MOL100 Lecture 1 - Prokaryotic and Eukaryotic Cells PDF

Cells and the molecules of life MOL100 – lecture 1 Nikon.com MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 1  1. The (macro-) molecules of life...

Cells and the molecules of life MOL100 – lecture 1 Nikon.com MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 1  1. The (macro-) molecules of life 2. Cells as fundamental units of life Proteins Prokaryotic cells Nucleic acids Eukaryotic cells Phospholipids (Saccharides) molecules cells organisms ecosystems saccharides (sugars) proteins lipids nucleic acids (DNA+RNA) from www.microbenotes.com from www.quizlet.com from www.commons.Wikimedia.org from www.worldatlas.com MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 2  Learning about molecular biology from model organisms C.elegans (roundworm) E.coli Arabidopsis thaliana yeast Drosophila mouse zebrafish images are not to scale! MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 3  All living organisms descended from a common ancestral cell a phylogenetic tree depicts evolutionary relationships Fig 1-22 (modified) MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 4  All living organisms descended from a common ancestral cell Because of their common evolutionary origin, many fundamental features are shared in all cells We can use "simple" organisms (model organisms) to learn about molecular biology (e.g. bacteria or yeast) All cells use a common set of "Molecules of life" Fig 1-22 (modified) MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 5  1. The (macro-) molecules of life Proteins (also lectures 2-5) Nucleic acids (also lectures 2 and 7-8) Phospholipids (also lectures 2 and 9) (Polysaccharides) (lecture 2) Nikon.com MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 6  The molecules of life – 1. proteins proteins are the most abundant macromolecules in cells they are chains of amino acids there are 20 different amino acids the sequence (order) of amino acids determines the 3- dimensional structure of proteins (lecture 3) https://pdb101.rcsb.org/motm/motm-about MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 7  The molecules of life – 1. proteins proteins can act as enzymes starch (stivelse) catalysis of chemical reactions (lecture 4) Amylase glucose ©Paul Sveda http://juliannetaylornutrition.com MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 8  The molecules of life – 1. proteins proteins can act as enzymes catalysis of chemical reactions (lecture 4) structural proteins (staining of microtubules in a skin cell) e.g. filaments of the cytoskeleton (required to regulate the shape of cells and for transport in cells) … there are also other classes of proteins! www.proteinatlas.org MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 9  The molecules of life – 2. nucleic acids DNA (deoxyribonucleic acid) consists of four different nucleotides: A, G, T and C two DNA strands form a double helix the two strands are complementary: A always binds to T, C always binds to G Fig. 6-1 MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 10  The molecules of life – 2. nucleic acids DNA (deoxyribonucleic acid) the complementarity allows to make copies of the DNA copying the DNA is essential for heredity (arvelighet) – lecture 9 Fig. 6-2 MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 11  The molecules of life – 2. nucleic acids DNA encodes the information for proteins (lecture 8) genes are functional units of the DNA strand DNA can be transcribed into RNA (ribonucleic acid) messenger RNAs (mRNAs) are translated into proteins the coding sequence determines which amino acids are used for the protein regulatory sequences determine when and where an RNA is produced there are also RNAs that are not translated into proteins (non-coding RNAs) Fig. 7-1 MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 12  The molecules of life – 3. phospholipids Phospholipids are amphipathic molecules: they have a hydrophilic ("water-loving") head and a hydrophobic ("water-fearing") tail ©2004 Pearson Education Inc Phophorous-containing head Glycerol fatty acid chains (hydrophobic tail) (charged) (not charged) MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 13  The molecules of life – 3. phospholipids In aqueous (watery) liquids, phospholipids arrange as bilayered (two-layered) membranes: the hydrophilic heads face towards the outside, the hydrophobic tails to the inside of the membrane cellular membranes (biomembranes) also contain many proteins and other lipids (for example cholesterol) biomembranes surround aqueous liquids to separate the inside of cells from the environment and to generate compartments in cells hydrophilic lecture 7 hydrophobic https://open.oregonstate.education/aandp/chapter/3-1-the-cell-membrane/ MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 14  Cells are fundamental units of life cells can look very different, but they can be grouped into two main classes: prokaryotic and eukaryotic cells Fig 1-22 (modified) MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 15  The structure of eukaryotic cells Eukaryotic cells can have different shapes and sizes, both among unicellular and within multicellular organisms Nevertheless, eukaryotic cells share many features Fig. 1-1 neurons can have processes that are over 1 meter long! MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 16  The structure of eukaryotic cells eukaryotic cells have several compartments compartments are specialized for different functions organelles are surrounded by a membrane (a lipid bilayer) not all compartments or specialized structures are surrounded by a membrane the cytoplasm is the content of a cell except the nucleus the cytosol is the aqueous part of the cytoplasm, after removal of the organelles Fig. 1-25 MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 17  The nucleus contains the genetic material The presence of the nucleus defines eukaryotic cells! (inner and outer membrane) Nuclear pores (contains chromatin) Fig. 1-17 MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 18  The nucleus contains the genetic material the DNA is wrapped around proteins (called histones), DNA plus proteins are the chromatin in eukaryotic cells, the chromatin is organized in linear pieces which are called chromosomes nuclear envelope chromosomes Nuclear pores (inner and outer membrane) (contains chromatin) Fig. 1-17 Fig. 1-18 MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 19  The nucleus contains the genetic material the nucleus is enclosed by the nuclear envelope, which consists of an inner and an outer membrane nuclear pores allow the exchange of molecules between nucleus and cytoplasm Nuclear pores (inner and outer membrane) (contains chromatin) Fig. 1-17 MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 20  The endoplasmic reticulum is the biosynthetic factory of the cell the endoplasmic reticulum (ER) is connected to the nuclear envelope and consists of membrane-enclosed sacs called cisternae the ER has two parts: the smooth ER and the rough ER the smooth ER is the site of lipid biosynthesis Fig. 1-23 MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 21  The endoplasmic reticulum is the biosynthetic factory of the cell the rough ER has ribosomes on its surface ribosomes are large molecular complexes consisting of many RNA and protein subunits the ribosomes translate mRNAs into proteins there are also free ribosomes in the cytosol the ER also produces membranes and transport vesicles ribosomes are an example of a specialized cellular structure that is not surrounded by a membrane Fig. 1-23 MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 22  The Golgi Apparatus: Shipping and Receiving Center cis face trans face (“receiving” side of (“shipping” side of the Golgi apparatus (or just Golgi) is a system of Golgi apparatus) Golgi apparatus) membrane-bounded sacs (cisternae) – similar to the ER the Golgi receives transport vesicles on the cis face (for example from the ER) it modifies proteins and lipids received from the ER and sorts them into transport vesicles that are released on the trans face (e.g. to the cell membrane) Cisternae Fig. 1-24 MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 23  Lysosomes are digestive organelles lysosomes contain enzymes that degrade macromolecules lysosomal enzymes work best in the acidic conditions inside the lysosome enzymes and membranes of the lysosomes are synthesized in the ER and Golgi lysosomes fuse with other vesicles that carry for example food molecules Fig. 1-25 Lysosome food vesicle from Campbell “BiologY” MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 24  Mitochondria use nutrients to generate ATP the chemical energy of nutrients (e.g. carbohydrates) is converted into ATP, which is used for many cellular processes that require energy this conversion consumes oxygen and is called cellular respiration (lecture 14) mitochondria have two membranes and contain DNA the inner membrane is folded into cristae there can be many mitochondria in one cell outer membrane inner membrane Matrix Cristae Fig. 1-19 MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 25  Chloroplasts capture the energy of light chloroplasts are organelles found in plants and algae they contain chlorophyll which helps to convert Carbon dioxide (CO2) and H20 into sugars and Oxygen (O2), this process is called photosynthesis (lecture 15) chloroplasts have two membranes and an internal membrane system of thylakoids that contains the chlorophyll Stroma (thylakoid) Fig. 1-21 MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 26  The cytoskeleton provides stability and flexibility the cytoskeleton is a network of different types of long filaments (fibres) that extend throughout the cytoplasm cytoskeleton (actin) cytoskeleton (microtubules) cytoskeleton (intermediate filaments) panel 1-2 MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 27  The cytoskeleton provides stability and flexibility the cytoskeleton is a network of different types of long filaments (fibres) that extend throughout the cytoplasm cytoskeleton (actin) cytoskeleton (microtubules) cytoskeleton (intermediate filaments) panel 1-2 MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 28  The cytoskeleton provides stability and flexibility the cytoskeleton is a network of different types of long filaments (fibres) that extend throughout the cytoplasm o microtubules o actin filaments o intermediate filaments the long filaments are chains of small subunits (tubulin for microtubules, actin for actin filaments) microtubules and actin filaments are very dynamic, that means they can grow and shrink quickly the cytoskeleton organizes the cell, keeps organelles in place and serves as rails for transport in the cell microtubules in green actin filaments in red intermediate filaments not shown MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 29  The cytoskeleton provides stability and flexibility the cytoskeleton is a network of different types of long filaments (fibres) that extend throughout the cytoplasm o microtubules o actin filaments o intermediate filaments the long filaments are chains of small subunits (tubulin for microtubules, actin for actin filaments) microtubules and actin filaments are very dynamic, that means they can grow and shrink quickly the cytoskeleton organizes the cell, keeps organelles in place and serves as rails for transport in the cell https://www.youtube.com/watch?v=I_xh-bkiv_c MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 30  in animals and plants, cells are organized in tissues, they are physically connected and communicate with each other molecules cells organisms saccharides (sugars) proteins lipids nucleic acids (DNA+RNA) from www.microbenotes.com from www.quizlet.com from www.commons.Wikimedia.org MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 31  Cells are connected by junctions in animals and plants, cells are organized in tissues, they are physically connected and communicate with each other in a sheet of cells (an epithelium) tight junctions prevent the leakage of fluid between the cells and they limit the movement of proteins in the cell membrane tight junctions from Campbell “Biology” MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 32  Cells are connected by junctions in animals and plants, cells are organized in tissues, they are physically connected and communicate with each other anchoring junctions bridge the cytoskeleton of neighbouring cells anchoring junctions from Campbell “Biology” MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 33  Cells are connected by junctions in animals and plants, cells are organized in tissues, they are physically connected and communicate with each other gap junctions are small channels that allow the exchange of small molecules and electric current gap junctions from Campbell “Biology” MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 34  Cells are connected by junctions in animals and plants, cells are organized in tissues, they are physically connected and communicate with each other gap junctions are small channels that allow the exchange of small molecules and electric current https://www.youtube.com/watch?v=RUuM9ehWkgQ gap junctions from Campbell “Biology” MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 35  Cell division of eukaryotic cells Replication is a key feature of living organisms all eukaryotic cells use a very similar program to divide (to replicate), this program is called the cell cycle the cell cycle consists of gap phase 1 (G1), synthesis phase (S), gap phase 2 (G2) and mitosis (M) in G1 phase, cells perform their specific function, which is different for different types of cells in S phase, the cell replicates its DNA (the hereditary information) G2 phase is in most cells shorter than G1 phase, the cell prepares for cell division cell division occurs in M phase if cells stop dividing, they do this most often in G1 phase and the cells are then said to be resting in G0 phase MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 36  Cell division of eukaryotic cells Replication is a key feature of living organisms all eukaryotic cells use a very similar program to divide (to replicate), this program is called the cell cycle the cell cycle consists of gap phase 1 (G1), synthesis phase (S), gap phase 2 (G2) and mitosis (M) in G1 phase, cells perform their specific function, which is different for different types of cells in S phase, the cell replicates its DNA (the hereditary information) G2 phase is in most cells shorter than G1 phase, the cell prepares for cell division cell division occurs in M phase if cells stop dividing, they do this most often in G1 phase and the cells are then said to be resting in G0 phase Fig. 18-2 MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 37  Cell division of eukaryotic cells Replication is a key feature of living organisms all eukaryotic cells use a very similar program to divide (to replicate), this program is called the cell cycle the cell cycle consists of gap phase 1 (G1), synthesis phase (S), gap phase 2 (G2) and mitosis (M) in G1 phase, cells perform their specific function, which is different for different types of cells in S phase, the cell replicates its DNA (the hereditary information) G2 phase is in most cells shorter than G1 phase, the cell prepares for cell division cell division occurs in M phase if cells stop dividing, they do this most often in G1 phase and the cells are then said to be resting in G0 phase https://www.youtube.com/watch?v=_aQXhors-OE MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 38  The structure of eukaryotic cells Compartmentalization facilitates the regulation of different cellular processes Fig. 1-25 MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 39  Prokaryotic cells Bacteria and Archaea constitute the Prokaryota in an evolutionary perspective, Archaea are more closely related to Eukaryota Fig 1-22 (modified) MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 40  Prokaryotic cells prokaryotic cells vary in size, but they are usually smaller than eukaryotic cells Escherichia coli (1 - 2µm) Epulospiscium fishelsoni (400 - 600µm) from Pitts et al., PLOS One, 2012 from Clements and Bullivant, J. Bacteriology, 1991 MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 41  The structure of prokaryotic cells Common to Bacteria and Archaea no nucleus the genome is mainly a circular DNA molecule in the nucleoid additional DNA as small circular plasmids no membrane-bound organelles cell wall made of proteins and sugars nucleoid Fig. 1-12 Differences between Bacteria and Archaea Cell membranes of Archaea are different from bacteria and eukaryotes transcription and translation machinery of Archaea is more similar to eukaryotes many genes from Archaea are found in eukaryotes, but not bacteria (e.g. cytoskeleton) MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 42  The structure of prokaryotic cells Loki's castle hydrothermal vent https://www.youtube.com/watch?v=d_yqE7VlAyw Archaea often live in extreme environments: high temperature high salt concentrations very acidic environment … but also in "normal" environments pxhere.com ©Jupiterimages/Stockbyte/Getty Images http://sehijpauleastusa.blogspot.com/ MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 43  The structure of prokaryotic cells despite the differences in cellular organization, many cellular and molecular processes are highly conserved (highly similar) between prokaryotes and eukaryotes this allows to use bacteria as model organisms for molecular biology MGNOnline Escherichia coli MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 44  Key points of today's lecture all cells have a common evolutionary origin proteins are chains of amino acids that fold into complex shapes proteins have many functions, they are the "workhorses" of the cell nucleic acids serve as carriers of the genetic information phosphoplipids are amphipathic molecules that form lipid bilayers eukaryotic cells contain membrane-surrounded, functionally specialized compartments that are called organelles prokaryotes are mainly unicellular organisms that lack a nucleus and organelles MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 45  Next lecture: Tuesday, 3. Sep 12:15-14:00 "Chemical foundations and chemical building blocks" Have a nice day! MOL100 MOL100 Universitet i Bergen Universitetet i Bergen 46