Basic Cell Structure Cells Basic building blocks of
Basic Cell Structure
Cells Basic building blocks of life Understanding of cell structure is critical to the study of biology
5 Characteristics of Life CELLS!!!! Homeostasis Metabolism Reproduction Genetic Material (DNA AND RNA) MUST HAVE ALL FIVE TO BE ALIVE
Cell Smallest living unit of an organism Grow, reproduce, use energy, adapt, respond to their environment
Cell Many cannot be seen with the naked eye A cell may be an entire organism or it may be one of billions of cells that make up the organism
Cells Divided and classified in many ways One common classification method is the presence or absence of a cell nucleus
Nucleus Relatively large structure with a cell Directs cell activities Some simple singlecelled organisms lack a nucleus
Nucleus Prokaryotes – have no nucleus (“pro means no”) Eukaryotes – have a nucleus (“eu means true”)
Prokaryotes Single celled organism Lacks a cell nucleus Internal structure is less complex than other cells
Prokaryotes Less complex than eukaryotes Still have many of the basic internal characteristics
Prokaryotes DNA is in a loop inside the cell, not in the nucleus Only one copy of their DNA (“haploid”)
Common prokaryote structures Cytoplasm Chromosomal material Cell membrane and wall Ribosomes Some have a flagellum for mobility
Eukaryotes Organism made up of cells that have a nucleus May have billions of cells like plant and animal kingdoms Plant Animal
Eukaryotes Typically are highly organized Infinite number of shapes and purposes Two copies of their DNA (“diploid”)
Eukaryotes Human body has at least 85 different cell types All eukaryotes have a number of structures in common
Common structures Organelles – smaller parts of the cell with specific funtions Cell membrane – acts as a gatekeeper
Cell membrane Controls what enters and leaves the cell Plants, algae and bacteria typically ALSO have a tough outer structure known as a cell wall
Cell wall Provides additional structure and protects the cell from pressure caused by movement of water Animal cells do not have walls
Cytoplasm Organelles are surrounded by a jelly like substance Primary component is water
Other important organelles Ribosomes Mitochondria Chloroplasts in plants
Nucleus Brain of the cell Site of genetic material Protects DNA from damage
Nucleus Controls activity of the cell Round or oval structure Typically found in the middle of the cell Appears darker than surrounding material
Nucleus Surrounded by a membrane that controls passage of materials in and out of the area
Nucleus Contains DNA is twisted into chromosomes to keep it from tangling (like a spool of thread)
Cytoplasmic Organelles are required for proper cell function Ribosome – make proteins for cellular use and communication
Mitochondria Energy factories Rod shaped Change food into molecules that can be used for energy
Mitochondria Contain their own special DNA Can replicate themselves
Chloroplast Found in plants and some other organisms Contain chlorophyll
Cellular processes Respiration Osmosis Diffusion Photosynthesis
Respiration Cells break down carbohydrates and other molecules to produce energy
Respiration Breaking down of sugar into water, carbon dioxide, and energy Energy is used to do the work of the cell
Osmosis & Diffusion Transport of raw materials, wastes, and synthesized materials out of the cell
Cellular reproduction Three ways Fission Mitosis Meiosis
Fission Prokaryotes Cell grows larger and makes a second copy of its DNA
Fission Two new cells are formed as the division grows inward from either side of the cell Two cells now called “daughter cells” Sometimes known as “binary fission”
Mitosis Eukaryotes Requires 6 stages
Mitosis Creates cells that are identical to the original cell.
Meiosis Division of sex cells
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