Unit 1 Topic 2: Structure of Life

Vocabulary practice flashcards covering cell structure, organelles, discovery timeline, endosymbiosis, and multicellular organization based on Unit 1 Topic 2 lecture notes.

Cell

The smallest unit of matter that can carry on all processes of life.

Robert Hooke

The scientist who was first to see and use the term 'cells' after examining cork and describing its structure as boxes.

Anton van Leeuwenhoek

The scientist who was the first to observe living cells using a microscope he created.

Cell Theory

The theory stating that: 1. All living things are made of cells; 2. Cells are the basic unit of structure and function; 3. Cells come from the reproduction of pre-existing cells.

Matthias Schleiden

The scientist who stated that all plants are made of cells.

Theodore Schwann

The scientist who stated that all animals are made of cells.

Rudolf Virchow

The scientist who conducted experiments demonstrating that cells are produced from pre-existing cells.

Lynn Margulis

The scientist who researched the evolution of eukaryotic cells in 1970.

Endosymbiosis

A theorized process in which early eukaryotic cells were formed from simpler prokaryotes, supported by mitochondria and chloroplasts having double membranes, their own DNA, and energy production capabilities.

Prokaryotes

Cells characterized by simple structure, absence of a nucleus, circular DNA, small size ($0.1{-}10\text{ }\frac{1}{\text{m}}\times 10^{-6}$ or $0.2{-}5\text{ }\frac{1}{\text{m}}\times 10^{-6}$), and lack of membrane-bound organelles (e.g., bacteria).

Eukaryotes

Cells characterized by complex structure, a true nucleus, linear DNA, larger size ($10{-}100\text{ }\frac{1}{\text{m}}\times 10^{-6}$), and membrane-bound organelles (e.g., plant and animal cells).

Organelle

Parts of the cell that perform specific jobs to maintain cell function.

Cell Membrane

A thin membrane surrounding a cell that controls what enters and exits the cell to maintain homeostasis.

Nucleus

A large organelle known as the 'brains of the cell' that contains all genetic information.

Nuclear Envelope

The double membrane surrounding the nucleus that controls what enters and exits the nucleus.

Nuclear Pores

Openings in the nuclear envelope.

Nucleolus

A dense circular area inside the nucleus where ribosomes are synthesized.

Chromatin

The stringy form of DNA filling the nucleus during interphase.

Cytoplasm

The fluid-filled area (cytosol) found between the nucleus and the cell membrane in which organelles reside.

Mitochondria

Large, oval-shaped organelle known as the 'powerhouse of the cell' that produces energy ($\text{ATP}$) for the cell.

Ribosomes

The most numerous non-membrane-bound organelles, consisting of small circular structures that serve as the site of protein synthesis.

Endoplasmic Reticulum

A network of membranes functioning like an internal 'molecule highway' to transport items within the cell.

Rough ER

Endoplasmic reticulum studded with ribosomes on its surface, responsible for producing proteins for export.

Smooth ER

Endoplasmic reticulum without ribosomes, responsible for synthesizing lipids (fats) and detoxifying cells.

Golgi Apparatus

A stack of membranes used to process, package, and secrete items from the cell using vesicles.

Lysosome

Small spherical organelles containing digestive enzymes used to break down macromolecules, harmful molecules, and invaders.

Peroxisomes

Small organelles that break apart $\text{H}_2\text{O}_2$ into water and oxygen.

Vacuole

A fluid-filled organelle used to store enzymes and waste, which is particularly large in plant cells.

Cytoskeleton

A network of protein fibers (microfilaments and microtubules) that maintains the cell's size and shape.

Microfilaments

Small protein filaments within the cytoskeleton that assist with cell movement.

Microtubules

Large strands within the cytoskeleton that support the cell's shape.

Centrioles

Microtubule structures located near the nucleus in animal cells that organize cell division.

Cilia

Short, numerous hair-like projections that assist in cellular movement or sweeping debris.

Flagella

Long, less numerous hair-like projections that assist in cellular movement.

Cell Wall

A hard, rigid layer outside the plasma membrane in plant cells that provides structural support and protection.

Plastids

A group of membrane-bound organelles in plants responsible for making and storing food.

Chloroplast

A double-membrane green plastid that manufactures food for plant cells through photosynthesis.

Unicellular Organism

An organism composed of a single cell (e.g., Paramecium, Amoeba).

Multicellular Organism

An organism composed of many cells working together (e.g., plants, animals).

Cell Specialization

The process by which undifferentiated stem cells become specialized cell types with unique functions.

Stem Cells

Undifferentiated cells that have the potential to differentiate into a wide variety of specialized cell types.

Multicellular Organization Hierarchy

The levels of structural organization in multicellular life: Organelles $\rightarrow$ Cell $\rightarrow$ Tissue $\rightarrow$ Organ $\rightarrow$ Organ System $\rightarrow$ Organism.