bio Flashcards
(63 cards)
What is the genetic material located inside the chromosome in the nucleus of the cell?
Deoxyribonucleic acid or DNA
Proteins called histones wrap DNA into structures called?
Nucleosomes
Nucleosomes which then fold further into what?
Chromosomes
Two identical halves of a replicated chromosome after the Synthesis phase or S phase of the cell cycle
Chromatids
the attachment points of the 2 chromatids of a chromosome
Centromere
Upper arm of the chromosome which is usually shorter
P arm
lower arms of the chromosome which is usually longer
Q arm
This is the long growth phase between cell divisions. Here, chromosomes are long and relaxed. It’s during this time a key event happens: chromosomes replicate, basically creating a copy of themselves.
Interphase
This is when the cell physically divides. Chromosomes condense and thicken, making them easier to distribute into the new daughter cells.
Mitotic phase ( Cell Division )
Interphase is the interval between two cell divisions. During this stage, the cell is not dividing; it obtains nutrients and metabolizes, grows, replicates its DNA in preparation for mitosis. The interphase is divided into three sub-stages, namely:
- First gap period or G1
- Synthesis stage or S phase
- Second gap period or G2
where
cell grows initially
synthesis of protein and ribonucleic acid or RNA occurs
mitochondria increase in number
First gap period or G1
where”
DNA are synthesized thus replicating the chromosomes in preparation for the next cell division.
Synthesis stage or S phase
where:
cell grows rapidly
cell prepares for the actual cell division
Second Gap period or G2
In eukaryotic cells, these types of cell division occur
Mitosis and Meisosis
Mitosis happens in four main stages. What are they?
prophase, metaphase, anaphase, and telophase
The repeated coiling of chromosomes occurs resulted to its thicker and shorter structure. These are made up of two sister chromatids that are identical to each because of the replication of DNA during the S phase.
The two chromatids are still attached at the centromere.
The nuclear membrane breaks down.
Prophase
Chromosomes align at the equatorial plane.
Each spindle fiber from both centrosomes connects to each chromosome through its kinetochore.
Metaphase
Spindle fibers begin to contract and become shorter. Continued contraction causes the separation of the genetically identical sister chromatids.
Centromeres divide.
The single chromatids move towards the opposite poles.
Anaphase
The chromosomes are now at the opposing poles of the spindle.
The microtubules disappear.
Two sets of chromosomes are surrounded by new nuclear membranes, completing the nuclear division process known as karyokinesis.
Cytoplasmic division called cytokinesis occurs concurrently, splitting the cell into two.
Telophase
t involves the physical separation of the cytoplasm. A contractile ring composed of actin and myosin microfilaments forms, constricting the cell and creating a structure resembling an hourglass.
A cleavage furrow forms, ultimately separating the two daughter cells,
each with the same number of chromosomes as the parent cell.
Cytokinesis
his is the kickoff stage where chromosomes condense and become visible
Leptotene
Here, homologous chromosomes (matching pairs) start to pair up with each other, a process called SYNAPSIS.
Zygotene
During this stage, the synapsis is complete, and homologous chromosomes can exchange genetic material through a process called crossing over.
Pachytene
The homologous chromosomes begin to separate slightly, but they remain connected at the points of crossing over, forming X-shaped structures called chiasmata.
Diplotene
