Viruses and Cell Types: Characteristics, Structures, and Functions in Biology

What are the key characteristics of viruses?

Viruses are acellular, consist of genetic material (DNA or RNA) surrounded by a protein coat, and cannot replicate independently.

What is the viral replication cycle?

The viral replication cycle typically includes attachment, penetration, uncoating, replication, assembly, and release.

What is the role of the protein coat in viruses?

The protein coat, or capsid, protects the viral genetic material and aids in the attachment to host cells.

How do viruses differ from living organisms?

Viruses lack cellular structure, do not carry out metabolic processes, and cannot reproduce without a host cell.

What types of genetic material can viruses contain?

Viruses can contain either DNA or RNA as their genetic material.

What are the two main classifications of cells?

Prokaryotic and Eukaryotic cells.

What is a key characteristic of prokaryotic cells?

They do not have a nucleus or membrane-bound organelles.

Example of Prokaryotic Cell

Bacterial cells.

What are the characteristics of eukaryotic cells?

They have a nucleus surrounded by a membrane and membrane-bound organelles.

Examples of Eukaryotic Cells

plants, animals, fungi, protists

What is a defining feature of plant cells?

They have a cell wall made of cellulose and chloroplasts for photosynthesis.

What is a defining feature of animal cells?

They do not have a cell wall or chloroplasts and are often irregularly shaped.

What type of organisms are classified as single-celled eukaryotes?

Amoeba, Paramecium (Protozoa), and Yeast (Fungi).

What type of organisms are classified as multicellular eukaryotes?

Fungi, plants, and animals.

What is the role of chloroplasts in plant cells?

They are the photosynthetic organelles that allow plants to produce their own food.

What is the plasma membrane?

A protective layer that surrounds both prokaryotic and eukaryotic cells.

How do prokaryotic cells compare in size to eukaryotic cells?

Prokaryotic cells are smaller and less complex than eukaryotic cells.

What type of nutrition do heterotrophs, such as animal cells, rely on?

They consume organic material for energy.

What is the significance of ribosomes in both prokaryotic and eukaryotic cells?

Ribosomes are essential for protein synthesis.

What is the function of the cell wall in plant cells?

It provides structural support and protection.

Prokaryotic cells

Cells that lack a nucleus and membrane-bound organelles.

Eukaryotic cells

Cells that have a nucleus and membrane-bound organelles.

Organelles common to plant and animal cells

Structures within cells that perform specific functions, such as mitochondria and ribosomes.

Organelles found only in plant cells

Structures such as chloroplasts and cell walls that are not present in animal cells.

Organelles found only in animal cells

Structures such as lysosomes and centrioles that are not present in plant cells.

Prokaryotes

Domain Bacteria & Archaea

Eukaryotes

Domain Eukarya: Protists, Fungi, Plants, Animals

Prokaryotic Cell

A cell that lacks a nucleus, with DNA in a nucleoid, no organelles other than ribosomes, and is typically small and primitive.

Eukaryotic Cell

A cell that has a nucleus and nuclear envelope, membrane-bound organelles with specialized structures/functions, and is much larger and more complex.

Surface Area to Volume Ratio

Cells must be small to maintain a large surface area to volume ratio, allowing increased rates of chemical exchange between the cell and its environment.

Villi

Finger-like projections on the wall of the small intestine that increase absorption of nutrients.

Microvilli

Projections on each cell that further increase the surface area for absorption.

Root Hairs

Extensions of root epidermal cells that increase surface area for absorbing water and minerals.

Nucleus

The control center of the cell, containing DNA and mRNA, surrounded by a double membrane (nuclear envelope) and continuous with the rough ER.

Ribosomes

Cellular structures composed of rRNA and protein that are responsible for protein synthesis.

Free Ribosomes

Ribosomes that float in the cytosol and produce proteins used within the cell.

Bound Ribosomes

Ribosomes that are attached to the endoplasmic reticulum and make proteins for export from the cell.

Endomembrane System

A system that regulates protein traffic and performs metabolic functions within the cell.

Endoplasmic Reticulum (ER)

A network of membranes and sacs involved in protein and lipid synthesis.

Rough ER

A type of endoplasmic reticulum with ribosomes on its surface, involved in packaging proteins for secretion.

Smooth ER

A type of endoplasmic reticulum without ribosomes, involved in synthesizing lipids and detoxifying drugs.

Golgi Apparatus

An organelle that synthesizes and packages materials for transport in vesicles.

Lysosomes

Organelles that contain hydrolytic enzymes for intracellular digestion and recycling of cellular materials.

Vacuoles

Membrane-bound vesicles for storage of materials such as food, water, and minerals.

Mitochondria

The site of cellular respiration, characterized by a double membrane and folds (cristae) for increased ATP production.

Chloroplasts

The site of photosynthesis, containing thylakoid disks and chlorophyll for capturing sunlight energy.

Endosymbiont Theory

The theory that mitochondria and chloroplasts share a similar origin, having been prokaryotic cells engulfed by ancestors of eukaryotic cells.

Peroxisomes

Organelles that break down fatty acids and detoxify alcohol, producing hydrogen peroxide in the process.

Cytoskeleton

A network of protein fibers that provides support, motility, and regulation of biochemical activities in the cell.

Centrosomes

Regions from which microtubules grow, also known as microtubule organizing centers.

Cilia

Short, numerous projections that aid in locomotion or move fluids across cell surfaces.

Flagella

Long, few projections that propel cells through water.

Extracellular Matrix (ECM)

A network outside the plasma membrane of animal cells, composed of glycoproteins, that strengthens tissues and transmits signals.

Intercellular Junctions

Structures that connect animal cells, including tight junctions, desmosomes, and gap junctions.