Cell Biology: Types of Cells and Organelles

Study Notes

Prokaryotic cells: simple, single-celled organisms lacking a nucleus, much smaller than eukaryotic cells
Eukaryotic cells: composed of single cell or trillions of cells, with similarities to prokaryotes but having more organelles

Cell membrane: controls entry into and out of cell
Nucleus: stores chromosomes/DNA, acts as the "brain" of the cell
Cytoplasm (cytosol): jelly-like substance within the cell, mainly composed of water
Endoplasmic reticulum: transports molecules around the cell
- Smooth: helps create cell membrane
- Rough: helps create molecules the cell needs
Golgi bodies/apparatus: captures and releases molecules from other cells
Mitochondria: creates energy the cell needs, referred to as the "powerhouse" of the cell
Ribosomes: makes necessary molecules for cells
Vesicles and vacuoles: transports material around the cell, can fuse with other membranes
Lysosome: destroys unneeded molecules inside the cell, acts as the "garbage disposal" of the cell
Peroxisomes: metabolizes waste
Centrosome (centrioles): used to help one cell split into two cells
Cytoskeleton: maintains the 3D structure of the cell

Small size is necessary for all cells
As the radius of a cell increases, its surface area increases, but its volume increases more rapidly
As a cell grows, it becomes less efficient, making it difficult for food to enter the cell and communicate with other cells

Found in most cells, with eukaryotic cells having DNA in the nucleus
DNA helps create molecules in the cell and acts as a blueprint for everything in the cell
Chromosome: linear stretch of DNA
Humans have 23 pairs of chromosomes
Chromatin: when DNA is string-like
Chromatid: during cell division, when chromosomes replicate and condense to create chromatid

Two main processes: interphase and mitosis/cytokinesis
Interphase: a cell resting and preparing for division
Mitosis/cytokinesis: the equal split of cytoplasm and organelles, resulting in two daughter cells with exact copies of DNA

Interphase:
- G0: cell is in a resting state
- G1: prepares for division, doubles in size, and centrosome doubles
- S: DNA replicates, creating exact copies of chromosomes
- G2: checks if DNA was copied properly
Prophase:
- Centrosomes move to opposite sides of the cell
- Doubled chromatin becomes sister chromatids
- Chromatids attach to each other at the centromere
- Nucleus disappears, and spindle fibers come from centrosomes and attach to chromatids
Metaphase:
- Homologous sister chromatids line up along the metaphase plate
- Sister chromatids are held perpendicular to the spindle fibers
Anaphase:
- Each sister chromatid is pulled toward the poles as spindle fibers shorten via the centromere
Telophase:
- Nucleus reforms, and chromatids uncoil and become chromatin
- Spindle fibers disappear, and temporarily, two nuclei are in one cell
- Cytoplasm pinches inward at the equator, creating a furrow
Cytokinesis:
- Cytoplasm and organelles are distributed between the two daughter cells