Final Flashcards
Types of Asexual Reproduction
- Binary Fission- amoeba, bacteria, ecoli
- Budding- yeast
- Spore Formation- fungi
- Fragmentation- flatworms (annelids)
- Vegetative Reproduction
- Parthenogenesis (virgin birth)- some reptiles
Advantages of Asexual Reproduction
- Efficient
- Don’t need to spend time finding a mate
- All organisms can reproduce
Disadvantages of Asexual Reproduction
- Lack of Genetic Diversity
- All organism respond same way to the environment
- Organisms lack the ability to adapt to changing environment
“Two fold cost of sex” Hypothesis
Only one half of the population is suitable to give birth, the other half is useless
Advantages of Sexual Reproduction
- Creates Genetic Diversity
- Genetic Variation: gives at least some members of a population an opportunity to survive a deadly disease or adverse scenario
- DNA repair: removing DNA damage by recombinational DNA repair during meiosis
Red Queen Hypothesis
It takes all the running you can do to keep in the same places which means that a population as a whole needs to continuously adapt to keep up with conditions and parasites
Origin of Sexual Reproduction
Protoeukaryote- Last eukaryotic common ancestor (LECA)
Basis of Sexual Reproduction (Meiosis) entails..
- Alteration of Ploidy
- Origination of Gametes
- Mating type regulated transmission of organelle genomes
Alteration of Ploidy
Increase in genome size and ploidy: more information to work with , increase in the genome size favors experimentation- allows for positive selection and accumulation of favorable mutations- allows for positive selection and accumulation of favorable mutations
Origin of the Gametes
Anisogametes (different gametes) and the recognition of “self” vs. “non self” is one of the key reasons for the origin of eukaryotic sex
Regulation of Organelle Genomes
Organelles such as mitochondria are only inherited from one sex. The rational is that the fusion of gametes would generate diploid zygotes with twice the organelle-genome tally- this guards against “heteroplasmy”, the presence of two or more different organelle genomes in the same organism
Types of Reproductive Processes: Oviparous
Female lay eggs which hatch outside the body (birds, fish)
Types of Reproductive Processes: Ovoviparous
Give birth to live young which hatch from eggs inside the body (snakes, lizards, and amphibians)
Types of Reproductive Processes: Viviparous
Give birth to live young which are nourished by contact between placenta and uterus (mammals)
Mammalian Reproduction Variations
- Induced vs Spontaneous Ovulation
- Delayed Fertilization (out of hibernation)
- Delayed Implantation (Embryonic diapause), (bears, seals, small carnivores, seals and sea lions), males and females often separate while foraging, copulation occurs when both sexes together on land during birth period: two types- obligate, facultative
- Spontaneous Abortion (Bruce Effect): the tendency for female rodents to terminate their pregnancies following exposure to the scent of an unfamiliar male
- Monozygotic Polyembryony
- Environmental control of gestation length
- Menopause
- Intrafollicular Fertilization
Endocrine Glands
Directly released into blood stream or lymph, ductless
ex. anterior pituitary
Exocrine Glands
Secretes many types of substances; have ducts; sweat, oil, wax, enzymes
ex. endometrial secretion of uterine milk
Paracrine Cell Hormone Communication
Hormone stimulates adjacent cells without entering the blood- releasing hormones
Autocrine Cell Hormone Communication
Hormone stimulates the same cell that secretes the hormone
Juxtacrine Cell Hormone Communication
Hormone stimulates the cell in contact- notch signaling
Intracrine Cell Hormone Communication
Hormone acts within the cell- steroid hormones
Classification of Hormones
- Source of origin
- Target Tissues
- Mode of action
- Biochemical Classification
Origin of:
Hypothalamus-
Pituitary-
- neuronal
- neuronal and endodermal
Terminology: Hypothalamus- Pituitary- Posterior Lobe of Pituitary- Anterior Lobe of Pituitary- Pituitary Stalk-
- Diencephalon
- Hypophysis
- Neurohypophysis, pars nervosa
- Adenohypophysis, pars distalis
- infundibulum, pars tuberalis
Connection between Anterior and Posterior
Pituitary has distinct nuclei that ends in the posterior.
Portal system- two capillary systems that are connected
Function of the hypothalamus
Regulates homeostasis, in reproduction its the regulator of the pituitary gland
Relationship between hypothalamus and pituitary
For every hormone released by the pituitary, there is a corresponding releasing hormone in the hypothalamus
Classification of GnRH
- made by the hypothalamus
- acts on the anterior pituitary
Classification of FSH/LH
-made by the anterior pituitary
-acts on the gonads
-control of reproductive function
LH- stimulates progesterone, FSH-stimulates growth hormones
Classification of Oxytocin
- made by hypothalamus
- stored by posterior pituitary
- acts on the ovary and testis for uterine contractions and to stimulate milk ejection
Classification of Prolactin
- made in the anterior pituitary
- targets the mammary gland
- milk production
Different types of neurohormones
Releasing, gonadotropins, sexual promotion, pregnancy maintenance, parturition, luteolysis
Example of releasing hormone
GnRH
Example of Gonadotropins
FSH, LH
Example of Sexual promotion and secondary sex characteristic hormones
estradiol, testosterone
Example of pregnancy maintenance hormone
progesterone, placental lactogen
Example of parturition hormones
oxytocin, relaxin
Example of a luteolysis hormone
PGF2a
What is a neurohormone
a hormone that is produced and released by neurons
Structures of hormones
- peptides- produced by hypothalamus, 11 amino acids, small
- glycoproteins- produced by pituitary
- steroid
- prostaglandin
What does structure say about function or origin of hormones
if produced by the hypothalamus then they are small peptides, if produced by the pituitary then they are glycoproteins
Role of GnRH
Promotes the release of FSH and LH at appropriate times in both sexes
What is GnRH stimulated by?
Estrogen ( surge center), Leptin
What is GnRH inhibited by?
- progesterone, testosterone, and estrogen (tonic center)
- estrogen inhibits GnRH release in the tonic center and stimulates it in the surge center
- estrogen in rapid pulses suppresses the tonic center
Effects of Oxytocin in the female
- Targets myometrium and endometrium, increases uterine tone
- promotes uterine PGF2a synthesis
- Milk let down
- Stimulates maternal behavior and bonding
Effects of Oxytocin in the male
- pre-ejaculatory movement spermatozoa in epidimal tail, ductus deferens, and ampulla
- Promotes PGF2a synthesis
Glycoproteins
-FSH, LH
- made of carbohydrate and protein: means they are antigenic and will degrade
- structure has 2 subunits: alpha which is different for each species and Beta which is unique for each hormone but the same in every species
(alpha tells you which species you are beta tells you which hormone you are)
FSH (Follicle Stimulating Hormone)
- Gonadotropin
- synthesized in the anterior pituitary
- glycoprotein
- targests gonands