Mitosis Flashcards
Prokaryotic Cell Cycle
Growth Phase, DNA Replication, Cell Division
Growth Phase
The cell grows and prepares for DNA replication, accumulating resources and increasing in size.
DNA Replication
The prokaryotic chromosome, which is circular, is replicated, starting from a single origin of replication.
Cell Division
The replicated chromosomes are separated, and the cell divides into two identical daughter cells through a process called binary fission.
Binary Fission
The cell membrane elongates and pinches inward, forming a septum that eventually separates the two daughter cells
DNA Replication Steps
Initiation, Elongation, Termination
Initiation
The process begins at specific regions on the DNA called replication origins, where the DNA strands are separated.
Elongation
Enzymes, like DNA polymerase, synthesize new DNA strands, using the original strands as templates.
Termination
The process ends when replication is complete, and the newly synthesized DNA molecules are separated.
Asexual Reproduction
It’s a method of reproduction where a single parent cell divides to produce two genetically identical offspring, without the involvement of gametes (sperm and egg) or meiosis.
Steps of Binary Fission
DNA Replication, Chromosome Segregation, Cell Elongation & Division, Daughter Cell Formation
DNA Replication
The single circular DNA chromosome of the parent cell is replicated, creating two identical copies.
Chromosome Segregation
The two copies of the DNA are then separated to opposite ends of the cell.
Cell Elongation & Division
The cell elongates, and a new cell wall (septum) forms in the middle, dividing the cell into two equal parts.
Daughter Cell Formation
Two genetically identical daughter cells are produced, each containing a copy of the original DNA.
Interphase Stage
G1, S Phase, G2
G1
The cell grows, performs its normal functions, and prepares for DNA replication.
S Phase
DNA replication occurs, resulting in two identical copies of each chromosome (sister chromatids).
G2
The cell continues to grow and prepares for mitosis, ensuring DNA replication is complete and any damage is repaired.
Mitosis:
The nucleus divides, separating the duplicated chromosomes into two identical sets.
Prophase:
Chromosomes condense, the nuclear envelope breaks down, and the mitotic spindle forms.
Prometaphase:
The nuclear envelope fragments, and the spindle fibers attach to the chromosomes.
Metaphase:
Chromosomes align at the center of the cell (metaphase plate).
Anaphase:
Sister chromatids separate and are pulled to opposite poles of the cell.
Telophase:
Chromosomes decondense, new nuclear envelopes form around each set, and the spindle fibers disappear.
Cytokinesis
The cytoplasm divides, resulting in two daughter cells, each with a complete set of chromosomes.
Sister Chromatids
These two identical copies are called sister chromatids, and they are joined together at a region called the centromere.
Cohesion
Sister chromatids are held together by proteins called cohesins
DNA Packaging
Nucleosomes are the fundamental units of DNA packaging in eukaryotic cells. They consist of DNA wrapped around histone proteins, forming a “beads on a string” structure.
Chromatin Formation
Nucleosomes aggregate to form chromatin, which is the material that makes up chromosomes.
Gene Expression Regulation
The arrangement and modifications of nucleosomes influence how easily DNA can be accessed by the cellular machinery involved in processes like transcription (gene expression), replication, and repair.
Transcription Regulation
Nucleosomes can act as barriers, preventing transcription machinery from accessing DNA, or they can be modified to allow access.
Oncogenes
Normally, these genes help cells grow and divide, but when they mutate, they can become “oncogenes” and cause cells to grow out of control.
Tumor Suppressor Genes
These genes normally help prevent cancer by controlling cell growth and division, but when they mutate, they can lose their ability to do so, allowing cancer to develop.
Inherited Mutations
Some cancer-causing mutations are inherited from parents, increasing an individual’s risk of developing certain types of cancer.
Acquired Mutations
Most cancer-causing mutations are acquired during a person’s lifetime due to exposure to environmental factors or random errors in DNA replication.
Stages Of Mitosis
Pro
Meta
Ana
Telo
Cyto
