Top1-Ch2-P15-19 Flashcards
Another word for bacteria under prokaryotes category?
eubacteria (true bacteria). Under this umbrella archaea is known as ancient bacteria.
Which of the three eubacteria, archaea and eukaryotes are most closely related?
Archaea are more closely related evolutionary to the eukaryotes than the eubacteria.
What is the nucleus difference between prokaryotic and eukaryotic cells?
Eukaryote has a nuclear envelope to form a nucleus which separates the DNA from the other cellular contents.
Whereas in prokaryotic cells the genetic material is in close contact with other components of the cell - a property that has important consequences for the way in which genes are controlled.
How is DNA packaged in eukaryotes?
In eukaryotes histones form tightly packed chromosomes. This complex of DNA and histone is termed chromatin.
From wikipedia: Chromatin is the combination of DNA and proteins that make up the contents of the nucleus of a cell.
Histones are highly alkaline proteins found in eukaryotic cell nuclei that package and order the DNA into structural units called nucleosomes.
A nucleosome is the basic unit of DNA packaging in eukaryotes, consisting of a segment of DNA wound in sequence around four histone protein cores. This structure is often compared to thread wrapped around a spool.
Histone proteins limit the accessibility of enzymes and other proteins that copy and read the DNA, but they enable the DNA to fit into the _______ ?
Nucleus
Do archaea and eubacteria have histones?
Archaea do but the structure of their chromatin is different to eukaryotic cells and eubacteria do not possess histones. So, they don’t have tight packed DNA making the reading and copying of DNA far simpler.
Genes of prokaryotic cells are generally on a _______ circular molecule of DNA - the chromosome of a prokaryotic cell.
single
What is a chromosome?
It is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences.
In eukaryotic cells genes are located on _______, usually linear DNA molecules (__________ chromosomes).
Note: same word is required.
multiple
How many chromosomes are there usually in eukaryotic and prokaryotic cells?
Eukaryotic usually have multiple chromosomes and prokaryotic cells usually have just one chromosome.
Are eukaryotic and prokaryotic usually unicellular or multicellular?
Prokaryotic unicellular
Eukaryotic unicellular and multicellular
What are viruses?
Neither eukaryotic nor prokaryotic because they have no cellular structure.
Simple structure of an outer protein coat surrounding nucleic acid (either DNA or RNA). Not primitive life. Can produce only within host cells. Evolved after cells. Closely related to hosts. Evolved from hosts. Good way to study hosts as virus genes have close relationship.
What are the three events that must take place for all cells to reproduce?
- Genetic information must be copied.
- Genetic information copies must be separated from each other.
- Cell must divide.
How do prokaryotic cells reproduce?
The circular chromosome of the bacterium replicates, move to opposite ends of the cell, are anchored to the cell walls, a cell wall forms between the two chromosomes producing two identical cells. The process is called binary fission.
Do eukaryotic cells reproduce like prokaryotic cells?
Yes, but the presence of multiple DNA molecules in the eukaryotic cells makes it more complex.
Name the three essential elements of a functional chromosome?
A Centromere - attachment point for spindle microtubules which is responsible for moving chromosomes in cell division.
A pair of telomeres - stable ends of chromosomes.
Origins of replication - the sites where DNA synthesis begins.
