Chapter 4 Flashcards
Binary fission
the methods of cell division used by prokaryotes
reasons for cell division
- Growth and
development - Maintenance
and repair - Reproduction
asexual reproduction
a method
of reproduction that produces
genetically identical cells without
the fusion of gametes (sex cells)
Plasmid
a small, circular loop
of DNA that is separate from a
chromosome, typically found
in bacteria
Steps of binary fission
D – DNA replication
E – Elongation
S – Septum formation
C – Cell division
There are three stages of the eukaryotic cell cycle:
Interphase
Mitosis
Cytokinesis
Interphase
the first stage of the
eukaryotic cell cycle which involves
cellular growth and duplication of
chromosomes. Composed of three
phases: G1, S, and G2
Mitosis
the second stage of
the eukaryotic cell cycle, which
involves the complete separation
of sister chromatids and nuclei
Cytokinesis
the division of the
cytoplasm and formation of two
daughter cells
Phases of interphase
G1phase
G0 phase
S phase
G2 phase
G1 phase
Cell growth: increasing the volume of its cytosol, synthesising proteins for DNA replication, replicating its organelles.
G0 phase
Cells that are not required to replicate rest in the G0 phase. Cells in G0 are either
quiescent or terminally differentiated. While quiescent cells are dormant and have the
ability to re-enter the cell cycle, terminally differentiated cells remain in G0 indefinitely
S phase
During the S phase, the cell replicates its DNA turning one chromosome into two
genetically identical sister chromatids.
G2 phase
cell continues to grow and prepare
itself for mitosis: increasing the volume of the cytosol, synthesising proteins in preparation for mitosis.
Four stages of mitosis
prophase, metaphase, anaphase, and telophase
Prophase
Prophase begins with the condensation into distinct chromosomes,
Simultaneously, the centrioles migrate towards
opposite ends (or poles) of the cell, and spindle fibres
begin to form. The nuclear membrane breaks down
and the nucleolus disappears.
Metaphase
In metaphase, the spindle fibres fully form and attach
to the centromere of each chromosome. This allows
the spindle fibres to guide the chromosomes towards
the equator of the cell where they line up.
Anaphase
The spindle fibres contract, splitting the centromere and
pulling sister chromatids to opposite ends of the cell.
Telophase
The chromosomes densely pack together at either
end of the cell, and new nuclear membranes form,
producing two genetically identical nuclei. The spindle fibres disintegrate and the chromosomes decondense.
cytokinesis.
In this stage, the cytoplasm divides and the
organelles evenly distribute themselves before separating into two daughter cells.
Cytokinesis in animals vs plants
Cleavage furrow vs cell plate
Apoptosis
Apoptosis is the natural and controlled death of cells within our body which plays an
important role in our development and day-to-day lives.
Mitochondrial pathway
the
pathway of apoptosis which
is initiated by the detection of
internal cellular damage. Also
known as the intrinsic pathway
Death receptor pathway
the
pathway of apoptosis which
is initiated by the reception of
extracellular death signalling
molecules. Also known as the
extrinsic pathway
Blebbing
the bulging of the
plasma membrane to form
apoptotic bodies
phagocyte a
a cell of the
immune system responsible
for engulfing and destroying
harmful microorganisms and
foreign material
stem cell
undifferentiated
cells with the capability of
differentiating into specialised cells
Specialised cells
cells which serve a
unique, particular function
Self renewal
Stem cells have the capacity to replicate without disrupting their ability to differentiate
by producing both a differentiated cell and a copy of themselves when they replicate
Potency
Stem cells are undifferentiated cells which can give rise to differentiated cells with a
specialised function
Totipotent
Stem cells that can differentiate
into any cell type.
Pluripotent
Stem cells that can differentiate
into multiple cell types.
Multipotent
Stem cells that can differentiate
into a limited number of
specialised cell types belonging to
a specific tissue or organ
