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Chapter 4: Cell Structure and Function
Cell theory
Cell theory has three components:
1. Every living organism has
at least one cell.
2. The cell is the smallest
unit of life
3. Only living cells can give
rise to new cells
mitosis or meiosis
1. Every organism is made of cell(s)
- Prokaryotic cells Bacteria, Archaea
- Prokaryotic cells Have NO nucleus
Have no membrane bound organelles
1. Every organism is made of cell(s)
- Eukaryotic cells contain: a membrane bound nucleus
DNA that is contained within the nucleus
membrane bound organelles.
- All eukarya (& protists) have one or more eukaryotic cells
2. Smallest unit of life
- The cell is the smallest unit that has all the
characteristics of life discussed in chapter 1
DNA
Energy utilization
Response to changes
Evolutionary change
Growth and development
3. Only cells can give rise to cells
- Cells are created by cell
replication
Mitosis (except germ cells)
Meiosis (germ cells only)
4.2 Cell components
- All prokaryotic and eukaryotic
cells have these components:
Plasma membrane Even plant cells have plasma membrane
Cytoplasm
DNA
The ability to obtain and utilize energy.
Plasma membrane
Plasma Membrane: Thin barrier separating inside of cell (cytoplasm) from outside environment
Function:
Isolate cell’s contents from outside environment
Regulate exchange of substances between inside and outside of cell
Allows communication and interaction with other cells
All prokaryotic and eukaryotic cells have a plasma membrane Even plant cells (though plants are special)
Phospholipid Bilayer : Double layer of phospholipids
- Lipid tails of phospholipids are unsaturated (C = C)
- Hydrophilic ends form outer border
- Hydrophobic tails form inner layer
Cytoplasm
All material and structures that lie inside of the plasma membrane, except for the nucleus. Cytosol
Salts and organic materials
Organelles
The fluid component of cytoplasm.
DNA
- Deoxyribose nucleic acid (DNA) Genetic material, aka the hereditary blueprint.
- All living organisms have DNA as their genetic
material.
Some viruses use RNA, but viruses are currently considered non-living by most scientists.
Nucleus Nucleoid vs nucleus
bound, the nucleoid is not.
prokaryotic cells only.
nucleus is found in
eukaryotic cells only.
Cells are really small
- Cells are very small due to
surface to volume ratios
greater volume
Greater nutrient and waste elimination needs.
This requires a GREATER surface area.
