Ch. 2 Chromosomes and Cellular Reproduction Flashcards
Histone
Special class of protein associated with DNA. Octagon segment utilized to form tightly packed chromosomes.
Chromatin
Complex of DNA and histone proteins.
binary fission
The way a prokaryotic cell divides. Circular chromosome replicates and the cell divides.
nuclear matrix
network of protein fibers highly organized internal scaffolding within nucleus.
homologous pair
two chromosomes alike in structure and size each carrying genetic information for the same set of hereditary characteristics.
allele
individual copies of a similar gene that encode different information. they do not need to be identical one might encode one variation and the other another variation.
diploid
cells that carry two sets of genetic information
haploid
single set of chromosomes
3 essential elements of a functional chromosome
- a centromere
- a pair of telomeres
- origins of replication
On the basis of the location of the centromere, chromosomes ar classified into 4 types: (from smallest to largest or normal)
- Telocentric
- Acrocentric
- Submetacentric
- Metacentric
Telomeres
Protect and stabilize the chromosome ends. Natural tips or ends of a linear chromosome.
Origins of replication
Sites on chromosome where DNA synthesis begins: they are not easily observed by microscopy. Can be multiple sites within eukaryotic chromosome.
Checkpoints
Key transition points in cell cycle where regulation of cell happens allows or prohibits cell progression.
Two major phases within cell cycle
Interphase and M phase (mitotic phase)
G0 non-dividing phase
phase where cells go in response to regulatory signals before entering G1/S checkpoint.
G1 Mitosis
phase where cell grows and proteins necessary for cell division are synthesized.
G1/S checkpoint
holds the cell in G1 until the cell has all the enzymes necessary for the replication of DNA
S phase
DNA synthesis in which each chromosome is duplicated. DNA synthesis must take place before the cell can enter mitosis.
G2
This phase of the cell cycle is where several additional biochemical events are necessary for the cell division to take place.
G2/M Checkpoint
Checkpoint where only cell’s who’s DNA is completely replicated and undamaged pass.
fertilization
Process in which two haploid gametes fuse and restore the number of chromosomes to its original diploid value
crossing over
a process in which homologous chromosomes exchange genetic information. Generates genetic variation and is essential for proper alignment and separation of homologous chromosomes. “tangle”
Chiasma
Each location where two chromosomes cross while “crossing over”
interkinesis
period between meiosis 1 and meiosis 2
