The Process of Cell Division Flashcards
Chromosome
genetic formation is bundled into packages of DNA
Where do most prokaryotes keep most of their genetic information?
in a singular circular chromosome
Eukaryotes have ________ chromosomes
multiple
how many chromosomes does a fruit fly cell have
8
how many chromosomes does a human cell have
46 (most)
Chromatin
complex of chromosome and protein
Nucleosome
the structure made when DNA wraps around 8 histones wice
Histone
most common protein used in DNA packaging
Coiling
when nucleosomes coil around each other
What does coiling produce
chromatin (IN = THIN)
Supercoil
when chromatin supercoils around each other
What does a supercoil produce
chromosomes
What makes it possible to separate DNA precisely during cell division
chromosomes
Cell Cycle
cycle in which a cell grows, prepares for division, and divides to form two daughter cells
How many phases does the cell cycle consist of
3
what are the 3 phases of the cell cycle
interphase, the mitotic phase, and cytokinesis
Binary Fission
the prokaryotic cell cycle, which is also a type of asxual reproduction
How many steps does Binary Fission consist of?
4
What are the four steps of Binary Fission?
1) The DNA (one circular chromosome) duplicates
2) The 2 DNA molecules attach to different regions of the cell
3) The cell membrane indents
4) The cell divides into two new cells
How many sub phases does Interphase have
3
What are the subphases of Interphase
1) {kinda iffy sub phase} Gap Ø
2) G₁
3) S
4) G₂
Gap Ø is aka
Gap Zero
G₁ is aka
Gap 1
S is aka
synthesis
G₂ is aka
Gap 2
Where is 90% of the cell cycles time spent in
interphase
Prior to synthesis how many chromosomes are present in human cells
46
Gap 1
basic growth of proteins, organelles, etc. Cell gets bigger and undergoes chemical processes
Gap Zero
cells that are not preparing to divide (normal)
Do all cells go through Gap zero at some point
MOST cells
Synthesis
where we copy genetic material. (duplicate chromatin)
How many chromatin are present at the end of synthesis?
92
Gap 2 is aka
the mitosis prep stage
Gap 2
duplicate centrosomes and centrioles (CENTRIOLES IN ANIMAL CELLS ONLY) also continue growing, double organelles, chemical reactions, etc.
What is the shortest phase of interphase
Gap 2
Centrosome
an organelle near the nucleus of a cell which contains the centrioles (in animal cells) and from which the spindle fibers develop in cell division.
Gap 1 and Gap 2 are periods of…
intense growth and activity
Mitotic phase
division of the nucleus
how many sub phases make up the mitotic phase
4
what are the four sub phases of the mitotic phase
PPMAT (Prophase, Prometaphase, Metaphase, Anaphase, and Telephase)
What is 10% or less of the cell cycle?
Mitotic Phase
What is the longest phase of mitosis
prophase
What occurs in prophase
- nuclear envelope and nucleolus break down
- genetic material condenses and duplicated chromosomes become visible as sister chromatids that are connect IN THEIR CENTROMERES
- the mitotic spindles start to grow and the centromeres and microtubules get farther and farther away from each other
What are spindle fibers made up of
microtubules
Centromeres
the region of a chromosome to which the microtubules of the spindle attach during cell division
What is the shortest phase of the mitotic phase
anaphase
What occurs in metaphase
the chromosmes with their mictorubles attached to a kinetochore on each of the sister chromatids line up in the middle and form a Metaphase plate
What occurs in Anaphase
- the chromosomes are split into sister chromatids - and now the sister chromatids are called CHROMOSOMES - because the cohesins are split
- sister chromatids are pulled back towards the poles of the cell via the cytoskeleton + microtubules
- the cell gets longer bc the other microtubules push push
What form is the genetic material in interphase
chromatin
What starts the pulling back of the chromosomes
the centromere
How do the spindle fibers break down
the chromosomes spit enzymes that break down the spindle fibers as they pull them back
Sister chromatids
two chromosomes joined together by a centromere
Genetic material is in what form for prophase
chromosome
During metaphase genetic material is
chromosomes
during anaphase genetic material is
sister chromatids to individual chromosomes
during anaphase genetic material is
sister chromatids turn into chromsomes (the individual sister chromatids)
What occurs in telephase
- Reform nuclear envelopes and nucleolus
- the spindle fibers break down (depolymerize)
- Unsupercoil chromosomes to become chromatin
- 2 daughter cells from in cell
Cytokinesis
completes cell division by splitting cell into two daughter cells
How does cytokinesis occur in animal cells
cleavage furrow is made and divide the cell into two and the cytoplasm splits
how is the cleavage furrow made
actin microfilaments make a ring like a butt with the help of myosin molecules and the butt gets deeper till it poops and makes 2 daughter cells
How does cytokinesis occur in plant cells
- golgi apparatus secretes parts of the cell wall (cellulose) also phospholipids in vesicles
- the vesicles line up in the middle of the cell
- the vesicles create a cell plate
- the cell plate fuses with the wall, splitting the cell
cell plate
made by the vesicles secreted by the golgi appartus during cytokinesis - is very flexible
genome
all the DNA (genetic information )
What did virchow say
all cells come from existing cells – idea of biogenesis
Biogenesis
creation of life
somatic
of the body
diploid
2 sets of chromosomes
Sister chromatids
the individual halves of a chromosome –> identical DNA molecules
chromatid
when the sister chromatids are joined together by a kinetochore in the centomere
Chromosome
tightly coiled DNA with proteins that condenses during prophase in cell division
Chromatin
histones and DNA not looped just the complex itself –> this is how DNA is stored
Kinetochore
protein that joins the two sister chromatids
Centromere
the region where sister chromatids connect
Cohesins
protein complexes where the sister chromatids originally connect
asters
the little baby mitotic spindle microtubules in prophase
what happens in Prometaphase
- the nuclear envelope go bye bye
- MICROTUBULES ATTACK –> invade nuclear area and the CENTROMERES get further away from each other
- chromosomes get fatter
- each of the 2 chromatids of a chromosome gain a kinetochore which attaches to microtubule
are the centrioles neccesary in prophase
no scientists discovered that they’re actually useless
Polymerize
when the spindle fibers elongate (push push push push) in anaphase
Where are the centrioles located in mitosis
in the centrosomes
job of centrioles
move the spindle fibers
Why do some of the microtubules in anaphase push push push
bc they don’t attach to kinetochores so they don’t have a reason to pull back also plays a part in the cleaveage furrow
How do the cohesins split in anaphase
an enzyme called separase cleaves them
How do the chromosomes get pulled back in
motor proteins on the kinetochores walk the chromosomes back along the microtubules while also depolymerizing the microtubule its attached to by chomping off and releasing its tubulin subunits
how do the non-kinetochore microtubules lengthen
they push push push and then when they’re next to each other they use motor proteins and ATP to walk away from another to elongate the cell
Cell Cycle Control System
a cyclically operating set of molecules in the cell that tells key events and also helps them happen
Cell Cycle check points
checkpoints in the cell checks if uits ready to go on to the next step and continue cell division
How many cell cycle checkpoints are there and what are they
`3: G1 G2 and M
What is the most important checkpoint and =why
G1 because if the cell doesn’t pass G1 it just goes back to GO and it doesn’t divide or do anything or go to the other stupid checkpoints because its not gonna waste its resources or energy because its not gonna work anyway
What happens in the G1 checkpoint
are the growth factors there is the cell big enough to go cell division are there enough nutrients
What happens at the M checkpoint
the kinetochores send signals saying that I not attached in not attached to the spindle fibers to the APC until they’re all attached and when they are APC gets active and you go into anaphase
When does the M checkpoint occur
right before anaphase
internal signals
messages from proteins and shit – mitosis cant happen if they’re not good
external signals
things outside the cell like nutrients its in or wtv cant do mitosis if not good
growth factor
protein released that tells cells to divide
