4.1 Flashcards
All ________ derive from other cells.
cells
The eukaryotic cell division cycle is __________
regulated
Eukaryotic cells divide by ________________
Mitosis
_____________is important in living organisms.
Cell death
__________cell division can lead to cancer.
Unregulated
______________plays important roles in the life cycle of an organism.
Cell division
Four main events occur in all organisms during cell division:______________, DNA replication, DNA segregation, and cytokinesis.
cell division signals
In ______________cell division __________ results in reproduction of the entire __________ organism.
prokaryotes
binary fission
single-celled
______________ in prokaryotes are usually external factors such as nutrient concentration and environmental conditions.
Cell division signals
Most prokaryotes have_________ chromosome, a single molecule of ______ . Often__________ but folded.
One
DNA
Circular
In prokaryotes, DNA replication starts/ originates at the_____________
ori region.
In prokaryotes, DNA replication ends/ terminus at the
ter region.
In prokaryotes, replication occurs as the DNA moves through a
protein replication complex.
When replication is complete in prokaryotes_____________ move to _________ end of cell
ori regions
Opposite
In prokaryotes, protein fibers form a_______ during cytokinesis.
ring
In prokaryotes, new cell wall materials are synthesized, resulting in the
separation of the two cells.
In eukaryotes,_______________ conditions are often suitable for cell division.
Internal environmental conditions
___________________in multicellular eukaryotes are related to the needs of the entire organism.
Cell division signals
DNA replication in eukaryotes starts at
many origins
Mitosis
Mitosis separates the newly replicated chromosomes into two new nuclei in eukaryotes.
One copy of each chromosome
One copy of each chromosome ends up in each daughter cell during eukaryotic cell division.
Cytokinesis
Cytokinesis proceeds differently in animal and plant cells.
cell cycle
The phases a cell passes through to produce daughter cells by cell division is called the cell cycle.
The cell cycle includes
The cell cycle includes interphase and M phase.
The nucleus
The nucleus is visible during interphase.
Interphase has three subphases
Interphase has three subphases: G1, S, and G2.
During G1 phase
During G1 phase, chromosomes are single (unreplicated).
Some cells enter a resting phase
Some cells enter a resting phase called G0.
G1 ends at the
G1 ends at the G1-to-S transition.
During S phase
During S phase, DNA replicates.
Sister chromatids
Sister chromatids remain together until mitosis.
During G2 phase
During G2 phase, the cell prepares for mitosis.
M phase includes
M phase includes mitosis and cytokinesis.
Specific signals
Specific signals trigger the transition from one phase of the cell cycle to another.
Progress through the cell cycle
Progress through the cell cycle is controlled by cyclin-dependent kinases (CDKs).
Protein kinases
Protein kinases catalyze transfer of a phosphate group from ATP to a protein.
This transfer of a phosphate group
This transfer of a phosphate group is called phosphorylation.
CDK is activated
CDK is activated by binding to cyclin.
Binding to cyclin
Binding to cyclin alters CDK’s shape and exposes the active site.
The restriction point (R)
The restriction point (R) is a control point at the G1-to-S transition.
Certain proteins
Certain proteins normally inhibit the cell cycle at the R point.
When these inhibitory proteins are phosphorylated
When these inhibitory proteins are phosphorylated by cyclin-CDK, they become inactive.
Progress through the cell cycle depends
Progress through the cell cycle depends on CDKs.
CDKs can be regulated
CDKs can be regulated by the presence or absence of cyclins.
Cyclins are present cyclically
Cyclins are present cyclically: they are made only at certain times in the cell cycle.
Cyclin-CDKs act at cell cycle checkpoints
Cyclin-CDKs act at cell cycle checkpoints to regulate progress through the cell cycle.
Growth factors
Growth factors are external signals that can regulate the cell cycle.
Growth factors activate cyclin synthesis
Growth factors activate cyclin synthesis, thereby activating CDKs and the cell cycle.
DNA molecules
DNA molecules are bound to proteins to form chromatin.
Cohesins
Proteins that hold sister chromatids together during G2.
Centromere
The region where cohesin is removed during mitosis.
Histones
Proteins with positive charges that pack and organize DNA molecules.
Phosphate groups
Negative groups of DNA that are attracted by histones.
Nucleosomes
Beadlike units formed by interactions between DNA and histones.
Compact
The state of chromosomes during mitosis, making them inaccessible to replication and transcription factors.
Segregation
The process defined by mitosis, while cytokinesis is the division of cytoplasm.
Nuclei
The two genetically identical products of mitosis.
Prometaphase
The phase of mitosis that follows prophase.
Spindle
The structure that moves sister chromatids apart during mitosis.
Centrosome
The structure that determines the orientation of the spindle.
Centrioles
The two components that make up a centrosome.
Plane
The position determined by centrosomes at which an animal cell will divide.
S phase
The phase during which centrosomes replicate.
Opposite ends
The location to which centrosomes move during prophase.
Poles
The “poles” toward which chromosomes move, identified by centrosomes.
Kinetochores
Structures that develop on each chromatid late in prophase.
Prometaphase
The phase during which the nuclear envelope breaks down and the spindle forms.
Metaphase
The phase during which chromosomes line up at the metaphase plate.
Anaphase
The phase defined by the separation of chromatids.
M phase cyclin-Cdk
The complex that activates the anaphase-promoting complex (APC).
Separase
The enzyme activated by APC that hydrolyzes cohesin.
Spindle assembly checkpoint
The checkpoint that occurs at the end of metaphase to ensure proper chromosome attachment.
Daughter chromosomes
The name given to chromatids after separation.
Centromere
The structure shared by chromatids.
Chromosomes
Structures that have their own centromere.
Motor proteins
Kinesins and dynein found in kinetochores.
Microtubules
Kinetochore structures that shorten, drawing chromosomes toward poles.
Pinches
The action of the cell membrane during cytokinesis in animal cells.
Contractile ring
A ring of microfilaments of actin and myosin that forms in animal cells during cytokinesis.
Vesicles
Structures that appear along the plane of cell division in plant cells from the Golgi apparatus.
Cell membrane
The new structure formed by the fusion of vesicles in plant cells.
Cell plate
The beginning of the new cell wall formed from vesicle contents in plant cells.
Necrosis
The process that occurs when a cell is damaged or starved of oxygen or nutrients.
Swells
The action of a cell during necrosis before bursting.
Apoptosis
Programmed cell death.
Neighbors
The cells from which a cell detaches during apoptosis.
Nucleosomes
The structures cut by enzymes during apoptosis.
Blebs
Membranous lobes formed during apoptosis.
Division
The process that cancer cells lose control over.
Tumors
Large masses of cells formed by almost continuous division of cancer cells.
Benign tumors
Tumors that grow slowly and remain localized.
Malignant tumors
Tumors that do not resemble the parent tissue and can invade surrounding tissue.
Metastasis
The process when cancer cells invade surrounding tissue and travel through the bloodstream or lymph system.
Growth factors
Positive regulators that stimulate cell division.
Retinoblastoma protein (RB)
A negative regulator that inhibits the cell cycle.
Eukaryotic cell division cycle is ______________
regulated
Process by which eukaryotic cells divide
mitosis
Role of cell death in living organisms
important
Consequence of unregulated cell division
cancer
Aspect of an organism’s life cycle where cell division is important
life cycle
Four main events in cell division
cell division signals, DNA replication, DNA segregation, cytokinesis
Result of cell division (binary fission) in prokaryotes
reproduction
Type of factors that are usually cell division signals in prokaryotes
external
Number of chromosomes in most prokaryotes
one
Region where DNA replication starts in prokaryotes
ori
Region where DNA replication ends in prokaryotes
ter
Structure through which DNA moves during replication in prokaryotes
protein replication complex
Movement of ori regions in prokaryotes when replication is complete
opposite ends of the cell
What happens to the cell membrane during cytokinesis in prokaryotes
pinches in
Type of fibers that form a ring during cytokinesis in prokaryotes
protein
Environmental conditions in eukaryotes suitable for cell division
internal
Relation of cell division signals in multicellular eukaryotes
needs of the entire organism
Number of chromosomes in eukaryotes
more than one
Where DNA replication starts on the chromosome in eukaryotes
many origins
Part of the cell cycle where DNA replication is limited in eukaryotes
one part
Process that separates newly replicated chromosomes into two new nuclei in eukaryotes
Mitosis
Number of copies of each chromosome in daughter cells during eukaryotic cell division
one
Type of cells where cytokinesis proceeds differently compared to animal cells
plant
Term describing phases a cell passes through to produce daughter cells
cell cycle
Other main phase of the cell cycle besides interphase
M phase
Cellular structure visible during interphase
nucleus
Three subphases of interphase
G1, S, G2
State of chromosomes during the G1 phase
unreplicated
Resting phase that some cells enter
G0
Point at which the G1 phase ends
G1-to-S transition
Phase during which DNA replication occurs
S
Structures that remain together until mitosis
sister chromatids
Process for which the cell prepares during the G2 phase
mitosis
Two processes included in the M phase
mitosis and cytokinesis
Type of signals that trigger transition from one phase of the cell cycle to another
specific signals
Type of molecules that control progress through the cell cycle
cyclin-dependent kinases (CDKs)
What protein kinase catalyzes the transfer of from ATP to a protein
phosphate group
What the transfer of a phosphate group is called
phosphorylation
Molecule to which CDK is activated by binding
cyclin
Aspect of CDK altered by cyclin binding
shape
Control point at the G1-to-S transition
restriction point (R)
Normal action of certain proteins at the R point
inhibit
Effect on inhibitory proteins when phosphorylated by cyclin-CDK
become inactive
Molecules on which progress through the cell cycle depends
CDKs
How CDKs can be regulated
by the presence or absence of cyclins
Presence of cyclins in the cell cycle
cyclically
external signals
growth factors
cyclin synthesis
What do growth factors activate, thereby activating CDKs and the cell cycle?
chromatin
To form what structure are DNA molecules bound to proteins?
cohesins
What proteins hold sister chromatids together during G2?
centromere
Where does cohesin remain during mitosis after most of it is removed?
histones
By what proteins are DNA molecules ‘packed’ and organized?
positive
What charges do histones have that attract the negative phosphate groups of DNA?
nucleosomes
What beadlike units are formed by the interaction of DNA and histones?
mitosis
During which phase are chromosomes so compact that they are inaccessible to replication and transcription factors?
mitosis
What process is defined by chromosome segregation?
cytokinesis
What is the division of cytoplasm called?
two nuclei
What does mitosis lead to the production of that are genetically identical?
five subdivisions of mitosis
What are the five subdivisions of mitosis?
spindle
What structure moves sister chromatids apart during mitosis?
centrosome
What cellular structure determines the orientation of the spindle?
two centrioles
What two structures make up the centrosome?
plane
What does the position of the centrosomes determine in an animal cell division?
S
During which phase do centrosomes replicate?
prophase
During which phase do centrosomes move to opposite ends of the nuclear envelope?
poles
What do centrosomes identify toward which chromosomes move?
late in prophase
When do kinetochores develop on each chromatid?
prometaphase
During which phase does the nuclear envelope break down and the spindle form?
metaphase
During which phase do chromosomes line up at the metaphase plate?
Anaphase
What is the term for the separation of chromatids?
M phase cyclin-Cdk
What controls the separation of sister chromatids during anaphase?
anaphase-promoting complex (APC)
What complex does M phase cyclin-Cdk activate?
separase
What does APC activate that then hydrolyzes cohesin?
spindle assembly
What type of checkpoint occurs at the end of metaphase?
APC
What does the spindle assembly checkpoint inhibit if a chromosome is not attached properly?
daughter chromosomes
What are chromatids called after separation?
centromere
What structure do chromatids share?
Chromosomes
What has its own centromere?
kinesins and cytoplasmic dynein
What motor proteins do kinetochores have?
kinetochore microtubules
What shortens to draw chromosomes toward poles?
pinches in
What happens to the cell membrane in animal cells during cytokinesis?
contractile
What type of ring forms in animal cells during cytokinesis?
Golgi apparatus
From where do vesicles appear along the plane of cell division in plant cells?
new cell membrane
What do these vesicles fuse to form in plant cells?
cell plate
What does the content of these vesicles form in plant cells?
Necrosis
What type of cell death occurs when a cell is damaged or starved of oxygen or nutrients?
swells and bursts
What happens to the cell during necrosis?
Apoptosis
What is the term for programmed cell death?
detaches
What happens to the cell’s connection to its neighbors during apoptosis?
chromatin
What is digested by enzymes that cut DNA between nucleosomes during apoptosis?
blebs
What membranous lobes does the cell form during apoptosis?
cell division
What do cancer cells lose control over?
tumors
What do cancer cells form as they divide almost continuously?
Benign
What type of tumors grow slowly and remain localized?
Malignant
What type of tumors do not resemble the parent tissue and can invade surrounding tissue?
Metastasis
What is the process by which cancer cells invade surrounding tissue and travel through the bloodstream or lymph system?
Metastasis
What type of positive regulators stimulate cell division?
growth factors
What type of positive regulators stimulate cell division?
retinoblastoma protein (RB)
What negative regulator inhibits the cell cycle?
