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Transcript
Cells and Cell Theory Life – How can it be defined(video)? What are the Characteristics of life? • Have a life span • Grow in size, reproduce and are able repair themselves • Can sense and respond to changes in their environment • Require energy (nutrition or photosynthesis) • Produce waste • Movement • Respiration (exchange gasses with environment) • Made up of cells Life simplified? All living things must have three general properties • Metabolism – All chemical process that occur within a living organism, resulting in energy production and waste products • Growth and Movement – The act or process of increasing in size – Changing ones position • Reproduction – The sexual or asexual process by which organism generate others of the same kind The Cell Theory States: • The cell is the basic unit of life – The cell can perform all the characteristic of living things • All living are made up of one or more cells • All cells come from preexisting cells • The overall health of the organism depends on the health of its individual cells The First Cell What came first the Chicken or the egg? Recall that all cells come from preexisting cells, which means you need a cell to make a cell–So where did the first cell come from? • The first cell likely formed through symbiosis – – A close relationship between two types of organisms that helped them to survive and prosper together better then apart. • The world is filled with trillions of bacteria. It is possible that many parts of the cell were once individual bacteria, that discovered it was easier to survive together, then a part 3.5 Billion Years Ago • Prokaryote (without a nucleus) • Only form as single cells Examples Bacteria – E. coli Some Algae – Blue-Green Viruses – Flu Red Blood Cells 20 000 different kinds today 1.5 billion years of evolution…. life develops a “brain” • Eukaryote (with a nucleus) • Form single to trillion celled organisms Examples Fungi – mushrooms Protozoa – amoeba (single celled) Plants – rose Animal – humans Organelles’ video ORGANELLES • Cells are the smallest unit of life, but like atoms, they are made up of smaller objects. In atoms we call them subatomic particles, in cells we call them organelles. • Organelles are small specialized structures that perform specific functions within a cell All cells have the following organelles Organelles Cell Membrane Many organelles have membranes like the vacuole and the nucleus Letter Location/Structure Function The “outer part” or Acts like a gate keeper. perimeter of a cell or eg. Controls what gets in organelle. and out DNA – genetic material Chromatin Ridden or hair like structures found in the nucleus The nucleus is guided by the DNA, which contains all of the bodies instructions for life Chromosomes look like butterflies, only occur during cell Eg. Instruction booklet division (mitosis) Cytoplasm A mixture of chemicals Carries the organelles. It is and water flowing the area where cell work is around the cell done eg. The cell’s environment The following organelles are found in many cells Nucleus found in eukaryote cells Cells with a nucleus Regulates all cell activity. eg. It is the boss Nucleolus Dark sphere found Makes ribosomes inside the nucleus note: Disappears during cell division (mitosis) Ribosomes Very smaller spheres attached to the Endoplasmic Reticulum Makes proteins for cell growth and reproduction Endoplasmic Reticulum (ER) Smooth and Rough A series of canals with ribosomes (rough and attached to the nucleus) or without ribosomes (smooth and closer to the cell membrane) 1. acts like a conveyor belt or road inside the cell 2. Provides a site for chemical reactions to occur Mitochondria Tiny, maze like structures Uses food and oxygen to make energy – ATP molecules eg. Site of cellular respiration Golgi Body also called G. Apparatus G. Complex stacks of flattened sacs Prepares and packs proteins and protein combinations for use inside or outside of the cell Vacuoles very large in plant cells stores water, food and and helps to support waste for later use the cell wall of a plant eg. It is a warehouse of goods The following are some unique organelles found in different cells Cell Wall found only in plants Protects and supports a plant cell Centrioles multi-tubular structure found mostly in animals only used on cell division Used to split the nuclear material Chloroplast Contains different colours of chlorophyll Green chlorophyll is the site of photosynthesis Makes food Lysosome spherical “balls” filled with digestive enzymes Recycles worn out products