Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
24 Cards in this Set
- Front
- Back
Glossary
|
CHAPTER 9
|
|
allele
|
One of two or more molecular forms of a gene that arise by mutation and code for different versions of the same trait.
|
|
asexual reproduction
|
Any reproductive mode by which offspring arise from a single parent and inherit the genes of that parent only.
|
|
chromosome number
|
All chromosomes in a given type of cell. See haploidy; diploidy.
|
|
crossing over
|
At prophase I of meiosis, an interaction in which nonsister chromatids of a pair of homologous chromosomes break at corresponding sites and exchange segments; genetic recombination is the result.
|
|
diploidy
|
Presence of two of each type of chromosome (i.e., pairs of homologous chromosomes) in a cell nucleus at interphase. Compare haploidy.
|
|
egg
|
Mature female gamete; an ovum.
|
|
fertilization
|
[L. fertilis, to carry, to bear] The fusion of a sperm nucleus with the nucleus of an egg, thus forming a zygote.
|
|
gamete
|
[Gk. gametes, husband, and gamete, wife] Haploid cell, formed by meiotic cell division of a germ cell; required for sexual reproduction. Eggs and sperm are examples.
|
|
gene
|
[German pangan, after Gk. pan, all; genes, to be born] Unit of information for a heritable trait, passed from parents to offspring.
|
|
germ cell
|
Animal cell of a lineage set aside for sexual reproduction; gives rise to gametes.
|
|
haploidy
|
Presence of only half of the parental number of chromosomes in a spore or gamete, as brought about by meiosis.
|
|
homologous chromosome
|
One of a pair of chromosomes that are identical in size, shape, and the genes they carry, and that line up with each other at meiosis I. The X and Y chromosomes differ in these respects but still function as homologues.
|
|
life cycle
|
A recurring pattern of genetically programmed events from the time individuals are produced until they themselves reproduce.
|
|
meiosis
|
[Gk. meioun, to diminish] Two-stage nuclear division process that halves the chromosome number of a parental germ cell nucleus, to the haploid number. Basis of gamete formation (and meiospore formation).
|
|
oocyte
|
Type of immature egg.
|
|
oogenesis
|
Process by which a germ cell develops into a mature oocyte.
|
|
prophase I
|
First stage of meoisis I. Each duplicated chromosome starts to condense. It pairs with its homologue; nonsister chromatids usually undergo crossing over and are attached to spindle. One pair of duplicated centrioles (if present) is moved to the opposite spindle pole.
|
|
prophase II
|
First stage of meiosis II. Spindle microtubules attach to each chromosome and move them to spindle's equator. A centriole pair (if present) is already at each spindle pole.
|
|
sexual reproduction
|
Production of offspring by meiosis, gamete formation, and fertilization.
|
|
sister chromatid
|
Of a duplicated chromosome, one of two DNA molecules (and associated proteins) attached at the centromere until they are separated from each other at mitosis or meiosis; each is then a separate chromosome.
|
|
sperm
|
[Gk. sperma, seed] Mature male gamete.
|
|
spermatogenesis
|
Formation of mature sperm from a germ cell.
|
|
spore
|
A reproductive or resting structure of one or a few cells, often walled or coated; used for resisting harsh conditions, dispersal, or both. May be nonsexual or sexual, as formed by way of meiosis. Some bacteria as well as sporozoans, fungi, and plants form spores.
|