Cell Structure and Function

A comprehensive set of vocabulary flashcards covering cell biology concepts, including types of microscopy, prokaryotic and eukaryotic structures, organelles, the endomembrane system, the cytoskeleton, and intercellular junctions.

Cell

The smallest unit of a living thing and the basic building block of all organisms.

Organism

A living thing that can be comprised of one cell, such as bacteria, or many cells, like a human.

Unified cell theory

A biological concept stating that one or more cells comprise all living things, the cell is the basic unit of life, and new cells arise from existing cells.

Microscope

An instrument that magnifies an object for study; derived from the Greek words micro- (‘small’) and -scope (‘to look at’).

Electron microscope

An instrument that uses a beam of electrons instead of light, providing higher magnification ($100,000\times$) and higher resolving power ($50\,\text{pm}$).

Prokaryote

A simple, mostly single-celled (unicellular) organism that lacks a nucleus or any other membrane-bound organelle.

Nucleoid

The central part of a prokaryotic cell where the chromosomal $DNA$ is localized.

Peptidoglycan

The chief component of the cell wall in most bacteria.

Flagella

Long, hair-like structures used for locomotion.

Pili

Structures used by bacteria to exchange genetic material during conjugation.

Organelle

Meaning ‘little organ,’ these are membrane-bound compartments or sacs within a cell that have specialized functions.

Plasma membrane

A phospholipid bilayer with embedded proteins that separates the internal contents of the cell from its surrounding environment.

Cytoplasm

The entire region of a cell between the plasma membrane and the nuclear envelope, consisting of organelles, cytosol, the cytoskeleton, and various chemicals.

Cytosol

The gel-like material of the cytoplasm in which cellular structures are suspended.

Nucleus

The most prominent organelle in a cell, which houses the cell’s $DNA$ and directs the synthesis of ribosomes and proteins.

Nuclear envelope

A double-membrane structure made of two phospholipid bilayers that constitutes the nucleus’s outermost portion.

Chromatin

Unwound protein-chromosome complexes that describe the material making up chromosomes both when condensed and decondensed.

Nucleolus

A darkly staining area within the nucleus responsible for aggregating ribosomal $RNA$ with proteins to assemble ribosomal subunits.

Ribosomes

Cellular structures responsible for protein synthesis, consisting of large and small subunits made of protein and $RNA$.

Mitochondria

Often called the ‘powerhouses’ of the cell, these organelles are responsible for making adenosine triphosphate ($ATP$) through cellular respiration.

Cell wall

A rigid covering external to the plasma membrane that protects the cell and provides structural support; primarily composed of cellulose in plants.

Chloroplasts

Plant cell organelles that carry out photosynthesis using water, carbon dioxide, and light energy to make glucose and oxygen.

Thylakoids

Interconnected and stacked fluid-filled membrane sacs within the chloroplast where light harvesting reactions occur.

Stroma

The fluid enclosed by the inner membrane of a chloroplast that surrounds the grana.

Chlorophyll

A green pigment in chloroplasts that captures the light energy driving photosynthesis.

Endosymbiosis

A mutually beneficial relationship in which one organism lives inside another; the theory explaining how mitochondria and chloroplasts originated from ingested bacteria.

Endomembrane system

A group of membranes and organelles in eukaryotic cells, including the nuclear envelope, lysosomes, vesicles, $ER$, and Golgi apparatus, that work together to modify, package, and transport lipids and proteins.

Endoplasmic reticulum ($ER$)

A series of interconnected membranous sacs and tubules that modify proteins (rough $ER$) and synthesize lipids (smooth $ER$).

Golgi apparatus

A series of flattened membranous sacs responsible for sorting, tagging, packaging, and distributing lipids and proteins.

Cytoskeleton

A network of protein fibers (microfilaments, intermediate filaments, and microtubules) that maintain cell shape and allow for movement.

Extracellular matrix

A network of proteins (like collagen) and carbohydrates secreted by animal cells that holds cells together and allows for intercellular communication.

The ________ is the basic unit of life.

Prokaryotes depend on ________ to obtain

some materials and to get rid of wastes.

diffusion (osmosis)

Which of the following organisms is a

prokaryote?

Which of the following is surrounded by two

phospholipid bilayers?

Which of the following is both in eukaryotic and

prokaryotic cells?

Which of the following is not a component of the

endomembrane system?

The process by which a cell engulfs a foreign

particle is known as:

Which of the following sequences correctly lists

in order the steps involved in the incorporation

of a proteinaceous molecule within a cell?

Explain how the formation of an adult human

follows the cell theory.

Humans start as a single fertilized cell that grows and divides into a full grown human. All of tissues, extracellular matrix, and organs develop from these cells, demonstrating that all living organisms are composed of cells and that cell division is fundamental to growth.

Antibiotics are medicines that are used to fight

bacterial infections. These medicines kill

prokaryotic cells without harming human cells.

What part or parts of the bacterial cell do you

think antibiotics target? Why?

Antibiotics typically target the bacterial cell wall and protein synthesis machinery, which are not present in human cells. This selective targeting allows antibiotics to effectively kill bacteria without harming human cells.

Explain why not all microbes are harmful.

Many microbes play essential roles in processes such as digestion, nutrient cycling, and environmental stability. Beneficial microbes contribute to human health by aiding digestion and protecting against pathogens.

You already know that ribosomes are abundant

in red blood cells. In what other cells of the body

would you find them in great abundance? Why?

Ribosomes are also abundant in cells that require high levels of protein synthesis, such as muscle cells and pancreatic cells. Muscle cells rely on ribosomes for the production of contractile proteins, while pancreatic cells produce digestive enzymes.