[GENETICS] MOD4

Prokaryotic cell

A cell found in bacteria and blue-green algae that does not have a nuclear membrane

Eukaryotic cell

A cell type that includes the majority of living species

Cytoplasm

The major portion of the protoplasmic material of a cell

Cytosol

The liquid portion of the cytoplasm

Nucleus

The dark-staining body of the cell and the primary director of cellular activity and inheritance

Endocytosis

The process involving formation of vesicles for engulfment

Exocytosis

The process involving formation of vesicles for release

Mitochondria

The organelle known as the powerhouse of the cell and responsible for ATP synthesis

Golgi apparatus

An organelle listed as part of the cytoplasmic organelles

Endoplasmic reticulum

An organelle found in the cytoplasm

Ribosomes

Cytoplasmic structures involved in cellular function

Centrosomes

Cytoplasmic structures associated with centrioles

Centrioles

Structures accompanying the centrosomes

Nuclear membrane

The membrane that is absent in prokaryotic cells and forms the double membrane of the nucleus in eukaryotic cells

Chromatin

The form of genetic material that is normally spread out and not readily identifiable

Chromosomes

Condensed genetic structures that become identifiable at the start of mitosis

Sister chromatids

Replicated chromosomes that remain together and are attached at the centromere by cohesins

Cohesins

Proteins that attach sister chromatids together at the centromere

Homologous pair of chromosomes

A pair of corresponding chromosomes

Kinetochore

A section of the centromere where spindle microtubules attach

Centromere

The primary constriction of a chromosome

Primary constriction

Another term for the centromere

Telocentric chromosome

A chromosome in which the p arms are not visible

Constriction

The process of tightly packing chromosomes

Satellite

A small chromosomal section formed by a secondary constriction

Satellite DNA

DNA consisting of abundant tandem repeats involved in chromosome segregation, genome organization, and chromosome end protection

Tandem repeats

Repeated DNA sequences such as ATG ATG ATG

Secondary constriction

A pinched region of a chromosome that can form a satellite and is often associated with the nucleolus

Nucleolus-organizing region

A specific point on a chromosome responsible for organization of a nucleolus

NOR

Abbreviation for nucleolus-organizing region

Nucleolus organizer

The chromosome containing the region responsible for organizing the nucleolus

rRNA

RNA that serves as a building block of the ribosome

Nucleolus

The site associated with synthesis of rRNA and ribosome formation

Chromomeres

Morphological markers of mitotic chromosomes listed with knobs

Knobs

Morphological markers of mitotic chromosomes listed with chromomeres

Cell division

The process involving mitosis and meiosis

Mitosis

Cell division in which genetic and chromosome composition is faithfully replicated in each daughter cell

Meiosis

Cell division in sexually reproducing organisms that reduces chromosome number by half

Binary fission

The method of reproduction used by bacteria

G1 phase

The longest phase of the cell cycle that prepares the cell for division together with S and G2

S phase

The synthesis phase in which DNA is replicated and DNA content doubles

G2 phase

The second gap period in which RNA and proteins necessary for chromosome synthesis are produced and the cell prepares for mitosis

Interphase

The period when the cell is not dividing and is preparing for cell division

M phase

The phase of the cell cycle in which mitosis occurs

DNA replication

The process occurring during S phase in which DNA is synthesized

DNA content during S phase

It doubles because sister chromatids or DNA content are duplicated

Prophase

The mitotic stage in which the nuclear envelope begins to disintegrate and the nucleolus disappears

Metaphase

The mitotic stage in which chromosomes align at the equatorial plate

Anaphase

The mitotic stage in which chromatids move toward opposite poles

Telophase

The mitotic stage in which the nuclear envelope and nucleolus reappear

Equatorial plate

The central region where chromosomes align during metaphase

Spindle fibers

Fibers that attach to kinetochores and help move chromosomes during cell division

Cytokinesis

The division of the cytoplasm following nuclear division

Cleavage furrow

The structure formed during cytokinesis in animal cells

Cell plate

The structure formed during cytokinesis in plant cells

G1 checkpoint

The checkpoint that checks the size of the cell

G2 checkpoint

The checkpoint that checks the integrity of DNA

M checkpoint

The checkpoint that checks proper chromosome alignment

Cell division arrest

What occurs when a cell fails to pass a cell-cycle checkpoint

Gene

A unit that codes for certain traits

DNA

A group of genes

Chromosome

A group of DNA

Genome

A group of chromosomes

Mutation

The process by which a different allele may arise from a gene

Meiosis I

The first nuclear division of meiosis and the reductional division

Meiosis II

The second nuclear division of meiosis and the equational division

Reductional division

A division in which chromosome number is reduced from diploid to haploid

Equational division

A division in which chromosome number remains haploid

Sexually reproducing organisms

Organisms in which meiosis occurs

Crossing over

The reciprocal exchange of genetic material between non-sister chromatids of homologous chromosomes during meiosis

Genetic variation

Variation produced in part through processes such as crossing over

Polar body

A cell formed during oogenesis that contains less cytosol and may divide further

Leptotene

The first substage of prophase I in which chromatin begins to condense and chromosomes become visible

Leptonema

Another name for leptotene

Zygotene

The prophase I stage in which chromosomes continue to shorten and thicken and initial alignment occurs

Zygonema

Another name for zygotene

Synaptonemal complex

A protein lattice that forms between homologous chromosomes and facilitates their pairing

Bivalent

A pair of paired homologous chromosomes

Pachytene

The prophase I stage characterized by further development of the synaptonemal complex and intimate pairing of homologs

Pachynema

Another name for pachytene

Synapsis

The intimate pairing of homologous chromosomes

Tetrad

A four-membered structure containing two pairs of sister chromatids

Diplotene

The prophase I stage in which sister chromatids begin to separate while remaining in contact at certain areas

Diplonema

Another name for diplotene

Chiasma

A point where non-sister chromatids have undergone genetic exchange through crossing over

Chiasmata

Plural form of chiasma

Diakinesis

The final substage of prophase I in which chromosomes pull farther apart and the nuclear envelope and nucleolus break down

Metaphase I

The stage in which bivalents align at the equatorial plane

Anaphase I

The stage in which homologous chromosomes separate from each other

Telophase I

The stage in which chromosomes regroup and two haploid daughter nuclei form

Interkinesis

The brief transitional stage between meiosis I and meiosis II during which chromosomes are not replicated

Prophase II

The stage similar to mitotic prophase but with half the chromosome number

Metaphase II

The stage in which chromosomes align on the equatorial plate of their respective spindles

Anaphase II

The stage in which sister chromatids separate and move toward opposite poles

Telophase II

The stage in which chromosomes uncoil, the nuclear membrane is reconstituted, and the nucleolus reappears

Haploid

A cell or nucleus having one set of chromosomes

Diploid

A cell or nucleus having two sets of chromosomes

After mitosis

The resulting cells are diploid

After meiosis I

The resulting cells are haploid

After meiosis II

The resulting cells are haploid