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Prokaryotes Eukaryotes Mammalian development
Unit 1: Theoretical Pillars of Biology
Lecture 1.6: Cells and Chromosomes
John D. Nagy
BIO 181: General Biology for Majors, Scottsdale Community College
2019 Revision
John Nagy Lec 1.6: Cells and Chromosomes 1/23
Prokaryotes Eukaryotes Mammalian development
Outline
1 Prokaryotes
2 EukaryotesCharacteristicsOrganellesGenetic organization
3 Mammalian developmentPatternsProcesses
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Prokaryotes Eukaryotes Mammalian development
Macromolecules self-organize
Stromatolites—giant mats of photosynthetic bacteria(cyanobacteria)
John Nagy Lec 1.6: Cells and Chromosomes 3/23
Prokaryotes Eukaryotes Mammalian development
Prokaryotic cell (Bacteria)
Key characteristics:
No nucleus or othermembrane-boundorganelles
One majorchromosome andmany smallchromosomes(plasmids)
Bacterialchromosomes tendto be circular
John Nagy Lec 1.6: Cells and Chromosomes 4/23
Prokaryotes Eukaryotes Mammalian development
Cell walls and cell membranes
Plasma (cell) membranes:
In all cells.
Composed of phospholipids (soap) and proteins.
Thin; behave like soap bubbles.
Cell walls:
In many prokaryotes, single-celled eukaryotes, all plantsand fungi.
Composed of carbohydrates (cellulose in plants, chitin infungi) or peptidoglycans (carbohydrates and proteins).
Rigid.
John Nagy Lec 1.6: Cells and Chromosomes 5/23
Prokaryotes Eukaryotes Mammalian development
Protein synthesis machinery
Cell structure: Ribosome
Ribosomes are cell structures (“organelles”) composed ofribosomal RNA (rRNA) and protein that construct proteins inall known cells. They are the fundamental cell structures.
John Nagy Lec 1.6: Cells and Chromosomes 6/23
Prokaryotes Eukaryotes Mammalian development
Bacterial DNA
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Prokaryotes Eukaryotes Mammalian development Characteristics Organelles Genetic organization
Eukaryotic cell
Key characteristics:
Has membrane-boundorganelles, including anucleus (stained green inpicture).
Has a cytoskeleton (stainedyellow in picture).
Most of the DNA is in thenucleus.
Nuclear chromosomes tendto be linear.
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Prokaryotes Eukaryotes Mammalian development Characteristics Organelles Genetic organization
Eukaryotes also have ribosomes...
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Prokaryotes Eukaryotes Mammalian development Characteristics Organelles Genetic organization
...along with a bunch of other stuff...
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Prokaryotes Eukaryotes Mammalian development Characteristics Organelles Genetic organization
...and even more stuff
Study the functions of structures on this and the previous slide.
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Prokaryotes Eukaryotes Mammalian development Characteristics Organelles Genetic organization
Eukaryotic DNA—Chromatin
See Cold Spring Harbor Labs, DNA Learning Center:dnalc.cshl.edu/resources/3d/08-how-dna-is-packaged-advanced.html
John Nagy Lec 1.6: Cells and Chromosomes 12/23
Prokaryotes Eukaryotes Mammalian development Characteristics Organelles Genetic organization
Condensed eukaryotic DNA
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Prokaryotes Eukaryotes Mammalian development Characteristics Organelles Genetic organization
Chromosomes pack into the nucleus
A 3-D model ofchromosomalpacking in anucleus.
Based onmathematicalmodel and anaylsisof experimentaldata.
Credit: Di Stefanoet al., NationalCentre for GenomicAnalysis (Spain).
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Prokaryotes Eukaryotes Mammalian development Characteristics Organelles Genetic organization
Chromosomal patterns in mammals
Spectral karyotype of a human female.
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Prokaryotes Eukaryotes Mammalian development Characteristics Organelles Genetic organization
Chromosomal patterns in mammals
Human pattern similar for all mammals and many othermulticellular eukaryotic organisms:
Definition: Diploid
Cells or organisms in which a majority of cells contain twocomplete sets of chromosomes are called diploid.
Definition: Haploid
Cells or organisms in which a majority of cells contain one setof chromosomes are called haploid.
Definition: Homologous chromosome
In diploid organisms, homologous chromosomes are similarin size, shape, location of the centromere and gene content.
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Prokaryotes Eukaryotes Mammalian development Patterns Processes
Early embryonic development
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Prokaryotes Eukaryotes Mammalian development Patterns Processes
Embryo to fetus
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Prokaryotes Eukaryotes Mammalian development Patterns Processes
Fetal development
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Prokaryotes Eukaryotes Mammalian development Patterns Processes
Process 1: Cell proliferation
Definition: Mitosis
Mitosis refers to division ofthe cell nucleus.
Definition: Cytokinesis
Cytokinesis is division of thecell contents.
Cells that fail to meetcheckpoint criteria typicallycommit suicide (apoptosis)Proliferation constructsaround 1013 new cells fromthe original zygote.
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Prokaryotes Eukaryotes Mammalian development Patterns Processes
Prior to mitosis, cells must replicate DNA
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Prokaryotes Eukaryotes Mammalian development Patterns Processes
Process 2: Differentiation
Definition: Differentiation
Differentiation is the process by which an unspecialized cell,often a stem cell, becomes specialized. In mammals, makes≈ 200 cell types.
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Prokaryotes Eukaryotes Mammalian development Patterns Processes
Process 3: Morphogenesis
Arrows point to cellsundergoing apoptosis.
Definition: Apoptosis
Apoptosis is geneticallyprogrammed cell death.
John Nagy Lec 1.6: Cells and Chromosomes 23/23
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