Chapter 4 Flashcards
Why do cells replicate?
- Growth and development
- Maintenance and repair
- Reproduction
Why do prokaryotes replicate?
To reproduce
What is binary fission?
the method of cell replication used by prokaryotes
What is exponential growth?
The rapid nature of binary fission, to replicate the number of cells into double
What is asexual reproduction?
A method of reproduction that produces genetically identical cells without the fusion of gametes
What is a plasmid?
A small, circular loop of DNA that is separate from the chromosome. The genes carried in plasmids provide bacteria with genetic advantages, such as antibiotic resistance.
What is the process of binary fission?
- Circular chromosome is uncoiled and the DNA and Plasmids are replicated
- Cell elongates to prepare for division and duplicated circular chromosomes migrate to opposite ends
- cell begins to undergo cytokinesis by pinching inwards and creating a septum
- Results in two genetically identical cells
Why do eukaryotes replicate?
- maintenance (cells constantly die and are replaced)
- growth (as a zygote)
What does the cell cycle consist of?
G1
Synthesis
G2
Mitosis
Cytokinesis
What is G1?
Gap 1 - cell prepares for mitosis by growing the cell (replicating organelles)
What is S?
Synthesis - single chromosome is replicated to make a sister chromatid
What is G2?
Gap 2 - cell further prepares to enter mitosis by growing, producing proteins and enzymes
What is the process of mitosis?
PMAT
Prophase - chromosomes condense with the nuclear membrane breaking down, centrioles and spindle fibres begin to form
Metaphase - chromosomes line up in the middle of the cell with the centromeres in a single line & attach to spindle fibres at the centromere
Anaphase - sister chromatids are pulled apart to either side of the cell via centrioles
Telophase - new nucleus forms around separate chromatids and begin to cleave
What is cytokinesis?
The cytoplasm splits and a new cell membrane forms around the two cells
How does cytokinesis split in animal cells?
A cleavage furrow forms (an indentation of the cell membrane) and meets in the centre to eventually divide in two