introduction Flashcards
What is embryology?
The science which describes the development process from a single cell (zygote) to a baby in 9 months
How many genes do humans have?
35,000
What is the maternal gamete called?
Oocyte
What is the paternal gamete called?
Sperm
What does the male gentle organ consist of?
The testis
The gentle ducts
The accessory glands
What do the testis do?
Produces sperm and secretes the male sex hormones
What do the testis consist of?
250 compartments called lobules
2-3 highly coiled seminiferous tubules
What two types of cells do the testis consist of?
Spermatogonia
Sertoil cells
What is the epididymis and where is it found?
A highly coiled duct behind the testis
What do the ovaries consist of?
Cortex and medulla
What is the cortex of the ovaries?
The cortex contains the ovarian follicles which undergo maturation to produce ova
What type of tissue does the medulla of the ovaries consist of?
The medulla consists of vascular connective tissue
What does the fallopian tube do?
Transmit the ovum to the uterus
What is the uterus?
A fast shaped muscular organ in which the embryo develops
What is mitosis?
The process by which one cell divides giving rise to two daughter cells that are genetically identical to the parent cell
What leads to genetic variability in meiosis?
Crossing over
Random distribution of homologous chromosomes
What happens during crossing over?
Interchange of chromatid segments between paired homologous chromosomes
Segments of chromatids break and exchange as homologous chromosome separate
What is chiasma?
The x-like structure that temporarily forms when crossing over occurs
What are polar bodies?
During meiosis for daughter cells are formed
Only one of these develops into a mature gamete
The other three are called polar bodies and they received little cytoplasm and degenerate
When oocytes and spermatocytes produce daughter cells, how many cells from each type develops into a mature gamete?
One from the oocyte
All four from the spermatocyte
What are the causes of birth defects?
Chromosomal abnormalities
Gene mutations
7% of major birth defects are caused by what ?
Chromosomal abnormalities
8% of major birth defects are caused by what?
Gene mutations
What is a dominant mutation?
It is when a mutant gene produces abnormality in single dose
What is a recessive mutation?
A mutation that requires both alleles to be mutated for it to show
What is monosomy?
When individual is missing a chromosome from a pair
What is trisomy?
When an individual has more than two chromosomes of a pair
What are structural chromosomal abnormalities?
They occur due to a loss of genetic material or rearrangement in the location of genetic material
What is non-disjunction?
Failure of separation of the homologous pair of chromosomes
Both has move into the same cell
When does non-disjunction occur?
In the first or the second meiotic division
Give an example of trisomy
Down syndrome
Give an example of monosomy
Turner syndrome
What is trisomy caused by?
when an ovum containing XX is fertilized with sperm containing X causing a zygote to have XXX
What is monosomy caused by?
When an ovum with no X chromosome is fertilized by a sperm with an X chromosome producing a zygote containing XO
When does non-disjunction occur?
Mitosis in an embryonic cell
Give an example of a condition non-disjunction produces
Mosaicism
What is translocation?
When a piece of chromosome breaks off and attaches to another chromosome
