Introduction: the cell (Dr. Boucrot) Flashcards
What is a cell ?
In biology, the cell is the basic unit of life.
What is an organism ?
An organism is a collection of specialized cells.
How many cells does the human body contain ?
Between 70 and 100 trillion cells (1 trillion = 10E12).
How many new cells are made every day in the human body ?
Around 300 billion.
What are the main differences between prokaryotic and eukaryotic cells ?
Prokaryotic cells have a 1-2 micron diameter, no nucleus, circular DNA (so one chromosome), divide by binary fission, rarely possess internal membranes, have 70S (50S+30S) ribosomes, no cytoskeleton, move via a rotary motor that drives bacterial flagellum, first appeared 3.5 billion years ago.
Eukaryotic cells have a 5-100 microns diameter, have a nuclear, linear DNA with multiple chromosomes and proteins, go through mitosis (to produce daughter cells) and meiosis (to produce gametes), possess lots of internal membranes (organelles), have 80s (60s+40S) ribosomes), cytoskeleton made of microtobules, move via dynein (that drives eukaryotic flagellum cilia), kinesin and myosin, first appeared 1.5 billion years ago.
What do we call the classification of organisms ?
Taxonomie.
What are the distinct growth and division stages of cells ?
G1 (RNA and protein synthesis), S (DNA replication), G2 (RNA and protein synthesis), M (cell division or mitosis) and cytokinesis (cytoplasm of mother cell split in two, giving two daughter cells. G1+S+G2 = interphase.
There is also G0, a resting state where the cell is actively preparing to divide and just performing its function (post-mitotic) e.g. neurons, certain liver cells storing carbohydrates.
What is mitosis ?
Mitosis is the cell division that produces two daughter cells form one mother cell, each daughter cell have the same number and kind of chromosomes as the mother cell. It occurs in four stages: prophase, metaphase, anaphase, telophase (and usually finishes with cytokinesis).
What is meiosis ?
Meiosis is a cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores.
How many chromosomes does the human genome contain ?
23 pairs of chromosomes (46 total).
How many basepairs does the human genome contain ?
Around 3.10E9 unique basepairs.
What is ploidy ?
Ploidy is the number of sets of chromosomes in a cell. (n=haploid, 2n=diploid, 3n=triploid, 4n=tetraploid…)
What is euploidy ?
Euploidy is having an integral set of chromosomes.
What is aneuploidy ?
Aneuploidy is not having ploidy (an integral set of chromosomes).
What does polarity mean in cells ?
Polarity in cells can mean a difference in electrical charge between two sides of the cell but it can also mean that one side of the cell is functionally different from the other.
How are differentiated cells produced and what are the parent cells called ?
Differentiated cells are produced by asymmetric division and the parent cells are called “stem cells”.