Meiosis, Gametogenesis and Reproduction Flashcards
Know the stages of meiosis and a brief statement about what occurs in each stage.
Meiosis I: Reductional division (reduced in 1/2) into 2 daughter cells. (diploid to haploid)
Meiosis II: Equational division: 4 cells with 2 chromatids each.
When does crossing over occur in meiosis?
During Prophase I
When do the centromeres divide in meiosis?
Anaphase II
When does independent assortment occur in meiosis?
Anaphase I (maternal and paternal chromosomes divide to each pole)
What is synapsis and when does it occur in meiosis?
Prophase I (Pairing of 2 homologous chromosomes)
Meiosis causes an increase in variability from generation to generation in two ways. Describe these 2 ways.
Crossing over
Independent assortment
Relate oogonium to meiosis and know the number of chromosomes it has.
Diploid: Goes through mitosis to form the primary oocyte
Relate primary oocyte to meiosis and know the number of chromosomes it has.
Diploid: Goes through meiosis I to form polar body and secondary oocyte
Relate secondary oocyte to meiosis and know the number of chromosomes it has.
Haploid: Goes through meiosis II to form gametes
Relate ootid to meiosis and know the number of chromosomes it has.
Haploid: The cell that matures into an ovum
Relate ovum to meiosis and know the number of chromosomes it has.
Haploid: the egg
Relate spermatogonium to meiosis and know the number of chromosomes it has.
Diploid: Goes through mitosis
Relate primary spermatocyte to meiosis and know the number of chromosomes it has.
Diploid: Goes through meiosis I
Relate secondary spermatocyte to meiosis and know the number of chromosomes it has.
Haploid: Goes through meiosis II
Relate spermatid to meiosis and know the number of chromosomes it has.
4 Haploid cells that mature to become sperm
Relate sperm to meiosis and know the number of chromosomes it has.
Final product of Spermatogenesis
Other than the terminology and the fact that one occurs in males and the other in females, describe several differences between oogenesis and spermatogenesis.
Location: female ovaries/fallopian tubes vs. male testis
# of functional gametes: 1 female and 4 male
Female: Discontinuous, Male: Continuous
Females form 400-500 gametes, Males form billions per week
Approximately how may sperm can a healthy college-aged male make per week?
About a billion per week
How long does the process of spermatogenesis take?
48 days
True or False: Oogenesis is a noncontinuous process.
True
What is a polar body?
The byproduct of Oogenesis
Oogenesis stalls prior to birth in females. At which stage of meiosis does oogenesis stall?
Prophase I
About how many primary oocytes does a female have at birth? About how many will she ovulate during her life?
500,000 to 750,000
Where does meiosis occur in each sex (what tissues)?
Female: ovaries/fallopian tubes
Male: Testies
Which sex is more likely to produce gametes with the incorrect chromosome number?
Females
Which sex is more likely to produce gametes with a new mutation?
Males
What is nondisjunction and how does it effect gamete production?
Mistakes in separation of chromosomes in meiosis causing mutations
Be familiar with the anatomy of the male and female reproductive system at the level discussed in lecture.
a
Describe the relative sizes of the egg and sperm.
Egg: size of a period on a piece of paper
Sperm: 60 Microns
Which (egg or sperm) contains more genetic information? Why?
Both the same because they both carry 1/2 of the genetic info from each parent: 23 chromosomes each to make 46.
Where are sperm made? Where are eggs made?
Sperm: testis
Egg: ovary/fallopian tube
About how many sperm are typically deposited into the vagina during sexual intercourse?
200 million
Approximately how many sperm reach the egg?
50
What are some of the barriers that a sperm faces when it tries to reach the egg?
Acid from the inner lining of the uterus,
mutations,
crowding
Where does fertilization occur? Distinguish between fertilization and syngamy.
In the uterus or fallopian tube.
Syngamy occurs after fertilization where the nuclei of the egg and sperm fuse to form a zygote. Upper 1/3 of oviduct.
About how long after fertilization does implantation occur? Where does implantation occur?
In the uterus about a week after fertilization.
About how long after fertilization does the placenta start to develop?
Second week after fertilization
Whose cells (mother’s or baby’s) are use to make the following structures: placenta, umbilical cord, chorion, amnion?
Placenta: both mother and embryo
Umbilical cord: baby’s blood
Amnion: inner membrane
Chorion: outer membrane
Whose gamete determines the sex of the baby - Mom’s or Dad’s?
Dads
The developing child is called an embryo up to 8 weeks after fertilization. From 8 weeks to birth, the developing child is called a fetus.
a
Identify the meaning of AID and AIH. Be able to give an example of when each could be used.
Artificial Insemination by Donor
Artificial Insemination by Husband
What does CVS stand for?
Chorionic Villus Sampling
Describe the process of CVS.
Catheter is inserted into mother’s cervix,
cells are collected from the chorion membrane,
6-10 weeks of pregnancy,
1 in 100 miscarriage
Describe the process of amniocentesis.
Amniotic fluid removed,
14-18 weeks pregenant,
cells from fetus are cultured,
1 in 200 miscarriage
Compare the pros and cons of CVS and amniocentesis. What factors would you need to consider if you had to choose one of these procedures over another?
1:100 vs. 1:200 miscarriage
Early pregnancy vs. later in pregnancy
Cost the same
Rank these in order of least risky to the fetus to most risky: amniocentesis, fetoscopy, ultrasound, CVS
Ultrasound, amniocentesis, CVS and fetoscopy
What are some ethical concerns regarding in vitro fertilization and pre-implantation genetic diagnosis?
How many embryos should the doctor implant?
Having a child just for a bone marrow transplant for another child?
What guidelines are used regarding in vitro fertilization?
Guidelines on how many embryos to implant based on age and other factors
What is a “favorable” situation regarding IVF?
Embryos haven’t been frozen, good quality, first cycle, previous success with IVF
