Chromosomes and Genetic Material
Somatic:46, Gamete: 23
What is the difference between mitosis and cytokinesis? Give two reasons the body needs mitosis.
Mitosis divides the nucleus (producing two identical nuclei). Cytokinesis divides the cytoplasm (producing two cells), Growth, and repair or replacement of damaged cells. Asexual reproduction is also acceptable.
What is the name of prokaryotic cell division?
Binary fission.
Give one example of an internal signal and one of an external signal.
Internal: checkpoint proteins sensing DNA damage, or cyclin–CDK levels. External: growth factors (such as PDGF), density-dependent inhibition, or anchorage dependence.
Name three ways cancer cells differ from normal cells.
What is the difference between chromosome and chromatid?
A chromosome is a single DNA molecule packaged with proteins. A chromatid is one of the two identical copies of a replicated chromosome (sister chromatids), joined at the centromere. Once separated, each chromatid is called a chromosome.
In which phase is DNA replicated? What is G0?
S phase, A resting, non-dividing state that cells can exit the cycle into from G1. Some cells stay there permanently (neurons), while others can re-enter the cycle.
Name two differences between eukaryotic and prokaryotic cell division.
What does CDK stand for? Which one stays at a constant level: the cyclin or the CDK? What happens to a CDK when a cyclin binds to it?
Cyclin-dependent kinase. The CDK. Cyclin levels rise and fall. The CDK becomes active and can phosphorylate target proteins to drive the cell cycle forward.
How do cells metastisize? Which tumors metastisize?
Spread of cancer cells from the original tumor to other parts of the body through blood or lymph. Malignant.
Which is more tightly packed and gene-silent: euchromatin or heterochromatin?
Heterochromatin. Euchromatin is loosely packed and transcriptionally active.
Draw out the cell cycle diagram
Draw!
Which protein forms the dividing ring in bacteria?
FtsZ
What two proteins make up MPF? At what point in the cell cycle does MPF activity peak? What does MPF cause the cell to do?
Cdk1 and M cyclin (cyclin B). At the G2/M transition and early M phase. It drops at the end of metaphase when cyclin B is degraded. It pushes the cell into mitosis (chromosome condensation, nuclear envelope breakdown, spindle assembly).
What is the difference between proto-oncogene vs oncogene?
A proto-oncogene is a normal gene that promotes cell growth and division. An oncogene is a mutated or overexpressed version that is hyperactive and drives uncontrolled division.
What is a gene, and what is a genome?
A gene is a segment of DNA that codes for a protein or functional RNA. A genome is the complete set of an organism’s DNA.
What happens to the chromosomes in metaphase? In anaphase?When does the nuclear envelope break down? When does it re-form?
In metaphase, chromosomes line up at the metaphase plate (equator). In anaphase, sister chromatids separate and move to opposite poles. It breaks down in prometaphase and re-forms in telophase.
Why do prokaryotic cells not need a mitotic spindle to separate their DNA?
Prokaryotes usually have a single, circular chromosome. After it is replicated from its single origin, the two copies attach to the plasma membrane at different points. As the cell elongates, the copies are carried apart. Eukaryotes have multiple linear chromosomes inside a nucleus, so they need a microtubule spindle to sort and separate each chromosome accurately.
What does the G1 checkpoint check for? What does the G2 checkpoint check for? What does the M (spindle) checkpoint make sure of before anaphase begins?
Cell size, nutrients, growth factors and DNA damage. Whether DNA replication is complete and the DNA is undamaged. That all chromosomes are properly attached to the spindle at their kinetochores.
What are tumor suppressor genes?
They inhibit the cell cycle, repair DNA, or trigger apoptosis.
What makes two chromosomes homologous?
One maternal and one paternal chromosome with the same size, shape, centromere position and gene order. They may carry different alleles.
What structure do microtubules form during mitosis? What do kinetochore microtubules do? Which type of microtubule pushes the poles apart?
The mitotic spindle. They attach to the kinetochores at the centromeres and pull sister chromatids apart toward the poles. Polar (interpolar) microtubules, which overlap and slide past each other.
Compare how the cell physically divides into two daughter cells in bacteria and in animal cells. Name the key structure or protein involved in each.
Which protein is called the “guardian of the genome”?
p53
Why does chemotherapy cause side effects like hair loss? What does a targeted therapy such as Gleevec do?
Chemotherapy targets all rapidly dividing cells, including normal ones like hair follicles, gut lining and bone marrow. It blocks the BCR-ABL protein in chronic myeloid leukemia, stopping its signal for uncontrolled division.