Ch. 29: Development and Inheritence Flashcards
Both the …. from parents (heredity) and … in the uterus (environment) play important roles in determining the … of a developing embryo and fetus and the …. of a healthy child.
Genetic material
Normal development
Homeostasis
Subsequent Birth
What are the steps from fertilization to birth? (8)
What is capacitation?
a 10 h process
-the change sperm undergo in the female reproductive tract that enables them to penetrate and fertilize an egg.
Only capacitated sperm are capable of …
Responding to chemical factors produced by the surrounding cells of the ovulated oocyte
Compare the structures and molecules of the 3 stages of sperm
Epididymal: plasma membrane contains complement of surface molecules (proteins and carbs)
Ejaculated: surface molecules become coated with seminal plasma proteins that mask the portions of the membrane molecules
Capacitated: when sperm are exposed to the female tract envrionment, these seminal plasma coating with some of surface molecules are removed, which exposes portions of molecules that can bind to zona pellicula of oocyte
What sperm receptor binds to the sperm head and what are the effects?
ZP3 glycoprotein
It triggers acrosomal reaction ->lead to enzyme release
What happens when sperm enters a secondary oocyte?
Oocyte completes meiosis
What forms the fertilized ovum?
Male pronucleus and female pronucleus fuse
Fusion of sperm cell with plasma membrane of 2nd oocyte results in what?
Syngamy, a process that blocks polyspermy – fertilization by more than one sperm
In a fast block to polyspermy the oocyte cell membrane…
depolarizes so another sperm cannot fuse
How many sperm are allowed to penetrate the oocyte in blocks to polyspermy?
only 1 sperm
What are the 2 mechanisms that ensure monospermy
Fast block to polyspermy: electrical barrier, preventing fusion of sperm and egg
*On contact of 1st sperm, Na diffuses into the oocyte from extracellular space
* Membrane depolarization prevents additional sperm from fusing with the oocyte membrane
Slow block to polyspermy: mechanical block to polyspermy, i.e. the fertilization membrane hardens and is impervious to further sperm.
*On sperm entry, Ca released by oocyte endoplasmic reticulum as part of preparation for cell division
* Cortical reaction: granules in plasma membrane rupture contents into extracellular space
* These zonal inhibiting proteins (ZIPs) destroy sperm receptors
Sperm already bound to receptors are forced to detach
What are the 3 characteristics of the IVF procedure regarding sperm swimming to the egg
- In the IVF procedure, sperm and eggs “interact” in a dish leading to insemination.
- They literally swim up to the egg and burrow toward the nucleus.
- The first one to get there wins, and all others are blocked out.
What are male fertilits issues in IVF procedure? What other procedure might they choose?
Male fertility issue: Sometimes sperm cannot latch onto and penetrate the egg.
They may choose to have Intra(within)-Cytoplasmic Sperm Injection (ICSI)
What are the 6 basic steps in IVF?
Ovary stimulation
Egg retrieval
Sperm retrieval-wash sperm
Fertilization
Embryo transfer
Progesterone
What is IVF and why is it done?
- IVF is a treatment for infertility or genetic problems. During IVF , mature eggs are collected (retrieved) from ovaries and fertilized by sperm in a lab. Then the fertilized egg (embryo) or eggs (embryos) are transferred to a uterus
- Sometimes, IVF is offered as a primary treatment for infertility in women over age 40. IVF can also be done for certain health conditions
What are 4 main health conditions that cause people to get IVF?
-
Fallopian tube damage or blockage:
This problem makes it difficult for an egg to be fertilized or for an embryo to travel to the uterus.
Ovulation disorders:
If ovulation is infrequent or absent, fewer eggs are available for fertilization which reduces the chances of pregnancy.
Endometriosis:
It occurs when the uterine tissue implants and grows outside of the uterus – often affecting the function of the ovaries, uterus and fallopian tubes.
Uterine Fibroids:
Fibroids are benign tumours in the wall of the uterus and are common in women in their 30s and 40s. These can interfere with implantation of the fertilized egg.
What is a stem cell and what does it have the ability to do?
A stem cell is a cell that is unspecialized (nonspecific in its functions) and has the ability to divide for indefinite periods and give rise to specialized (functionally specific) cells.
What are the 5 principle types of stem cells and what are each of them based on?
They are based on their ability to differentiate
1. Totipotent
2. Pluripotent
3. Multipotent
4. Oligopotent
5. Unipotent
What are totipotent stem cells? What are some examples?
Ccells that have the potential to form all of the nearly 220 different types of cells found in the human body.
Examples: a zygote (fertilized ovum) and cells (blastomeres) produced from the first several divisions of a zygote (blastocyst).
What are pluripotent stem cells? What do they have the potential to from and what can’t they develop into? What are some examples?
- Tissue-specific stem cells, are cells of an embryo past five days of development and are derived from totipotent stem cells.
- They have the potential to form many (but not all) cells of the body. They cannot develop into extraembryonic structures such as the placenta, chorion, umbilical vesicle, and umbilical cord.
- Examples: primary germ layers (endoderm, mesoderm, and ectoderm) and cells derived from them which go on to form the various tissues and organs of the body.
What are multipotent stem cells? What are some examples?
Cells that can differentiate into a group of closely related cells.
Examples: mesenchymal cells that can form almost all types of connective tissue and hemopoietic cells that can develop into myeloid stem cells and lymphoid stem cells.
What are oligopotent stem cells? What are some examples?
- Stem cells that develop into only a few cell types.
- Examples: myeloid stem cells and lymphoid stem cells that differentiate into the different types of blood cells.
What are unipotent stem cells? What are some examples?
- Stem cells produce only one cell type.
- Examples epidermal stem cells, which develop into epidermal cells only, and spermatogonia, which develop into sperm only.
What is cell potency? What gives a cell greater potency?
Cell potency is a cell’s ability to differentiate into other cell types.
The more cell types a cell can differentiate into, the greater its potency.
What do adult stem cells include?
- Hematopoietic stem cells
- Mesenchymal stem cells
- Neural stem cells
- Epithelial stem cells
- Skin stem cells
Describe what hematopoietic stem cells give rise to
Gives rise to all of the types of blood
Describe what mesenchymal stem cells give rise to
Gives rise to osteocytes, chondrocytes, adipocytes, and other connective tissue
Describe what neural stem cells give rise to
Gives rise to neurons, astrocytes, and oligodendrocytes
Describe what epithelial stem cells give rise to
Gives rise to cells lining the digestive tract (absorptive cells, goblet cells, paneth cells, enteroendocrine cells)
Describe where skin stem cells occur in and give rise to
Occur in the basal layer of the epidermis and at the base of the hair follicles
Give rise to new epidermal layers of skin.