Cells and Cell Specialization

Topics: Cell, Eukaryote, Cell nucleus Pages: 5 (1157 words) Published: November 25, 2012
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”)
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)
1.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
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
-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. skin 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...
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