BIOFOUND 4.1 Cell Division and Mitosis

binary fission

process of cell division used in the replication of prokaryotic cells

DNA replication

first step of binary fission: the chromosome is duplicated so the cell has 2 complete copies of its DNA sequence

chromosome segregation

second step of binary fission: two copies of the chromosome are physically separated to the opposite ends of the cell

cytokinesis

third step of binary fission: the cell membrane pinches in the middle to separate the two cells

cell separation

fourth step of binary fission: the pinched membrane combines with itself so that the 2 separate cells are made

cell cycle

The replication process in eukaryotes that occurs in the series of defined phases

Interphase

Periods between rounds of mitosis

First gap (G1) Phase

The phase of growth and performing physiological jobs: cells becomes larger to make more organelles and proteins in each cell perform specialized life functions (most of the cells life is spent in this phase)

synthesis (S) Phase

The phase where the cells chromosomes are copied

Second Gap (G2) phase

used by the cell to prepare for mitosis the copy of the chromosome that was made during the S phase is checked for copying errors and errors are repaired

Prokaryotic chromosomes

typically only have one chromosome that is circular and shape which is not contained inside a nucleus (kept in nucleoid instead), performs supercoiling

eukaryotic chromosomes

Have multiple chromosomes that are linear in shape contain a centromere Stored in the nucleus and wrapped around proteins, called histones

how many chromosomes are in human cells?

46 total in 23 nearly identical pairs

homologous chromosomes

The chromosomes of each pair from a human cell

human chromosomes during interphase

During the S phase, each homologous chromosome has two complete copies stuck to each other

sister chromatids

The identical copies of each homologous chromosome

Centromere

The region of the chromosome or chromatids are attached to each other

cohesins

used to stick the two sister chromatids together at the centromere

kinetochore

Protein based structure, where the mitotic spindle attaches to the chromosomes

prophase

The first stage of mitosis where chromatin condenses into dense distinct mitotic chromosomes, reorganizes into a structure called mitotic spindle

Prometaphase

The second stage of mitosis where the nuclear envelope breaks apart and releases chromosomes into the cytoplasm

metaphase

The third stage of mitosis where the mitotic spindle makes small adjustments that lineup each homologous chromosome at the middle of the cell

anaphase

The fourth stage of mitosis were digestive enzymes destroy cohesions holding the sister chromatids together, The mitotic spindle pulls the chromatids to the opposite end of the cell

telophase

The fifth step of mitosis where the nuclear envelope reforms around the segregated chromosomes

cytokinesis (in animals)

The sixth stage of mitosis Where are the mitotic spindle brakes down and cell separation takes place