Cells
Basic unit of life
Organisms can be single cells or collections of many cells (multicellular)
Cell #’s are important, critical to growth, development, and healing
DNA in cells is the genetic information used to make RNA and proteins
Domains of Life
Archae
Does not have a nucleus
Prokaryote
e.g. Methanococcus
Bacteria
No nucleus
Prokaryotic
E.g. E. coli
Eukarya
Has a nucleus
Eukaryote
E.g. amoeba, plant, human
Types of cells
Prokaryotic
Lack a nucleus
E.g. bacteria
Eukaryotic
Has a nucleus and various other organelles
Macromolecules in Cells
Nucleic Acids
E.g. DNA, RNA
Used for genetic material
Proteins
E.g. actins, polymerases
Used for structures, enzymes
Lipids
E.g. P-Lipids, fats, oils
Used for membranes, fat droplets
Carbohydrates
E.g. sugars, starches
Used for energy (fuel)
Note: Humans are multicellular organisms
Formed by eukaryotic cell division and differentiation
> 260 cell types (derived by cell differentiation
Examples of differentiated cells:
Epithelial
Muscle
Nerve
connective
Animal Cell
Surrounded by the plasma membrane
Contains a nucleus and cytoplasm with specialized organelles
Structures and Functions of Organelles
Endoplasmic Reticulum
Membrane network
Rough ER has ribosomes, smooth ER does not
Site of membrane protein synthesis and folding; lipid synthesis
Golgi Apparatus
Stacks of membrane-enclosed sacs
Site where sugars are made and linked into starches or joined to lipids or proteins; proteins finish folding; secretions stored
Lysosome
Sac containing digestive enzymes
Degrades debris, recycles cell contents
Mitochondrion
Two membranes; inner membrane enzyme-studded
Releases energy from nutrients
Participates in cell death
Nucleus
Porous sac containing DNA
Separates DNA from the rest of the cell
Peroxisome
Sac containing enzyme
Breaks down and detoxifies various molecules
Ribosome
Two associated globular subunits of RNA and protein
Scaffold and catalyst for protein synthesis
Vesicle
Membrane-bounded sac
Temporarily stores or transports substances
Nucleus
Surrounded by double layered nuclear membrane
Contains:
Nuclear pores that allow movement of some molecules in and out
Nucleolus = site of ribosomal RNA production
Chromosomes = composed of DNA and proteins
Genetic headquarters
Contains DNA inherited from both parents
Nuclear envelope has 2 membranes connected by nuclear pores
Nuclear pores are protein complexes that keep DNA inside the nucleus but allow selected RNA and proteins to move through pore
Example of secretory cell: making milk
Illustration of organelle functions and interactions in the making of milk proteins and fat droplets
1. Genes that encode milk proteins and contain enzymes are transcribed into mRNA
2. mRNA exits through nuclear pores
3. mRNA moves to surface of rough ER, where proteins are synthesized on ribosomes using amino acids in the cytoplasm
4. Lipids are synthesized in the smooth ER
5. Sugars are synthesized and proteins folded in the Golgi apparatus, then both are released in vesicles that bud off of the Golgi apparatus
6. Protein and sugar-laden vesicles move to the plasma membrane for release. Fat droplets pick up a layer of lipid from the plasma membrane as they exit the cell
Golgi Apparatus
Final protein folding
Stores secreted material
Forms sugars, glycoproteins, and glycolipids
Vesicles of material are released * * Lysosomes break down bacteria, cellular debris, and nutrients contain > 40 types of digestive enzymes
Tay-Sachs is an inherited lysosomal storage disorder
Peroxisomes
Contain several types of enzymes for degradation and synthesis
Break down long fatty acids and complex biochemicals, partial oxidation
Synthesize bile acids, e.g. NA salt of cholic acid
Detoxify peroxides (R-O-O-H R-O-H)
Abundant in liver and kidney cells
