Fichas de aprendizaje Genetics: A Conceptual Approach Chapter 4 | Quizlet

Sex

Male or female

Sex determination

Specification of sex (male or female). Sex-determining mechanisms include chromosomal, genic, and environmental sex-determining systems.

Hermaphroditism

A condition in which an individual has both female and male gonads and functions as both a male and female in sexual reproduction by producing both sperm and eggs.

Monoecious organism

Individual organism that has both male and female reproductive structures.

Dioecious organism

Belongs to a species whose members have either male or female reproductive structures.

Sex chromosome

Chromosomes that differ morphologically or in number in males and females.

Autosome

Chromosome that is the same in males and females; nonsex chromosome.

Heterogametic sex

The sex (male or female) that produces two types of gametes with respect to sex chromosomes. For example, in the XX-XY sex-determining system, the male produces both X-bearing and Y-bearing gametes.

Homogametic sex

The sex (male and female) that produces gametes that are all alike with regard to sex chromosomes. For example, in the XX-XY sex-determining system, the female produces only X-bearing gametes.

Pseudoautosomal region

Small region of the X and Y chromosomes that contains homologous gene sequences
Makes them able to pair during meiosis

XX-XO system

grasshoppers
XX-female
XO-male
O is a lack of a chromosome

XX-XY system

XX - female
XY - male
mammals

ZZ-ZW system

-ZZ-male-
homogametic
-ZW-female-
heterogametic
-Birds, snakes,
butterflies, some amphibians, and fishes

Genic sex determination

Sex determination in which the sexual phenotype is specified by genes at one or more loci, but there are no obvious differences in the chromosomes of males and females.

Haplodiploidy system

Haploid set - male
Diploid set - female
Bees, wasps, and ants

Sequential hermaphroditism

A reproductive pattern in which an individual reverses its sex during its lifetime.
Can be both male and female, but not at the same time

Genic balance system

Sex-determining system in which sexual phenotype is controlled by a balance between genes on the X chromosome and genes on the autosomes.

X: A ratio

Ratio of the number of X chromosomes to the number of haploid autosomal sets of chromosomes; determines sex in fruit flies.

Turner syndrome

Human condition in which cells contain a single X chromosome and no Y chromosome (XO). Persons are female in appearance but do not undergo puberty and have poorly developed female secondary sex characteristics; most are sterile but have normal intelligence.

Klinefelter syndrome

Human condition in which cells contain one or more Y chromosomes along with multiple X chromosomes (most commonly XXY but may also be XXXY, XXXXY, or XXYY). Persons are male in appearance but frequently possess small testes, some breast enlargement, and reduced facial and pubic hair; often taller than normal and sterile, most have normal intelligence.

Triplo-X syndrome

Human condition in which cells contain three X chromosomes. A person has a female phenotype without distinctive features other than a tendency to be tall and thin; a few without distinctive features other than a tendancy to be tall and thin; a few such women are sterile, but many menstruate regularly and are fertile.

Sex-determining region Y (SRY) gene

On the Y chromosome, a gene that triggers male development.

Sex-linked characteristic

Characteristic encoded by autosomal genes and expressed in only one sex. Both males and females carry genes for sex-limited characteristics, but the characteristics appear in only one of the sexes.

X-linked characteristic

Characteristic determined by a gene or genes on the X chromosome.

Y-linked characteristic

Characteristic determined by a gene or genes on the Y chromosome.

Hemizygosity

Possession of a single allele at a locus. Males of organisms with XX-XY sex determination are hemizygous for X-linked loci because their cells possess a single X chromosome.

Nondisjunction

Failure of homologous chromosomes or sister chromatids to separate in meiosis or mitosis.
When this happens with the Xs, half of the eggs receive two copies of the X chromosome and the other half receive only a Y chromosome

Dosage compensation

Equilization in males and females of the amount of protein produced by X-linked genes. In placental mammals, dosage compensation is accomplished by the random inactivation of one X chromosome in the cells of females.

Barr body

Condensed, darkly staining structure that is found in most cells of female placental mammals and is an inactivated X chromosome.

Lyon hypothesis

Proposes that one X chromosome in each female cell becomes inactivated (a Barr body) and suggests that which of the X chromosomes becomes inactivated is random and varies from cell to cell.

Egg

DNA
All of cell stuff
Larger than sperm

sperm

Only DNA
Small

Monoecious

both male and female reproductive structures in the same organ

dioecious

Either male of female parts

genic sex determination

genotypes at one or more loci determine the sex of an individual
Not a particular chromosome
plants, fungi, protozoans, fish

Environmental sex determination

the environment determines sex of offspring
Temp in turtles
Limpets position in stack

X:A Ratio

greater than 1-metafemale-most die
1 Female
1-0.5 Intersex-mix of traits
0.5 Male
Less than 0.5 Metamale-weak and sterile

Reciprocal cross

a cross in which the phenotypes of the male and female are reversed compared with a prior cross