Chapter 12 (Cell Division) Flashcards
What is the continuity of life-based on?
cell division
What is the cell cycle?
life of a cell aka formation to the division
What does cell division result in?
two daughter cells that are genetically identical to 1 parent cell
What are the types of cells?
somatic cells and gametes
What are somatic cells?
non-reproductive cells that are found all over the body and have two sets of chromosomes
What is a cell that has two sets of chromosomes called?
diploid cell
What are gametes?
reproductive cells (sperm and egg) that have half as many chromosomes
What are gametes for?
utilization for the next generation of organisms
What is a cell that has half as many chromosomes called?
haploid cell
What is chromatin?
DNA that is loosely wrapped around proteins/complex of DNA and proteins
Where is chromatin found?
the nucleus
What protein is wrapped around the DNA in chromatin?
histone proteins
What are chromosomes?
condensed chromatin aka condensed DNA
What are chromatids?
the long part that is replicated and attached to the original chromosome
What are sister chromatids?
identical copies of chromosomes that is due to the replication of DNA
I (chromosome) —> I.I (sister chromatids) —-> I I distributed
What is the centromere?
where two sister chromatids are most closely attached
What are the sister chromatids held together at the centromere by?
cohesin proteins
What are the two main phases the cell cycle consists of?
mitotic phase (M phase) and Intererphase
What are the steps of the M-phase?
Prophase, metaphase, anaphase, telophase, and cytokinesis
What is mitosis?
division of the nucleus (a division of the chromosomes)
How much of the cell’s life is in the M-phase?
10 percent
What is cytokinesis?
division of the rest of the cell and the content within the cytoplasm
What is the result of the M-phase?
two daughter cells that go into their own cell cycle
What is interphase?
rest of the cell cycle that excludes the M-phase
How much of the cell’s life is in the Interphase?
90%
What are the phases of interphase?
G1, S, and G2
What is the G1 and G2 phases of interphase?
cell functioning and growth
What is the S (synthesis) phase of the interphase?
DNA replication THAT HAPPENS BEFORE MEIOSIS/MITOSIS so that there is enough genetic material for daughter cells in the cell division
When does the S phase happen?
before mitosis/meiosis and in between G1 and G2
Does every cell go through an interphase?
no, not every cell goes through it fast and completely
How does the cell control its own division?
system of molecular interactions that happens internally in the cell with the help of proteins in the cytoplasm
What is the Intrinsic Cell Cycle Checkpoint Pathway?
ensure the orderly progression of cell cycle events and are activated at different transition points to prevent premature entry into the next cell cycle event
What are three checkpoints?
G1, G2, Mphase checkpoint
What is the G0 checkpoint?
non-dividing state/resting state of a cycle, no more dividing
When would a cell go to the G0 checkpoint?
After the G1 checkpoint assessment, cell decides to go to the resting state instead of proceeding to the S-phase
What does the G1 checkpoint check for?
if the cell is big enough to divide after duplicating organelles
What does the G2 checkpoint check for?
if the DNA is fully replicated
What does the M phase checkpoint check for?
if the chromosomes correctly lined up and if there is a spindle formed
What are the two types of regulatory proteins in the control checkpoints?
cyclins and cyclin-dependent kinases (cdk)
What do cdk’s do?
undergo phosphorylation
Are cdks usually active or inactive?
inactive
Are cdks present in the cell or not?
present
Are cyclins present in the cell?
they have to be synthesized and then later they get degraded
What is an example of a cyclin-cdk complex?
MPF
What does MPF (maturation/mitosis promoting factor) do?
cyclin-cdk complex that phosphorylates proteins of nuclear membrane to begin fragmenting nuclear membrane
When is the mitotic spindle formed?
prophase
What is the mitotic spindle?
apparatus that allows mitosis to happen and it controls chromosomal movements during mitosis
What is the mitotic spindle made up of?
microtubules
What is the centrosome?
microtubule-organizing center that starts the process of making the spindle
What is a centriole?
found within a centrosome, they are microtubule units (2 cylinders)
When the centrioles go towards opposite ends of the cell, what forms around each spindle pole?
an aster
What is an aster?
cellular structure shaped like a star, consisting of a centrosome (that bubble around the centrioles)
What is the role of an aster?
microtubules that help spindle anchor at one end fo the cell
What are the types of spindle microtubules?
kinetochore and non-kinetochore (aka polar microtubules)
What do non-kinetochore (aka polar microtubules) do?
pushes spindle apart
What do kinetochores do?
attach to the center of a chromosome and are the sites for microtubules to grab on to
How is a kinetochore made?
assembles on the centromere and links the chromosome to microtubule polymers from the mitotic spindle
What happens in the prophase?
creation of the spindle apparatus, condensation of chromatins to form chromosomes, the nuclear membrane breaks down, attachment of microtubules from spindle to chromosomes
What happens in metaphase?
all chromosomes within a cell line up at the metaphase plate
What happens in anaphase?
replicated chromosomes get pulled apart to form separate chromatids, cleavage (cutting) of cohesin proteins
During anaphase, what happens to the nonkinetochore microtubules?
they start overlapping and pushing apart to elongate the cell, eventually, they degrade as they separate and motor proteins take over
What happens in telophase?
genetically identical nuclei form at opposite ends of cell, nuclear envelope reforms, chromosomes loosen up, spindle broken down
What happens in cytokinesis?
already happening by the time anaphase or telophase rolls around, division of cytosol and organelles to form a cleavage furrow based on microfilaments under plasma membrane
What does cell division allow for in a multicellular organism?
development from a single fertilized egg and continue to function as cell repair all over the body
What is a genome?
cell’s DNA/its genome
In somatic cells, where are the chromosomes inherited from, and how many?
23 from each parent for a total of 46 chromosomes
What units are added to make the spindle fibers elongate?
adding units of tubulin
How do spindle fibers shorten?
losing the subunits of tubulin
What does a plant cell produce instead of a cleavage furrow?
cell plate
Where did mitosis evolve from?
simpler prokaryotic mechanisms of cell
reproduction
