Unit 3 Flashcards
Blastema cells
Divide up to 50x faster than human cells.
All cells on earth
Come from other cells
Purpose of cell division
Expanding populations, and replacing cells lost to wear and tear
Cells in multicellular organisms
No meant to divide immediately
Binary fission
Prokaryotic cells reproducing. Double in size, replicate chromosomes, and split. Includes a B, C, D period
B period
DNA synthesis and cell enlargement
C period
Chromosomes seperated on opposite sides of the cell
D period
Membrane pinches and 2 daughter cells are made
Bacteria and archaea use
A single circular packet of DNA
In an abundance of nutients
Bacteria and archaea do not have a B period
Segregation
Proposed by François Jacob. 2 chromosomes attach to the plasma membrane and are pulled apart, passive replication
Origin of replication (Ori)
Where chromosomes replicate. In the center and then moves to the poles
Cytoplasmic division
Inward constriction of cytoskeletal proteins. The cell wall and plasma membrane forms and divides. Only works with one chromosome
Eukaryotic missing a chromosome
Bad, often lethal
Chromatid
Eukaryotes adaptation to hold 2 double stranded DNA
Binary fission and evolution
Variation proving intermediates in the evolutionary pathway. Some nuclear membranes dissociate while others don’t
Mitosis
Daughter cells are identical to the parent (clones)
Mitosis occurs because of 3 things
- Master programing allows for orderly and timely progression
- DNA is copied almost perfectly
- Cables and motors of the cytoskeleton divide chromosome
Meiosis
Different than the parent. 1/2 the chromosomes of a normal cell, makes gametes and spores
Chromosome
Nuclear units of genetic info divided by mitotic cell division. Made up of DNA and proteins
Diploid 2n
Most eukaryotes. Have 2 of each chromosome (46)
Haploid, n
23, one copy of each chromosome
Ploidy
Multiples of n bigger than 2
Sister chromatid
2 copies of a chromosome held together by sister chromatid cohesion until segregation
Chromosome segregation
Equal separation of sister chromatids
Interphase
Longest phase and is comprised of G1, G2, G3 phases