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Cell Structure. Cytology. All cells have a plasma membrane that separates the cell’s internal parts from the environment organelles (internal structures in the cytoplasm) cytoplasm (jelly like spooge, mostly water). Prokaryotes vs Eukaryotes.
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Cytology • All cells have • a plasma membrane that separates the cell’s internal parts from the environment • organelles (internal structures in the cytoplasm) • cytoplasm (jelly like spooge, mostly water)
Prokaryotes vs Eukaryotes • Prokaryotes lack most of the membrane bound organelles, have DNA in a concentrated region, tend to grow rapidly and divide often. Smaller than eukaryotes… • Includes cyanobacteria and bacteria
Eukaryotes • Protists, fungi, plants and animals… • specialized membrane bound organelles (nucleus), nuclear membrane • eukaryotes (10 - 100 micrometers) much larger than prokaryotes (.2 - 5 micrometers)
Cell size • Surface to volume ratio limits size of cell. • Volume increases at the cube of the diameter (V=d3) • Surface area increases at the square of the diameter (A=d2) • As a cell grows its volume increases at a rate faster than its surface area
Cell shape • Form follows function • similar functions in different organisms have similar shapes
Cell structure • See drawing on page 89 • What is the largest organelle? • What is the fluid outside of the nucleus but inside of the cell called? • What is the fluid inside of the nucleus called?
Nucleus • Has a double membrane and many nuclear pores • contains the nucleolus where ribosomes are assembled • Ribosomes important in the process of synthesizing protiens • leaves through the nuclear pores and ...
Nucleus contains DNA • Genetic material stored in nucleus… • Chromatin are seen in cells that are not dividing • Chromosomes are seen in cells that are dividing • How are they related?
Endoplasmic reticulum • Sets of membranes connected to the nuclear and plasma membranes • channelize cytoplasm • two types of ER - • rough ER • smooth ER
Golgi complex • Stacks of flattened membranes • sorts and modifies proteins from the ER • finished products are stored in cytoplasm or exports them through the plasma membrane
Mitochondria • Power plant in the cell • site of cellular respiration (converts organic molecules to ATP) • double membrane bound • have a small amount of their own DNA
Chloroplasts • Site of photosynthesis • also double membrane • contain pigments (chlorophyll and others) • also have their own DNA… • what does this suggest?