Meiosis, Gametogenesis and Reproduction

Question 1

Know the stages of meiosis and a brief statement about what occurs in each stage.

Answer 1

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.

Question 2

When does crossing over occur in meiosis?

Answer 2

During Prophase I

Question 3

When do the centromeres divide in meiosis?

Answer 3

Anaphase II

Question 4

When does independent assortment occur in meiosis?

Answer 4

Anaphase I (maternal and paternal chromosomes divide to each pole)

Question 5

What is synapsis and when does it occur in meiosis?

Answer 5

Prophase I (Pairing of 2 homologous chromosomes)

Question 6

Meiosis causes an increase in variability from generation to generation in two ways. Describe these 2 ways.

Answer 6

Crossing over

Independent assortment

Question 7

Relate oogonium to meiosis and know the number of chromosomes it has.

Answer 7

Diploid: Goes through mitosis to form the primary oocyte

Question 8

Relate primary oocyte to meiosis and know the number of chromosomes it has.

Answer 8

Diploid: Goes through meiosis I to form polar body and secondary oocyte

Question 9

Relate secondary oocyte to meiosis and know the number of chromosomes it has.

Answer 9

Haploid: Goes through meiosis II to form gametes

Question 10

Relate ootid to meiosis and know the number of chromosomes it has.

Answer 10

Haploid: The cell that matures into an ovum

Question 11

Relate ovum to meiosis and know the number of chromosomes it has.

Answer 11

Haploid: the egg

Question 12

Relate spermatogonium to meiosis and know the number of chromosomes it has.

Answer 12

Diploid: Goes through mitosis

Question 13

Relate primary spermatocyte to meiosis and know the number of chromosomes it has.

Answer 13

Diploid: Goes through meiosis I

Question 14

Relate secondary spermatocyte to meiosis and know the number of chromosomes it has.

Answer 14

Haploid: Goes through meiosis II

Question 15

Relate spermatid to meiosis and know the number of chromosomes it has.

Answer 15

4 Haploid cells that mature to become sperm

Question 16

Relate sperm to meiosis and know the number of chromosomes it has.

Answer 16

Final product of Spermatogenesis

Question 17

Other than the terminology and the fact that one occurs in males and the other in females, describe several differences between oogenesis and spermatogenesis.

Answer 17

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

Question 18

Approximately how may sperm can a healthy college-aged male make per week?

Answer 18

About a billion per week

Question 19

How long does the process of spermatogenesis take?

Answer 19

48 days

Question 20

True or False: Oogenesis is a noncontinuous process.

Answer 20

True

Question 21

What is a polar body?

Answer 21

The byproduct of Oogenesis

Question 22

Oogenesis stalls prior to birth in females. At which stage of meiosis does oogenesis stall?

Answer 22

Prophase I

Question 23

About how many primary oocytes does a female have at birth? About how many will she ovulate during her life?

Answer 23

500,000 to 750,000

Question 24

Where does meiosis occur in each sex (what tissues)?

Answer 24

Female: ovaries/fallopian tubes
Male: Testies

Question 25

Which sex is more likely to produce gametes with the incorrect chromosome number?

Answer 25

Females

Question 26

Which sex is more likely to produce gametes with a new mutation?

Answer 26

Males

Question 27

What is nondisjunction and how does it effect gamete production?

Answer 27

Mistakes in separation of chromosomes in meiosis causing mutations

Question 28

Be familiar with the anatomy of the male and female reproductive system at the level discussed in lecture.

Answer 28

a

Question 29

Describe the relative sizes of the egg and sperm.

Answer 29

Egg: size of a period on a piece of paper Sperm: 60 Microns

Question 30

Which (egg or sperm) contains more genetic information? Why?

Answer 30

Both the same because they both carry 1/2 of the genetic info from each parent: 23 chromosomes each to make 46.

Question 31

Where are sperm made? Where are eggs made?

Answer 31

Sperm: testis Egg: ovary/fallopian tube

Question 32

About how many sperm are typically deposited into the vagina during sexual intercourse?

Answer 32

200 million

Question 33

Approximately how many sperm reach the egg?

Answer 33

50

Question 34

What are some of the barriers that a sperm faces when it tries to reach the egg?

Answer 34

Acid from the inner lining of the uterus, mutations, crowding

Question 35

Where does fertilization occur? Distinguish between fertilization and syngamy.

Answer 35

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.

Question 36

About how long after fertilization does implantation occur? Where does implantation occur?

Answer 36

In the uterus about a week after fertilization.

Question 37

About how long after fertilization does the placenta start to develop?

Answer 37

Second week after fertilization

Question 38

Whose cells (mother’s or baby’s) are use to make the following structures: placenta, umbilical cord, chorion, amnion?

Answer 38

Placenta: both mother and embryo Umbilical cord: baby's blood Amnion: inner membrane Chorion: outer membrane

Question 39

Whose gamete determines the sex of the baby - Mom’s or Dad’s?

Answer 39

Dads

Question 40

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.

Answer 40

a

Question 41

Identify the meaning of AID and AIH. Be able to give an example of when each could be used.

Answer 41

Artificial Insemination by Donor | Artificial Insemination by Husband

Question 42

What does CVS stand for?

Answer 42

Chorionic Villus Sampling

Question 43

Describe the process of CVS.

Answer 43

Catheter is inserted into mother's cervix, cells are collected from the chorion membrane, 6-10 weeks of pregnancy, 1 in 100 miscarriage

Question 44

Describe the process of amniocentesis.

Answer 44

Amniotic fluid removed, 14-18 weeks pregenant, cells from fetus are cultured, 1 in 200 miscarriage

Question 45

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?

Answer 45

1:100 vs. 1:200 miscarriage Early pregnancy vs. later in pregnancy Cost the same

Question 46

Rank these in order of least risky to the fetus to most risky: amniocentesis, fetoscopy, ultrasound, CVS

Answer 46

Ultrasound, amniocentesis, CVS and fetoscopy

Question 47

What are some ethical concerns regarding in vitro fertilization and pre-implantation genetic diagnosis?

Answer 47

How many embryos should the doctor implant? | Having a child just for a bone marrow transplant for another child?

Question 48

What guidelines are used regarding in vitro fertilization?

Answer 48

Guidelines on how many embryos to implant based on age and other factors

Question 49

What is a “favorable” situation regarding IVF?

Answer 49

Embryos haven't been frozen, good quality, first cycle, previous success with IVF