Molecular Biology Primer Angela Brooks, Raymond Brown, Calvin Chen, Mike Daly, Hoa Dinh, Erinn Hama, Robert Hinman, Julio Ng, Michael Sneddon, Hoa Troung, Jerry Wang, Che Fung Yung

Three main branches to the tree of life According to the most recent evidence, there are three main branches to the tree of life. Prokaryotes include Archaea (“ancient ones”) and bacteria. Eukaryotes are kingdom Eukarya and includes plants, animals, fungi and certain algae.

Life begins with Cell A cell is a smallest structural unit of an organism that is capable of independent functioning Fundamental working units of every living system. All cells have some common features

Cells 70% water 7% small molecules 23% macromolecules Chemical composition-by weight 70% water 7% small molecules salts Lipids amino acids nucleotides 23% macromolecules Proteins Polysaccharides lipids biochemical (metabolic) pathways translation of mRNA into proteins

2 types of cells: Prokaryotes v.s.Eukaryotes Reverse sides Delete continues

Prokaryotes and Eukaryotes, continued Single cell Single or multi cell No nucleus Nucleus No organelles Organelles One piece of circular DNA Chromosomes No mRNA post transcriptional modification Exons/Introns splicing

Prokaryotes v.s. Eukaryotes Structural differences Eubacterial (blue green algae) and archaebacteria only one type of membrane-- plasma membrane forms the boundary of the cell proper The smallest cells known are bacteria Ecoli cell 3x106 protein molecules 1000-2000 polypeptide species. Eukaryotes plants, animals, Protista, and fungi complex systems of internal membranes forms organelle and compartments The volume of the cell is several hundred times larger Hela cell 5x109 protein molecules 5000-10,000 polypeptide species Structural differences Two columns labelled prokaryotes and eukaryotes

Prokaryotic and Eukaryotic Cells Chromosomal differences Prokaryotes The genome of E.coli contains amount of t 4X106 base pairs > 90% of DNA encode protein Lacks a membrane-bound nucleus. Circular DNA and supercoiled domain Histones are unknown Eukaryotes The genome of yeast cells contains 1.35x107 base pairs A small fraction of the total DNA encodes protein. Many repeats of non-coding sequences All chromosomes are contained in a membrane bound nucleus DNA is divided between two or more chromosomes A set of five histones DNA packaging and gene expression regulation Chromosomal diffecernces Two labelled columns Succinct in descriptioon >90% encodes proteins Many repeats of noncoding sequences Delete weights

Surrounding the Cell

Cell Membrane Outer membrane of cell that controls movement in and out of the cell Double layer http://library.thinkquest.org/12413/structures.html

Cell Wall Most commonly found in plant cells & bacteria Supports & protects cells http://library.thinkquest.org/12413/structures.html

Inside the Cell: Organelles

Nucleus Directs cell activities Separated from cytoplasm by nuclear membrane Contains genetic material - DNA

Nuclear Membrane Surrounds nucleus Made of two layers Openings allow material to enter and leave nucleus http://library.thinkquest.org/12413/structures.html

Chromosomes In nucleus Made of DNA Contain instructions for traits & characteristics http://library.thinkquest.org/12413/structures.html

Chromosomes Organism Number of base pair number of Chromosomes --------------------------------------------------------------------------------------------------------- Prokayotic Escherichia coli (bacterium) 4x106 1 Eukaryotic Saccharomyces cerevisiae (yeast) 1.35x107 17 Drosophila melanogaster(insect) 1.65x108 4 Homo sapiens(human) 2.9x109 23 Zea mays(corn) 5.0x109 10

Nucleolus Inside nucleus Contains RNA to build proteins http://library.thinkquest.org/12413/structures.html

Cytoplasm Gel-like mixture Surrounded by cell membrane Contains hereditary material

Endoplasmic Reticulum Moves materials around in cell Smooth type: lacks ribosomes Rough type (pictured): ribosomes embedded in surface http://library.thinkquest.org/12413/structures.html

Ribosomes Each cell contains thousands Make proteins Found on ribosomes & floating throughout the cell http://library.thinkquest.org/12413/structures.html

Mitochondria Produces energy through chemical reactions – breaking down fats & carbohydrates Controls level of water and other materials in cell Recycles and decomposes proteins, fats, and carbohydrates http://library.thinkquest.org/12413/structures.html

Golgi Bodies Protein 'packaging plant' Move materials within the cell Move materials out of the cell http://library.thinkquest.org/12413/structures.html

Lysosome Digestive 'plant' for proteins, fats, and carbohydrates Transports undigested material to cell membrane for removal Cell breaks down if lysosome explodes http://library.thinkquest.org/12413/structures.html

Vacuoles Membrane-bound sacs for storage, digestion, and waste removal Contains water solution Help plants maintain shape http://library.thinkquest.org/12413/structures.html

Chloroplast Usually found in plant cells Contains green chlorophyll Where photosynthesis takes place http://library.thinkquest.org/12413/structures.html

All Cells have common Cycles Born, eat, replicate, and die

Signaling Pathways: Control Gene Activity Instead of having brains, cells make decision through complex networks of chemical reactions, called pathways Synthesize new materials Break other materials down for spare parts Signal to eat or die

Example of cell signaling

Cells Information and Machinery Cells store all information to replicate itself Human genome is around 3 billions base pair long Almost every cell in human body contains same set of genes But not all genes are used or expressed by those cells Machinery: Collect and manufacture components Carry out replication Kick-start its new offspring (A cell is like a car factory)

Overview of organizations of life Nucleus = library Chromosomes = bookshelves Genes = books Almost every cell in an organism contains the same libraries and the same sets of books. Books represent all the information (DNA) that every cell in the body needs so it can grow and carry out its vaious functions.