Prokaryotic and Eukaryotic Cells
Characteristics of Prokaryotic Cells
• Prokaryotic cells have single circular chromosomes as their genetic information contained within a nucleoid region.
• Prokaryotes are divided into bacteria and archaea. Most are small, single-celled with a simple structure
• They possess a cell wall surrounding their plasma membrane.
• They lack membrane-bound organelles, distinguishing them from eukaryotic cells.
• Prokaryotes divide binary fission, resulting in identical daughter cells (no genetic variation) as their mother
Eukaryotic Cells
• Eukaryotic cells include organisms such as fungi, protists, plants, and animals.
• They contain membrane-bound organelles or essentially compartments where specific biological processes occur, including a
nucleus that houses genetic material.
• Eukaryotic cells reproduce through mitosis by advancing through a cell cycle to produce 2 genetically identical daughter cells.
Genetic Material and Chromosomes
Chromosome Structure and Function
• Chromosomes are structures that contain the genetic material, DNA. The physical location of a gene on a chromosome is referred to
as its locus.
• A karyotype is indeed a photographic or computer-generated representation of an individual’s complete set of chromosomes,
arranged and analyzed by cytogeneticists. It’s a visual tool used to examine the number, size, and structure of chromosomes to
detect any abnormalities or genetic disorders.
, • Homologous chromosomes are similar chromosomes from each parent but not identical. They are the same size; they have the same
genes in the same locations, but the sequence of the genes may vary (allele) on each homologous chromosome.
o The exception is the sex chromosomes. The X and Y chromosomes are NOT homologous to each other
Cell Division Processes
Mitotic Cell Division
• The cell cycle includes interphase (G1, S, G2) and mitotic phases (prophase, prometaphase, metaphase, anaphase, telophase and
cytokinesis).
• Somatic cells (body cells, non-sex cells) are diploid and undergo mitosis throughout the life of the organism. Depending on the type of
cells (adult neurons are terminally differentiated and are not considered to divide) the frequency of mitosis can vary.
• Restriction points are critical checkpoints in the cell cycle, such as the G1 phase restriction point.
o Cells must meet specific molecular criteria to proceed past these points. Once cells pass through a checkpoint, they are
committed to the next stage in the cell cycle
Mitotic Spindle Apparatus
• The spindle apparatus or mitotic spindle is the structure responsible for organizing and sorting the chromosomes during mitosis; also
known as
• MTOC- microtubule-organizing center- A structure in a cell from which microtubules begin to grow.
o In animals cells the MTOCs are called centrosomes, cellular structure from which microtubules emanate.
o During cell division in eukaryotes, the spindle pole is one of two sites in the cell where microtubules originate.
, o In animal cells, centrioles are a pair of cylindrically shaped structures found within the centrosome.
o Astral microtubules emanate outward from the centrosome toward the plasma membrane. They are important for positioning
of the spindle apparatus in within the cell
o Polar microtubules extend from the spindle poles and overlap in the middle of the spindle, contributing to the spindle's
structure and helping to push the poles apart during anaphase
o Kinetochore microtubules have attachments at kinetochores, which are protein complexs bound to the centromeres of
individual chromosomes
Characteristics of Prokaryotic Cells
• Prokaryotic cells have single circular chromosomes as their genetic information contained within a nucleoid region.
• Prokaryotes are divided into bacteria and archaea. Most are small, single-celled with a simple structure
• They possess a cell wall surrounding their plasma membrane.
• They lack membrane-bound organelles, distinguishing them from eukaryotic cells.
• Prokaryotes divide binary fission, resulting in identical daughter cells (no genetic variation) as their mother
Eukaryotic Cells
• Eukaryotic cells include organisms such as fungi, protists, plants, and animals.
• They contain membrane-bound organelles or essentially compartments where specific biological processes occur, including a
nucleus that houses genetic material.
• Eukaryotic cells reproduce through mitosis by advancing through a cell cycle to produce 2 genetically identical daughter cells.
Genetic Material and Chromosomes
Chromosome Structure and Function
• Chromosomes are structures that contain the genetic material, DNA. The physical location of a gene on a chromosome is referred to
as its locus.
• A karyotype is indeed a photographic or computer-generated representation of an individual’s complete set of chromosomes,
arranged and analyzed by cytogeneticists. It’s a visual tool used to examine the number, size, and structure of chromosomes to
detect any abnormalities or genetic disorders.
, • Homologous chromosomes are similar chromosomes from each parent but not identical. They are the same size; they have the same
genes in the same locations, but the sequence of the genes may vary (allele) on each homologous chromosome.
o The exception is the sex chromosomes. The X and Y chromosomes are NOT homologous to each other
Cell Division Processes
Mitotic Cell Division
• The cell cycle includes interphase (G1, S, G2) and mitotic phases (prophase, prometaphase, metaphase, anaphase, telophase and
cytokinesis).
• Somatic cells (body cells, non-sex cells) are diploid and undergo mitosis throughout the life of the organism. Depending on the type of
cells (adult neurons are terminally differentiated and are not considered to divide) the frequency of mitosis can vary.
• Restriction points are critical checkpoints in the cell cycle, such as the G1 phase restriction point.
o Cells must meet specific molecular criteria to proceed past these points. Once cells pass through a checkpoint, they are
committed to the next stage in the cell cycle
Mitotic Spindle Apparatus
• The spindle apparatus or mitotic spindle is the structure responsible for organizing and sorting the chromosomes during mitosis; also
known as
• MTOC- microtubule-organizing center- A structure in a cell from which microtubules begin to grow.
o In animals cells the MTOCs are called centrosomes, cellular structure from which microtubules emanate.
o During cell division in eukaryotes, the spindle pole is one of two sites in the cell where microtubules originate.
, o In animal cells, centrioles are a pair of cylindrically shaped structures found within the centrosome.
o Astral microtubules emanate outward from the centrosome toward the plasma membrane. They are important for positioning
of the spindle apparatus in within the cell
o Polar microtubules extend from the spindle poles and overlap in the middle of the spindle, contributing to the spindle's
structure and helping to push the poles apart during anaphase
o Kinetochore microtubules have attachments at kinetochores, which are protein complexs bound to the centromeres of
individual chromosomes
