Cells, Cell Division, and Cell Specialization Fundamentally Different Types of Cell Prokaryotic Cell- single celled: only DNA+ structure (“before nucleus”) E. g. zygote-complete DNA Eukaryotic Cell-multi-celled (“after nucleus”) ProkaryotesEukaryotes DNAIn “nucleoid” regionWithin membrane-bound nucleus ChromosomesSingle, circularMultiple, linear OrganellesNoneMembrane-bound organelles SizeUsually smallerUsually larger- 50 times OrganizationUsually single-celledOften multicellular Sexual ReproductionNoneMeiosis: Combination of DMA from 2 cells 3 postulates of cell theory (Created by Schleiden, Schwann) . All living things are composed of cells 2. All cells from pre-existing cells (e. g. through cell division) 3. Cells are the basic functional units of living organisms Functions of organelles OrganelleIn business termsFunctions CytoplasmPlace to work-suspends organelles -stores substances that are needed for later -many chemical reactions take place CytoskeletonPlace to work-transports vesicles and organelles -determines cell shape E. g. while blood cell: uses it to reach and swallow bacterium Ribosome/ EnzymesWorkers-makes proteins that enter the ER for modification NucleusThe boss-protects DNA chromosome: large continuous piece of DNA, containing many genes -gene: many sets of instructions on a chromosome, make functional products -nucleolus: region of DNA that codes ribosomes -nuclear pore: holes in a nuclear membrane Endoplasmic Reticulum Internal transportation-transports materials throughout the cell with its branching tubes and pockets -brain: assists with production, release of hormone -muscles: involved with muscle contraction Golgi ApparatusExports transportation-collect and process materials to be removed from the cell -make and secrete mucus Cell MembraneSecurity/ export/import-support the cell allow some substances to enter while keeping others out (semi-permeable) Chloroplasts Cash flow-absorb light energy for photosynthesis? the process of converting carbon dioxide and water in glucose and oxygen using chlorophyll MitochondriaSpender of cash-make energy available to the cell -contains enzymes? convert stored energy into a easily usable form ( cellular respiration) LysosomesWaste removal/ recycling-digestive system of cell? break down waste from both inside and outside the cell Vacuoles Storage-contain substance, removing unwanted maintaining internal turgor pressure within the cell
Differentiating between plant and animal organelles AnimalsPlants Lysosome: present in all animal cells but not allCell Wall: provides structural support, prevents cells from rupturing, outside of cell membrane Centrioles: involved in cell divisionChloroplasts: absorb light energy for photosynthesis? the process of converting carbon dioxide and water in glucose and oxygen using chlorophyll Vacuole: a portion of the cell membrane may turn inside out to form a vacuole to digest the engulfed objectVacuole: controls turgor pressure, much larger Reasons who cells must divide 1.
Reproduction -all cells use division to reproduce -single celled organisms: split to form new organism (asexual reproduction) -multi celled organisms: 2 parental cells combine to form new organism (sexual reproduction) 2. Growth -transport of nutrients and waste across the cell limits cell size (diffusion: from highly concentrated areas to lower concentrated areas) -movement of chemical occurs by diffusion? cells get too large, chemical and water can’t move fast -only way to get bigger and still function properly is to add more cells 3. Repair/Regeneration -needed to stay alive E. g. kin cells replaced daily, red blood cells replaced ever 120 days, breaking bones or cuts and blisters: new cells needed to fill the gaps -replaces lost cells Why do cells specialize? Cells have exact same DNA in its nucleus? location and chemical messages from other cells activate certain genes. As a result each cell has a unique function in which they must perform Types of stem cells “Undifferentiated” Totipotent-“embryonic” stem cells E. g. zygote ?Completely undifferentiated E. g. cells from first few divisions after fertilization ? Can become any type ? Destroys the embryo when collected Pluripotent- “adult” stem cells E. g. trophoblast Already partially differentiated and located in specific body tissues E. g. bone marrow, umbilical cord ? Can become many types, but not all Multipotent ? Can only differentiate into a limited range of cell types Cancer- What and how it forms What: When genes that control the duration of interphase get mutations (random changes in DNA code) that causes a cell to grow out of control. As a result it forms a tumor (lumps of cells) that doesn’t fully differentiate or function properly, using valuable resources Tumor Types 1. Benign (non-cancerous): cells don’t interfere or invade other cells, but large masses can crowd nearby tissues 2.
Malignant (cancerous): interferes or invades other cells, nearby tissues and potentially mestasize Mestasize: process of cancer cells dividing and going to other places in the body by breaking away from an invasive primary tumor, forming additional secondary tumors Causes of Cancer 1. Cellular: DNA is copied improperly during S phase of cell cycle 2. Environmental: mutations caused by carcinogens (E. g. chemicals, energy, some viruses) Methods of Screening Cancer -Pap smear (cervical cancer) -Mammogram (breast cancer) -Colonoscopy (colorectal cancer) -PSA blood test (prostate cancer) -Self-Examination
Biopsy: removal of body tissue for laboratory examination (E. g. taken with endoscope) Methods of diagnosing cancer -Endoscopy: Camera and tissue extractor -X-ray: uses radiations to get images of tissues -Ultrasound: uses sound waves to create images of soft tissues -CT/Cat Scan: Computer Axial Tomography creates #. D images MRI Scan: Magnetic Resonance Imaging creates #. D image using magnetic fields and radio waves and computer analysis Different methods of treating cancer -Surgery: physically removing -Chemotherapy: treating with a series of drugs that target rapidly dividing cells -Radiation: killing cancer cells with target radiation
Biophotonics: uses beams of light to detect and treat cancer Different parts of the cell cycle- Description Interphase: -period before a cell divides -longest part of the cycle (3/4 of its time) -cell grows, performs daily functions and chromosomes are duplicated S-Stage of Interphase Strands of the SNA are copied but remain attacted to the original protein Mitosis: process by which all cells divide (to divide up the DNA that has been copied and create 2 identical cells each with a complete set of chromosomes Prophase: duplicated chromosomes shorten and thicken (chromatin begins to condense by supercoiling, wrapping around protein balls -nuclear membrane starts to dissolve) -spindle fibres (made of microtubles) form -centrioles move to opposite ends (poles of the cell) Metaphase: -double stranded chromosomes line up along the equator (middle of the cell) Anaphase: -each double stranded chromosome splits and the single stranded chromosomes travel along the spindle fibres to opposite ends of the cell -sister chromatids get pulled apart
Telophase: -chromosomes reach the opposite poles of the cell and become longer and thinner -new nuclear membrane forms around each set of chromosomes -spindle fibres disappear -supercoiled DNA begins to uncoil to form chromatin again Cytokinesis: -division of cytoplasm and cellular organelles (pinching off to form individual cells) Plant cells: grow a new cell plate built with proteins to form a new membrane) Result: mother cell splits in half to form 2 daughter cells Drawing the cell cycle