Unit 6 Cell Division

Parent cell

The cell that divides to give rise to two daughter cells

Daughter cell

A daughter cell is a new cell that forms when an original cell (called a parent cell) divides

DNA replication

The biological process where a cell makes a complete copy of its DNA before it divides

Nuclear division

The process where a cell's nucleus divides to separate its duplicated genetic material (chromosomes) into new nuclei

Cytokinesis

The physical process of cell division that divides the cytoplasm of a parent cell into two daughter cells

Mitiosis

A process of cell division where a single cell splits into two genetically identical daughter cells, each with the same number of chromosomes

Somatic

Any normal body cell in a multicellular organism that is not a sperm or egg cell

Gamete

A reproductive cell (x cell) of an animal or plant that unites with another cell during sexual reproduction

Germline cell

A germline cell is any biological cell in a multicellular organism that gives rise to gametes (eggs and sperm) and passes genetic information on to the next generation

Myosin filament

A bundled polymer of myosin motor protein molecules that converts chemical energy into mechanical force to drive muscle contraction and cellular movement

Cleavage furrow

Groove that pinches an animal cell in two during cytokinesis.

Centrifugal

A laboratory technique that uses high-speed rotation to separate components of a biological sample based on their size, shape, and density using centrifugal force

Equatorial plane

The imaginary center line or flat region inside a dividing cell where chromosomes line up during the metaphase stage of cell division

Cell plate

Structure that forms during the division of plant cells

Oogenesis

The biological process of forming a mature female gamete (ovum or egg cell)

Budding

A type of asexual reproduction where a new, genetically identical organism develops as a small outgrowth, or bud, from the parent organism

Binary fission

A form of asexual reproduction where a single-celled organism or organelle copies its genetic material and splits into two identical daughter cells

Sexual reproduction

A biological process where two parent organisms combine their genetic material through the fusion of specialized sex cells (gametes) to create a genetically unique offspring

Asexual reproduction

A type of reproduction where a single parent creates genetically identical offspring without the fusion of sex cells or gametes

Meiosis

A specialized type of cell division that reduces the chromosome number by half, turning one diploid cell into four haploid genetics

Anucleate

A cell that does not have a cell nucleus

Cell cycle

An ordered series of events where a cell grows, copies its DNA, and divides into two new daughter cells

Chromosome

A thread-like structure made of a long DNA molecule tightly coiled around support proteins called histones, which package and protect genetic information inside cells

Histones

A family of basic, positively charged proteins found in the nucleus of eukaryotic cells that package and order DNA into structural units called nucleosomes

Chromatid

One of the two identical halves of a replicated chromosome that stays joined together before cell division

Sister chromatids

Two identical copies of a single replicated chromosome that are joined together at a region called the centromere

Centromere

The specialized, constricted region of a chromosome that links sister chromatids and attaches to spindle fibers during cell division

Nucleosome

A basic unit of DNA chromatin in eukaryotic organisms.

Interphase

The long preparatory phase in the Cell Cycle where a cell grows, copies its DNA, and gets ready to divide into two new cells

Chromatin

A highly organized condensed structure made up of DNA, RNA, and proteins that forms the chromosomes in the nucleus of a cell

Microtubules

Microscopic, hollow tubes made of protein subunits that give eukaryotic cells their shape and help transport internal materials

Kinetochore

A large protein structure that assembles on the centromere of a chromosome during cell division

Motor proteins

convert chemical energy from ATP into mechanical work, moving along the cell's cytoskeletal filaments

Prophase

the first stage of cell division in both mitosis and meiosis, where chromatin condenses into visible chromosomes

Metaphase

the stage of cell division (mitosis or meiosis) where condensed chromosomes line up in the middle of the cell

Anaphase

the stage in cell division where replicated chromosomes split and are pulled apart to opposite ends of the cell

Telophase

the final stage of cell division in both mitosis and meiosis where separate sets of chromosomes reach the opposite poles of a cell and new nuclear membranes form around them

Meiosis I

the first round of a special type of cell division called meiosis that reduces the number of chromosome sets from two (diploid) to one (haploid)

Meiosis II

the second part of cell division in sexually reproducing organisms, where sister chromatids separate to produce four unique haploid gametes

Homologous

sharing a similar physical structure, anatomical position, or genetic origin due to descent from a common ancestor, even if the current function is different

Haploid

means a cell has only one complete set of chromosomes (written as n)

Diploid

has two complete sets of chromosomes (written as 2n)

Non-disjunction

the failure of homologous chromosomes or sister chromatids to separate properly during cell division (mitosis or meiosis)

Aneuploidy

a cell division error where a cell has an abnormal number of chromosomes that is not a clean multiple of the basic haploid set

Germ-line cells (gametes)

the specialized population of cells in a multicellular organism that pass on genetic material to the next generation, encompassing both the actual sex cells (gametes) and their precursor stem cells

Oocytes

an immature female reproductive cell produced in the ovaries that develops into a mature egg

Ovulation

the biological process in which a mature egg (ovum) is released from an ovary into the fallopian tube

independent assortment

the alleles of two or more different genes are sorted into gametes (sex cells) independently of one another

Crossing over

the biological process where paired homologous chromosomes swap matching segments of their DNA

Bivalent (tetrad)

a pair of joined homologous (matching) chromosomes that comes together during the first division of meiosis

Chiasma

the X-shaped physical points of contact where non-sister chromatids of homologous chromosomes exchange genetic material during meiosis

Differentiation

the process where less specialized cells undergo changes to develop specialized structures and functions

Differential gene

a gene whose activity level—measured by how much RNA or protein it produces—changes significantly between two different biological conditions

Expression

the process by which the information encoded in a gene is used to direct the assembly of a protein molecule.

Stem cells

cells with the potential to develop into many different types of cells in the body

Stem cell niche

a local microenvironment that directly promotes or protects a population of stem cells

Totipotent

having the ability to differentiate into all cell types

Pluripotent

a cell can divide and turn into almost any type of specialized cell in the body

Multipotent

a type of stem cell that can develop into a limited range of specialized cells within a specific tissue, organ, or family of cells

Zygote

the single, diploid cell that forms when a sperm cell fuses with an egg cell during fertilization

Blastocyst

an early stage of a mammalian embryo, consisting of a hollow ball of about 100 to 200 cells that forms roughly five to six days after an egg is fertilized

Morula

a solid, spherical ball of 16 to 32 cells (called blastomeres) that forms during early embryonic development after a fertilized egg (zygote) undergoes rapid cell division

Fertilization

the fusion of male and female gametes (sperm and egg) to form a single diploid cell called a zygote

Morphogen

a signaling molecule that spreads through developing tissue from a localized source to form a concentration gradient, instructing cells to develop into different specialized types based on its local concentration

Morphogen gradient

a varying concentration of signaling molecules in developing tissues that tells cells where they are located and what type of cell to become

Ectoderm

the outermost of the three primary germ layers that forms in an animal embryo during early development

Mesoderm

the middle layer of the three primary germ layers in a developing animal embryo, sitting between the outer ectoderm and the inner endoderm.

Endoderm

the innermost of the three primary germ layers in an early animal embryo