Questions # 8 Flashcards
October 17-22 (42 cards)
What is the cell cycle?
The repeating sequence of growth and division through which cells pass each each generation.
What are the two main problems cells need to solve in order to divide, and which is more important?
- Make sure there is two times as much cytoplasm, organelles, ect.
- Make sure daughter cells get exact copy of genome.
How do prokaryotic cells divide?
Binary fission
How do prokaryotes know when they have finished replicating their genomes?
Two replication complexes meet on opposite sides of origin of replication (terminus of replication)
Where do bacteria add new cell wall and plasma membranes as they grow?
Between mesosomes
How do prokaryotes ensure that each cell gets a copy of the genome after cell division?
Plasma memvran pinches between mesosomes; cell wall forms between mesosomes.
How do eukaryotic cells divide?
Mitosis (growth, repair, replace)
Why is cell division more complicated in eukaryotic cells than prokaryotic cells?
Genome is larger and organelles must be replicated.
why is there some much protein associated with DNA in eukaryotes?
Organizes and compresses DNA (histones)
What is chromatin, and and what is the difference between heterochromatin and euchromatin?
Chromatin: state of chromosomes when they are thin and spread out in the nucleus during interphase.
Euchromatin: open book
Heterochromatin: closed book
What are histones?
Positively charged proteins which DNA wraps around and neutralizes causing it to condense and organize.
What are nucleosomes, and what is their function?
fundamental packing unit of DNA which compresses DNA. This octamer histone core is made up of two H2A, H2B, H3, H4
How can our cells compress 2 meters of DNA into a nucleus less than um long
Dna–>(histone)–>nucleosome–>solenoids–>extended section chromosome–>cordinoid loop–>metaphase chromosome
(six nucleosomes= solenoid)
What are the conventional five levels of compression, and why is it controversial?
- nucleosome
- solenoid
- extended section chromosome
- condensed loop
- metaphase chromosome
What are chromosomes?
Structure in which genetic material is stored and transmitted to next generation composed of histones and DNA.
What are homologous chromosomes?
similar copies of some DNA molecule; get one from mom and one from dad
What are sister chromatids, and how do they differ from homologous chromosomes?
Sister chromatids are identical copies of the same DNA molecule
Homologous chromosomes are similar copies of the same DNA
What are centromere
site where sister chromatids are attached…until anaphase.
What is a kinetochore?
Protein attached to centromere to which microtubules attach.
What is a karyotype and why is it useful?
- array of individual’s chromosomes
- can be used to detect genetic defects, aneuploidy, and cancer
What is ploidy?
Number of homologous chromosomes
2n diploid two copies of each chromosome
1n haploid one copy of each chromosome (ie. gametes)
What are the two stages and five divisions of the eukaryotic cell cycle?
Interphase/Cell division
G1 Mitosis
S Cytokinesis
G2
What are the three divisions of interphase and what happens in each?
G1 -primary growth phase -longest phase -follows cytokinesis -make more cell organelles -determine if conditions favor cell division (spf checkpoint) S -DNA synthesis G2 -quality control -no DNA damage? conditions ok to divide? (mf check point) -chromosomes begin to condense -cells start building mitotic apparatus
What are the four phases of mitosis and what happens during each?
Prophase -chromosomes condense -mitotic apparatus forms -centrioles migrate to poles -nuclear membrane dissolves -microtubules attach to kinetochore Metaphase -chromosomes in center -cell checks that spindle is connected to kinetochores *M checkpoint Anaphase -chromatids pulled to opposite sides of cell Telophase -nuclei reforms -chromosomes decondense -mitotic apparatus disassembled Cytokinesis -division of cytoplasm (ring of actin at cleave furrow;vesicles form making cell plate)
