CO2 BIO

CELL CYCLE

the series of events a cell goes through as it grows, prepares for division, and divides

CELL DIVISION

the process in which one parent cell divides to produce new daughter cells

BINARY FISSION

a type of cell division used by bacteria in which one cell divides into two genetically identical cells

CLONAL

cells that are genetically identical copies of the original cell

CHROMATIN

DNA wrapped around proteins called histones

NONDIVIDING CELL

a cell whose chromatin is loosely packed so its genes can be accessed and expressed

CELL PREPARING TO DIVIDE

a cell in which replicated chromosomes become tightly coiled and compact so they can be moved during cell division

EUKARYOTIC CELL CYCLE

the sequence of stages a eukaryotic cell goes through as it grows, prepares for division, and divides

INTERPHASE

the stage when a cell grows, performs its normal functions, and copies its DNA in preparation for division

G1

the first growth stage of interphase, when the cell grows, performs its normal functions, and makes materials needed for DNA replication

G0

a non-dividing state in which a cell performs its normal functions without preparing to divide

S PHASE

the stage of interphase when the cell copies its DNA

G2

the second growth stage of interphase, when the cell makes proteins and other components needed for cell division

G1 “GROWTH” PHASE

the cell grows, carries out its functions, increases its organelles, and prepares materials for DNA synthesis

S “SYNTHESIS” PHASE

the stage when DNA is replicated and DNA damage can be repaired

G2 “GROWTH” PHASE

the cell produces proteins needed for division, such as microtubule proteins, and chromosomes begin to condense

CHROMOSOME

a long DNA molecule wrapped around proteins; after replication, it consists of two sister chromatids

SISTER CHROMATIDS

two identical copies of a replicated chromosome that are attached to each other

CENTROMERE

the region where sister chromatids are joined together

KINETOCHORES

protein structures that form at the centromere and allow spindle fibers to attach to chromosomes during division

MITOSIS

division of the nucleus that produces two genetically identical nuclei

CYTOKINESIS

division of the cytoplasm and cell contents after nuclear division

ASTER

an arrangement of short fibers that radiate outward from a centrosome

POLAR SPINDLE FIBERS

spindle fibers that extend toward the center of the cell and overlap with fibers from the opposite pole

KINETOCHORE SPINDLE FIBERS

spindle fibers that attach to the kinetochores of chromosomes

CELL CORTEX

a mesh of cytoskeletal elements located just beneath the cell membrane

CONTRACTILE RING

a ring of proteins that contracts and pulls the cell membrane inward during animal-cell cytokinesis

CLEAVAGE FURROW

the indentation that forms as an animal cell's membrane is pulled inward during cytokinesis

CELL PLATE

a structure that forms in the middle of a plant cell and eventually becomes the new cell wall separating the daughter cells

IMPORTANCE OF MITOSIS

mitosis allows organisms to grow, develop, repair damaged tissues, and replace old or lost cells

SOMATIC CELLS

body cells that are not directly involved in reproduction; they are diploid and divide by mitosis

SEX CELLS

reproductive cells such as sperm and eggs; they are haploid and are produced through meiosis

PROPHASE

the stage of mitosis when chromosomes condense, the spindle begins forming, and centrosomes move toward opposite sides of the cell

EARLY PROPHASE

chromatin condenses into visible chromosomes, the nucleolus disappears, the nuclear envelope begins breaking down, and centrosomes have duplicated

PROMETAPHASE

the stage when the nuclear envelope breaks down completely and spindle fibers attach to chromosome kinetochores

METAPHASE

the stage when chromosomes line up along the middle of the cell

ANAPHASE

the stage when sister chromatids separate and move toward opposite ends of the cell

TELOPHASE

the stage when chromosomes reach opposite poles, new nuclear envelopes form, and cytokinesis begins

DIPLOID NUMBER

the total number of chromosomes in a diploid cell, represented as 2n

DIPLOID CELL

a cell containing two complete sets of chromosomes, one inherited from each parent

MATERNAL

inherited from the mother

PATERNAL

inherited from the father

MEIOSIS

a type of cell division that produces four genetically different haploid cells from one diploid cell

MEIOSIS I

the first division of meiosis, in which homologous chromosomes separate

MEIOSIS II

the second division of meiosis, in which sister chromatids separate

HAPLOID (n)

having one complete set of chromosomes

PROPHASE I

the stage of meiosis I when homologous chromosomes pair up and crossing over occurs

SYNAPTONEMAL COMPLEX

a protein structure that connects paired homologous chromosomes during meiosis

SYNAPSIS

the pairing of homologous chromosomes during prophase I

BIVALENT

a paired set of homologous chromosomes, with each chromosome containing two sister chromatids

TETRAD

the four chromatids present when two homologous chromosomes pair during meiosis

CROSSING OVER

the exchange of genetic material between nonsister chromatids of homologous chromosomes

GENETIC RECOMBINATION

the creation of new combinations of genetic material through processes such as crossing over

CHIASMATA

the points where homologous chromosomes remain connected after crossing over

METAPHASE I

the stage when homologous chromosome pairs line up randomly along the middle of the cell

ANAPHASE I

the stage when homologous chromosomes separate and move to opposite poles, while sister chromatids remain together

TELOPHASE I

the stage when homologous chromosomes reach opposite poles and the cell may divide, producing haploid cells

PROPHASE II

the stage when chromosomes condense again and new spindle fibers form

METAPHASE II

the stage when chromosomes line up individually along the middle of each cell

ANAPHASE II

the stage when sister chromatids separate and move toward opposite poles

TELOPHASE II

the stage when nuclei reform and cytokinesis produces four haploid cells

INDEPENDENT ASSORTMENT

the random arrangement of homologous chromosome pairs during metaphase I, producing different combinations of chromosomes in daughter cells

GAMETES

haploid reproductive cells, such as sperm and egg cells

ANIMAL LIFE CYCLE

a life cycle in which animals are mainly diploid and produce haploid gametes through meiosis

SPERMATOGENESIS

the process of producing sperm cells

OOGENESIS

the process of producing egg cells

CHECKPOINTS

control points in the cell cycle that make sure the cell is ready to move to the next stage

APOPTOSIS

programmed cell death in which a cell is intentionally broken down

CANCER

uncontrolled cell division caused by changes or mutations that affect genes controlling cell growth and division

BENIGN TUMOR

an abnormal mass of cells that grows excessively but does not spread to other parts of the body

MALIGNANT TUMOR

a cancerous tumor that can invade other tissues and spread to other parts of the body

PROTO-ONCOGENES

normal genes that help regulate cell growth but can cause cancer if mutated

TUMOR-SUPPRESSOR GENES

genes that normally help prevent uncontrolled cell division; loss of their function can contribute to cancer

p53 GENE

a tumor-suppressor gene that helps stop the cell cycle when DNA is damaged, promotes DNA repair, and can trigger apoptosis

EUPLOIDY

having the correct number of complete chromosome sets for a species

ANEUPLOIDY

having an abnormal number of individual chromosomes

KARYOTYPE

an organized display of an individual's chromosomes arranged according to their size, shape, and banding pattern

NONDISJUNCTION

failure of chromosomes to separate properly during cell division

MONOSOMY

having only one copy of a particular chromosome instead of the normal two

TRISOMY

having three copies of a particular chromosome instead of the normal two

TRISOMY 21

a condition in which a person has three copies of chromosome 21

DOWN SYNDROME

a genetic condition caused by having an extra copy of chromosome 21; also called trisomy 21

AUTOSOMAL TRISOMIES

conditions caused by having three copies of one of the autosomal chromosomes

TURNER SYNDROME (XO)

a condition in which a female has only one X chromosome; it can be associated with short stature and a broad chest

KLINEFELTER SYNDROME (XXY)

a condition in which a male has an extra X chromosome, commonly associated with underdeveloped testes and other physical differences