Cell Division (4) Flashcards
What process do prokaryotes such as bacteria and archaebacteria divide by?
Binary fussion
What are the basic genetic material of a bacterial cell?
- F-plasmid
- R-plasmids
- Chromosomal DNA
Plasmid DNA (def)
- extrachromosomal circular DNA molecules
- each contain an orgin or replication, and genes or enzymes
Orgin of replication in plasmids (def)
specific region recognized by DNA replication enzymes
R-plasmids (def)
contain antibotic resistance genes that allow some malicious bacteria to develop resistance to common antibiotics
F-plasmids (def)
fertility plasmids containing genes for making F-pili (reproductive part to transmit DNA during bacterial mating)
transmitted through sexual mating
replicate individually of the bacterial cell division
C-factors (def)
colicinogenic (can cause cancer) factors contain genes coding for toxins
important for the survival of the bacterial
Chromosomal DNA (3 facts)
circular chromosomal DNA, DNA is in the nucleoid region
each cell contains a single orgin of replication and is bound to plasma membrane
chromosomal DNA replicates once per cell division
Binary fission (def)
once a bacterium cell replicates its chromosomal DNA and sufficient number of plasmid DNA, the plasma membrane grows inwards to divide, and new cell wall is formed between
Mitosis
Process by which eukaryotic cells replicates their DNA into 2 identical copies and divided into two identical cells
- all somatic and vegetative cells (cells of multicellular organisms) divide by mitosis
Genetic elements of eukaryotic cells
- linear chromosomes organized into chromatin
Chromatin
DNA and protein loosely dispersed in the nucleus
Nucleosomes
small beads of DNA and histones
When and how are chromosomes formed in cell division?
During the metaphase stage
chromosomal dna -> nucleosomes -> chromatin -> chromosomes
- chromosomal DNA is bound to histone group of proteins (DNA bound around histones to form nucleosomes)
- comdensed nuclesomes form looped domains of chromatin
- looped domains condense to form chromosomes
Reproductive cells of eukaryotes’ name and number of chromosomes?
name: gametes
number: half the number of somatic cells
chloroplasts and mitochondria contain their own …
chromosomes similar to prokaryotic chromosomes (circular DNA)
chloroplasts and mitochondria replicate by …
their own binary fission
sister chromatids
a replicated chromosome that created two strands attached at the ceter
. not double stranded
centromere
central region of the attachment of sister chromatids
telomeres
ends of the chromosomes of sister chromatids
How many origins of replication do eukaryotic chromosomes have?
multiple origins of replication because the chromosomes are large
What are the two major phases of the cell cycle?
interphase, and mitotic (M) phase
What are the phases of the Interphase?
G1, S, G2,
What are the phases of the Mitotic (M) phase (mitosis + cytokinesis) ?
- prophase
- prometaphase
- metaphase
- anaphase
- telophase
- cytokinesis
G1 (gap 1) phase:
- rapid growth and metabolic activity
- centrioles repliate in the middle of the MTOC (in plants) or centrioles (in animals) with microtubules coming out from the center
S-phase (DNA Synthesis) phase:
chromosomes replicate along with their proteins, but still loosely disperesed as chromatic
replicated DNA is identical to parental chromosome
G2 (Gap 2) phase:
- growth and final preparation phase
- all organelles and membranes are duplicated
- chloroplasts and mitochondria have replicated by binary fission
Prophase:
- all the preparation for cell division occur
- nucleolus disappears
-chromatin forms chromatids - the 2 pairs of centrioles/asters move to opposite sides
- and mitotic spindle from from MTOC or centrioles
Prometaphase:
- nuclear envelope disappears
- microtubules of spindle fibers attached somewhere
Kinetochore:
microtubes of spindle fibers are connected to chromosomes at these places
I think it is the centromere of sister chromatids
Kinetochore fibers:
Fibers attached at the kinetochore