Chapter 4: Sex Determination and Sex-Linked Genes

sexual reproduction

reproduction that results in genetically distinct parents

sperm and ovum

what are the gametes?

female gametes

larger and less mobile gametes

male gametes

smaller and more mobile gametes

phenotype

sex is a ______

no because they can have two X chromosomes so they have calico coloration, but also have a Y chromosomes which is male phenotype

are calico cats always female?

monoecious

produces male and female gametes on the same flower

dioecious

distinct male and female individuals that make their respective gametes

genetically, chromosomally, or envrionmentally

how can sex be determined?

passes on a new generation before possibly dying out

female cannabis plants can become hermaphrodites if conditions are stressful, why is this adaptive?

chromosomal sex determination

sex is inherited like other genetically determined characteristics; genes are on chromosomes

sperm

which gamete determines the sex of offspring?

homogametic

organism that produces one type of sex chromosome

heterogametic

organism that produces two different sex chromosomes

females

what is the homogametic sex in humans?

female

what is the homogametic sex in grasshoppers? (XO system)

males

who is the homogametic sex in birds, butterflies, snakes, and some fishes? (ZW system)

autosomes

all other chromosomes besides sex chromosomes

sex chromosomes

chromosomes that determines an organisms sex

psudoautosomal region

homologous nucleotide sequences at the tips of the X and Y chromosomes in mammals that allow for pairing and recombination during male meiosis

X from mom and Y from dad

which sex chromosome comes from which parent?

SRY

which gene determines maleness?

turner syndrome

XO; disease affecting ~1/3000 female births, resulting in underdeveloped secondary sex characteristics, sterility, shortness, low hairline, broad chest, and folds on skin on neck

required for survival

no one has ever been known to lack both X chromosomes, what does this imply about the X chromosome?

klinefelter syndrome

multiple Xs and at least 1 Y; affects about ~1/1000 male births and causes small gonads, reduced hair, tallness, and sterility

poly-x females

triple-x syndrome or more (rare); ~1/1000 female births leading to tallness, thinness, sterility (rare) and intellectual disability (rare), however has you increase the number of Xs you have more severe intellectual disabilities and various physical problems

at least one X is required for development, no Y leads to a female phenotype, fertility related genes are on the X and Y chromosome and females need both Xs to be fertile, extra Xs lead to developmental disruption and various health issues

what are some general conclusions we can make about sex chromosome numbers?

true

T/F": male-determining gene is on the Y and males can have multiple Xs as long as they have a Y