99 Questions
What are the two main categories in which all living cells are classified?
Prokaryotes and eukaryotes
Which of the following is a characteristic of prokaryotic cells?
Lack true nucleus
Which organisms are typically categorized as prokaryotes?
Bacteria and Archaea
Which type of cell can be both single-celled and multicellular?
Eukaryotic cells
What distinguishes eukaryotic cells from prokaryotic cells?
Having true nuclei
Which type of cell encodes genetic information in DNA?
all of the above
Which category of cells includes plants, animals, fungi, and protists?
Eukaryotic cells
What defines the boundaries of a living cell?
A cell membrane (plasma membrane)
Which domain do prokaryotic cells belong to?
Bacteria and Archaea
Which type of cell is typically single-celled?
Prokaryotic cells
Which of the following is an example of a eukaryotic single-celled organism?
Amoeba
What is a common feature of both prokaryotic and eukaryotic cells regarding genetic information?
They encode genetic information in DNA.
Which of the following are not considered eukaryotic cells?
Bacteria and Archaea
What is the shape of DNA in Prokaryotes?
Circular
Where is the DNA located in Prokaryotes?
In the nucleoid
What do Prokaryotes lack in terms of organelles?
Membrane-enclosed organelles
How do Prokaryotes reproduce?
Binary fission
What is the shape of DNA in Eukaryotes?
Linear
Where is the DNA located in Eukaryotes?
In the nucleus surrounded by a nuclear envelope
What are the two processes involved in cell division for Eukaryotes?
Mitosis and meiosis
What is the method of reproduction in Eukaryotes?
Mitosis and/or meiosis
What is the method of reproduction in Prokaryotes?
Binary fission
What is the typical size range of bacterial cells?
0.5-2.0 μm
Which type of bacteria can measure up to 60 μm in length?
Cyanobacteria
What term is used to describe bacteria that can have varying shapes in a single culture?
Pleomorphism
What shape is associated with the term "coccus"?
Spherical
How is the arrangement "tetrads" characterized?
4 cells in a cube
What is the result of division in three planes for cocci bacteria?
Sarcinae
How do bacilli bacteria divide?
a and b
What is the term for random division in grapelike clusters?
Staphylo
Which type of bacteria can only divide in one plane?
Bacilli
What is the term used to describe bacteria shaped like a Rod-shaped?
Bacilli
What term is used to describe rigid wavy-shaped spiral bacteria?
Spirillum
What is the function of the bacterial cell wall?
Preventing osmotic lysis
Which structure lies outside the cell membrane?
Cell wall
What is the composition of peptidoglycan?
Polysaccharide chains cross-linked by polypeptides
What is the additional molecule found in the cell wall of G+ve bacteria?
Teichoic acid
Which type of bacteria have a thick layer of peptidoglycan?
G+ve bacteria
What forms the outermost layer of the cell wall of G-ve bacteria?
Outer membrane
Why are G-ve bacteria less sensitive to many antibiotics?
Because of the presence of lipopolysaccharides
What attaches the outer membrane to peptidoglycan in G-ve bacteria?
Lipoproteins
What is the function of 'porins' in the outer membrane?
Forming water-filled channels for transport
Which type of bacteria has an outer membrane composed of lipopolysaccharides?
G-ve bacteria
Which structure is considered one of the reasons why G-ve bacteria are less sensitive to many antibiotics?
Outer membrane
What are Lipopolysaccharides (LPS) also known as?
a and b
What is the function of Lipopolysaccharides (LPS) in bacterial cells?
They identify G-ve bacteria
What is the integral part of the outer membrane of bacterial cells?
Lipopolysaccharides (LPS)
What is the role of Lipid A in G-ve bacteria?
It is responsible for toxic properties
What is the function of the Periplasmic space?
It contains digestive enzymes
Which type of bacteria is more likely to have a well-observed Periplasmic space?
G-ve bacteria
What is the main function of transport proteins in the Periplasmic space?
Transferring metabolites into the bacterial cytoplasm
How do antibiotics like penicillins and cephalosporins control bacteria?
They inhibit the formation of peptidoglycan cross-links
Which enzyme in tears and other body fluids digests peptidoglycan?
Lysozyme
What distinguishes Mycoplasma from other bacteria in terms of cell wall?
They have no cell wall
How do Mycoplasma protect themselves from osmotic swelling and bursting?
sterols
What are wall-deficient bacteria strains that lose the ability to form a cell wall called?
L-forms
How can bacteria lose the ability to form a cell wall and become L-forms?
Naturally or due to chemical treatment
What role do L-forms play in diseases?
They play a role in chronic or recurrent disease
What is the function of the cell membrane in bacterial cells?
all of the above
What is the primary composition of the cell membrane?
Phospholipids and proteins
What is the structure of the cell membrane bilayer?
Hydrophilic and hydrophobic chains of phospholipids
Which component is responsible for adding rigidity to the cell membrane in Mycoplasma?
Sterols
How is the fluid mosaic model described?
phospholipid in fluid state, proteins form mosaic pattern.
How does some antimicrobial kill bacteria by affecting the cell membrane?
It causes leaks in the cell membrane
What is the role of proteins in the cell membrane?
They act as carriers and form pores for material entry
In addition to phospholipids and proteins, what does Mycoplasma have in its cell membrane for added rigidity?
Sterols
What are some of the functions performed by the cell membrane in bacteria that are similar to those carried out by mitochondria in eukaryotic cells?
ATP production and respiration
Which antimicrobial agents kill bacteria by causing leaks in the cell membrane?
Polymyxin and daptomycin
What is the composition of cytoplasm in bacterial cells?
4/5 water, 1/5 dissolved substances
Where do most anabolic and catabolic reactions occur in bacterial cells?
Cytoplasm
What is the function of ribosomes in bacterial cells?
Protein synthesis
How is the size of ribosomes and their subunits determined?
Sedimentation rate
What is the composition of a whole bacterial ribosome?
30S + 50S subunits
What is the nuclear region in bacterial cells?
Region containing genetic material
What are plasmids in bacterial cells?
smaller circular molecules of DNA
What is sporulation in bacterial cells?
Preparation for adverse conditions
What are the main components of a bacterial spore?
dipicolinic acid + ca+2 +water
What is the role of dipicolinic acid in bacterial spores?
contribute to heat resistance
How long can bacterial endospores survive in adverse environmental conditions?
More than 10,000 years
What triggers the germination of bacterial endospores?
very little water & are highly resistant to heat, drying, acids, bases, disinfectants & even radiation
What is the composition of a flagellum?
Protein
What is the function of a flagellum in bacterial cells?
Locomotion
How is the flagellum attached in the cell membrane?
It extends out of the cell
What is a bacteria with a single polar flagellum called?
Monotrichous
In which type of bacteria are flagella located at both ends?
Amphitrichous
What is chemotaxis?
a and b
What is the term for movement away from a repellent?
Negative chemotaxis
How do bacteria detect changes in concentration for chemotaxis?
Certain structures on cell surface
What is the special type of flagella in spirochetes called?
a and b
What is the composition of pili?
Pilin
What is the function of conjugation pili?
DNA transfer between bacterial cells
How does attachment pili contribute to pathogenicity?
Enhancing colonization on cell surfaces
What is glycocalyx composed of?
Polysaccharides
What is the purpose of a capsule in certain bacteria?
Protection from host defenses
What is the main function of a slime layer?
Protecting against drying
What are microbial biofilms?
Surface-associated communities with an extracellular matrix
What is dental plaque an example of?
Biofilm
How do biofilms affect bacterial resistance to antimicrobials?
Enhanced tolerance/resistance
What percentage of chronic human infections are estimated to be implicated with biofilms?
Around 80%
Test your knowledge of cell classification and characteristics with this quiz. Explore topics like prokaryotic cells, eukaryotic cells, genetic information, and cell categories.
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