Chapter 7: Fertility

What is a gamete?

A gamete is a reproductive cell that contains half as many chromosomes as a somatic cell.

Where are gametes produced?

Gametes are produced in the paired gonads, such as the ovaries or testicles.

What type of cell division gives rise to gametes?

Meiosis is the type of cell division that gives rise to gametes.

What is the difference between diploid (2n) and haploid (n) cells?

Diploid cells have a full set of chromosomes, while haploid cells have a reduced number of chromosomes resulting from meiosis.

How many chromosomes are in human somatic cells?

Human somatic cells contain 46 chromosomes.

How many chromosomes do human gametes have?

Human gametes, such as sperm and egg cells, contain 23 chromosomes.

What happens to the chromosome number during meiosis?

The chromosome number is reduced, beginning with diploid cells and ending with haploid cells.

What must occur before meiosis begins?

Meiosis is preceded by an interphase stage in which the DNA is replicated.

How many rounds of division occur in meiosis compared to mitosis?

Meiosis involves two rounds of cell division, whereas mitosis involves only one round of division.

What is separated during meiosis I?

Meiosis I separates the members of one homologous pair of chromosomes from each other.

What is the state of a cell after telophase I of meiosis?

Each daughter cell is haploid, and the chromosomes are composed of two sister chromatids.

What is separated during meiosis II?

Meiosis II separates the sister chromatids of one chromosome from each other.

What is crossing over?

Crossing over is the exchange of genetic information between homologous pairs of chromosomes during prophase I of meiosis.

What is the consequence of crossing over and recombination?

It increases genetic diversity by increasing the number of genetically distinct gametes an individual can produce.

What is random alignment in meiosis?

The random alignment of members of a homologous pair at metaphase I regarding which member of a pair faces which pole.

What is the consequence of the random alignment of chromosomes?

It shuffles the combination of chromosomes a gamete receives, allowing humans to make over 8 million genetically different gametes.

What is meiotic nondisjunction?

Nondisjunction is the failure of chromosomes to separate properly during meiosis.

What is the consequence of meiotic nondisjunction?

It produces individuals with too many or too few chromosomes who are less fertile than those with 46 chromosomes.

How does age affect fertility in males and females?

Gamete production decreases with age, causing the time to pregnancy to increase.

When do egg cells begin developing in human females?

Egg cells begin developing inside the developing ovary while the female fetus is still inside its mother's uterus.

When does meiosis pause and resume in human females?

Meiosis pauses in females from their birth until puberty, and then it continues through the reproductive years.

What structural features do mature sperm develop?

Sperm mature and develop a head, a midpiece, and a tail or flagellum.

Where are sperm produced?

Sperm are produced in the seminiferous tubules inside each testis.

What is the function of the epididymis?

It stores sperm before they travel through the vas deferens to the urethra.

What path does a sperm cell follow during delivery?

A sperm cell travels from the seminiferous tubules to the epididymis, then through the vas deferens, and finally into the urethra.

What is semen?

Semen is composed of sperm combined with secretions from various glands.

Which glands add secretions to sperm to provide energy and aid development?

The seminal vesicles, prostate gland, and bulbourethral glands.

What is the function of the urethra in human males?

The urethra is a passageway that delivers both sperm and urine.

What is the correct term for the female external genitalia?

The vulva and clitoris.

What happens to an egg cell during ovulation?

A mature egg cell leaves the ovary and is ovulated into the oviduct, leaving behind the corpus luteum.

What path does an unfertilized egg cell follow?

An unfertilized egg cell travels from the ovary to the oviduct, into the uterus, and through the cervix.

What is the function of the cervix?

The cervix is located at the base of the uterus and secretes mucus that keeps sperm alive longer to aid fertilization.

What structure must a fertilized egg travel through to reach the uterus?

A fertilized egg cell must pass through the oviducts.

Where does a fertilized egg implant to develop?

A fertilized egg implants in the uterus.

How can sexually transmitted infections cause infertility?

They can cause tissue damage to the tube-like ducts that gametes move through, which blocks gamete movement and prevents fertilization.

Roughly how many genes are in the human genome?

There are roughly 20,000 genes in the human genome.

What does the root word "gon-", "gono-", or "gonado-" mean?

It means seed or generation.

What does the root suffix "-genesis" mean?

It means generation of or birth of.

What does the root prefix "homo-" mean?

It means the same.

What does the root prefix "oo-" mean?

It is from the Greek word for egg.

What do the roots "soma-" and "-some" mean?

They mean body.

What does the root suffix "-ploid" mean?

It means sets of chromosomes.

What does the root prefix "meio-" mean?

It means to make smaller.

What is the difference between sexual and asexual reproduction?

Sexual reproduction involves two parents and produces genetically unique offspring, while asexual reproduction involves a single parent and produces genetically identical offspring.

What are the odds for a newly born baby to be XX or XY?

There is a 50% chance for a baby to be XX (female) and a 50% chance to be XY (male), determined by whether the sperm carries an X or a Y chromosome.

What structure does a mature egg enter immediately after leaving the ovary?

The oviduct.

After traveling through the oviduct, where does an unfertilized egg go before exiting through the cervix?

The uterus.

Where do sperm travel immediately after being produced in the seminiferous tubules?

The epididymis (for storage and maturation).

What tube carries sperm from the epididymis to the urethra during delivery?

The vas deferens.