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Cellular Classification & Organelles: A Look at the Endomembrane System. Biology 111 Holyoke Walsh. Cells. http://www.youtube.com/watch?v=IcevP5tkWH0&feature=related. COMPARING CELLS. The size & shape of a cell relates to its function . . Cells. All cells are classified as either - PowerPoint PPT Presentation
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Cellular Classification & Organelles: A Look at the Endomembrane System
Biology 111
Holyoke Walsh
Cells
• http://www.youtube.com/watch?v=IcevP5tkWH0&feature=related
COMPARING CELLS
• The size & shape of a cell relates to its function.
Cells
• All cells are classified as either 1. Prokaryote2. Eukaryote
Prokaryote Cells• no membrane bound nucleus, chromosomes
grouped together in an area called the "nucleoid"• no membrane bound organelles• smaller than eukaryotes
• have cell wall and cell membrane, some have a capsule on the outside
• ribosomes make protein• consist of bacteria and
archaebacteria• Appendages
include: fimbriae/pili, flagella
*pili are usually longer and fewer than fimbriae, both function for attachment and recognition of host cells (pili has a function for sexual reproduction)
Figure 4.4a
E. coli
Eukaryotes• has a membrane bound nucleus• has membrane bound organelles in cytoplasm• Organelles perform specific functions• much larger than prokaryotes
Organisms within the animal, plant, fungi and protista kingdoms are all eukaryotes
We will be spending a lot of time on organelles and their functions.
Figure 4.6b
Figure 4.7b
Prokaryote vs Eukaryote CellsEndosymbiosis theory:
All organelles seem to share many properties with bacteria. Lynn Margulis proposed endosymbiont hypothesis: that organelles derived from ancient colonization of large bacteria (became the eukaryotic cell) by smaller bacteria (became the mitochondria, chloroplast, etc.) Symbiosis = "living together". *Mitochondria & Chloroplasts have their own DNA
Animation at Microbiological Concepts
Commonalities…of all cells!!
• Plasma Membrane• Cytoplasm• Chromosomes (DNA)• Ribosomes
Key Differences?
• The location of their DNA; membrane bound organelles
• Prokaryote = nucleoid region• Eukaryote = nucleus
Prokaryote vs. Eukaryote
Prokaryote or Eukaryote??
Prokaryote or Eukaryote??
Prokaryote or Eukaryote??
Eukaryotes• In addition to the plasma membrane at its outer
surface, a eukaryotic cell has extensive & elaborately arranged internal membranes, which divide the cell into compartments.
• These provide different local environments that facilitate specific metabolic functions, so incompatible processes can go on simultaneously in a single cell
• The plasma and organelle membranes participate directly in the cell’s metabolism b/c many enzymes are built right into the membranes themselves.
Cell Membranes..in general
• Phospholipid bilayer• Embedded proteins• Each type of membrane has a unique
composition of lipids and proteins suited to that membrane’s specific function
Ex: enzymes embedded in the mitochondrial membrane function in cellular respiration…which creates the ATP energy our cells need to function!
Cell Membrane
Pg 64
Eukaryotes…genetic info…
• Two cellular components involved with the genetic control of the cell are the NUCLEUS & the RIBOSOMES
NUCLEUS
The Nucleus
The Nucleus• Nuclear envelope contains nuclear pores for some things to enter and
exit (nucleoplasm within)• Chromatin is DNA and proteins, when the cell begins to divide, chromatin
condenses and forms chromosomes• DNA remains in the nucleus, it sends instructions to the cytoplasm via
messenger RNA• RNA directs the synthesis of proteins on ribosomes in the cytoplasm• Nucleolus assembles ribosomes within the nucleus, ribosomes contain
the "tools" to construct proteins
Chromosomes – made of DNA/Protein!
• DNA: Polymer of millions of nucleotidesNucleotide = Deoxyribose Sugar (pentose)+Phosphate + Nitrogen Base
29
One Strand of DNA• The backbone of
the molecule is alternating phosphates and deoxyribose sugar
• The teeth are nitrogenous bases.
phosphate
deoxyribose
bases
DNA Double Helix
T
G
C
G
G
A
C
C
A T Bases: Cytosine C Thymine T Adenine A Guanine G
http://www.youtube.com/watch?v=qy8dk5iS1f0
Ribosomes
• Made of some RNA (genetic info) and Protein• each is composed of two subunits, one large
and one small• Non-membranous organelles• Vary in size (smaller in prokaryotes)• Main function is to carry out protein
synthesis.
Ribosomes cont…• Cells that have high rates of protein synthesis have
particularly high rates of ribosomes• Located in the cytoplasm/ER (structurally identical)• Free ribosomes – function within the cytosol (ie.
enzymes that catalyze reactions)• Attached ribosomes – generally destined for
insertion into organelles membranes or for export (cells that secrete enzymes)
• Why does the human pancreas have millions of ribosomes?
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