Embryology Flashcards
What is this the definition of?
Type of cell division which reduces the chromosome number by half, creating 4 haploid cells, each genetically different from their parent cell.
Meiosis
Name the benefits of Meiosis?
- increase in number of variation in a species
- improves the chance of that species will then be able to adapt to any changes in its environment
- after an egg and sperm combine, the diploid number is restored, and no accumulation of genetic material occurs over subsequent generations.
What is this the definition of?
a cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typically of normal tissue growth.
mitosis
True or false
Mitosis creates identical copies of our original cells allows our skin/liver to be able to mass produce.
True
Whats a major disadvantage of Mitosis?
all of the organisms in a population of all of the plants in an area will have the exact same DNA. If a new disease comes along every single organism will be wiped out -if one can’t fight it, none of them can.
What is Gametogenesis?
the process in which cells undergo meiosis to form gametes.
What does Telophase mean?
2 nuclei present
Prophase means…?
Chromosomes now presents
Metaphase means…?
Chromosomes are lined up on the middle of the spindle
Anaphase means…?
chromatids start to move away from eachother.
Interphase means…?
chromosomes not visible but DNA being replicated
meiosis, leads to __% of the number of chromosomes and DNA strands within the sex cells?
50%
fill In the numbers
In somatic cells, primordial germ cells have __ pairs (__ Chromosomes)
2, 46
XY sex chromosomes are Male or Female?
Male
XX sex chromosomes are Male or Female?
Female
Autosome means…?
any chromosome which isn’t a sex chromosome
Fill in numbers:
Male germ cells undergo __ divisions yielding __ identical spermatozoa
2,4
Fill in numbers:
Female germ cells undergo __ divisions yielding __ large oocytes and / small non functional polar bodies
2, 1, 2/3
Chiasma means…?
a point where pair chromosomes remain in contact during the first metaphase of meiosis, and at which crossing over and exchange of genetic material occur between the strands.
define spermatogenesis?
The production or development of mature spermatozoa.
What is the male sex hormone?
Testosterone.
When does spermatogenesis occur?
at puberty.
True or false:
spermatogenesis occurs from birth to death.
False.
Puberty till death.
Capacitation means…?
the physiological changes sperm must undertake in order to have the ability to swim faster and penetrate the egg.
Define Oogenesis?
the production or development of an ovum.
What is primary oocyte enclosed by?
tightly enclosed in a single layered squamous capsule of epithelial follicle cells - the primordial follicle
How many eggs lost at birth
700,000
how many eggs lost at puberty?
400,000
Number of primordial follicles peaks at 5 months foetal development?
7 million
What are the 3 hormones that interplay during menstrual cycle?
hypothalamic, pituitary, ovarian
GnRH stands for?
Gonadotropin releasing hormone
FSH stands for?
Follicle Stimulating Hormone
What hormone is ‘LH’?
Leuterizing hormone
How many follicles proliferate forming a capsule around the oocyte?
5-12
The connective tissue surrounding the follicles differentiates into two layers during menstrual cycle, what are they called?
theca interna, theca externa
