The Cell and Its Structure Practice Flashcards

Comprehensive practice flashcards covering eukaryotic and prokaryotic cell structures, bacterial shapes, Gram-staining characteristics, and endospore formation based on the lecture notes.

According to the lecture, what are the three fundamental shapes of bacteria?

Spherical or Cocci ("Berries"), Spiral (having one or more twists), and Bacilli (rod-shaped).

What is the meaning of the word "Eucaryotes" based on its Greek roots?

"eu" means true and "caryo" means nut or nucleus.

What are the common examples of Spiral-shaped bacteria mentioned in the notes?

$Vibrio cholera$ and $Treponema pallidum$.

What is the typical size of a eukaryotic cell?

Larger than or greater than $5\,µm$.

What are the four components of the eukaryotic nucleus?

Nucleoplasm, Chromosomes, Nucleolus, and Nuclear Membrane.

Describe the composition of eukaryotic ribosomes.

They are $80S$ ribosomes consisting of a large subunit ($60S$) and a small subunit ($40S$).

What specific materials provide rigidity to the cell walls of fungi?

Chitin.

What is the function of sterols within the eukaryotic cytoplasmic membrane?

They give stability to the membrane, which is especially important for cells without a cell wall.

How does the lecture define photosynthesis?

The process by which light energy is used to convert carbon dioxide and $H_{2}O$ into $CHO$ and $O_{2}$.

What is the structural difference between flagella and cilia?

Flagella are long, thin, whiplike structures, while cilia are hairlike structures that are shorter than flagella.

What are the three ways a prokaryote is distinguished from a eukaryote?

The way its DNA is packaged, the makeup of its cell wall, and its internal structures.

Describe the four types of prokaryotic flagella arrangement.

(a) Monotrichous, (b) Amphitrichous, (c) Lophotrichous, and (d) Peritrichous.

What are axial filaments, and what movement do they facilitate?

Also known as periplasmic flagella or endoflagella, they are found in spirochetes and cause a corkscrew movement.

What is the function of fimbriae in bacterial cells?

They allow for attachment and are mostly responsible for microbial colonization on inanimate objects.

What is the composition and function of a bacterial Pilus (Pili)?

Made of the protein pilin, they are elongate, rigid tubular structures used in conjugation (sex pilus), primarily in Gram-negative bacteria.

Differentiate between a bacterial capsule and a slime layer.

A capsule is neatly organized, bound tightly, denser, and thicker; a slime layer is unorganized and loose, protecting bacteria from loss of water and nutrients.

What are the structural layers of a Gram-negative cell envelope?

It consists of three layers: the outer membrane, a thin cell wall (peptidoglycan), and the cytoplasmic membrane.

Which substance in the Gram-negative outer membrane acts as an endotoxin?

Lipid A.

What are the primary components of an acid-fast cell wall?

Large amounts of waxes known as mycolic acids, which make the cell wall hydrophobic.

What is the function of porin proteins in Gram-negative bacteria?

They form membrane channels that provide access for relatively small molecules while blocking certain antibiotics like penicillin and digestive enzymes like lysozyme.

What is the structural composition of the bacterial nucleoid?

A single long circular molecule of double-stranded DNA (bacterial chromosomes) with no histones and no nuclear envelope.

Which antibiotics are mentioned as inhibitors of protein synthesis in bacteria?

Erythromycin and Chloramphenicol.

What is the function of metachromatic granules (volutin) in bacterial inclusions?

They are involved in the synthesis of $ATP$.

What chemical factors contribute to the heat resistance of bacterial endospores?

A high content of calcium and dipicolinic acid.

Is sporulation in bacteria considered a method of reproduction?

No, sporulation is not a means of reproduction; it is a way to form dormant bodies for survival.

What triggers the germination of a bacterial endospore?

The presence of water and a specific germination agent that stimulates hydrolytic enzymes to digest the cortex.

Compare the size of prokaryotic and eukaryotic ribosomes.

Prokaryotic ribosomes are $70S$ (small); eukaryotic ribosomes are $80S$ (large), though eukaryotes have $70S$ ribosomes within their organelles.

Compare the chromosomal structure of prokaryotes and eukaryotes.

Prokaryotes have a single circular chromosome lacking histones; eukaryotes have multiple linear chromosomes associated with histones.