CELL CYCLE Flashcards
Is the process by which a single cell divides into two or more daughter cells
Cell division
Cell division can occur through two main mechanisms: ________ and ________
Mitosis and Meiosis
is the process by which a single cell divides into two identical daughter cells
Mitosis
during this phase, it grows, replicates, its chromosomes and prepares for cell division
Interphase
Interphase is composed of
G1 Phase (cell growth)
S phase (DNA synthesis)
G2 Phase (cell growth)
also called the first gap phase
G1 Phase
cell grows physically larger in this phase, copies organelles and makes the molecular building blocks it will need in later steps
G1 Phase
-The cell synthesizes a complete copy of the dna in its nucleus
-also duplicates a microtubule-organizing structure called the centrosome
S Phase
the centrosomes help separate DNA during what phase
M phase
the cell grows more, makes proteins and organelles and begins to reorganize its contents in preparation for mitosis
G2 PHASE
_____phase ends when mitosis begins
G2 Phase
M PHASE (PMAT)
Prophase
Metaphase
Anaphase
Telophase
the chromatin in the nucleus condenses into visible chromosomes
Prophase
responsible for organizing spindle fibers
centrosome
the nuclear envelope breaks down allowing the spindle fibers to attach to the chromosomes
Prophase
in this phase, the chromosomes line up along three equator of the cell called the _________
Metaphase
Metaphase Plate
during this stage the sister chromatids of each replicated chromosome separate are pulled towards opposite poles of the cell by the spindle fibers 
Anaphase
during this phase, the chromosomes reach the opposite poles of the cell, and the nuclear envelope begins to reform around each set of chromosomes 
Telophase
The spindle fiber is assembled, and the cell begins to prepare for ________
Cytokinesis
Is the process by which the cell divides into two daughters cells
Cytokinesis
In animal cells a _______ and _________ forms around the cell contracting and pinching the cell membrane until the cell is divided into two separate cells
Contractile ring of actin
Myosin Filaments
cells in _____ phase are not actively preparing to divide. The cell is in a in a quiescent(inactive) stage that occurs when cells exit the cell cycle
G0 Phase
what are the cell cycle checkpoints
G1 checkpoint
G2 Checkpoint
M checkpoint
What ate the things to consider in G1 checkpoint?
- Size
- Nutrients
- Molecular Signals
- Dna Integrity
- Dna replication
The cell examines whether all the sister chromatids are correctly attached to the spindle microtubules
M Checkpoint
True or False. The cycle will not proceed until all the chromosomes are firmly attached to at least two spindle fibers from opposite poles of the cell.
True
_______ and ________ cues trigger signaling pathways inside the cell that activate or inactivate a set of core proteins that move the cell cycle forward
Internal and External cues
promote progress of the cell to the next phase
Positive Regulation
Halts the cycle
Negative Regulation
are named such because they undergo a constant cycle of synthesis and degradation during cell division
POSITIVE REGULATORS
Cyclins
when cyclones are synthesize, they act as an activating protein, and find CDK forming a
Cyclin Cdk complex
CDK
Cyclin Dependent Kinases
Is an enzyme that adds negatively charged phosphate, groups to other molecules in the process called_________
Cyclin dependent protein Kinase (CDKs)
Phosphorylation
Through this process, CDK signal the cell that it is ready to pass into the next stage of the cell cycle
Phosphorylation
Mechanism of cyclin action
- Cyclin binds and activates CDK
- Cdk activates target protein to regulate cell cycle
- cyclin destroyed
are a group of tumor, suppressor proteins, common in many cells
NEGATIVE REGULATORS
Retinoblastoma Proteins
The ______ and ______ designations referred to the functional molecular masses of the proteins in kilodaltons
53 and 21
How important are the control points in the cell cycle for the growth and development of an organism?
it allows certain genes to check for problems and hold the cycle for repairs if something goes wrong
explain what would happen if there were no control points in the cell cycle
cells divide without order and accumulate genetic errors that can lead to a cancerous tumor
how long does the cell cycle take for humans?
24 hours
True or false different cells take different length of time to complete the cell cycle
true
Salivation begins in metaphase when the chromosomes duplicate true or false
false
Mitosis occurs in somatic or body cells, give examples
Liver heart skin stomach
how many chromosomes do humans have?
46
The total number of chromosomes in the somatic cell
Diploid Number
diploid means_________ and is written as _______
2 sets
2n
This is the process by which a single cell divides into four daughters house, each with half the number of chromosomes of the parent cell
Meiosis
Meiosis is critical for sexual reproduction as it allows for the production of _______
gametes
For males, meiosis produces_______
4 sperm
For females, meiosis produces
1 egg
The other 3 cells are called ______, they give up their cytoplasm to nourish the 1 good egg
Polar bodies
If humans deployed number is 46. What is its haploid number?
23
Daploid number of a dog is 78, what is its haploid number
39
when does meiosis occur in males?
Beginning at puberty
when does meiosis occur in females?
Before birth
Human have 46 chromosomes in their somatic cells, but_________ chromosomes in their sex cells
23 (half ng chromosome number)
Processed by which an egg and sperm unite
Fertilization
Fertilized egg is called
zygote
organism in early stage of development
Embryo
__________are chromosomes with genes for the same trait, arranged in the same order
Homologous Chromosomes
gene form for each variation of a trait of an organism
Allele
PHASES OF MEIOSIS
PMAT I
PMAT II
in this phase, each pair of homologous chromosomes to form a_______
Prophase I
Tetrad
the homologous chromosomes come together, and the four chromatids overlap
Tetrad
The exchange of genetic material by non-sister chromatids
Crossing Over
shortest phase
Metaphase I
occurs where pairs of homologous lineup independently of other pairs, orientation toward the poles
Independent Assortment
- spindle fibers attached to the centromeres of each pair
- centromeres do not split like they do in mitosis
Anaphase I
- spindle fibers break down
- chromosomes uncoil
- Cytoplasm Devides
Telophase I
The chromosomes condensed and then nuclear envelope breaks down, crossing over occurs
Prophase I
Pairs of homologous chromosomes move to the equator of the cell
Metaphase I
homologous chromosomes move to the opposite poles of the cell
Anaphase I
chromosomes gather at the polls of the cells. the cytoplasm divides
Telophase I
A new spindle forms around the chromosomes
Prophase II
chromosomes lineup at the equator
Metaphase II
Centromeres divide. chromatids move to the opposite poles of the cell
Anaphase II
nuclear envelope forms around each set of chromosomes, the cytoplasm divides
Telophase II