Cell Division, Cell Cycle and Differentiation Flashcards
Define Genome
All the DNA in a cell constitutes the cell’s genome.
Explain what chromatin is
Eukaryotic chromosomes consist of chromatin, a complex of DNA and protein that condenses during cell division
Explain what somatic cells are
Somatic cells (non-reproductive cells) have two sets of chromosomes
Explain what gametes are
Reproductive cells: sperm and egg, have half as many chromosomes as somatic cells
How are chromosomes distributed during eukaryotic cell division?
In preparation for cell division, DNA is replicated and the chromosome condenses
Each duplicate chromosome has two sister chromatids (joined copies of the original chromosome), attached along their lengths by cohesion
The centromere is the narrow ‘waist’ of the duplicated chromosome, where the two chromatids are most closely attached
What are the 2 main stages of eukaryotic cell division and explain them?
Mitosis - the division of the genetic material in the nucleus
Cytokinesis - the division of the cytoplasm
What type of reproduction produced gametes?
Gametes are produced by a variation of cell division called meiosis
Meiosis yields nonidentical daughter cells that have half as many chromosomes as the parent cells
What are the 2 main phases in the cell cycle?
Mitotic (M) phase - mitosis and cytokinesis
Interphase - cell growth and copying of chromosomes in preparation for cell division
What is the purpose of the cell cycle?
For cells to grow and divide
What percent of the cell cycle is interphase and what subphases can it be divided into?
Interphase makes up 90 of the cell cycle, it can be divided into:
G1 phase
S phase
G2 phase
At what stage of the cell cycle do chromosomes duplicate?
S phase
Name the 4 phases of the cell cycle, what is also included in the cell cycle?
G1 - Gap 1
S - DNA Synthesis
G2 - Gap 2
M - mitotic phase
G0 - super rest
R - Restriction phase
Name and explain the stages of mitosis
Prophase - breakdown of nuclear membrane; microtubules from mitotic spindle apparatus, chromosomes condense
Metaphase - Chromosomes fully attached to the spindle
Anaphase - Microtubule motor and spindle shortening pull chromosomes to the sister poles
Telophase - Chromosomes decondensed and nuclear envelopes are formed; cytokinesis
Name and Explain the 2 transient cytoskeleton structures that mediate M phase in animal cells
Mitotic spindle and contractile ring
The mitotic spindle assembles first to separate the duplicated chromosomes. Then, the contractile ring assembles to divide the cell in two. Whereas the mitotic spindle is based on microtubules, the contractile ring is based on actin and myosin filaments.
Explain what a mitotic spindle is
A structure made of microtubules that control the chromosome movement during mitosis
Explain the role of the centromere in animal cells
Assembly of spindle microtubules begins in the centrosome, the microtubule organization center
Explain what happens during prometaphase
The centrosome replicates during interphase, forming two centrosomes that migrate to opposite ends of the cell during prophase and prometaphase
During prometaphase, some spindle microtubules attach to the kinetochores of
Explain what kinetochores are
Protein complexes that are associated with centromeres
Explain what happens in metaphase at the metaphase plate
At metaphase, the chromosomes are all lined up at the metaphase plate, a plane midway between the spindle’s two poles
Explain what happens during metaphase
At metaphase, the chromosomes are aligned at the equator of the spindle, midway between the spindle poles. The kinetochore microtubules on each sister chromatid attach to opposite poles of the spindle
Explain what happens during cytokinesis
During cytokinesis of an animal cell, the cytoplasm is divided in two by a contractile ring of actin and myosin filaments, which pinches the cell into two daughters, each with one nucleus
Explain cytokinesis in animal and plant cells
In animal cells, cytokinesis occurs by a process known as cleavage, forming a cleavage furrow
In plant cells, a cell plate forms during cytokinesis
Explain the process of binary fission in bacteria
Prokaryotes (bacteria and archaea) reproduce by a type of cell division called binary fission
In binary fission, the chromosome replicates (beginning at the origin of replication), and the two daughter chromosomes actively move apart
The plasma membrane pinches inward, dividing the cell into two
Explain cell cycle control systems
The cell cycle appears to be driven by specific chemical signals present in the cytoplasm
The sequential events of the cell cycle are directed by a distinct cell cycle control system, which is similar to a clock
The cell cycle control system is regulated by both internal and external controls
The clock has specific checkpoints where the cell cycle stops until a go-ahead signal is received
What is RB?
Retinoblastoma protein (p105). Gatekeeper for the cell cycle
How do multicellular organism develop from a fertilized zygote?
Cell Division
Cell Differentiation (muscle cells, nerve cells, blood cells, etc.)
Morphogenesis (organization of differentiated cells into tissues and organs)
Explain what happens once a fertilised zygote is formed
Fertilized zygote undergoes mitotic divisions and develops and into a blastocyst with an inner cell mass (that will from the embryo associated yolk sac and amnion) and the trophoblast that will adhere/implant into he uterus
The gastrula forms when the embryo is approximately 14-16 days old in humans
Explain the process of gastrulation
Gastrulation is a phase early in the development of animal embryos, during which embryo morphology is restructured by cell migration. The single-layered blastula is recognised into a structure with three germ layers, know as the ectoderm, mesoderm, and endoderm. Gastrulation if followed by organogenesis, when individual organs develop
Explain embryonic development
Genes play a role in controlling cell fate specification and organizing normal development
Certain genes (eg. HOX) are considered master switches in this process
The genes required for normal human development, encode many different gene products, including cell signalling, transcription factors, components of the extracellular matrix, enzymes, transport proteins and other systems.
How do multicellular organism develop from a fertilized zygote?
Cell Division
Cell Differentiation (muscle cells, nerve cells, blood cells, etc.). Cell fates.
Morphogenesis (organization of differentiated cells into tissues and organs). Cell fates.
Cells Require Energy to Survive, Grow, Differentiate and Die.
Explain what stem cells are and give some characteristics of stem cells
Stem cells produce cells that differentiate into the tissue of our body (~200 cell types in the body)
Characteristics:
Self-renewal
Can divide without limit (but do so infrequently)
Not terminally differentiated
Daughter cells may become a stem cell or enter into terminal differentiation
Often reported to be rare and found in a niche
What are the classes of stem cells?
Embryonic
Adult
What types of stem cells are there and explain them
Stem cells are:
Totipotent - Generate all cell types
Pluripotent - Generate all cell types except placenta
Multipotent - Generates several cell types blood
Unipotent - Generate one cell type single type of neuron
Where in the body have stem cells been found?
Blood
Skin
Brain
Pancreas
Liver
Breast
Colon
What is apoptosis?
Programmed cell death
