Bio 5B Animal Reproductive systems

sexual reproduction in mammals

Copulatory organ in males (penis).

Testis usually in scrotum (suspended sack of skin and smooth muscle).

-Internal fertilization.

-Most viviparous.

-Amnion, chorion and allantoids

Hormonal levels determine expression of distinctive sexual characteristics

sexual dimorphism

Differences in physical characteristics between males and females of the same species.

size, coloration, morphology

Diploid

Contains two full sets of chromosomes, one set is inherited from each parent. Humans: 46 chromosomes

haploid

Contain just one set of chromosomes.

Gametes: Sperm cells and egg cells required for sexual reproduction

mitosis

Final product: 2 diploid daughter cells (2n) identical to the mother cell

sexual anisogamous reproduction

Recombination of genetic material from two individuals to create a third individual. Needs fertilization of an egg.

In humans:
- Eggs fertilized by X-bearing sperm become females (XX).
- Eggs fertilized by Y-bearing sperm become males (XY)

sex assignments in humans

A newborn baby is assigned a "biological sex" that reflects the genitals present at birth and the child's chromosomes

hormonal cycles in females

Hormonal fluctuations and specific periods of fertility.

menstrual cycle...
Luteinizing hormone, FSH, estrogen, progesterone

ovarian cycle in female humans

hormonal fluctuations and specific periods of fertility

hypothalamus= GnRH

Pituitary
- LH: Luteinizing hormone
-FSH: follicle stimulating hormone

ovaries= growing follicle, estrogen and progesterone

uterine menstrual cycle

LOOK AT PHOTO

sexual reproduction

-Isogamous: the fusion of morphologically similar gametes, having similar shapes and sizes

-Anisogamous: Dioecious (male and fem)
hermaphroditic (monoecious)

asexual reproduction

- Fission (bacteria)

- budding (marine invertebrate)

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- parthenogenesis (large animals and all-female, they have one stimulus that makes the development of an egg

sexual reproduction in spiders

Dioecious (male and female)

The male uses special cavities in his pedipalps and

*PEDIPALPS TRANSFER SPERM (look at photo)

sexual reproduction in insects

• Dioecious.
• release of Pheromones, courtship behavior, etc

sexual reproduction in vertebrates

external fertilization (fish release sperm into water)

internal fertilization (elephants have sex) birds, lizards

meiosis

Final product: 4 haploid daughter (n) cells not identical to the mother cell

A cell division in which the genetic information in the new cells is not identical to that of the original cell, "scrambles genetic information".

It results in cells with half the chromosomes of the parent cell, produces 4 daughter haploid cells, genetically variable and used in reproduction

human genotype

Total of 46 chromosomes per somatic cell: Diploid number: Two sets of chromosomes per cell. Only gametes are Haploid: 23 chromosomes per gamete

you can tell if male or female with 23rd chromosome
female: XX
male XY

(look at photo)

pregnancy in eutherian mammals

Well-developed chorioallantonic placenta.

• Long gestation period in the uterus

Uterus: Muscular organ of the female reproductive system

Placenta: The vascular structure, both embryonic and maternal through which the fetus is nourished

Parental care in mammals

young may be altricial (completely dependent on mother ex: birds) or precocial (can walk immediately ex: zebra

components in milk produced by female mammals or women

the initial milk produced (colostrum) contains

- antibodies (immunoglobin, IgA)
- lactoferrin (protein: bactericide, fungicide)
- white blood cells