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35 Cards in this Set
- Front
- Back
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what is a gamete
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a cell that fuses with another cell during fertilization. (ovum and sperm)
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what is gametogenesis
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the process through which gametes (oocytes and spermatozoa) are produced in the adult
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what process distributes the chromosomes during gametogenesis
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meiosis
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what is the function of meiosis
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to increase genetic variability, create 4 sperm (spermatogenesis), 1 ovum, 3 polar bodies (oogenesis
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what is ploidy
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number of copies of
each chromosome present in the nucleus |
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how many chromosomes does the human cell have
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46 (23 pairs)
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how many chromosomes do the gametes have following meiosis
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23
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what happens during meiosis 1
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replication of genetic material, crossing over, alignment, disjunction, 2 secondary gametes that have 23 duplicated chromosomes
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what happens during meiosis II
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alignment disjunction at the centromere into 4 hapliod gametes
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aneuploidy
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abnormal number of chromosomes, can happen w/ mistakes in meiosis
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what is the most common autosomal trisomy
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Downs syndrome
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what causes polyploidy
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(having more than 2 sets of chromosomes) caused by fertilization by two sperm, lack of separation of polar bodies, most spontaneously abort
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what is mosaicism
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when an individual has two or more cell populations with different genetic makeup from the same zygote
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what is chirmerism
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when an individual has two different populations of cells from different zygotes
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what are the types of mistakes in genetic structure?
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Breakage (radiation of chemical teratogens) reciprocal and unbalance translocations, deletions, duplications
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what is the zona pellucida
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a glycoprotein that surrounds the plasma membrane of an oocyte. It helps bind spermatozoa and is required to initiate the acrosome reaction, degrades five days after fertilization
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what is the corona radiata
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2 or 3 layers of follicular cells that surround the ovum and provides vital proteins to the cell
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what are the steps of fertilization
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Phase 1-penetration of corona radiata
Phase 2-sperm binding (SED1 protein) and penetration of zona by the acrosomal rxn Phase 3 sperm and tail enter oocyte, second meiotic division w/ production of second polar body |
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what is the zona (cortical) reaction
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when a sperm penetrates an egg granules under the plasma membrane are released that change the surface and prevent other sperm from fertilizing
fast component-change in resting potential of oocyte plasma membrane prevents further binding of sperm slow component-release of cortical granules containing NZs that destroy sperm receptors (ZP3) |
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what are the types of mistakes in genetic structure?
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Breakage (radiation of chemical teratogens) reciprocal and unbalance translocations, deletions, duplications
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what is the zona pellucida
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a glycoprotein that surrounds the plasma membrane of an oocyte. It helps bind spermatozoa and is required to initiate the acrosome reaction, degrades five days after fertilization
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what is the corona radiata
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2 or 3 layers of follicular cells that surround the ovum and provides vital proteins to the cell
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what are the steps of fertilization
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Phase 1-penetration of corona radiata
Phase 2-sperm binding (SED1 protein) and penetration of zona by the acrosomal rxn |
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what is the zona (cortical) reaction
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when a sperm penetrates an egg granules under the plasma membrane are released that change the surface and prevent other sperm from fertilizing
fast component-change in resting potential of oocyte plasma membrane prevents further binding of sperm slow component-release of cortical granules containing NZs that destroy sperm receptors (ZP3) |
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what are identical twins
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Identical – monozygotic
(one zygote) -- twins form when a single fertilized egg splits into two genetically identical parts. • Share the same DNA set, thus they may share many similar attributes. Since physical appearance is influenced by environmental factors and not just genetics, identical twins can actually look very different |
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what are frateral twins
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Fraternal – or dizygotic
(two zygotes) -- twins develop when two separate eggs are fertilized and implant in the uterus. • The genetic connection is no more or less the same as siblings born at separate times. They may look alike, or they may not |
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what are polar (half identical) twins
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Polar body twins are believed to occur when
the mother's egg splits before fertilization and the polar body is also fertilized by a different sperm. • Twins share half their genes in common (from the mother) and the other half different (from the two sperm). They share some features of identical twins and some features of fraternal twins and are so-called half-identical twins. |
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what is a zygote
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fusion of 2 haploid gametes to make a diploid cell
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what does fusion of pronuclei mean
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the sight of two pronuclei in an ovum is the first sign of successful fertilization, when the nuclei fuse the chromosomes combine and become a diploid nucleus, mitotic division of the zygote begins, embryogenesis begins
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what is cleavage
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series of cell mitotic divisions, cell division w/o significant growth. producing a cluster of cells the same size as the original zygote.
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what are blastomeres
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the first cells of a dividing zygote
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what is a morula
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an embryo at the early stage of development. a solid ball of blastomeres contained within the zona pellucida. 3-4 days
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what is the blastocyst
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when the morula forms a blastocoel cavity and becomes a blastocyst . blastocyst has the blastocoel surrounded by the trophoblast and the inner cell mass, zona pellucida begin to dissipate 4-5 days when the blastocyst secrets proteases and the blastocytes hatches out of the zona
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whats the difference b/t pluripotent cells and totipotent stem cells
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pluripotent stem cells can differentiate into all three germ layers, totipotent stem cells can grow into an entire organism
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what cells are the totipotent stem cells of the blastocyst
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inner cell mass, blastomeres are also totipotent
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