Cell Structure

Cytology n 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 n Prokaryotes lack most of the membrane bound organelles, have DNA in a concentrated region, tend to grow rapidly and divide often. Smaller than eukaryotes… n Includes cyanobacteria and bacteria

Eukaryotes n Protists, fungi, plants and animals… n specialized membrane bound organelles (nucleus), nuclear membrane n eukaryotes ( micrometers) much larger than prokaryotes ( micrometers)

Cell size n Surface to volume ratio limits size of cell. n Volume increases at the cube of the diameter (V=d 3 ) n Surface area increases at the square of the diameter (A=d 2 ) n As a cell grows its volume increases at a rate faster than its surface area

So what?

n Form follows function n similar functions in different organisms have similar shapes Cell shape

Cell structure n See drawing on page 89 n What is the largest organelle? n What is the fluid outside of the nucleus but inside of the cell called? n What is the fluid inside of the nucleus called?

Nucleus n Has a double membrane and many nuclear pores n contains the nucleolus where ribosomes are assembled n Ribosomes important in the process of synthesizing protiens n leaves through the nuclear pores and...

Nucleus contains DNA n Genetic material stored in nucleus… n Chromatin are seen in cells that are not dividing n Chromosomes are seen in cells that are dividing n How are they related?

Endoplasmic reticulum n Sets of membranes connected to the nuclear and plasma membranes n channelize cytoplasm n two types of ER - –rough ER –smooth ER

Golgi complex n Stacks of flattened membranes n sorts and modifies proteins from the ER n finished products are stored in cytoplasm or exports them through the plasma membrane

Mitochondria n Power plant in the cell n site of cellular respiration (converts organic molecules to ATP) n double membrane bound n have a small amount of their own DNA

Chloroplasts n Site of photosynthesis n also double membrane n contain pigments (chlorophyll and others) n also have their own DNA… n what does this suggest?