Chapter 12: Mitosis Flashcards
Cells make copies of themselves via what processes
Mitosis and Cytokinesis
what the cell copies are called
daughter cells
cell divison functions
reproduction
growth and development
tissue renewal
How long can a red blood cell live before it is replaced
4 months
How long can a white blood cell live before it is replaced
1 year
How long can a skin cell live before it is replaced
2-3 weeks
How long can a colon cell live before it is replaced
4 days
How long can a nerve cell in the brain live before it is replaced
our entire life and even longer
“body cells”
somatic
have the total
number of chromosomes of the adult
organism
somatic
“Sex cells”
germ
reproductive cells, have
half the total number of chromosomes of the
adult organism.
germ
long, thin DNA fiber and proteins (only found when cell is not replicating DNA
chromatin
condensed form of a DNA molecule with its attached proteins (observed under microscope during replication)
chromosome
Place where chromatids attach
centromere
how many chromosomes do humans have?
46
how many chromosomes do fruit flies have?
8
how do eukaryotic cells reproduce or copy?
mitosis
how do prokaryotic cells reproduce or copy?
binary fission
steps of binary fission
on notes
Longest part of the cycle; cell
increases mass, duplicates DNA. The cell can
stop in interphase if environmental conditions
deteriorate.
Interphase
what happens during interphase?
cell increases in mass
duplicates DNA
parts of Interphase
Gap 1 (G1)
DNA Synthesis (S)
Gap 2 (G2)
what does Gap 1 (G1) do
cell growth before DNA replication
what does Synthesis (S) do
DNA replication
what does Gap 2 (G2) do?
cell prepares for division
five parts of mitosis
- Prophase
- Prometaphase
- Metaphase
- Anaphase
- Telophase
what happens in prophase?
- Chromosomes begin condensing and become
visible - The nucleoli disappear
- microtubules begin to form and become visible
and Extend from each replicated centrosome
what happens in prometaphase?
- The nuclear envelope begins to break down
- Some microtubules attach to the kinetochore
- Some microtubules attach to each other from
opposite poles within the cell and extend and force the cell to enlarge
A 3-layer protein structure (disk) that is located at
or near the centromere of each chromosome
kinetochore
The area where microtubules (kinetochore fibers)
attach to the chromosome
kinetochore
Region of the chromosome where sister chromatids are attached in the condensed chromosome
Centromere
A microtubule organizing and production center
centrosome
9 pairs of triplet microtubules found within the centrosome of animal cells
centriole
what happens at metaphase?
- Centrosomes at opposite poles (ends) of cell
- Chromosomes are moved to the center of
the cell by microtubules and are line up
along the metaphase plate
what is the cell’s equator called?
metaphase plate
what happens in anaphase
- The 2 chromatids physically separate when the
centromere divides. - Each daughter chromosome is hen “pulled” to
opposite ends of the cell by a shortening of the
microtubules attached to chromatids - Other microtubules (attached to each other from o
opposite poles) increase in length which increases
the cell size
what mechanism is used by the Motor proteins that “walk” the chromosomes along the kinetochore fibers to opposite poles as these fibers shorten from the
kinetochore end
“Pac-man” mechanism
division of one nucleus into 2 genetically identical nuclei)
mitosis
what happens in telophase?
*The chromosomes at the opposite ends uncoil
* A new nuclear envelope forms
* The spindle fibers break down and disappear.
* Mitosis is complete.
brief synopsis of cytokinesis
The cytoplasm is cleaved in half and the
new cell membrane grows to enclose both
cells (the original cell and the daughter cell).
[different in plant and animal cells]
how does cytokinesis happen in plant cells?
A double membrane cell plate formed by vessicles
(produced by Golgi Apparatus)
–> Between the membrane, the cell wall will form
how does cytokinesis happen in animal cells?
Process known as cleavage
– A cleavage furrow is formed
* Furrow deepens until
cell is pinched in two
Made of a contractile ring of actin and myosin
proteins
cleavage furrow
The frequency of cell division varies with
the type of cells
what cells in a mature human do not divide at all?
nerve and muscle cells
3 main checkpoints of the Cell-Cycle Control System
G1(both during interphase)
G2
M Phase (during Mitosis)
what regulates the cycle
Rhythmic fluctuations in the concentration of
particular molecules
Some of these regulatory molecules are what
protein kinases
enzymes which activate proteins by phosphorylating them
Protein kinases
The activity of some kinases are dependent on
regulatory proteins (cyclins) which attach to the
kinases and activate them making them what
cyclin-dependent kinases (Cdks)
Mitosis promoting factor triggers the cell’s passage
through the G2 checkpoint into the Mitosis Phase
MPF
also destroys its own cyclin which deactivates
itself
MPF
remains intact to then interact with
new cyclin if available
CDK portion
A signal that delays anaphase originates at the what
kinetochores that aren’t yet attached to microtubules
how does the anaphase Promoting Complex (APC) become active?
when all of the kinetochores have attached to the microtubules
is a protein released by certain body cells that stimulates other cells to divide
a growth factor
is made by platelet blood cells (important in wound healing) is required for division of fibroblasts (cells that secrete fibers in connective tissue)
platelet-derived growth factor
(PDGF)
what does the Binding of PDGF to its specific receptors (T-K receptors) do?
triggers a signal transduction pathway
that ends in cell division
When the cell population reaches a certain
density, the amount of required growth factors
and nutrients available to each cell becomes
insufficient to allow continued cell growth
Density-Dependent Inhibition of Cell Division
what happens bc of Density-Dependent Inhibition of Cell Division
crowed cells stop dividing
(extracellular matrix of a tissue)
substratum
In order to divide the cells must be attached to what?
substratum
When abnormal cells are not destroyed, they may
proliferate to form a what?
tumor
an unregulated growing mass of cells within otherwise normal tissue
tumor
If the cells remain at this original site, the mass is
called a
benign tumor
is invasive enough to impair normal function of 1 or more organs of the body.
malignant tumor
Only an individual with a what is said
to have cancer
malignant tumor
properties of a malignant tumor
- Abnormal cell cycle; excessive proliferation
- May have unusual number of chromosomes
- Lost attachments to neighboring cells and
extracellular matrix - Angiogenesis
stimulation of new blood vessels
angiogenesis
This spread of cancer beyond their original sites is
called
metastasis
If a tumor metastasizes it is usually treated with what?
radiation and chemotherapy
cell suicide controlled by the p53
gene. This is done after the cell has performed
its function or if the cell becomes altered in
ways such as infection or cancerous
transformation that might pose a threat to the
whole body.
apoptosis
In cancer cells the what has been tampered with
or shut down.
p53
normally induces apoptosis if a cell’s DNA gets damaged.
p53
