What are the main criteria for classifying cells?
1) Presence or absence of a nucleus
2) Size
3) Types of organelles
What are the key points of modern cell theory?
All organisms are made of cells
The cell is the smallest unit of life
All new cells come from pre-existing cells
What features are common to all cells (4)?
Plasma membrane: boundary regulating entry/exit
Ribosomes: synthesize proteins using mRNA
Cytoplasm (cytosol): fluid containing cell structures
Biological molecules: DNA, proteins, carbohydrates
Compare prokaryotes and eukaryotes in terms of nucleus, size, and organelles.
Nucleus: Prokaryotes = none; Eukaryotes = present
Size: Prokaryotes smaller (~10× smaller); Eukaryotes larger
Organelles: Prokaryotes have few/simple, no membrane-bound; Eukaryotes have complex, membrane-bound organelles
How does surface area-to-volume (S:V) ratio affect cell function?
As cells get larger, volume increases faster than surface area, slowing material exchange. Cells optimize size and use organelles to maintain efficient transport and reactions.
Make connection of S:V
Running through a shallow pool, less water easier movement, faster exchange, high S:V
What are the main components of the endomembrane system and their functions (4)?
Rough ER: protein synthesis
Smooth ER: lipid synthesis
Golgi apparatus: protein modification, sorting, cisternal maturation
Lysosomes: macromolecule digestion, autophagy
Secretory pathway of a protein
1) Protein enters rough ER
2) Protein exits ER
3) Protein enters cis-Golgi cisterna
4) Moves to medial Golgi
5) Moves to trans Golgi
6) Packaged into transport vesicles, secreted or sent to other destinations
How are proteins “sorted” to their destinations?
- Proteins have “zip code” signals (carbohydrate)
- Sorting largely occurs in trans golgi
- Transport vesicles bud
- Cytosolic and membrane proteins cause transport vesicles to attach and fuse at different destinations
What are the three ways cells recycle material into lysosomes?
1) Receptor-mediated endocytosis: selective uptake using receptor proteins (material outside the cell/pocket style)
2) Phagocytosis: membrane extends around large particles (Pac-Man style)
3) Autophagy: recycling of cell’s own damaged or unnecessary components
What is the difference between free and bound ribosomes?
Free ribosomes found in cytoplasm
Bound ribosomes attached to rough er
Where is RNA transcribed, transported, and translated?
RNA is transcribed in the nucleus, transported to the cytoplasm, and translated on ribosomes.
Describe cytosol/cytoplasm, Eu or Pro.
Fluid between plasma membrane and organelles; site of cellular processes including protein synthesis and metabolism. Eu and Pro
What is the nucleoid, Eu or Pro?
Clustering loops of DNA in prokaryotes; houses most genetic material, Pro.
What is the function of the nucleus, Eu or Pro?
Stores/transmits info, assembles ribosome subunits, provides structural support. Eukaryotes.
What is the structure and function of ribosomes, Eu or Pro?
Made of large and small rRNA/protein subunits; synthesize proteins; Pro and Eu.
What are the functions of rough and smooth ER, and what do they contain Eu or Pro?
Rough ER: protein synthesis and processing, contains receptors for selected proteins. Eu
Smooth ER: lipid synthesis and processing, contains enzymes for phospholipid synthesis. Eu
Describe the Golgi apparatus, Eu or Pro
MSP
Series of flattened, stacked sacs (cisternae); modifies, sorts, and packages proteins and lipids. Eu
What is the function of lysosomes and what do they contain, Eu or Pro?
Digest and recycle macromolecules; contains transporters and proton pumps. Eu (animal)
What are vacuoles and peroxisomes, Eu or Pro?
Vacuoles: storage, digestion, recycling; single membrane with transporters. Eu
Peroxisomes: oxidize fatty acids and compounds; single membrane with transporters. Eu
What is the function of mitochondria and chloroplasts, Eu or Pro?
Mitochondria: double membrane; inner enzymes produce ATP. Pro
Chloroplasts: double membrane plus interior sacs; produce sugars via photosynthesis. Eu
What is the cytoskeleton, Eu or Pro?
Long, thin protein filaments; provides structural support, movement of materials, and sometimes whole cell movement. Eu and Pro.
Ribosomes are made of
two subunits and RNA
