Chapter 9 Flashcards
(42 cards)
What do some types of Chemotherapy target?
Some types of chemotherapy target Mitosis
What is Taxol? What does it treat? How?
- From bark of Pacific Yew tree
- Treats ovarian and breast cancer
- It binds to microtubules, stabilizing them, the cell cannot divide after mitosis
- Makes the cell unhealthy*
What is Vinblastine?
- From Madagascar Periwinkle
- These plants produce this so the animals don’t eat them cause of the negative effects
How does Vinblastine work?
It binds to tubulin, stopping the formation of microtubules
- Cells cannot form spindle fibers needed to move the chromosomes
What is Colchicine?
- It treats gout (attacks of acute inflammatory arthritis—a red, tender, hot, swollen joint.)
- Stops the microtubules from forming, has very slow movement
Are normal animal cells haploid or diploid?
Diploid (2n)
When cells multiply by asexual means, the number of chromosomes is _________
kept at 2n
Number of chromosomes in:
Humans?
Mosquitos?
Dogs?
Humans= 46 (2x23) Mosquitos= 6 (2x3) Dogs= 78 (2x39)
Do the life cycles of diploid organisms require a haploid phase?
Yes it is called meiosis
In animal life cycles, a mechanism is required to reduce the number of chromosomes in half so that what?
So that following fertilization, the number of chromosomes returns to the original level
Meiosis
The process of producing haploid (1n) cells for sexual reproduction
- It keeps the # of cells constant from generation to generation
Homologous chromosomes
Also called what?
Contain different versions of the same information
- A pair of chromosomes
- Also called a Tetrad
What are duplicated chromosomes also called?
Sister chromatids
What does Meiosis consist of? What is the result?
Meiosis consists of one replication of the cellular DNA, but has 2 cell divisions
- This leads to the production of 4 haploid cells rather than 2 diploid cells
In prophase I:
What happens during the Synapsis?
What happens during Recombination?
Synapsis = homologous chromosomes line up- 4 chromatids are stuck together Recombination = Crossing over occurs between the pairs
How long does Meiosis take in human sperm cells?
It can take up to a month, with Prophase I taking up to a week alone
In human egg cells, Prophase I begins during ___________, and Meiosis is completed _______________
In human egg cells, Prophase I begins during fetal development, and Meiosis is completed just prior to egg release
What is the process of Crossing over? Is there a benefit?
In synapsis, the homologous DNA segments can interact and in some cases pieces of DNA can be swapped from one chromatid to another
- Benefit is that it increases variation
Chiasma
The point where two homologous non-sister chromatids exchange genetic material during chromosomal crossover during meiosis
What are the 5 steps to crossing over?
1) Homologous chromosomes condense
2) Synapsis begins(protein between chromosomes)
3) Bivalents form (protein connects chromosomes)
4) Crossing over occurs
5) Chiasma becomes visible as chromosome arms separate during late prophase
What is the benefit of crossing over?
It increases genetic variability of offsprings, and can lead to new phenotype combinations
In which phase do the tetrads line up together at the cell equator and then the chromosome pairs separate?
Metaphase I
In which phase do the sister chromatids stay together as the pairs are separated?
Anaphase I
Interkinesis
- After cytokinesis I
- No DNA replication between the 1st & 2nd meiotic division
- does not go back to an interphase stage
