Unit C - Cloning, abnormal cell division, and cell growth Flashcards
What is Cloning?
The process in which identical offspring are formed from a single cell or tissue.
Does sexual or asexual reproduction create cloning?
Asexual
What is the blastula stage?
when the fertilized cell is a blastocyst.
Why can’t you clone an animal in the gastrula (gastrulation) phase?
because the germ layers & most other cells are already differentiated.
What are the 3 steps of cloning?
- Removal of the nucleus of an unfertilized egg
- extract a nucleus of a cell in the blastula stage
- Transplant the Totipotent nuculus
Define Totipotent.
a nucleus that is able to brng a cell from an egg to adult
When are cells in mammals totipotent?
before the 8 cell stage of cleavage.
What is the definition of monozygotic?
developed from a single fertilized cell, as identical twins.
What is the definition of dizygotic?
developed from two fertilized cells, as fraternal twins.
Are dizygotic cells twins?
No, they have different DNA
Which cells escape the aging process and the biological clock?
Spermatocytes and cancerous cells.
What are the three theories of cell aging/cell death?
- Aging is caused by mutations
- Aging genes shut down chemical reactions within the body
- Aging occurs when cell lineages die out (telomeres)
What are Telomeres?
Ends of chromosomes that shorten during DNA replication
Shortening Telomeres is a potencial theory to cell aging.
What is the definition of cancer?
A broad group of diseases characterized by the rapid, uncontrolled growth of cells → forms a mass & shortens interphase.
What is the difference between the cells formed from Meiosis compared to mitosis?
During meiosis, the amount of chromosomes each cell has is halved (haploid cells)
What does sexual reproduction help with in diversification?
It helps ensure a recombination of genes, ↑ species diversity.
What are the two processes that Meiosis takes advantage of to produce genetically distinct gametes?
By “crossing over” and independent assortment.
What is independent assortment?
The different ways a cell organizes itself in metaphase I can lead to different gene combinations, as different genes are pulled to different ends of the spectrum.
what are polar bodies? How many are made?
Certain cells made in meiosis in the female reproductive system have a smaller amount of cytoplasm and often die.
While 2 are directly made in the process, the first polar body can reproduce causing net total of 3.
Are primary oocytes and spermatocytes created before, or after meiosis I?
Before.
What does tetrad mean?
Homologous duplicated chromosomes that are aligned gene by gene.
4 chromatids…
What are synapses?
The process of moving the homologous pairs together in mieosis
What is “crossing over” in meiosis?
The exchange of DNA between paired homologous chromosomes in the tetrad in Prophase I
What are the 4 parts of Prophase I?
- Chromosomes condense and become visible
- Nuclear membrane begins to dissolve
- Synapsis form creating tetrads
- the tetrads begin to cross over (exchanging genes)
What are the 3 parts of Metaphase I?
- Homologous chromosomes attach to microtubules (spindle fibers)
- Homologous pairs line up at the equatorial plate (each pair is made of a paternal and maternal chromosome)
- Each pair will align INDEPENDENTLY OF OTHER PAIRS (independent assortment)
What are the only part of Anaphase I?
Homologous duplicated chromosomes in tetrads separate and move toward opposite poles.
What is segregation in meiosis? When does it happen?
The separation of homologous pairs in such a way that either the maternal or paternal chromosome can be in either cell.
Anaphase I.
What are the 2 parts of Telophase I and Cytokinesis I?
- A nuclear membrane begins to form around each set of duplicated chromosomes.
- two daughter cells form from cleavage furrows, or from the development of a cell wall through a cell plate.
Meiosis II is very similar to what process? What is different?
Mitosis.
Because there are only 23 duplicated chromosomes, each cell becomes a haploid instead of a diploid.
At the end of meiosis II how many gametes are produced, and how many are viable a male or female?
4 gametes are produced
Male - all four are viable
Female - one is viable; resulting in 3 polar bodies (not viable)
What are the processes that increase genetic diversity in a species?
- Crossing over in Meiosis
- Independent Assortment in Meiosis
- Fertilization
What is the definition of nondisjunction?
Chromosomes or chromatids that do not separate as they should during meiosis.
This can lead to cells having too many, or too few chromosomes
What is the definition of monosomy?
When one chromosome is lost due to nondisjunction, being unable to make a normal homologous pair.
What is the definition of trisomy?
When one chromosome is gained due to nondisjunction, having three chromosomes instead of a normal homologous pair.
why does a monosomy or a trisomy zygote impact the entire baby?
Because once they divide, all the cells in the body will contain an abnormal number of chromosomes.
What is Chorionic Villus Sampling?
A process of collecting cells from the chorion to test for chromosomes.
What is Amniocentesis?
A process by which a syringe draws fluid from the amniotic fluid to test its chromosomes.
What is the nondisjunction that causes Down syndrome?
Trisomy 21.
What is asexual reproduction? What is the key process involved in it?
A process in which a parent organism produces genetically identical offspring.
Mitosis
Are gametes involved in Asexual Reproduction?
No gametes are involved.
What is conjugation?
How a bacterium can transfer its genetic material to another bacterium.
Not a form of reporduction.
What is parthenogenesis?
A form of asexual reproduction in which an unfertilized egg develops into an adult.
(Fertilized egg (female offspring, diploid), and Unfertilized Egg (Male offspring haploid).
What cells are involved in Mitosis?
Stomatic cells
What cells are involved in meiosis?
Germ cells
What is the function of Mitosis?
Growth of organism and replacement. Maintains genetic continuity.
What is the function of Meiosis?
Increases genetic diversity of offspring.
