Cellular structure, function, communication, and apoptosis

Who first observed dead cells and coined the term 'cell'?

Robert Hooke (1665) observed cork cells.

Who first observed living cells?

Antonie van Leeuwenhoek (1674) observed single-celled organisms in pond water.

Who discovered the nucleus?

Robert Brown (1831).

What are the three principles of the Cell Theory?

1. All living things are made of cells. 2. The cell is the basic unit of life. 3. All cells come from pre-existing cells.

Who contributed to the Cell Theory?

Matthias Schleiden, Theodor Schwann, and Rudolf Virchow.

What type of cells evolved first?

Prokaryotic cells (Bacteria & Archaea) ~3.5 billion years ago.

What limits the size of cells?

Surface Area-to-Volume Ratio (SAVR) - cells need enough surface area to exchange materials efficiently.

What adaptation allowed organisms to grow larger despite cell size limitations?

Multicellularity (~600 million years ago).

What do all cells have in common?

Plasma membrane, cytoplasm, DNA, and ribosomes.

How do prokaryotic and eukaryotic cells differ?

Prokaryotes: No nucleus, single circular DNA, no membrane-bound organelles. Eukaryotes: Nucleus, multiple linear chromosomes, organelles.

What is chromatin?

Uncondensed DNA found in the nucleus.

What is a chromosome?

Condensed DNA that forms during cell division.

What is the function of the nucleus?

Stores genetic material (DNA) and controls cell activities.

What is the function of ribosomes?

Protein synthesis.

What is the function of the rough ER?

Modifies and transports proteins.

What is the function of the smooth ER?

Synthesizes lipids and detoxifies substances.

What is the function of the Golgi apparatus?

Modifies, sorts, and packages proteins.

What is the function of lysosomes?

Breaks down waste and worn-out cell parts.

What is the function of mitochondria?

Generates ATP (energy) for the cell.

What is the function of chloroplasts?

Performs photosynthesis (in plant cells).

What are the three components of the cytoskeleton?

Microtubules, microfilaments, and intermediate filaments.

What is the function of microtubules?

Provide structure, assist in transport, form spindle fibers.

What is the function of microfilaments?

Help with movement (muscle contraction, cell shape).

What is the function of intermediate filaments?

Provide structural support to the cell.

What is the extracellular matrix (ECM)?

A network of proteins (e.g., collagen) that supports animal cells.

What are the four types of cell junctions?

Tight junctions, desmosomes, gap junctions, plasmodesmata.

Which type of junction prevents leaks between cells?

Tight junctions (e.g., in intestines).

Which type of junction anchors cells together?

Desmosomes (e.g., in skin cells).

Which type of junction allows communication between animal cells?

Gap junctions (e.g., in heart cells).

Which type of junction allows communication between plant cells?

Plasmodesmata.

What is the endomembrane system?

A network of organelles involved in protein synthesis and transport.

What organelles are part of the endomembrane system?

Nucleus, ribosomes, ER, Golgi, vesicles.

What is the endosymbiosis theory?

Mitochondria and chloroplasts evolved from free-living bacteria engulfed by a larger cell.

What evidence supports the endosymbiosis theory?

Mitochondria & chloroplasts have their own circular DNA (mtDNA, cpDNA) and double membranes.

What is mtDNA and cpDNA?

mtDNA = Mitochondrial DNA, cpDNA = Chloroplast DNA.

What are the three steps of cell signaling?

1. Reception 2. Transduction 3. Response.

What are the three types of cell signaling?

Paracrine (local), Endocrine (hormonal), Synaptic (nervous system).

What is apoptosis?

Programmed cell death.

What organelle is involved in apoptosis?

Mitochondria.

What enzymes break down proteins during apoptosis?

Caspases.