Mutations
meiosis
Mitosis
Genetic Information
Cell Cycle
100
What is a nondisjunction?
An error in meiosis where the members of a chromosome pair fail to separate during anaphase.
100
What is the purpose of meiosis?
The purpose of meiosis is to make four haploid gametes (egg and sperm)
100
100
Define a Gene
A DNA sequence, the codes for a particular character
100
Name the three places in the cell cycle where checkpoints occur
G1 Checkpoint
G2 Checkpoint
Metaphase Checkpoint
200
What is Klinefelter syndrome, what are three symptoms that occur in people with it, and how would someone reduce these symptoms?
Klinefelter syndrome occurs when there is an extra X chromosome in a male. Symptoms of this disorder include abnormally small testes, breast enlargement, and is sterile. To reduce these symptoms a man can take testosterone.
200
When do homologous chromosomes exist in Meiosis?
In Prophase I, metaphase I, anaphase I, telophase I, prophase II, metaphase II
200
During telophase what is formed in the middle of a plant cell and what does it do? Why does is a plant cell’s process of cytokinesis different from an animal cell’s?
During telophase, a cell plate is formed down the middle of the plant cell, splitting it into two daughter cells that are separated by a new wall. A plant can not perform cytokinesis like an animal cell because the cell wall is too stiff and does not bend enough to allow it to pinch to form two cells like the cell membrane does.
200
What is are homologous chromosomes, and where can it be found?
Homologous chromosomes are chromosomes, with the same genes in the same place, they can be found during mitosis.
200
What are the names and functions of the control systems in G1?
Growth Factor - proteins or hormones that give a cell a go signal to undergo mitosis
Density-dependent Inhibition - when a cell stops dividing once they realize that there is no room for them in the body
Anchorage Dependance - the cells have to be anchored to a surface in order to divide
300
Can cells mutate in prophase I of meiosis?
yes, because when they are crossing over they can make mistakes that are called chromosome mutation. Examples would be a deletion, duplication, and translocation.
300
What is a karyotype and what does a doctor look for when observing one (use the chromosome mutations to help answer this question)?
A karyotype is the systematized arrangement of chromosomes pairs in descending order of size. When a doctor examines a karyotype, he is looking for extra chromosomes, missing chromosomes, missing portions of a chromosome, extra portions of a chromosome, and portions of a chromosome that have broken off and reattached.
300
Where do the chromosomes align during metaphase and why do they do this?
Chromosomes align at the metaphase plate and they do this in order to help ensure that the sister chromatids will split evenly when they are pulled apart by the microtubules in the next step.
300
How many pairs of homologous chromosomes does the average person have, and how many chromosomes does someone with down syndrome have and why?
The average person has 23 pairs of homologous chromosomes, and someone with down syndrome has 47 chromosomes because they have three copies of chromosome 21
300
What occurs during G0 and how does it come back out?
When a cell is in G0, it is no longer actively preparing to divide, however it is still doing its job as a cell. A cell comes out of division if they get a signal that a cell has been destroyed and needs to be replaced.
400
What makes Sickle cell anemia different from most genetic disorders?
Sickle cell anemia is different because it can have a positive effect on someone. If a person is a carrier, meaning they only have one mutated gene and one normal hemoglobin gene, they have a protective factor against malaria. While a carrier isn’t completely immune, they are much less likely to get malaria.
400
What is crossing over, what is the purpose, and when does it occur? How would meiosis change is crossing over did not occur?
Crossing over is the exchange of DNA between two homologous chromosomes. The purpose is to create a new combination of genes that are different from the parent so that there is genetic diversity. If crossing over did not occur, there would be no genetic variation and therefore the offspring of the cells would be identical to the parent. This defeats the purpose of meiosis because the point is to create variation in DNA.
400
What is the dotted line that the black line is pointed to called, and what does it lead to?
It is a cleavage furrow, and it is an indentation that appears in the cell’s surface when it is preparing to divide. It is the beginning of when the cell pinches it's cell membrane and cytoplasm down the middle to create two identical daughter cells. This process is also known as cytokinesis.
400
How are homologous chromosomes paired up? Why are they paired up that way?
Homologous chromosomes are paired up based on their size. This is because the chromosomes have to have the same genes and the same number of DNA sequences. The number of DNA sequences determines the length, so if the sequences have to be the same, the length is the same.
400
In what stages in the life of a human would the cell cycle be most rapid and why?
The cell cycle would be the most rapid in the periods of growth in a human being such as during the embryo and infant stages. This is because the purpose of mitosis is to create more cells when they are needed, and during growth is when more and more cells need to be formed in order for tissue to grow or possibly be repaired.
500
You have 37 cells and they each have 7 pairs of chromosomes. After 19 of them go through mitosis, how many total individual chromosomes are left?
784 individual chromosomes
500
You have a mutated cell, (as seen below) how many chromosomes will be in each of the four haploid daughter cells?
Cell 1 - 3 chromosomes
Cell 2 - 1 chromosome
Cell 3 - 2 chromosomes
Cell 4 - 2 chromosomes
500
You have a mutated cell, it has reached the prophase of mitosis, is it still possible for this cell to stop mitosis?
Yes, the cell can still reach the third checkpoint in metaphase and correct the chromosomal problem
500
Do asexual organisms have homologous chromosomes? Why or why not? Explain what would change about the reproductive process if they were to have or not have homologous chromosomes.
Homologous chromosomes contain one chromosome from each parent cell. Since asexual reproduction only involves one organism, homologous chromosomes would be impossible to achieve. If asexual organisms were to have homologous chromosomes, the end result would be totally different. Instead of creating an identical organism, it would create an organism that isn’t exactly the same as the parent, which would defeat the purpose of asexual reproduction.
500
If a cell is mutated, how is it able to divide? What is the cell cycle like of a mutated cell?
A mutated cell is able to divide if it forces its way through the G1 checkpoint. It then becomes a cancer cell. Cancer cells reproduce even when they are not needed, and each of the cell’s descendants continues to mutate further. Eventually, all of these unneeded cells form a tumor. During the early stages of a tumor, angiogenesis occurs, which creates new blood vessels, allowing the growth of the tumor to accelerate. The cells are then able to travel through the vessels to move to other types of the body and metastasis occurs, which is the colonization of related tumors throughout the body.