3.9b Female Reproductive System

Uterus generally small (size of orange) before pregnancy

1. Ovary - Meiosis - produces gametes (eggs)
2. Oviducts - Carry eggs to uterus
- Location where fertilisation takes place (in green)
3. Wall of uterus (muscle) - stretches during pregnancy and contracts during childbirth
4. Lining of uterus - accepts and develops egg -> embryo -> child (placenta)
5. Cervix - entrance to uterus for sperm
6. Uterus space - place where embryo develops
7. Vagina - Collects sperm cells

3.9a Male Reproductive System

Recall the structure and function of the male and female reproductive systems

1. Bladder - Stores urine

2. Testis - Meiosis (produces gametes - sperm cells)

3. Epididymis - Stores sperm cells

4. Vas deferens - Carries sperm cells to penis (tube)

5. Prostate - adds 20/30% of volume of semen, contains sugars, alkali (neutralise acidic secretions within vagina)

6. Seminal Vesicles - 70% of semen, contains "
Sperm cells are combined with prostate and seminal vesicle secretions to create semen

7. Urethra - Takes semen down penis, also exit for urine

8. Penis - Carry sperm cells into vagina during sexual intercourse

3.12 Amniotic fluid

Understand how the developing embryo is protected by amniotic fluid

Surrounding embryo - Amniotic fluid

Protects embryo
Fluid (largely water)
- Cannot be compressed
- Absorbs pressure

Prevents damage to embryo

Source

3.11 Placenta

Describe the role of the placenta in the nutrition of the developing embryo

Uterus - water-filled environment (amniotic fluids)

Embryo can't digest, breathe or excrete

Placental structure:
- Umbilical cord
Blood vessels lead from embryo (via umbilical cord) to placenta

Source

Placenta grows out of embryo
Grows into wall of uterus

Glucose, amino acids, fats etc.
Travels through maternal blood vessel
Taken into embryo through placenta

Mother's blood -> placenta -> embryo's blood

Source

Efficiency
1. Large surface area
2. Thin barrier

CO2/Urea produced by embryo
Travels into mother via placenta

3.24c Mitosis 3

Stages of Mitosis

1. Interphase - Resting stage
DNA replication
Unable to see chromosomes

2. Prophase - Nucleus membrane breaks down
Chromosomes are now visible
Pair of chromatids
Beginning of mitosis

3. Late Prophase - Chromatids move towards spindles
Network of protein molecules (Spindle / fibres)
Extend from one pole of the cell to the other

4. Metaphase - Centramere joins to spindle fibre
Chromosomes are in the middle

5. Anaphase - Separation of the pair of chromatids
Spindle fibre shortens
Pulls chromatids apart
Move to the poles of the cell

6. Telophase - End of mitosis
Nucleus begins to reform around the chromosomes
Formation of two nuclei
Two sets of chromosomes at opposite ends of the cell

=======

Cytokinesis - Cell splits into two
NOT part of mitosis
Membrane fuses across the equator to form two new cells
Both cells have one chromosome - Same as the parental cell

Source: http://www.ba-education.com/dna/mitosis.jpg

3.24b Mitosis 2

How are copies of chromosomes made?

DNA replication
- Chromosome copies itself
- Held together by centromere
- 'Pair of chromatids'

Source: http://www.youtube.com/watch?v=f3c36gGDlRg

- Takes place inside the nucleus when it is still intact
- Process cannot be seen
- Interphase of cell cycle

3.24a Mitosis 1

Understand that division of a diploid cell by mitosis produces two cells which contain identical sets of chromosomes

Mitosis - Form of cell division -> Growth / Increase in the number of cells

Number of chromosomes in a cell - Diploid number (2n)
Humans - 2n = 46
Cats - 2n = 38
etc…

After cell division
- Each cell has a diploid nucleus
- Both cells are identical / daughter cells
- Inside the nuclei:
1. Same number of chromosomes
2. Same set of chromosomes (Duplicated)

Source: https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjEHtB-J0eLzuY29DfQ-kV0iHFOg9UHrLKaXA8FLJPA1bIAkVROoYAzl_Cy-bD403KqMyVNoFlGrEXqbInMT57_F6IVASWO1c5UOfgeZ0bOqd-wtAIBiR6qFR99zSIuXebd7igkfPPrWK4/s320/mitosis.gif