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MSU - BIOL 1144 - Spring 2018 - Bio 2 week 14 - Class Notes

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MSU - BIOL 1144 - Spring 2018 - Bio 2 week 14 - Class Notes

School: Mississippi State University
Department: Biology
Course: Biology II
Professor: Thomas Holder
Term: Spring 2015
Tags: Biology
Name: Bio 2 week 14
Description: These notes will be on the final.
Uploaded: 04/25/2018
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background image BIO 1144  4/17/18­4/24/18 I. Timing of reproduction  a. Combination of environmental cues and hormonal activity  b. Tropical species with stable temperatures and food supply may reproduce several 
times a year
c. Temperate animals have seasonal reproductive cycle reflecting fluctuations in 
environmental conditions 
d. Can synchronize production of offspring with favorable conditions by: i. Females storing sperm ii. Delaying ovulation and storing sperm  iii. Delaying implantation  iv. Seasonal mating followed by immediate implantation and pregnancy  II. Menstrual cycle (28­day uterine cycle)  a. *ovarian effects: (ovarian cycle)  i. Days 1­13: follicular phase (FSH is dominating hormone) ii. Day 14: ovulation  iii. Days 15­28: luteal phase (LH is dominating hormone)  b. *uterine cycle: (uterine cycle)  i. Days 1­5: menstrual phase (outer portions of endometrium slough off, 
discharged and loss of blood) 
ii. Days 6­14: proliferative phase (increasing estrogen and build­up of 
endometrium) 
iii. Days 15­28: secretory phase (increasing progesterone to maintain uterine 
lining build­up) 
III. 3 types of mammalian pregnancies a. Monotremes (like platypus) – lay eggs  3 mammal species  b. Marsupials (kangaroo, opossum) – extremely underdeveloped young must 
complete development in pouch, where nourishment is provided 
weak hormonal  system, 8­40 days gestation  c. Eutherian mammals – retain their young for a prolonged period and nourish 
young via placenta 
20 days – 19 months; enhanced hormonal system  IV. Pregnancy  a. First event in  implantation  i. In humans within 8­10 days of fertilization  b. Endometrial glands provide initial nutrients  c. Placenta then develops from combination of maternal and fetal tissue  d. Placenta’s fetal portion  (chorion) has chorionic villi providing a large surface  area for exchange of gases, nutrients, and other solutes  e. Blood of mother and fetus  do not mix  V. Animal development (c. 52)  a. Embryonic development 
background image b. Cellular differentiation  c. Most animals have similar embryonic development process  d. Most higher animals develop with 3 germ layers (tissue layers) (triploblastic)  endoderm, mesoderm, ectoderm e. 5 stages of development i. 1. Fertilization  ii. 2. Cleavage iii. 3. Gastrulation  iv. 4. Neurulation  v. 5. Organogenesis  vi. *some animals may also include larval form  f. Figure 52.1 VI. Event 1: fertilization a. Initial contact of egg and sperm followed by  acrosomal reaction  i. Enzymes dissolve jelly­like layer allowing sperm to contact the plasma 
membrane of the egg
b. Sperm head fuses with plasma membrane and penetrates the egg, releasing its 
nucleus 
c. Fast block to polyspermy – fusion depolarized egg so that no more sperm may 
enter
d. 1N egg + 1N sperm = 2N zygote i. 2N is unique genetic combo VII. Event 2: cleavage  a. Repeated cell divisions without cell growth  b. Cycle can occur very quickly in species that develop externally  c. Blastomeres – half size daughter cell produced at each division  d. After formation of outer epithelial layer, embryo forms a  blastocoel – cavity  inside hollow ball of cells (blastula)  e. Mammals  blastocyst 

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School: Mississippi State University
Department: Biology
Course: Biology II
Professor: Thomas Holder
Term: Spring 2015
Tags: Biology
Name: Bio 2 week 14
Description: These notes will be on the final.
Uploaded: 04/25/2018
5 Pages 42 Views 33 Unlocks
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  • 24/7 Homework help
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