chapter 11 Flashcards
cell division
what are reasons for cell division
reproduction
growth and development
tissue renewal
what is the product of binary fission
produces 2 identical daughter cells
what is the product of mitosis
produces 2 identical daughter cells
what types of cells use mitosis
somatic cells
what types of cells use binary fission
amoeba and bacteria
what types of cells use meiosis
germ cells
sperm/egg
what is the product of meiosis
produces 4 identical daughter cells
when is DNA organized uncondensed
when genes are being transcribed or expressed
when is DNA condensed
when genes are inaccessible during cellular division (chromosomes)
what is the centromere
where two sister chromatids are attached
how are sister chromosomes attached
cohesins- complex of adhesive proteins
how many chromosomes are sister cells composed of
1
how do chromosomes divide
a single chromosome replicates and then the sister cell divides into 2 identical daughter cells
what are the 5 steps of mitosis
prophase prometaphase metaphase anaphase telophase/cytokinesis
what occurs during prophase
chromatin condenses
mitotic spindle forms
centrosomes start to move
what occurs during prometaphase
nuclear envelope fragments
microtubules attach to chromatids or those of the opposite spindle
what occurs during metaphase
chromosomes convene on metaphase plate
what occurs during anaphse
sister chromatids separate
microtubules shorten
what occurs during telophase/cytokinesis
nuclear envelope reforms
cytoplasm divides
two daughter cells form
what is the longest phase
metaphase
what is the shortest phase
anaphase
whats the difference between mitosis and cytokinesis
mitosis is division of the nucleus
cytokinesis is division of cytoplasm
mitotic phase
mitosis and cytokinesis occur
what is binary fission
asexual reproduction
how often do cancer cells divide
uncontrollably
what was the longest phase of the cell cycle
G1
DNA duplication is part of mitosis.
false
how often do muscle/nerve cells divide
they don’t divide
how often do liver cells divide
they can divide, but only do when needed
how often do skin cells divide
frequently
what are the steps that occur during binary fission
- chromosomes replicate
- origin of replication is copied and one end moves towards the other
- the cell separates
- plasma membrane and new cell wall grow
what does the eukaryotic cell cycle display
timing and rate of cell division in plants and animals is crucial to normal growth, development, and maintence
cell cycle control system
cyclically operating set of molecules in the cell that triggers and coordinates events in the cell cycle
(“stop” and “go” signals)
what does the M checkpoint ask?
are all chromosomes attached to the spindle?
what does the G1 checkpoint ask?
is DNA damaged?
what does the G2 checkpoint ask?
is all DNA replicated?
what is the most important checkpoint in mammalian cells?
G1
what will occur if a cell receives a “yes” at the G1 checkpoint
it will enter G1, S, G2, M and divide
what will occur if a cell receives a “no” at the G1 checkpoint
it will go the the undividing G0 state
what phase are most cells in the human body located
G0
why is the M checkpoint so important
It makes sure that cells do not end up with missing or extra chromosomes
what is the cell cycle clock
two types of regulator molecules control the pace of the cycle
what are protein kinases
enzymes that activate or inactivate other protein molecules by phosphorylating them
what are cyclins
proteins that activate cyclin-dependent kinases (Cdks)
what is the M phase promoting factor
cyclin-Cdk complex activity
MPF functions to
- trigger cells past the G2 checkpoint and into M phase
- phosphorylating a wide range of proteins
Whats the G1 phase
the cell degrades cyclin and recycles Cdk molecule
What is the S phase - G phase
synthesis of cyclin and is prevented from degradation
what occurs at the end of G2
Cdk and cyclin combine to form MPF
when enough is produces, it moves to mitosis
what product is released at the end of anaphase in mitosis
Cdk
