Sexual Reproduction


Terms in this set (...)

Sex cells. 1/2 the number of chromosomes of a body cell
Sexual reproduction
Genetic variation
Production of gametes
Gametes female
Gametes male
Sperm production, takes place in testes and makes for 4 monoploid cells
Egg production, takes place in ovary, makes 1 functional monoploid cell and 3 nonfunctional polar bodies
Monoploid or haploid
1/2 the normal number of chromosomes
2 divisions resulting in 4 monoploid cells
Homologous Pairs
A pair of chromosomes that carry corresponding genes for the same traits
Crossing over
During meiosis homologous pairs may swap genes = genetic diversity
Genetic recombination
Swapping genes resulting in diversity
Non disjunction
When homologous chromosomes fail to separate during meiosis, causes mutation in chromosome
Steps to meiosis
1.chromosomes replicate 2.genes cross over 3. Chromosomes separate
Interphase 1
Replication of genetic information
Prophase 1
Homologous chromosomes one from each parent pair up to form a tetrad, crossing over occurs
Metaphase 1
Tetrad a line up in the middle
Anaphase 1
Homologous chromosomes are pulled apart by spindle fibers
Telophase 1
2 new nuclei containing double stranded chromosomes (2n), cytokinesis occurs and 2 cells are formed
Prophase 2
2n daughter cells from first meiotic cell division prepare for the second division
Metaphase 2
Chromosomes line up in the middle
Anaphase 2
Sister chromatids are pulled apart by spindle fibers
Telophase 2
4 (n) nuclei are formed, cytokinesis occurs to produce haploid gametes
Each has (n) number of chromosomes in the nucleus, the haploid number
Where gametes are produced
Male gonad
Testes (located inside the scrotum)
Pouch that holds two testes away from body to keep them cooler for optimum sperm production
Tubes connecting testes to vas deferens where sperm matures
Vas deferens
Sperm duct;tube that transports sperm during ejaculation
Cut vas deferens to prevent sperm in ejaculation (only secretory fluids released)
Cowlper's gland
Secretes fluid to aid in sperm movement
Seminal vesicle
Secretes nourishing fluid
Prostate gland
Located below bladder, surrounds urethra, contracts to prevent urine in ejaculation, secretes fluid that neutralizes pH of vagina
Sperm + fluids
Part of both male and female reproductive and excretory systems, passage for semen and urine out of the body
Allows for internal fertilization
Femal gonad
Produces eggs
Fallopian tubes
Oviduct; transports egg to uterus by peristalsis , where fertilization takes place
Muscular organ where embryo implants
Opening leading from uterus to vagina , during labor this dilates to allow baby to pass through
Birth canal place where baby passes out of mothers body during birth, place where sperm is deposited
Pituitary gland
Stimulates other glands to release hormones
Stimulates the development of male sex organs & secondary sex characteristics
FSH/follicle stimulation hormone
Stimulates the growth of a follicle
Bunch of cells where an egg matures
Stimulates uterine wall thickening (preparing for possible embryo)
LH/ luteinizing hormone
Stimulates formation of the corpus luteum & triggers ovulation (egg released from ovary)
Triggers final preparation of the uterine walls
Days 1-14
High FSH-egg matures
Release of estrogen-uterine wall thickens
Day 14
High LH levels-egg is released
Days 14-28
1.Corpus luteum secretes progesterone- thickens uterine wall releases hormones for embryonic development 2. If no pregnancy occurs: progesterone levels decrease then
Decrease of progesterone cause of uterine wall
Sperm (n) meets egg (n) forms zygote (2n)
External fertilization
Occurs outside the body of the female ex: aquatic animals
Internal fertilization
occurs inside the body of the female ex: terrestrial animals
internal fertilization characteristic
protective of young
animals whose young are born in an immature state, females carry young in pouches, newborn attaches to her nipples and gains nutrients from her milk until it has grown.
In Vitro fertilization
mature ova and sperm are fertilized in a petri dish in a lab
How does the zygote grow into an embryo?
Cleavage, series of rapid mitotic divisions
Solid ball of cells
Hollow ball of cells
Blastocyst implants on wall of uterus Days 6-7
Indented blastula in which cells are positioned as they will be in the adult
Digestive and respiratory linings
Gene regulation
The presence of hormones and chemicals during embryonic development can switch on genes. This determines the cells function
Specialization of embryonic cells, genes get turned on
Day 21
Embryo has body systems
Transports nutrients and oxygen to baby from mom and wastes and carbon dioxide to mom from baby, no blood mixes
Umbilical cord
A structure in placental mammals that contains blood vessels connecting the placenta to the embryo
Membrane that surrounds the embryo and contains fluid that protects the developing embryo
Amniotic fluid is withdrawn and analyzed for genetic mutations in developing fetus
Embryonic development
Chorion-outer membrane for protection, inside forms fetal side of placenta
Chorionic villus sampling (CVS)
Chorionic villi , small fingerlike projections, our snipped off, and since they are a fetal origin, they can be analyzed to see the genetic makeup of the fetus
Factors that affect fetal development
Diet, smoking, alcohol, drugs
Monozygotic identical twins
One sperm fertilizes one egg to form one zygote that splits, clones
Dizygotic fraternal twins
Two eggs fertilized by two different sperm