Unit one Flashcards
What are the stages of the cell cycle?
Interphase ( G1, S, and G2) and M phase
What happens during Interphase of the cell cycle
G1: the cell grows
G0: non dividing stage the cell may enter
G1/S checkpoint: after this the cell is committed to dividing
S: DNA duplicates
G2/M checkpoint
What happens during the M phase of the cell cycle?
After G2/M checkpoint the cell can divide. Mitosis and cytokinesis (cell division) take place.
What are the phases of mitosis?
Interphase, Prophase, Prometaphase, Metaphase, Anaphase, Telophase
What is occurring during interphase?
The nuclear membrane is present and the chromosomes are relaxed.
What is occurring during prophase?
Chromosomes condense. Each chromosome possesses two chromatids. The mitotic spindle forms
What occurs during prometaphase
The nuclear membrane disintegrates. Spindle microtubules attach to chromatids
What occurs during metaphase?
Chromosomes line up on the metaphase plate
What occurs during anaphase?
Sister chromatids separate and move toward opposite poles
What occurs during telophase
Chromosomes arrive at spindle poles. The nuclear membrane re-forms, and the chromosomes relax.
What occurs during cytokinesis?
Cytoplasm divides. In plant cells, a cell wall will form. In meiosis when the cytoplasm divides to produce 2 cells each has half the original number of chromosomes
What are the stages of meiosis?
Meiosis 1: Prophase 1, Metaphase 1, Anaphase 1, Telophase 1
Meiosis II: Prophase II, Metaphase II, Anaphase II, Telophase II –> products
What occurs during prophase I?
Chromosomes begin to condense and the spindle forms. Homologous chromosomes pair. Crossing over takes place, and the nuclear membrane breaks down.
What occurs during metaphase I?
Homologous pairs of chromosomes line up along the metaphase plate
What occurs during anaphase I?
The two chromosomes (each with two chromatids) of a homologous pair separate and move toward opposite poles
What occurs during telophase I?
Chromosomes arrive at the spindle poles
What happens during interkinesis?
In some types of cells, the spindle breaks down, chromosomes relax, and a nuclear membrane re-forms, but no DNA synthesis takes place.
What occurs in prophase II?
Chromosomes condense, the spindle forms, and the nuclear membrane disintegrates
What occurs during metaphase II?
Individual chromosomes line up on the metaphase plate
What occurs during anaphase II?
Sister chromatids separate and move as individual chromosomes toward opposite spindle poles
What occurs during Telophase II?
Chromosomes arrive at the spindle poles; the spindle breaks down and a nuclear envelope reforms
differentiate between prokaryotes and eukaryotes in regards to nucleus, genome, and membrane bound organelles
prokaryotes: no nucleus, relatively small cell diameter (1-10 micrometers), usually one circular DNA molecule, DNA is not complexed with histones in bacteria but some histones in archaea, relatively small amount of DNA, no membrane bound organelles
Eukaryotes: contain a nucleus, relatively large cell diameter (10-100 micrometers), multiple linear DNA molecules, DNA is complexed with histones, relatively large amount of DNA, contains membrane bound organelles
explain binary fission
reproduction of a prokaryotic cell. The circular chromosome replicates at the origin of replication. The new replicated chromosomes move to opposite ends of the cell. A new cell wall forms producing two cells with identical chromosomes.
what is a diploid organism
diploid organisms have two complete sets of chromosomes in each cell. cells that carry two sets of genetic information are diploid. Humans are diploid, they have 23 pairs of chromosomes but 46 chromosomes