Cell Structure and Division Lecture Notes

Comprehensive vocabulary flashcards covering cell theory, organelle functions, DNA structure, and the stages of the cell cycle and mitosis based on lecture content.

Cell Theory

The scientific theory that organisms consist of one or more cells, the cell is the smallest unit of life, and all cells arise from existing cells through growth and division.

Plasma Membrane

A semipermeable phospholipid bilayer containing proteins and carbohydrates that regulates the passage of materials into and out of the cell cytoplasm.

Ribosomes

Membraneless organelles composed of RNA subunits, assembled in the nucleolus, and utilized for protein synthesis in the cytoplasm or on the Rough ER.

Rough ER (Endoplasmic Reticulum)

A region of the endoplasmic reticulum studded with ribosomes where proteins are synthesized and subsequently modified by enzymes.

Smooth ER (Endoplasmic Reticulum)

A region of the endoplasmic reticulum lacking ribosomes that serves as the site for lipid synthesis, fatty acid breakdown, and toxin degradation.

Golgi Apparatus

The organelle responsible for sugar synthesis and the refinement, storage, and distribution of proteins and lipids received from the ER via vesicles.

Lysosomes

Vesicle sacs that function in intracellular digestion and are responsible for triggering apoptosis (programmed cell death).

Peroxisomes

Vesicles that function to degrade metabolic byproducts such as alcohol and hydrogen peroxide.

Vacuoles

Membrane-bound sacs used to store water, amino acids, sugars, and wastes.

Mitochondria

The energy powerhouse of the cell that specializes in ATP formation and cellular respiration; they contain their own DNA, RNA, and ribosomes.

Microtubules

Cytoskeleton components that move cellular structures to different locations and facilitate cell movement via cilia and flagella.

Microfilaments

Cytoskeleton components that reinforce cell shape, aid in cell contractions, and form the internal structure of microvilli.

Nucleus

The organelle that keeps DNA isolated and protected from cytoplasmic reactions and controls the movement of substances to and from the cytoplasm.

Histones

Proteins around which DNA strands are coiled to form nucleosomes, allowing the DNA to take up less space.

Chromatin

The state of DNA when it is loosely coiled and the cell is not currently dividing.

Chromosome

DNA that has been supercoiled in preparation for cell division; each eukaryotic species has a characteristic number of these.

Centromere

The specific region of a chromosome where two sister chromatids are held together.

Kinetochore

An attachment site for spindle fibers (microtubules) found on each centromere during nuclear division.

Interphase

The portion of the cell cycle consisting of $G1$ (growth), $S$ (synthesis/DNA duplication), and $G2$ (protein synthesis for division).

Mitosis

The process of nuclear division in somatic (body) cells that results in two diploid daughter cells; it functions in growth, cell replacement, and tissue repair.

Prophase

The first stage of mitosis where duplicated chromosomes condense, the nuclear envelope breaks down, and centrioles migrate.

Metaphase

The stage of mitosis where chromosomes are completely condensed and align at the metaphase plate.

Anaphase

The stage of mitosis during which the cell elongates and sister chromatids are pulled apart toward opposite poles.

Telophase

The final stage of mitosis characterized by the formation of nuclear envelopes around each set of chromosomes.

Cytokinesis

The division of the cytoplasm to form two daughter cells, often achieved through a contractile ring mechanism.