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Biology
Cell structure and function boils down to the idea that each subcellular component has a structure that supports a singular job.
Summary
- Ribosomes are non membrane structures with rRNA and protein, they build proteins by reading mRNA
- Endomembrane system (ER, Golgi, lysosomes, vacuole, transport vesicles, nuclear membrane, plasma membrane) work together to modify package and transport proteins lipids and polysaccharides.
- Rough ER handles protein synthesis and supports compartmentalization.
- Smooth ER handles lipid synthesis and detoxification.
- Mitochondria have a double membrane, folded inner membrane increases surface area so ATP is made more efficiently during aerobic respiration.
- Lysosomes use hydrolytic enzymes to digest material and take part of apoptosis.
- Vacuoles store material and in plants regulate turgor pressure
- Chloroplasts have a double membrane and do photosynthesis in plants and photosynthetic algae.
Plasma Membrane
Boundary that separates the inside of the cell from the outside. Phospholipid bilayer, meaning 2 layers of phospholipid. Hydrophilic head, hydrophobic tail, so the heads face the outsides and the tails face the insides.
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Nucleus
Stores genetic information (DNA) and directs cell activity. Nucleolus is where rRNA is produced and ribosomal subunits are produced.
Nuclear envelope is a double membrane. Surrounds nucleus and regulates movement of materials between nucleus and cytoplasm. Continuous with ER.
Ribosomes
Ribosomes are non membrane structures with rRNA and protein, they build proteins by reading mRNA. Found in all forms of life. Reflects common ancestry of all known life.
Free ribosomes float in the cytosol and produces proteins for the cell. Bound ribosomes attach to the rough ER and produce proteins for export or membranes.
Endoplasmic Reticulum
Rough ER's membrane is embedded with ribosomes, making it look rough. Helps carry out protein synthesis and compartmentalization. Proteins made here are packaged into transport vesicles to be sent to the Golgi complex.
Smooth ER handles lipid synthesis and detox.
Endomembrane System
Endomembrane system (ER, Golgi, lysosomes, vacuole, transport vesicles, nuclear membrane, plasma membrane) work together to modify package and transport proteins lipids and polysaccharides.
- Nuclear envelope - continuous to ER, regulates transport in and out of nucleus
- ER - synthesizes and modifies proteins and lipids
- Golgi complex - packages, modifies and sorts molecules
- Lysosomes - digests cellular material
- Vacuoles - membrane bound sacs involved in storage
- Transport vesicles - shuttle materials between components
- Plasma membrane - final destination for many packages
Golgi Complex
!Pasted image 20260817103921.png Folds and chemically modifies synthesized cellular packages like proteins. Vesicles enter at the cis face and exit from the trans face.
Example of chemical modification that occurs in the aforementioned is glycosylation, which adds sugars to proteins.
Mitochondria
Mitochondria have a double membrane, folded inner membrane increases surface area so ATP is made more efficiently during aerobic respiration.
Space inside inner membrane is mitochondrial matrix.
Lysosomes
Membrane enclosed sacs containing hydrolytic enzymes used to digest material. Breaks down macromolecules, ingested material and worn down cellular components and recycle cellular material. Also play a part in apoptosis (planned cell death).
Vacuoles
Store material and in plant cells handle turgor pressure (pressure from plasma against cell wall), which helps keeps cell wall rigid.
In animal cells there are more and are smaller.
Chloroplasts
Double membrane, handle photosynthesis, only found in plant and photosynthetic algae cells.
Plant Cells vs Animal Cells
- Ribosomes are in all cells.
- Membrane bound organelles (nucleus, Golgi, mitochondria, lysosomes, vacuoles, chloroplasts) are features of eukaryotic cells.
- Plant cells have chloroplasts, a central vacuole and a cell wall.
- Animal cells have multiple smaller vacuoles.