ch 3 chromosome transmission during cell division and sexual reproduction Flashcards
chromosomes
the structures within living cells that contain the genetic material; genes are physically located within the chromosomes; biochemically, a chromosome contains a very long segment of dna (genetic material) and proteins (bound to dna and provide it with organized structure)
chromatin
the complex of dna and proteins that’s found within eukaryotic chromosomes
prokaryote
(also known as bacteria and archaea)
refers to the observation that their chromosomes are not contain within a separate nucleus in a cell
nucleoid
a darkly staining region that contains the genetic material of mitochondria, chloroplasts, or bacteria
eukaryote
(also known as eukarya)
- one of the three domains of life
- a defining feature of these organisms is that their cells contain a membrane bound nucleus and membrane bound organelles
- some simple eukaryotic species are single-celled protists and yeasts; more complex multicellular species include fungi, plants, and animals
organelle
a specialized structure within a cell that is surrounded by a single or double membrane
nucleus
a membrane bound organelle in eukaryotic cells where the chromosomes are found
cytogenetics
the field of genetics that involves the microscopic examination of chromosomes
cytogeneticist
the scientist who studies chromosomes under a microscope
somatic cell
any cell of the body except for gametes and germ-line cells that give rise to gametes
gamete
- a reproductive cell (usually haploid) that can unite with another reproductive cell to create a zygote
- sperm and egg cells are types of gametes
germ cell
the gametes (sperm and egg cells)
karyotype
a photographic representation of all the chromosomes within a cell; reveals how many chromosomes are found within an actively dividing somatic cell
dipoid
an organism or cell that contains two sets of chromosomes
homologs
structures that are similar to each other due to descent from a common ancestor; a homolog can be one of the chromosomes in a pair of chromosomes; genes can be homologs when they are descended from a common gene
allele
alternative form for a specific gene
locus (loci)
the physical location of a gene or other dna segment within a chromosome
asexual reproduction
a form of reproduction that doesn’t involve the union of two gametes; at the cellular level, a preexisting cell divides to produce two new cells
multicellularity
consisting of more than one cell
binary fission
the physical process whereby a bacterial cell divides into two daughter cells; during this event, the two daughter cells become separated by the formation of a septum
cell cycle
- in eukaryotic cells, a series of stages through which a cell progresses in order to divide
- phases are G for gap, S for synthesis (of genetic material), and M for mitosis (which includes cytokinesis)
- there are two G phases, G1 and G2
- interphase: G1, S, G2
- mitosis: prophase, prometaphase, metaphase, anaphase, telophase
interphase
the series of phases G1, S and G2, during which a eukaryotic cell spends most of its life
restriction point
a point in the G1 phase of the cell cycle at which a cell becomes committed to progress to cell division
chromatids
following chromosomal replication in eukaryotes, the two copies that remain attached to each other in the form of sister chromatids
centromere
a segment of a eukaryotic chromosome that provides an attachment site for the kinetochore
sister chromatids
pairs of replicated chromosomes that are attached to each other at the centromere; typically identical; also called a dyad
monad
a single chromatid within a dyad
kinetochore
a group of proteins that attach to the centromere during meiosis and mitosis
mitosis
a type of nuclear division into two nuclei during which each daughter cell receives the same complement chromosomes
mitotic spindle apparatus
(also known as spindle apparatus and mitotic spindle) during cell division in eukaryotic cells, a structure composed of microtubules that sorts the chromosomes
microtubule-organizing centers (mtocs)
a structure in a eukaryotic cell from which microtubules grow
centrosome
a cellular structure from which microtubules come from
spindle pole
during cell division in eukaryotes, one of two sites in cells where microtubules originate
centrioles
a pair of structures within each centrosome of animal cells
astral microtubules
the microtubules that come outward from the centrosome toward the plasma membrane
polar microtubules
the microtubules that project toward the region where the chromosomes will be found during mitosis; they overlap each other and play a role in pushing the spindle poles apart
kinetochore microtubules
the microtubules that are connected to kinetochores on chromosomes
decondensed
- less tightly compacted
- used to describe chromosomes during interphase
prophase
the first phase of mitosis; the chromosomes have already replicated and begin to condense; the mitotic spindle apparatus starts to form
condensed
- forming a more compact structure
- used to describe chromatids in prophase
prometaphase
the second phase of mitosis; during this phase, the nuclear membrane vesiculates and the mitotic spindle is completely formed
metaphase plate
the plane along which pairs of sister chromatids align during metaphase
metaphase
the third phase of mitosis; the chromosomes align along the central plane of the spindle apparatus and the formation of the spindle is completed
anaphase
the fourth phase of mitosis; as anaphase proceeds, half of the chromosomes move to one pole, and the other half move to the other pole
telophase
the fifth stage of mitosis; the chromosomes have reached their respective poles and decondense
cytokinesis
the division of a single cell into two cells; the nuclei produced in mitosis are segregated into separate daughter cells during cytokinesis
cleavage furrow
a constriction that causes the division of an animal cell into two cells during cytokinesis
cell plate
the structure that forms between two daughter plant cells and leads to the separation of the cells by the formation of an intervening cell wall
meiosis
a form of nuclear division in which the sorting process results in the production of haploid cells from diploid cell
haploid
refers to a cell that contains hald of the genetic material found in somatic cells; for a species that is diploid, a haploid gamete contains a single set of chromosomes
leptotene
first stage of prophase of meiosis I
zygotene
the second phase of prophase of meiosis I
synapsis
the event in which homologous chromosomes recognize each other and then align themselves along their entire lengths
pachytene
the third stage of prophase of meiosis I; paired chromosomes shorten and thicken, the two chromatids of each separate, and exchange of segments between chromatids may occur.
bivalent
a structure in which two pairs of homologous sister chromatids have synapsed (aligned) with each other
tetrad
- the structure formed by the association of four sister chromatids during meiosis
- a group of four fungal spores contained within an ascus
crossing over
a physical exchange of pieces between homologous chromosomes that most commonly occurs during prophase of meiosis
chiasma
(plural chiasmata) the site where crossing over occurs between two chromosomes; resembles greek letter chi χ
diplotene
the fourth stage of prophase of meiosis I
diakinesis
the fifth stage of prophase of meiosis I; when the separation of homologous chromosomes is complete and crossing over has occurred
sexual reproduction
the process whereby parents make gametes (sperm and egg) that fuse with each other in the process of fertilization to begin the life of a new organism
gametogenesis
the production of gametes
isogamous
describes a species that produces morphologically similar gametes
heterogamous
describes a species that produces two morphologically different types of gametes
sperm cell
a male gamete; sperm are small and usually travel relatively far distances to reach the female gamete
egg cell
a female gamete that is usually very large on nonmotile; also known as an ovum or egg
spermatogenesis
the production of sperm cells
oogenesis
the production of egg cells
gametophyte
the haploid generation of plants
sporophyte
the diploid generation of plants
pollen grain
the male gametophyte of flowering plants; also called pollen
embryo sac
in flowering plants, the female gametophyte that contains an egg cell
endosperm
in flowering plants, the material in the seed, which is 3n and nourishes the developing embryo
x-linked inheritance
the inheritance pattern in certain species that involves genes that are located only on the x chromosome
chromosome theory of inheritance
a theory of sutton and boveri that the inheritance patterns of traits can be explained by the transmission patterns of chromosomes during meiosis and fertilization
sex chromosomes
a pair of chromosomes (X and Y in animals) that differ between males and females and determine sex in a species
heterogametic sex
in species with two types of sex chromosomes, the heterogametic sex produces two types of gametes; in mammals, the male is heterogametic bc sperm can contain either an X or a Y chromosome
homogametic sex
in species w two types of sex chromosomes, the homogametic sex produces only one type of gamete; for example in mammals the female is the homogametic sex because an egg can only produce an X chromosome
autosomes
chromosomes that are not sex chromosomes
x-linked genes
(also called x-linked alleles) genes (or alleles of genes) that are physically located within the x-chromosome
testcross
- an experimental cross between a recessive individual and an individual whose genotype the experimenter wishes to determine
- an experimental cross used for mapping the distance between genes in which an individual that is heterozygous for two or more genes is crossed to an individual that is homozygous recessive for those same genes