gb prefinals Flashcards
is a cycle of stages that a cell pass through to allow them to divide and produce new cells. It is sometimes referred to as “cell division cycle.”
cell cycle
The two main parts of the cell cycle are:
mitosis and interphase.
- New cells are born through the division of their “parent” cell, producing two “daughter” cells from one single “parent” cell.
Mitosis
- the longest part of the cell cycle; the phase of growth and DNA replication between mitotic cell divisions.
Interphase
10
hrs
Gap1
5-6
hrs
Synthesis
3-4
hrs
Gap2
2
hrs
Mitosis
64 mins
Prophase
8 mins
Metaphase
12 mins
Anaphase
32 mins
Telophase
2 weeks
Skin cell
4 months
Red blood cell
300-500 days
Liver cell
4-5 days
Intestine (internal lining)
16 years
Muscles & other tissues
consists of at least three distinct stages during which the cell grows, produces new organelles, replicates its DNA, and finally divides.
Interphase
In this stage, the cell gets nutrients, creates and uses proteins and other molecules, and starts the cell division process by replicating the DNA.
Interphase
Interphase is divided into three stages:
Gap 1 (G1 stage), Synthesis (S stage), and Gap 2 (G2 stage).
The purpose of interphase in all cell types is
to ready the cell for cell division, which happens in a different stage of the cell cycle.
- During this stage, the cell performs its normal functions, and grows in size. The cell replicates the necessary proteins (RNA and protein synthesis) and organelles like ribosomes and mitochondria (includes chloroplasts in the case of plants).
This allows the cell to increase its energy production and overall metabolism
Gap 1 (G1 Stage)
where the cell checks if it is ready for the next stage.
Is the cell big enough to accommodate genetic replication?
Is the environment (in the cell) suitable?
G1 checkpoint”
where the cell makes a copy of its entire set of chromosomes.
All of the cell’s resources (like energy) are dedicated to replicating the DNA. Therefore, cell functions that has no business in DNA replication is slowed.
synthesis
This process starts with the two entwined strands of DNA being “unzipped” by various proteins. Other proteins, known as polymerase enzymes, start creating new strands to pair with each half of DNA.
synthesis
Thus in this stage, the cell which has normally have a 46 chromosomes (diploid or 2n) has double the amount of chromosomes (4n).
synthesis
which is also characterized by protein production.
(Gap 2 or G2)
What happens here is the cell adds volume to the cytoplasm (increasing the size of the cell) and replicates a lot of organelles. For animal cells, mitochondria are replicated so the cell can provide more energy for the dividing cells. As for plant cells, mitochondria and chloroplasts must be replicated to provide the daughter cells with organelles capable of producing enough energy.
(Gap 2 or G2)
Organelles and structures such as centrioles and nucleolus are also duplicated for cell division.
(Gap 2 or G2)
G2 is the shortest in the whole interphase process.
(Gap 2 or G2)
Has the DNA been replicated?
Is the cell big enough?
Is the environment suitable for cell division?
(Gap 2 or G2) checkpoint
is the step in the cell cycle that the newly duplicated DNA is separated, and two new cells are formed.
Mitosis
—is important because:
For single-celled eukaryotes, this is their only way of reproduction (asexual)
For multi-celled eukaryotes, mitosis is how a single zygote develop into another organism.
Growth and development of an organism
Cell regeneration for tissue/organ repair, wound healing
Mitosis
Mitosis is important because:
For single-celled eukaryotes, this is their only way of reproduction (asexual)
For multi-celled eukaryotes, mitosis is how a single zygote develop into another organism.
Growth and development of an organism
Cell regeneration for tissue/organ repair, wound healing
The M stage is divided into
mitosis and cytokinesis.
During the prophase, the DNA is condensed. During interphase, when the DNA is replicated, it is in a loose and open form to allow enzymes to do their work on the DNA and create a new strand. However, if the DNA is in this form (chromatin), they will tangle and break if the cell will try to move it.
A. Early Prophase
During prophase, the cell’s machinery packages the DNA around special proteins, called histones, which allow it to condense into very tight packages (what do you call this form?). These tight packages of DNA can now be moved around with ease.
Centrioles start to migrate on the cell’s poles and there’s also production of early spindle fibres. The nuclear envelope starts to disappear.
A. Early Prophase
In order for the duplicated chromosomes to be split up, the microtubules have to reach them. In prometaphase, the nuclear envelope surrounding the chromosomes falls apart. This membrane was separating the DNA from the cytosol of the cell. When the nuclear envelope dissolves, the microtubules are allowed to extend from the centromeres to the chromosomes.
B. Prometaphase (Late Prophase)