Evolution, Cell Theory, and Cell Division

Flashcards covering key vocabulary and concepts from lectures on evolution, cell theory, cell structure, and cell division.

Evolution

The theory that all living things are related and that the diversity of life changes over time to adapt to an ever-changing environment.

Common Ancestry

The concept that all living things have evolved from a shared ancestor.

Cell Theory

All living organisms are made of cells, and all cells come from other cells.

Cell Membrane

Also called plasma membrane, it's a structure common to all cells.

Cytoplasm

Also called cytosol, it's a structure common to all cells.

DNA-based Chromosomes

Used to make RNA in all cells, it's a structure common to all cells.

Ribosomes

A structure common to all cells.

Prokaryotes

The earliest cells on our planet, which today includes two divergent groups: the bacteria and the archaea.

Eukaryotes

Cells that evolved after prokaryotes, characterized by internal membranes, membrane-bound organelles, and a complex cytoskeleton.

Endomembrane System

An interconnected set of membranous organelles in eukaryotic cells, including the nucleus, endoplasmic reticulum, and Golgi apparatus.

Nucleus

The organelle in the eukaryotic cell that houses the DNA, defined by a double-membraned nuclear envelope.

Endoplasmic Reticulum (ER)

A high-surface area structure made of folded sheets and tubes of membrane found next to the nucleus. There are domains of smooth ER, largely involved in lipid and carbohydrate synthesis, and rough ER where ribosomes dock to make membrane or secreted proteins.

Golgi Apparatus

Responsible for sorting and shipping proteins and other materials to their destinations in the cell. Also plays a major role in modifying proteins and synthesizing secreted carbohydrates.

Membrane Bound Organelles

They have at least two layers of membranes separating from the cytoplasm, and they are self-replicating. Examples include mitochondria and chloroplasts.

Endosymbiosis

The process by which membrane-bound organelles like mitochondria and chloroplasts originated from bacteria.

Cytoskeleton

An internal network of proteins that supports eukaryotic cells, composed of microfilaments, intermediate filaments, and microtubules.

Microfilaments

Long, fibrous polymers of the protein actin that form networks supporting the cell membrane.

Intermediate Filaments

Bundles of fibrous proteins that act like cables that resist stretching forces, preventing cell membranes from tearing or connecting cell structures together.

Microtubules

Cylinders formed from polymerization of tubulin proteins, forming rigid structures that support the shapes of cells and help organize the cell contents.

Extracellular Matrix (ECM)

Helps organize cells in a tissue.

Tight Junctions

Arrays of proteins closely connect the membranes of neighboring cells, making a waterproof seal that prevents movement of solutes between cells.

Desmosomes

Rivet-like structures tightly connecting two cells together at their cell membranes, and connecting to the cytoskeletons of both cells via intermediate filaments.

Gap Junctions

Hollow protein structures spanning the membranes of neighboring cells, creating a continuous channel of cytoplasm that allows free diffusion of molecules between cells.

Binary Fission

Process by which prokaryotes divide, where a cell grows longer, replicates its DNA, and divides in half, making two cells.

Mitosis

Separation of the DNA (chromosomes) equally into two daughter cells.

Cytokinesis

The physical division of the cell and cytoplasmic contents into two cells.

Cell Cycle

A predictable series of events in the lifespan of a cell that is highly regulated.

Interphase

The time between divisions.

G1 Phase

A newly formed daughter cell has one copy of every chromosome and begins to serve some function in an organism.

S Phase

Cell makes a copy of all of its DNA.

G2 Phase

Following DNA replication a cell will have two copies of every chromosome and be ready to divide.

M Phase

Cell enters mitosis following G2 phase and divides.

G1 Checkpoint

Determines when a cell should initiate DNA replication by proceeding to S phase.

G2 Checkpoint

Determines if the cell is ready to divide.

M Checkpoint

Occurs during metaphase, preventing anaphase initiation until all chromosomes are correctly connected to the spindle and properly aligned at the center.

Cyclin-Dependent Kinases (CDKs)

A family of enzymes that regulate cell division by activating other enzymes.

Cyclins

A family of proteins controlling CDKs. Individual cyclins will bind to specific CDKs and turn them on, which will in turn activate the correct proteins to move on to the next phase of the cell cycle.