Cell Biology and Ecological Organization

Flashcards covering the vocabulary of cell biology, including historical discoveries, cell theory, levels of organization, and detailed organelle functions based on lecture notes.

Cytology

The study of cell biology.

Levels of biological organization

Cells, Tissues, Organ, Organ System, Organism.

Levels of ecological organization

Organism, Population, Community, Ecosystem, Biosphere.

Cell

The smallest unit that is capable of performing life functions.

Robert Hooke (1665)

An English Scientist who conducted a study about cells by slicing a cork and observing it under a microscope.

Anton Van Leeuwenhoek (1670)

Observed the first tiny living organism from a droplet of rain, which he called "Animalcules."

Robert Brown (1831)

A botanist who discovered the "Nucleus" in plant cells, serving as the transmitter, controller of information, and carrier of genes.

Felix Dujardin (1835)

A French Biologist who discovered "Sarcode," later known as protoplasm, which is a membrane made up of nucleus and cytoplasm.

Matthias Jakob Schleiden (1838)

Discovered plant cells and stated in his work on phytogenesis that all parts of the plant organism are composed of cells.

Theodor Schwann (1839)

A German zoologist who discovered animal cells and declared that "All living things are composed of cells and cell products" in his book Microscopical Researches.

Rudolf Virchow (1858)

A German Physician who justified that new cells come from other cells.

Postulates of Cell Theory

1. All living organisms are composed of one or more cells. 2. The cell is the basic unit of structure and organization in organisms. 3. Cells arise from pre-existing cells.

Unicellular organisms

Organisms composed of a single cell, such as Bacteria and Protists.

Multicellular organisms

Organisms composed of many cells, including Protists, Fungi, Plants, and Animals.

Prokaryotes

Organisms that have prokaryotic cells, which do not have a nucleus or membrane-bound organelles.

Eukaryotes

Organisms that have eukaryotic cells, which contain a nucleus and structures called organelles that carry out specific functions.

Nucleoid region

An area in prokaryotic cells where circular DNA is found, characterized by having no physical boundary or enclosure.

Capsule (Slime layer)

A layer surrounding the cell wall and plasma membrane made of polysaccharides; it traps water to prevent drying and protects against phagocytosis.

Cell Membrane

The outer membrane of a cell consisting of a double layer of phospholipids (bilayer) that controls movement in and out of the cell.

Cell Wall

A structure made of carbohydrates—cellulose in plants—that supports and protects cells; found in plants and bacteria but not animal cells.

Cytosol

Occupies about $50 \, \%$ of cell volume and is the site of many chemical reactions (metabolism).

Cytoskeleton

A protein-based structure that helps maintain cell shape and move organelles; consists of microfilaments (made of actin) and microtubules (made of tubulin).

Nucleus

The control center of the cell that contains genetic material (DNA) and is separated from the cytoplasm by a nuclear membrane.

Nucleolus

A dense region of chromatin inside the nucleus that contains RNA to build proteins.

Nuclear Pores

Open portals of communication between the nucleus and the cytoplasm.

Endoplasmic Reticulum (ER)

An interconnected highway within the cell; the Smooth type lacks ribosomes, while the Rough type is studded with ribosomes and makes proteins.

Ribosomes

The protein factories of the cell.

Golgi Bodies

Also called Golgi apparatus; an organelle responsible for protein processing, modification, sorting, and repackaging into vesicles.

Lysosome

Organelles containing digestive enzymes that break down proteins, fats, carbohydrates, and waste; they also transport undigested material to the cell membrane.

Vacuoles

Membrane-bound sacs for storage of water, waste, toxins, and enzymes; they are larger than vesicles.

Tonoplast

The specific membrane that surrounds the central vacuole in plant cells.

Mitochondria

The site of cellular respiration where chemical energy is changed into $ATP$; they contain maternal DNA.

Chloroplast

The site of photosynthesis in plant cells which contains green chlorophyll pigment and converts inorganic compounds into sugar using solar energy.

Centrioles

Paired structures found only in animal cells, made of microtubules, which form the mitotic spindle to pull chromosome pairs apart during cell division.

Peroxisomes

Organelles that catalyze chemical reactions and break down toxins; contains catalase to break hydrogen peroxide into $H_2O$ and $O_2$ gas.