotion
- Some bacteria have flagella or pili for motility and attachment to surfaces.
Nutrition
- Phototrophic bacteria, like Cyanobacteria, produce their food through photosynthesis.
Shapes and Arrangements
- Bacterial cells can be spherical (cocci), rod-shaped (bacilli), or spiral-shaped (spirilla).
- Cocci can be arranged in diplococci (pairs), streptococci (chains), staphylococci (clusters), or sarcinae (cube-like packets).
- Bacilli can be arranged in diplobacilli (pairs) or streptobacilli (chains).
Cell Wall and Membrane
- The cell wall is a rigid structure providing shape and protection from osmotic lysis.
- The cell membrane is a thin, flexible structure regulating the passage of substances into and out of the cell.
Cytoplasm and Nucleoid
- The cytoplasm is the jelly-like substance filling the cell, where most metabolic reactions take place.
- The nucleoid is the region of the cytoplasm containing the cell's DNA, not enclosed by a membrane.
Ribosomes and Other Structures
- Ribosomes are small, granular organelles responsible for protein synthesis, found in the cytoplasm and on the surface of the endoplasmic reticulum.
- Some bacteria have additional structures like flagella, pili, and capsules.
Gram Stain
- Gram staining classifies bacteria as gram-positive (thick peptidoglycan layer) or gram-negative (thin peptidoglycan layer and outer membrane).
Other Important Features
- Motility: some bacteria can move using flagella.
- Spore formation: some bacteria produce endospores, which are dormant and resistant to harsh environments.
- Capsule: some bacteria have a layer of slimy material surrounding the cell wall, protecting them from the immune system.
Learn about the characteristics, structure, and importance of bacteria, single-celled prokaryotic organisms that can be pathogenic or beneficial. Discover their role in biogeochemical cycles.
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