Cell Biology and Cell Cycle Practice Flashcards

Comprehensive practice flashcards covering the principles of cell theory, key scientists, structural differences between prokaryotes and eukaryotes, organelle functions, and the mechanisms of mitosis and meiosis.

Cell Theory

A fundamental theory in biology stating that all living organisms are made of one or more cells, the cell is the basic unit of structure and function, and all cells come from pre-existing cells.

Robert Hooke (1665)

The first scientist to use the term "cell" after observing tiny box-like compartments in a thin slice of cork using a compound microscope.

Antonie van Leeuwenhoek (1674)

Known as the Father of Microbiology, he improved microscope lenses and was the first to observe living cells like bacteria and protozoa, calling them "animalcules."

Matthias Schleiden (1838) - Plants

A scientist who studied different kinds of plants and concluded that all plants are made of cells, establishing the cell as the basic building block of plants.

Matthias Schleiden (1838) - Animals

A scientist who studied animal tissues and concluded that "All animals are made of cells," helping develop the first two principles of Cell Theory.

Matthias Schleiden (1838) - Pre-existing Cells

The scientist who proposed that all cells come from pre-existing cells, stating "Omni cellula e cellula," which added the third principle of the Cell Theory.

Prokaryotic Cells

Simple, small cells ($1-10\,\mu m$) without a nucleus or membrane-bound organelles; DNA floats in the nucleoid region, and they reproduce by binary fission.

Eukaryotic Cells

Larger ($10-100\,\mu m$), more complex cells with a true nucleus and membrane-bound organelles; they can be unicellular or multicellular and reproduce by mitosis or meiosis.

Plasmids

The circular DNA structure typically found in prokaryotic cells.

Cell Membrane

A layer in both plant and animal cells that acts as a "security guard," letting some molecules in but keeping out harmful ones.

Cell Wall

The outer layer of plant cells made of strong materials like cellulose that provides protection; also found in fungi (chitin) and bacteria (peptidoglycan).

Cytoplasm

A substance found in both plant and animal cells made of dissolved molecules used for various cellular processes.

Nucleus

The "control center" of the cell that contains all the chromosomes and controls growth and reproduction.

Nucleolus

A structure found inside the nucleus made of RNA and protein that looks like a nucleus inside of a nucleus.

Chloroplast

The organelle where photosynthesis takes place, converting light energy from the sun into sugars; found only in plant cells.

Mitochondria

Known as the "powerhouse" of the cell, this organelle performs cellular respiration to turn nutrients into energy.

Golgi Apparatus

Acts as the "delivery man" in the cell, turning combinations of molecules into complex molecules to be stored or sent out of the cell.

Smooth Endoplasmic Reticulum

An organelle consisting of a group of tubes attached to the nucleus important for the creation and storage of lipids.

Rough Endoplasmic Reticulum

A group of bumpy membranes attached to the nucleus that works with ribosomes to synthesize and pack proteins.

Vacuole

A storage bubble for food and nutrients; plant cells typically have one large central version, while animal cells have small and many versions.

Ribosomes

Known as the "protein builders or machine worker" of the cell, these structures are found in both plant and animal cells.

Peroxisome

An organelle with digestive enzymes in its membrane that breaks down nutrients like amino acids, cholesterol, and fatty acids.

Lysosome

Found only in animal cells, it acts as the "suicidal bag" and uses enzymes to help digest and break down food.

Centrioles

Organelles present in animal cells but rare in lower plant forms, involved in cell division.

Cell Modification

The process of changing the structure, genetic material, or functions of a cell naturally or artificially to give it new abilities.

CRISPR-Cas9

A genetic modification technique that acts like a scissors to cut and replace DNA segments.

CAR-T cell therapy

An immunotherapy that modifies a patient's own T cells in the lab to target and kill cancer cells.

Epigenetic Modification

Changing gene expression without altering the DNA sequence, often by adding chemical tags like DNA methylation or histone modification.

Cell Cycle

A series of events involving growth, DNA preparation, and division that forms new cells; essential for tissue repair and reproduction.

Interphase

The longest phase of the cell cycle where the cell is not dividing but growing and preparing for division; includes $G_1$, $S$, and $G_2$ phases.

$G_1$ Phase

The First Gap Phase where the cell grows in size, produces organelles, and performs normal metabolic activities.

S Phase

The Synthesis Phase where DNA replication occurs, resulting in duplicated chromosomes held together by a centromere.

$G_2$ Phase

The Second Gap Phase where the cell continues growing and synthesizes proteins needed for division, like spindle fiber proteins.

Prophase

The first stage of mitosis where chromatin condenses into chromosomes, the nuclear membrane breaks down, and spindle fibers begin to form.

Metaphase

The mitotic stage where chromosomes align along the metaphase plate and spindle fibers attach to centromeres via the kinetochore.

Anaphase

The stage of mitosis where centromeres split and sister chromatids are pulled apart toward opposite poles by spindle fibers.

Telophase

The final stage of mitosis where chromosomes uncoil back into chromatin, nuclear membranes reform, and spindle fibers disassemble.

Cytokinesis

The division of the cytoplasm; forms a cleavage furrow in animal cells and a cell plate in plant cells.

Meiosis

A type of cell division that reduces the chromosome number from diploid ($2n$) to haploid ($n$), producing four genetically unique gametes.

Homologous chromosomes

A matching pair of chromosomes (one from each parent) that have the same size, shape, and genes.

Prophase I

The phase of Meiosis I where synapsis occurs and crossing over happens at the chiasma to create new genetic combinations.

Independent Assortment

The random orientation of maternal and paternal homologous chromosome pairs at the metaphase plate during Metaphase I.

Anaphase II

The stage in Meiosis II where centromeres split and sister chromatids separate and move to opposite poles.