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CELLS. Chapter 3. A. The Early Years Robert Hooke (1660) 1st person to see the outlines of cells Antonie van Leeuwenhoek (1673) developed high magnification lenses 1st record of microorganisms Matthias Schleiden & Theodore Schwann (1839) & Rudolph Virchow (1855) - PowerPoint PPT Presentation
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Chapter 3
CELLS
A. The Early Years Robert Hooke (1660)
1st person to see the outlines of cells Antonie van Leeuwenhoek (1673)
developed high magnification lenses1st record of microorganisms
Matthias Schleiden & Theodore Schwann (1839) & Rudolph Virchow (1855)contributed to the cell theory
Cell Theory1. All living things are composed
of cells. [Schleiden & Schwann]2. All cells come from
preexisting cells. [Virchow]
B. Cell Size Most are 1-100m in diameter Smallest? Largest? Why can’t cells grow to be as large
as a car?- surface area/volume ratio- as cell grows, its volume increases
more rapidly than its surface area
C. Types of Cells3 basic types:BacterialArchaean ProkaryoticEukaryotic
1. Bacterial cells 1-10 m in diameter NO membrane-bound organelles1 circular DNA molecule located in nucleoid region
plasma membrane, cytoplasm & ribosomes
most have a cell wall (peptidoglycan)may have a polysaccharide capsuleEx. bacteria & cyanobacteria
2. Archaean cells1-10 m in diameterNO membrane-bound organellescell walls lack peptidoglycanhave characteristics of both
bacteria & eukaryotic cells
Ex. methanogens, extreme halophiles & extreme thermophiles
3. Eukaryotic cells10-100 m in diameter nucleus & other membrane-bound
organelles2 or more linear DNA molecules
located in nucleusplasma membrane, cytoplasm &
ribosomessome have a cell wall (cellulose or chitin) Ex. plants, animals, fungi, protista
Generalized Generalized Animal Cell Plant Cell
D. Organelles of Eukaryotic CellsOrganelles compartmentalize a
cell’s activities.1. Nucleus
surrounded by a double membrane (nuclear envelope), perforated with nuclear pores
contains DNA & nucleolus (stores RNA nucleotides)
functions to separate DNA from rest of cell
Nucleolus
2. Endoplasmic reticulum (ER) interconnected network of
membranes extending from nucleus to plasma membrane
Rough ER - studded with ribosomes site of protein synthesis (most will
be exported out of the cell)Free ribosomes in the cytoplasm synthesize proteins that remain in cell.
Smooth ER - lacks ribosomessite of lipid synthesiscontains enzymes that detoxify
drugs & poisons
3. Golgi apparatus stacks of membrane-enclosed
sacs
Functions: links simple carbohydrates
together to form starch links simple carbohydrates to
proteins (glycoprotein) or lipids (glycolipid)
completes folding of proteins temporarily stores secretions (milk)
Organelle interaction in a mammary gland cell.
#/cell variescontain DNA inherited from female parentsite of cellular respiration (production
of ATP)
4. Mitochondriadouble-membrane
outer is smooth inner is highly
folded (cristae)
5. Chloroplastspossess 3 membranes
outer/inner membranes surround stroma 3rd membrane system folded into
flattened sacs (thylakoids)
#/cell varies contain DNA found in plants & protists function in photosynthesis
6. Lysosomes (suicide sacs)vesicles containing > 40 types of
digestive enzymes
function to recycle damaged organelles, break down cellular byproducts & destroy invading microbes
7. Peroxisomesvesicles containing several types
of enzymes (produced in cytoplasm) found in all eukaryotic cells function to help cell use oxygen &
metabolize potentially toxic compounds
E. The Endosymbiont TheoryProposes that chloroplasts and
mitochondria evolved from once free-living bacteria engulfed by larger archaea.
Based on fact that mitochondria & chloroplasts resemble certain bacteria (size, shape, membrane structure & method of making proteins).