Mitosis and Sexual Life Cycles

Interphase

The phase where the cell grows, prepares for division, and duplicates its chromosomes.

Mitosis

The process of separating the copies of chromosomes and moving them to opposite ends of the cell.

Cytokinesis

The division of the cytoplasm to produce two genetically identical daughter cells.

Genome

A cell’s complete set of DNA, including all of its genes.

Chromatin

The complex of DNA and proteins that forms chromosomes in the nucleus.

Sister chromatids

Joined copies of the original chromosome, formed during DNA replication.

Centromere

Region of a chromosome where sister chromatids are most closely attached.

Gamogenesis

The formation of haploid sex cells (gametes) in the gonads.

Fertilization

The process of uniting male and female gametes to form a diploid zygote.

Cleavage

The series of rapid mitotic divisions that occur after fertilization.

Gastrulation

The process of cell migration that establishes the three primary layers of an embryo.

Organogenesis

The formation and development of organs in the embryo.

MPF

Maturation-Promoting Factor, a cyclin-Cdk complex that triggers the cell's passage into mitosis.

Cyclin

A protein that regulates the cell cycle by changing in concentration.

Checkpoint

Control points in the cell cycle where signals regulate progression.

G1 checkpoint

A control point where a cell decides whether to continue in the cell cycle or enter a nondividing state (G0).

M checkpoint

A control point in mitosis that ensures all chromosomes are properly attached to the spindle before proceeding.

Density-dependent inhibition

The phenomenon where crowded cells stop dividing.

Asexual reproduction

Reproduction arising from a single organism, resulting in genetically identical offspring.

Sexual reproduction

Reproduction involving two parents, resulting in genetically unique offspring.

Meiosis

A type of cell division that results in four haploid cells containing half the number of chromosomes of the diploid parent cell.

Diploid cell

A cell that contains two sets of chromosomes.

Haploid cell

A cell that contains a single set of chromosomes.

Zygote

The fertilized egg, a diploid cell formed by the union of two haploid gametes.

Cross-Over

The exchange of genetic material between homologous chromosomes during prophase I of meiosis.

Metastasis

The spread of cancer cells to locations distant from their original site.

Interphase

the cell grows; in preparation for cell division, the chromosomes are duplicated, with the genetic material (DNA) copied precisely.

Mitosis

the chromosomes' copies are separated from each other and moved to the opposite ends of the cell.

Cytokinesis

the cell divides into two daughter cells, genetically identical to each other and to the parent cell.

Cell division

the unique capacity to procreate, like all biological functions, has a cellular basis, and the continuity of life.

Asexual reproduction

an amoeba, a single

Genome

a cell's DNA genetic information.

Chromatin

entire complex of DNA and proteins that is the building material of chromosomes.

Sister chromatids

joined copies of the original chromosome.

Cohesins

protein complexes.

Centromere

a region made up of repetitive sequences in the chromosomal DNA where the chromatid is attached most closely to its sister chromatid.

Gamogenesis

occurs in the gonads, resulting in haploid gametes (sex cells).

Fertilization

activation of egg and sperm, diploid zygote.

Cleavage

mitotic division of zygote → multicellular embryo.

Gastrulation

cell migration that establishes primitive layers.

Organogenesis

organs grow and differentiate.

G1 phase

metabolic activity and growth.

S phase

metabolic activity, growth, and DNA Synthesis, where duplication happens.

G2 phase

metabolic activity, growth, and preparation for cell division.

Prophase

the chromatin fibers become more tightly coiled, condensing into discrete chromosomes, observable with a light microscope.

Prometaphase

the nuclear envelope fragments and the microtubules extending from each centrosome can now invade the nuclear area.

Kinetochore

a specialized protein structure that has now formed at the centromere of each chromatid.

Kinetochore microtubules

some of the microtubules that attach to the kinetochors, which jerk the chromosomes back and forth.

Metaphase

the centrosomes are now at opposite poles of the cell

Metaphase plate

a plane that is equidistant between the spindle's two poles where the chromosomes' centromeres lie

Anaphase

is the shortest stage of mitosis, often lasting only a few minutes

Cohesin protein

a protein that is cleaved to allow the two sister chromatids of each pair to separate suddenly

Daughter chromosomes

the two new chromosomes that begin moving toward opposite ends of the cell during anaphase

Telophase

two daughter nuclei form within the cell, and nuclear envelopes arise from the fragments of the parent cell's nuclear envelope

Nucleoli

reappear during telophase

Cleavage furrow

a shallow groove in the cell surface near the old metaphase plate in animal cells

Mitotic phase

the reproductive phase of the cells

Mitotic spindle

begins to form in the cytoplasm during prophase

Centrosome

subcellular region containing material that functions throughout the cell cycle to organize the cell microtubules

Aster

a radial array of short microtubules extends from each centrosome

Cytokinesis in plant cells

involves vesicles derived from the Golgi apparatus moving along microtubules to the middle of the cell to produce a cell plate

Binary fission

division in half, refers to this process and to the asexual reproduction of single

Origin of replication

the process of cell division is initiated when the DNA of the bacterial chromosome begins to replicate at a specific point on the chromosome

Chromosome replication

begins at the origin, where one copy of the origin is now at each end of the cell

Dinoflagellates

unicellular eukaryotes where the chromosomes attach to the nuclear envelope, which remains intact during cell division

Microtubules

Structures that pass through the nucleus inside cytoplasmic tunnels, reinforcing the spatial orientation of the nucleus.

Nuclear envelope

A barrier that remains intact during cell division in diatoms and some yeasts.

Spindle

A structure formed by microtubules within the nucleus that separates chromosomes during cell division.

Cell cycle control system

A cyclically operating set of molecules in the cell that triggers and coordinates key events in the cell cycle.

Checkpoint

A control point where stop and go

Cyclin

A protein that gets its name from its cyclically fluctuating concentration in the cell.

G0 phase

A nondividing state where most cells of the human body are found.

Growth factor

A protein released by certain cells that stimulates other cells to divide.

G1 checkpoint

A checkpoint where a cell exits the cell cycle and enters G0 in the absence of a go

M checkpoint

A checkpoint in mitosis where a cell receives a stop signal if any chromosomes are not attached to spindle fibers.

Anchorage dependence

The requirement for cells to be attached to something, such as the inside of a culture flask or the extracellular matrix of tissue, in order to divide.

Cancer cells

Cells that do not heed the normal signals regulating the cell cycle and can divide indefinitely in culture if given nutrients.

Transformation

The process by which cells in culture acquire the ability to divide indefinitely.

Benign tumor

Abnormal cells that may remain at the original site if their genetic and cellular changes don't allow them to move to or survive at another site.

Malignant tumor

Tumors that include cells whose genetic and cellular changes enable them to spread to new tissues and impair the functions of one or more organs.

Meiosis

A special type of cell division that produces cells with half the chromosomes of the parent cells.

Heredity

the transmission of traits from one generation to the next

Genetics

the study of both heredity and inherited variation

Genes

parents endow their offspring with coded information in the form of hereditary units

Gametes

the vehicles that transmit genes from one generation to the next

Somatic cells

humans have 46 chromosomes in them

Gene's locus

a gene's specific location along the length of a chromosome

Eukaryotic organisms

can reproduce asexually by mitotic cell division, in which DNA is copied and allocated equally to two daughter cells

Clone

an individual or group of individuals that are genetically identical to its parent

Sexual reproduction

two parents give rise to offspring that have unique combinations of genes inherited from the two parents

Genetic variation

an important consequence of sexual reproduction

Karyotype

images of the chromosomes are arranged in pairs, starting with the longest chromosomes

Homologous chromosomes (homologs)

the two chromosomes of a pair have the same length, centromere position, and staining pattern

Sex chromosomes

the X and Y chromosomes

Diploid cell

any cell with two sets of chromosomes

Haploid cells

gametes contain a single set of chromosomes

Fertilization (alternative definition)

the union of gametes in fusion of their nuclei

Zygote (fertilized egg)

diploid because it contains two haploid sets of chromosomes

Alternation of generation

includes both diploid and haploid stages that are multicellular

Sporophyte

multicellular diploid stage