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EUKARYOTIC CELL ORGANIZATION
I.
Internal Stuctures
A.
More complex than prokaryotic cells
Compartmentalized - organelles:
Areas with specific functions isolated in membrane bound compartments
B.
Nucleus:
Largest organelle
Most conspicuous
Contains the cells genetic material:
DNA
Eukaryotic DNA:
Organized into chromosomes
Complexes with histone (basic protein)
Linear in arrangement
Chromosomes:
Always more then one (2 to 100+)
Each chromosome contains some but not all the cells genetic
information
Nucleoli:
One or more per nucleus
Function:
Assembly of ribosomes
Nuclear membrane:
Surrounds:
Chromosomes
Nucleoli
Contains pores:
C.
D.
E.
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9nm in diameter
3000 - 4000 per nucleus
Allow communication between the nucleus and cytoplasm
F.
Endoplasmic reticulum:
Continuous with the outer bilayer of the nuclear membrane
Communications network:
Coordinates metabolic activities
Site of lipid synthesis
Supplies membrane material to other organelles
Responsible for:
Synthesis and distribution of protein that is exported from the cell
Two types of ER:
Smooth ER:
Not associated with ribosomes
Contributes :
New cell membrane
New Golgi membrane
Rough ER:
Associated with ribosomes:
Involved in synthesis and distribution of:
Exported proteins
Membrane proteins
Hormones
Enzymes
G.
Golgi apparatus:
Stacks of smooth membranes:
Packages proteins for export:
Makes lysosomes:
Packages of digestive enzymes
H.
Mitochondria:
Size:
1 m in diameter
1 - 3 m in length
Contain the enzymes of respiration and oxidative phosphorylation
Enclosed in double sterol-free membrane:
Outer smooth phospholipid membrane
Infolded inner membrane
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Cristae - Cristae contain enzymes which function in ATP
production
Matrix
Matrix contains:
DNA:
Circular
Naked
Ribosomes (prokaryotic-like)
Large amounts of protein
Are self-replicating
Have unique genetic code
I.
II.
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Chloroplasts:
Found in all eukaryotic organisms that carry out photosynthesis:
Contain chlorophyll
Surrounded by:
Three phospholipid membranes:
Outer membrane
Inner membrane
Thylakoid membrane
Thylakoid membrane contains chlorophyll arranged in:
Grana:
Stacks of thylakoid membrane
Light reactions of photosynthesis occur in the grana
Stroma:
Dark reactions of photosynthesis occur in the stroma:
Stroma contains:
Naked circular DNA
Prokaryotic-like ribosomes
Similarities between mitochondria, plastids and bacteria:
A.
Suggest that these organelles originated as prokaryotic cells:
B.
Trapped in an eukaryotic cell:
C.
Became dependent for their existence on the eukaryotic cell:
D.
Both contain:
Naked circular DNA
Prokaryotic-like (70s) ribosome
E.
Membranes of bacteria, plastids, and chloroplast contain no sterols.
F.
Antibiotics that kill or inhibit bacteria by interfering with 70s ribosome function
also inhibit protein synthesis in mitochondria and plastids
G.
Great similarity between base sequences of ribosomal RNA of:
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Mitochondria
Chloroplasts
Bacteria
III.
Sexual Reproduction:
A.
Occurs as part of the life cycle of most eukaryotic organisms
B.
Regular and ordered process
C.
Primary function:
Genetic Recombination:
Produces new gene combinations on which natural selection can
act.
D.
During sexual reproduction:
Chromosome number is reduced to 1n (haploid number) during formation
of gametes:
Sperm and eggs
Gamete formation is followed by fusion of sperm and egg:
Forms zygote:
Has the original chromosome number: Diploid number 2n
E.
Sexual reproduction also occurs in prokaryotic cells:
Process is not ordered:
Almost never involves whole chromosome complements of two cells:
Seems haphazard
DNA transferred in one direction:
From donor to recipient
Mechanisms by which DNA is transferred are specialized:
Conjugation
Transformation
Transduction
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