Mitosis Flashcards
How does prokaryotix cell division occur
binary fission- cell divides into two halves
how long does is take a bacteria cell to divide
20 minutes
where does replication of DNA begin in prokaryotes and how does it proceed
the origin, procees bi-directionally
how many genomes end up in each prokaryotic daughter cell
one genome
the two repleicated origins in prokaryotic cell migrate to ___ of the cell while replication continues
the poles (ends)
Once replication in a prokaryotic cell is complete, the _____ _______ grows inward and what happens?
plasma membrane; a new cell wall is synthesized
what is catenation?
rings of DNA seperated into 2 seperate copies
where does eukaryotic cells store genetic information
in chromosomes
eukaryotic chromosome count ranges from what
10-50 chromosomes
how many chromosome do humans have?
46 chromosomes, 23 pairs
Why are the 23 pairs considered “nearly identical”
they have the same gene, same order, but dna sequence may be slightly different
the cell cycle is divided into three parts, name them
cell growth and activity
nuclear division (mitosis)
divison of the cytoplasm (cytokinesis)
what is the order of the cell cycle?
G1 (growth 1), S phase, G2 (growth 2), mitosis, cytokinesis
what is the difference between mitosis and meiosis
mitosis is a growth process, meiosis is a process of sexual reproduction
What happens in mitosis?
replicated DNA is divided equally and precisely, generating daughter cells
What are daughter cells
exact copies of parent cells
What happens in meiosis?
daughter nuclei with half the number of chromosomes are produced from the parental nucleus (arrangement of genes is different than the parent cell)
how is DNA seperated in mitosis?
mitotic cytoskeleton (microtubules)
heredity information within the nucleus is distributed how
among individual linear DNA molecules
what can happen when DNA combine with protein
stabilizes DNA molecule and can help pack DNA during cell division and influences the expression of indiviual genes
each chromosome is composed of…
one DNA molecule and associated proteins
what is a chromatin?
DNA + protein
how are two sister chromatids joined together?
by a centromere
what protein packages DNA to fit in nucleus
histone proteins
in a ______, an eight-protein _________ _____ particle forms when DNA winds areound histones H2A, H2B, H3, H4
nucleosome, nucleosome core
nucleosomes and linkers appear as….
beads on a string
the solenoid model predicts what
the nucleosomes spiral helically with about 6 nucleosomes per turn
Chromatin packing continues at higher levels with….
euchromation and heterochromatin
difference between euchromatin and heterochromatin?
euchromatin is loosely packed genes that are highly expressed and heterchromatin are densely packed genes that are less expressed
replicated chromosomes are called
sister chromatids
sister chromatids are held together by
sister chromatid cohesion
cohesion is a
protein complex
what is the equal distribution of chromosomes into each daughter nuclei called
chromosome segregation
what is ploidy
the number of chromosomes sets in a cell or species
some microorganismz have only one copy of each type of chromosome in nuclei they are…
haploid, n
eukaryotes (most) hace two copies of each type of chromosome in nuclei, they are…
diploid, 2n
plants can have 3,4, or more complete sets of chromosomes in each cell they are…
polyploid
homologous chromosomes are
two chromosomes of each pair in a diploid cell, they have the same genes in same order in DNA
what is a karyotpye
individuals particular array of chromosomes
human sex cells are
haploid
human body cells are
diploid
homologous chromosomes are sister chromatids joined at the
centromere
what is the protocal for preparing cells for a karyotype?
- add sample to culture medium that has a stimulator for growth and division of cells, incubate at 37 degrees celsius
- stain the cells so chromosomes are distinguished
- view stained cells under microscope with digitial imaging system and take a photograph
what phase of the cell cycle is the longest and primary growth phase
Gap Phase 1 (G1)
what phase of the cell cycle replicates DNA
Synthesis (S)
what phase of the cell cycle do organelles replicate and microtubules organize
Gap Phase 2 (G2)
What phase is subdivided into 5 phases
mitosis (M)
what phase seperates the cell into 2 new cells
cytokinesis (C)
what is different about G1 than other phases
it varies in length, other phases are typically uniform in length
what phases make up interphase
G1, S phase, G2
what type of cells often go into G0 phase
neurons
what is G0 phase
a phase after G1, where cells stop dividing, may or may not re-enter cell cycle
what are the steps of mitosis
- prophase
- prometaphase
- metaphase
- anaphase
- telophase
in s phase chromosomes are
copied and held together
in G1 phase the cell makes
proteins and other molecules for S phase
in G2 phase the cell makes
proteins and other molecules needed for mitosis
how long does the cell cycle take
24 hours
how long is the cell in G1
10 hours
how long is the cell in S phase
9 hours
how long is the cell in G2
4 hours
how long is the cell in Mitosis
1 hour
how many checkpoints does the cell cycle have and where are they
3
G1/S checkpoints
G2/M checkpoint
Mitotic spindle checkpoint
cytokinesis divides
the cytoplasm
how are the stages of mitosis characterized
by location and behavior of the chromosomes
G1 to S phase is an irrevsible transition (T/F)
true
what makes microtubules
alpha and beta tubulin
the centrosome is the main ____ ___ _____ (MTOC) of animal cells and protists
microtubule organizing center
centrioles not involved in spindle formation are
duplicated and divided
asters are
radial array of microtubules in animals (not plants)
centrosomes seperate into two parts with one old and one new centriole in
early prophase
in G1 of interphase, chromosomes are
unreplicated and found in the nucleus
in G2 of interphase, chromosomes are
double at all points (contain 2 sister chromatids), found in nucleus
why don’t spindles form in plants
they dont have centrioles
what happens in prophase
spindle apparatus assembles, condensation continues, nuclear envelope starts to disintergrate, nucleolus disappears
spindle microtubules grow from centrosomes at opposite spindle poles toward center of cell in…
prometaphase
what is a kinetochore microtubule?
bind to kinetochore, connects at centromere
what does a nonkinetochore microtubule do?
overlaps each other from opposite spindle pole, crossover at spindle midpoint
what phase do kinetochore form on each sister chromatid at centromere?
prometaphase
in prometaphase chromosomes begin to move where
towards the center of cell “congression”
what happens in metaphase
spindle microtubules move chromosomes into metaphase plate, condensation gives each chromosome a characteristic shape
when does anaphase begin
when centromeres split
what happens in anaphase
cohesion proteins are removed from chromosomes and sister chromatids, (now called chromosomes) are pulled to opposite poles
what are the two forms of movement in anaphase
Anaphase A- kinetochores pulled toward poles
Anaphase B- poles move apart
What is used in Anaphase A to pull kinetochore microtubules
motor proteins at the spindle points dissesmble microtubules (depolymerization)
What is used in Anaphase B
nonkinetochore molecules enlongate cell, motor proteins walk in opposite direction (polymerization)
what happens in telophase
spindle apparatus is dissembles and chromosomes decondense, returning to extended state, nuclear envelope is formed around each set of chromosomes, RNA transcription resumes
what happens in cytokinesis
two daughter cells are formed
how are animal, protists, and fungi cells seperated?
furrow (contractile ring)
how are plant cells seperated
cell plate forms and cuts cytoplasm in two
how is the plane of cytoplasmic division determined
by the layer of microtubules that persists at former spindle midpoint (metaphase plate)
what are the 5 types of histone proteins and how many copies are there of each?
H1=1
H2A=2
H2B=2
H3=2
H4=2
