Unit 1 Basic Biological Principals
Studying Life • Biology: The Study of life • All organisms (a living things) have eight characteristics that make them living
Studying Life • Living things are based on a universal genetic code. • All organisms store their information in the form of DNA • DNA is copied and passed from parents to offspring • http://www.pbs.org/wgbh/evolution/library/04/4/l_044_02.html
Studying Life 2. Organisms Grow and Develop • Each organism has a specific pattern of growth and development • Example: A single egg is fertilized, divides, cells become specialized to do different functions • http://www.youtube.com/watch?v=xmsTccmRMh4
Studying Life 3. Organisms Respond to their Environment • Stimulus: a signal to which an organism responds • Organisms can respond to a number of stimuli. Example: Invasion of territory • http://www.youtube.com/watch?v=XgRHKLyBkMU
Studying Life • Organisms are made of cells • Composed of one or more cells • Smallest unit of an organism • Cells can grow, respond to surroundings, reproduce • http://www.youtube.com/watch?v=ZK6YP1Smbxk
Studying Life • Taken as a group, organisms evolve • Groups of organism evolve, or change over time. • Evolution links all life forms to a common origin more then 3.5 billion years ago • Evidence: from fossils, proteins, DNA sequence, similar structures • http://www.pbs.org/wgbh/evolution/library/11/2/e_s_1.html
Studying Life • Organisms obtain and use material and energy • Must take in energy and materials to grow, develop and reproduce • Metabolism: combination of chemical reactions through which an organism builds up or breaks down materials • http://www.dnatube.com/video/156/introduction-to-metabolism
Studying Life • Organism maintain a stable internal environment • Homeostasis: Keeping a stable internal environment even when external conditions change • http://www.phys.unsw.edu.au/biosnippets/
Studying Life • Organisms reproduce • Sexual reproduction: Cells from two parents unite to form the first of a new organism, genetically different from parents • Asexual Reproduction: Single organism produces offspring identical to itself
Check Point • What eight characteristics do all living things share?
Life is Cellular • Brief timeline of the development of life on Earth: • 4.6 billion years ago the Earth was formed • 3.5 billion years ago the first life arose: prokaryotic bacteria • 1.5 billion years ago eukaryotic cells arose • ½ billion years ago the Cambrain explosion: multi-celled eukaryotes arose • 3 million years ago our earliest ancestors, the hominids, appeared
Life is Cellular • Types of Cells: • Prokaryote: Cells that do not separate their genetic material within a nucleus • Eukaryote: Cells with a nucleus that separates the genetic material from the rest of the cell • http://dsc.discovery.com/videos/assignment-discovery-shorts-eukaryote-prokaryotes.html
Life is Cellular • Prokaryotes and Eukaryotes Similarities • Both have DNA as their genetic material • Both have a plasma membrane • Both contain RNA • Both are made from the same basic chemicals: carbohydrates, proteins, nucleic acids, lipids • Both have ribosomes • Both regulate the flow of materials into and out of them • Both have similar basic metabolism (photosynthesis/reproduction) • Both require a supply of energy • Both are highly regulated by sensing systems to sense their environment
Life is Cellular • Prokaryotes and Eukaryotes Differences • Eukaryotes contain a nucleus with DNA, prokaryotes do not have a nucleus, their DNA floats freely in the cytoplasm • Eukaryotes contain many different organelles, prokaryotes do not, some only contain ribosomes • Eukaryotes are about ten times larger then prokaryotes • Both may have cell walls but prokaryotes are made of different material then eukaryotes • Flagella (structures that help cells move) are arranged differently in both types of cells. Far more complex in Eukaryotic cells them prokaryotic cells
Life is Cellular • Evolution of cells: • Present day cells evolved from a common prokaryotic ancestor • Endosymbosis: Certain organelles were acquired into eukaryotes by engulfing prokaryotes. This is seen with the mitochondria and chloroplast. They both have separate DNA, are similar in size to bacteria and reproduce by dividing in two • Thought to have evolved in aerobic and photosynthetic bacteria
Check Point • How are eukaryotic and prokaryotic cells different?
Cell Structure • Cell Organization • The cell is divided into two major parts • The cytoplasm • The nucleus
Cell Structure • The Cytoplasm • Portion of the cell outside the nucleus • Prokaryotes and eukaryotes both have a nucleus • The cytoplasm holds the organelles • Organelles- structures in the cell that act like specialized organs that make the cell run correctly and efficiently • http://www.youtube.com/watch?v=rABKB5aS2Zg&feature=related
Cell Structure • The Nucleus • Contains nearly all the cell’s DNA and, with it, coded instructions for making proteins and other important molecules • Surrounded by a double membrane called the nuclear envelope with nuclear pores, which allow materials in and out, like RNA and proteins
Cell Structure • The Nucleus • Chromosomes, which carry the cell’s genetic information, are housed in the nucleus. • Chromosomes are spread out and threadlike through the nucleus. In this state they are called chromatin- a complex of DNA bound to proteins • Nucleolus- small dense region in the nucleus, where assembly of ribosomes begins • http://www.youtube.com/watch?v=tRo73dzVfuo
Check Point • What is the function of the cell nucleus?
Cell Structure • Vacuoles • Large, sac-like, membrane enclosed • Store materials like water, salts, proteins and carbohydrates • Central vacuole- In plant cells, filled with liquid to increase rigidity • Contractile vacuole- In unicellular organisms and some animals, pumps excess water out of the cell. • http://www.youtube.com/watch?v=zW9B3jC-1Xc • http://www.youtube.com/watch?v=hUkZwSHZjhY
Cell Structure • Vesicles • Smaller then vacuoles, membrane enclosed structures • Store and move materials between cell organelles and the cell surface
Cell Structure • The Cytoskeleton • Network of protein filaments that give cells their shape, internal organization and movement • May carry materials from one part of the cell to another or move the entire cell
Cell Structure • The Cytoskeleton • Microfilaments: Made of a protein called actin, tough flexible frame work that supports the cell. Also help the cell move (amoebas crawl along the surface with cytoplasm movement) • Microtubules: hollow structure made up of tubulin. Maintain cell shape, cell division (form mitotic spindle used to separate chromosomes) • Centrioles are microtubules found in animal cells only that help with cell division • Microtubules also build cilia and flagella which control movement • http://www.youtube.com/watch?v=5rqbmLiSkpk&feature=related
Check Point • What are the functions of vacuoles, lysosomes, and the cytoskeleton?
Cell Structure • Ribosomes • Ribosomes are small particles of RNA and protein • Proteins are assembled here by following instructions from DNA • Protein factory • http://www.youtube.com/watch?v=Jml8CFBWcDs
Cell Structure • Endoplasmic Reticulum • ER is where lipid components of the cell membrane, proteins and other components are assembled • Rough ER: Ribosomes are found on its surface. Newly made proteins leave the ribosomes and are inserted into the rough ER were they are modified. These proteins will be released, secreted or transported to other areas of the cell • Smooth ER: No ribosomes attached, contain enzymes that synthesis membrane lipids and detoxify drugs (liver) • http://www.youtube.com/watch?v=PASnAaulK-Y
Cell Structure • Golgi Apparatus • Proteins from the rough ER come here to get modified, sorted, and packaged for storage in the cell or release outside the cell • Puts the finishing touches on the proteins • Looks like flattened sacs of membranes • http://www.youtube.com/watch?v=bD4z27ASN1M
Check Point • What organelles help make and transport proteins?
Cell Structure • Chloroplast • Solar power for plants • Capture energy from sunlight and convert in into food that contains chemical energy in a process called photosynthesis • Membrane bound, contain chlorophyll • Have their own genetic information, DNA, endosymbiotic with prokaryotes • http://www.youtube.com/watch?v=LTglday5zak
Cell Structure • Mitochondria • Power plants of cell • Convert chemical energy stored in food into compounds that are more convenient for the cell to use • Two membranes with the inner membrane folded to increase surface area • Mitochondria only come from the egg during fertilization, so all the mitochondria in the worlds population come from the mother • Have their own genetic information, DNA, endosymbiotic with prokaryotes • http://www.youtube.com/watch?v=RrS2uROUjK4
Check Point • What are the functions of chloroplast and mitochondria?
Cell Structure • Cell Wall • Main function is for support, shape and protect • Not found in animals cells • Porous, allow water, oxygen, carbon dioxide and other substances to pass through easily • Cell walls are found in all plants. Made of cellulose
Cell Structure • Cell Membranes • Cell membrane regulates what enters and leaves the cell and protects and supports the cell • Made of a lipid bilayer which gives the membrane its chemical properties. Fatty acid head of a lipid is called hydrophilic (water loving), the tail is hydrophobic (water hating) • http://www.youtube.com/watch?v=-aSfoB8Cmic
Cell Structure • Cell Membrane • Fluid Mosaic Model: Proteins are embedded in the lipid bilayer and can “float” so it looks like the membrane is moving or fluid • Carbohydrates are attached to the proteins and act as identification cards, the proteins act as channels or pumps to get materials through or help change the shape of the cell • Selectively permeable: Some material can pass through the membrane some can not • http://www.youtube.com/watch?v=ULR79TiUj80
Check Point • What is the function of the cell membrane?
Cell Specialization/Differentiation • Cell differentiation starts from a single fertilized egg, with one set of DNA and cellular components. Each cell in the organism has the same genetic blueprint. • There are three basic categories of cells that make up the mammalian body: Germ cells ( give rise to sperm and ova), somatic cells (body cells that for different tissues and organs) and stem cells (able to divide for an infinite period and give rise to specialized cells) • During differentiation certain genes are turned on, or become activated, while other genes are switched off, or inactivated • http://www.teachersdomain.org/resource/tdc02.sci.life.stru.different/
From One Cell To Many • Embryo: developmental stage from which an adult organism is gradually produced • Differentiation: Process by which cells become specialized. During the development of an organism, cells differentiate into many types • Differentiation determines a cells identity, how a cell will spend its life • In mammals adult cells do reach a point at which their differentiation is complete, they can no longer become other types of cells
Check Point • How do cells become specialized for different functions?
Stems Cells and Development • Totipotent: a cell that can literally do everything, to develop into any type of cell in the body. Only the fertilized egg and the cells after the first few divisions are totipotent
Stem Cells and Development • Human Development • Blastocyst: After four days of development a hollow ball of cells with a cluster of cells inside known as the inner cell mass. • The cells begin to specialize, outside cells form tissues that attach to the mother, inside cells are called pluripotent, can develop into most, but not all, of the body’s cell types
Stem Cells and Development • Stem Cells: the unspecialized cells from which differentiated cells develop. Sit at the stem of development from which different cell types form • Embryonic Stem Cells: they are the pluripotent cells. Can form into other cells, large amount of research • Adult Stem Cells: Referred to as multipotent, meaning they can develop into many types of differentiated cells. Have limited potential. Example bone marrow cells • http://www.youtube.com/watch?v=mUcE1Y_bOQE
Check Point • What are stem cells?
Stem Cell Research • Potential benefits • Stem cells offer the potential benefit of using undifferentiated cells to repair or replace damaged cells and tissues • Ethical Issues • Human embryonic stem cell research is controversial because the arguments for it and against it both involve ethical issues of life and death. Harvesting embryonic stem cells means killing the embryo
Check Point • What are some possible benefits and issues associated with stem cell research?
Cell Specialization/Differentiation • Levels of organization • Somatic cells differentiate into different levels of organization • Tissues • Organs • Organ Systems
Cell Specialization/Differentiation • Tissues • Group of similar cells that perform a particular function • Epithelial Tissue: line in interior and exterior of the body, skin and stomach lining • Connective tissue: provides support and connects the body parts, fat cells, bone cells, blood cells. Produce collagen, give tissues strength and resilience • Nervous tissue: transmit nerve impulses • Muscle tissue: provide movement, some we control, like arm and leg, some we do not, like your pupil
Cell Specialization/Differentiation • Organs • A group of different types of tissues that work together to perform a single function or many related functions • Organ Systems • A group of organs that perform closely related functions