Prokaryotes & Eukaryotes All living cells can be divided into two groups: • Prokaryotic cells – simple cells – Single-celled organisms (bacteria and blue-green algae) • Eukaryotic cells – more complex cells – Single-celled organisms (protists) – Compose multi-cellular organisms (protists, fungi, plants and animals) Feature Function Prokaryotes Eukaryotes Cell (plasma) Regulate material entering All All membrane and exiting cell DNA Stores genetic material All All Cell wall Protect cell, provide shape All Some (plants) Cytoplasm Fluid inside cell All All Nucleus Houses DNA None All Ribosomes Site of protein synthesis All All Flagella Aid cell in locomotion Some Some Mitochondria Site of ATP synthesis None All Endoplasmic Synthesis of proteins and None All Reticulum lipids Golgi Storage and packaging of None All apparatus substances Lysosomes & Digest particles None All Peroxisomes Vacuoles Storage of material Some Some Plasmids Small pieces of DNA that Some None can exit the cell Plastids Contain food or pigments None Some (plants) Biology 4A Prokaryotes & Eukaryotes Prokaryotic Bacterial Cell Eukaryotic Plant Cell Eukaryotic Animal Cell Biology 4A Cellular Processes Energy conversions Photosynthesis – conversion of radiant energy (sunlight) into chemical energy (glucose), occurs in chloroplasts of autotrophs 6CO2 + 6H2O + energy → C6H12O6 + 6O2 Chemosynthesis – conversion of unusable chemical energy (methane) into usable chemical energy (carbohydrates) Adenosine triphosphate (ATP) – molecule which living things use to release and store energy, becomes adenosine diphosphate (ADP) when energy is released Glycolysis – process of producing 2 ATP by breaking down glucose into pyruvic acid, first step of respiration Aerobic respiration – respiration in which, after glycolysis, pyruvic acid is broken down into carbon dioxide and water, net gain of 36 additional ATP Anaerobic respiration – respiration in which, after glycolysis, pyruvic acid is broken down into either lactic acid or alcohol, does not provide ATP, allows glycolysis to continue Biology 4B Cellular Processes Synthesis of New Molecules DNA Replication 1. Helicases unwind and unzip DNA at replication forks 2. Free floating nucleotides bond to exposed bases 3. DNA polymerase bind nucleotides to each other in 5’ to 3’ direction a. Leading strand – elongates toward replication fork continuously b. Lagging strand – elongates away from replication fork discontinuously (called Okazaki fragments), bonded together by DNA ligase 4. New molecules each contain one original and one new strand Transcription – process by which a portion of DNA nucleotide sequence is used to produce a complementary mRNA strand by RNA polymerase Translation – process by which information in mRNA strand is used to create amino acid chain (polypeptide chain) by ribosomes and tRNAs Lipogenesis – process of synthesizing lipids from intermediates of cellular respiration, occurs along smooth endoplasmic reticulum Biology 4B Cellular Processes Transport of Molecules Intracellular transport – within the cell • Many molecules float freely through cytoplasm • Others are carried by motor proteins (kinesin) or the endoplasmic reticulum and Golgi apparatus Intercellular transport – in and out of the cell through plasma membrane Passive transport – does not use energy, movement down concentration gradient (high to low concentration) • Diffusion – net movement of small, nonpolar molecules directly through phospholipid bilayer • Facilitated diffusion – net movement of larger molecules and ions through ion channels or carrier proteins • Osmosis – net movement of water molecules through membrane Active transport – uses energy (ATP), movement up concentration gradient (low to high concentration) • Ion pumps – proteins that move ions one way • Cotransport – coupled passage of two molecules in the same direction (symport) or different directions (antiport) Homeostasis – ability of a cell to maintain stable internal conditions independent of environment, accomplished by passive and active transport • Carbonic acid – buffer that helps regular pH Biology 4B Biology 4C - Viruses Parts of Viruses capsid bacteriophage animal virus membranous tail envelope tail fibers Viruses vs. Cells Viruses Cells DNA or RNA Only DNA Need host for replication Can reproduce independently Never contain organelles Can contain organelles Do not convert energy Convert energy Replication Cycles Lytic Lysogenic Biology 4C Biology 4C - Viruses Human Viral Diseases AIDS • Loss of immune system effectiveness • Caused HIV - human immunodeficiency virus • Period of dormancy before loss of immune system • Prevention • No vaccine (yet) • Limit and avoid transmission Influenza (the flu) • Fever, fatigue, and respiratory infections • Can be deadly • Caused a variety of influenza viruses • Can mutate rapidly and blend together • Prevention • Seasonal vaccine • Limit transmission The Common Cold • Fever, fatigue, and respiratory infections • Caused a variety of rhinoviruses • Prevention • No vaccine • Limit transmission Hepatitis A • Inflammation of liver, jaundice (yellow) appearance • Caused a hepatitis A virus in food and water • Prevention • Vaccine • Limit transmission Biology 4C Cell Cycle Cell cycle – the sequence of cell growth and division that occurs in a cell between the beginning of one cell division and the beginning of next cell division • Interphase (G1, S, G2) – period in which cell prepares for division. DNA and organelles replicate. • Mitotic phase (mitosis and cytokinesis) – period in which cell divides into two daughter cells. Ensures that daughter cells receive correct number of chromosomes. Biology 5A Cell Cycle Mitosis – the process by which each daughter cell receives an exact copy of chromosomes present in parent cell • Prophase – chromatin coils into chromatid, centrioles move apart, spindle fibers form • Metaphase – chromosomes arranged along spindle equator by spindle fibers, centromeres attach to separate spindle fibers • Anaphase – spindle fibers shorten and pull chromatids apart at the centromere • Telophase – chromatids reach opposite poles, spindle fibers disappear, nuclear membrane forms, chromosome uncoil Cytokinesis – the division of the cell’s cytoplasm into two daughter cells • Animal cell – cell membrane pinches together, groove forms until membrane separates • Plant cell – cell plate extends outward until it divides cells Biology 5A Cell Cycle DNA replication – the process by which DNA is copied into a new strand, occurs during S phase of interphase • Semiconservative replication – each new molecule contains one original and one new strand • Helicase unwinds DNA and break hydrogen bonds between complementary base pairs o Replication fork – site which separation occurs • Free-floating nucleotides bond to exposed bases (A & T, C & G) • DNA polymerase bond nucleotides to each other in 5’ to 3’ direction o Leading strand: elongates continuously toward replication fork o Lagging strand: elongates discontinuously as Okazaki fragments away from replication fork, sealed by DNA ligase Why is the cell cycle important? • Cells are limited in size. Large organisms need to be multicellular. Proper cell division ensures daughter cells have correct DNA • Mode of reproduction for unicellular organisms • Mode of growth, maintenance, and replacement for multicellular organisms Biology 5A Specialized Cells Specialized Plant Cells Cell Feature Function Concentric circles of Transport water and Root cells vascular tissue minerals upward Hairs protruding from cell Absorb water and minerals Root cells walls from soil Concentric circles of Transport water and Stem cells vascular tissues minerals throughout plant Thick-walled cells around Stem cells Provides support outer edge Cells have many Leaf cells chloroplasts, arranged in Carry out photosynthesis layers Specialized Animal Cells Cell Feature Function Deliver oxygen to body Red blood cells Contain hemoglobin cells Contain filaments that can Cause movement of body Muscle cells contract parts or substances Epithelium cells Cells packed tightly Form a protective cover (exterior skin) together Epithelium cells High surface area Exchange molecules (internal lining) Contain dendrites and Transmit electrical signals Nerve cells axon throughout body Biology 5B Cell Differentiation Stem cells – cells that can differentiate into a variety of specialized cell types Specialized cells – cells with specific structure and function • Examples: blood cells, leaf cells Cell differentiation – process of converting stem cells into more specialized cell types in multicellular organisms How does cell differentiation occur? • Proteins are produced by the cell – Direct the modification of the cell’s structure – Allow the cell to begin carrying out specialized functions • Role of DNA – Segments not needed are coiled tightly around histones – Segments needed are transcribed into proteins • Role of RNA – mRNA transcript used to create protein during translation – Small RNA remove introns from mRNA strands • Change the protein produced – Small RNA can bind and degrade mRNA strands • Stop protein from being produced • Role of environment – Neighboring cells can send signaling proteins to alter gene expression – Temperate can alter gene expression – Low oxygen concentration can suppress gene expression Biology 5C Cell Cycle and Cancer Cell cycle – the sequence of cell growth and division that occurs in a cell between the beginning of one cell division and the beginning of next cell division • End of G1 – vital checkpoint,