The Cell Cycle Flashcards
What best distinguishes living vs non-living?
The ability to reproduce
Key Function of Cell Division (3):
1) Asexual Reproduction
2) Growth and Development
3) Cell Replacement
Asexual Reproduction
Unicellular organisms divide to form individual organisms
–> Prokaryotes, unicellular eukaryotes (yeast, amoebas, etc.)
Cell Division’s Role in Growth and Development
Multicellular organisms divide to grow –> Enables organisms to develop from a single cell to a complex cell system
Cell Division’s Role in Cell Replacement
Tissue renewal/repair:
Replacing cells that die from accidents or normal wear and tear
What must be highly coordinated for proper cell division?
The timing of DNA replication and the actual cell division
Genome
All of a cell’s DNA (all the genetic info)
Eukaryote vs Prokaryote Genome
Eukaryotes = Genome containing multiple DNA molecules
Prokaryotes = Genome containing usually only one DNA molecule
Chromosomes
DNA wrapped in protein –> DNA-Protein Complex
–> Carry genes which specify an organism’s inherited traits
Gene
A segment of DNA
Replicated vs UN-replicated chromosomes
Replicated Chromosome = “X Shape” –> TWO DNA molecules
UN-Replicated Chromosome = NOT “X shape”
–> ONE DNA molecule
When in the cell cycle do we see replicated chromosomes?
During cell division (mainly mitosis)
–> DNA is usually kept in its unreplicated form
What do the chromosome proteins do?
Control chromosome structure (folding) and function (gene expression)
Chromatin
All the DNA and proteins of chromosomes
–> (kind of referring to all chromosomes)
Every species has a ________________ ______________ of chromosomes
1) Characteristic
2) Number
of chromosomes DOES NOT EQUAL
sophistication
Human Somatic Cells Chromosomes
46 Total Chromosomes –> 23 pairs (one from mom and the other from dad to form the pairs)
Gamete Chromosomes
1/2 the number of chromosomes as a somatic cell
Form of DNA when NOT dividing
OR
when DNA is REPLICATING!
Each chromosome is in the form of a long, thin chromatin fiber (uncondensed/uncoiled)
–> Cannot see using light microscope
Form of DNA AFTER Replication
OR
When cell is dividing
The chromosomes condense; each chromatin fiber becomes densely coiled and folded (“X shape”)
–> CAN see using a light microscope
Sister Chromatids
Copies of the same chromosome that are joined together (make up the classing “X shape’)
What holds sister chromatids together?
Cohesins
Cohesins
Proteins that hold sister chromatids together along their length
Centromere
A specialized sequence of DNA where sister chromatids most CLOSELY attach/tether
A centromere is NOT a _______________
A centromere IS a _________ _______________
1) Location
2) DNA sequence
How do centromeres cause greater tethering between the sister chromatids?
Due to proteins that recognize and bind to centromere DNA
Importance of centromere
Important for proper splitting of the sister chromatids during segregation
Chromosome Arm
The portion of a chromosome to either side of the centromere
Cell Cycle
The life of a cell from the time it is first formed during division of a parent cell until its own division into 2 daughter cells
Two main processes must alternate to allow for proper cell division:
1) Doubling the genome –> Chromosome replication
2) Separation of the duplicated genome into exactly one half –> Chromosome segregation
The cell cycle is split into two overall phases
1) Interphase
2) M-Phase
Steps of Interphase
1) G1 phase
2) S phase
3) G2 phase
Purpose of Interphase
Sets up and readies the cell to undergo mitosis and cell division
–> Accounts for around 90% of the cell cycle
M-Phase
1) Mitosis
2) Cytokinesis