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DNA
DNA molecule is made up of DNA nucleotides make nucleic acid. it is made up of two strands that are wrapped around in helical manner by hydrogen bonds.
It carries genetic information essential for the growth, development, and reproduction of all living organisms.
it is linear in eukaryotes, wrapped around histones ( nucleosome ) and compressed even further into (chromatins ).
chromosomes
structures made up of 2 sister chromatids. total 46 chromosomes in a cell .
each chromatid is made up of a DNA molecule.
Before nuclear division the DNA replicates by semi conservative replication and is then condensed into chromosomes 1. compact 2. fat 3. condensed
1 chromosome = 2 chromatids / 2 DNA molecule . total 92 DNA molecules .
during which phases is our cell diploid
G1 phase, s phase.
During which phases is cell haploid
by the end of S phase, G2 phase and M phase.
describe the G1 phase
the cell grows by taking in water through osmosis and increasing its protoplasm
It becomes metabolically active
RNA synthesis for proteins
synthesis of proteins, fats and enzymes
Describe the S phase (synthesis phase )
DNA synthesis occurs
DNA is replicated to make daughter strands by semi conservative replication
DNA molecules go from 46 chromatins to 92 Chromatids
Describe G2 phase
After DNA synthesis it is condensed into visible chromosomes
faulty DNA is repaired ( mutations )
If it cannot be repaired, it must get killed by WBC
tubulin ( proteins ) synthesis occur
microtubules
Made up of dimers. Dimer is made of proteins tubulin ( alpha and beta ) . The dimers then condense together end to end to form long hollow tube lliek structure that make microtubules.
microtubule make. centrosome that is made of two centrioles perpendicular to each other . spindle fibers.
interphase
interphase is the stage of the cell cycle where the cell prepares for division, consisting of G1, S, and G2 phases.
kinetochores
Protein complexes that assemble on the centromere of chromosomes during cell division. They play a crucial role in the movement of chromosomes by attaching to spindle fibers and ensuring proper segregation of chromosomes into daughter cells when they are shortened .
centromere
The region of a chromosome where the two sister chromatids are joined together. It is the site where kinetochores form during cell division, facilitating the separation of chromatids.
spindle fibers
Structures made of microtubules that arise from the centrosome and attach to kinetochores. They help in the movement of chromosomes during cell division by pulling sister chromatids apart.
chromatid
One half of a replicated chromosome. Each chromosome consists of two sister chromatids joined at the centromere before they are separated during cell division.
centrosome
An organelle that serves as the main microtubule organizing center of the cell. It is critical in the formation of the spindle apparatus during mitosis and meiosis.
Importance of mitosis
Importance of mitosis
Mitosis is crucial for growth, tissue repair, and asexual reproduction, ensuring that each daughter cell inherits an identical set of chromosomes.
prophase
In prophase, chromosomes condense and become visible, the nuclear envelope and nucleolus disappear, and centrosomes move to opposite poles while spindle fibers begin to form.
Metaphase
In metaphase, chromosomes align at the cell's equatorial plane. Spindle fibers originating from the centrosomes attach to kinetochores of the chromosomes from either sides
Anaphase
During anaphase, centromeres split into two the sister chromatids are pulled apart toward opposite poles of the cell as spindle fibers shorten, ensuring each new cell will receive an identical set of chromosomes.
Telophase
In telophase, the nuclear envelope starts to reform around each set of chromosomes, nucleolus reappear and the chromosomes begin to decondense back into chromatin.
Cytokinesis
Cytokinesis is the process that divides the cytoplasm of a parental cell into two daughter cells by splitting from middle, usually occurring immediately after mitosis.
Telomers
Telomere is the repetitive sequence of DNA at the end of a chromosome that protects genesfrom the chromosome shortening that happens at each cell division.
HOW TO PREVENT THE LOSS OF GENES
Add extra nucleotides at each end of the DNA molecule telomeres so this way the DNA polymerase stops somewhere in the telomere region and not on the Vital Region of the DNA so the important DNA are hence protected But the telomeres will shorten every time the DNA replicates so add telomere length every time the DNA replicates by the help of enzyme telomerase
Add extra nucleotides to the telomeres of DNA to protect vital regions during replication, as telomeres shorten each time DNA replic
Stem cells
stem cells are undifferentiated cells capable of forming various specialized cell types and have the ability to self-renew by dividing may times by mitosis .
totipotent
zygote
most potent
most versatile
It can divide to produce diff types of specialized sells including placenta.
pluripotent
pluripotent embryo
versatile
potent
It can also divide to produce difft ypes of specialized cells except placenta
Multipotent
Bone marrow stem cells in adults
least potent
least versatile
They can only divide to produce blood cells
few genes are expressed
