Studied by 3 people
The Cell Cycle-Mitosis and Meiosis
What is the goal of the cell cycle/ life cycle?
For the cell to divide into two daughter cells
What are the four processes of cell cycle?
Cell growth
DNA replication
Chromosomes in daughter cells
cell division
What is the biggest part of the cell cycle for bacteria?
Cell growth and DNA replication
How does the cell cycle in prokaryotic organisms happen?
The chromosomes are distributed through binary fission?
What are the three phases of bacterial cell cycle?
B period: end of cell division to DNA replication
C period: the time the chromosomes assemble
D period: time after chromosome replication and end of cell cycle
What is the process by which eukaryotes split?
Mitosis( evolution of binary fission)
Which is the biggest phase of cell cycle in bacteria? B phase, C phase or D phase
C period
Where does bacterial chromosomal replication start? (a specific site)
A site called The origin of replication in the middle of a cell.
how they work: the replication start and go on opposite ends by catalysts. The origins go to different poles to pull chromosomes in app direction. The plasma membrane grows apart.
What are the four phases of mitosis ?
G1 phase(growth)
S phase(synthesis)
G2 phase( gap 2 or growth 2)
M phase ( mitosis and cytokinesis)
What is interphase?
End of mitosis all the way to the beginning of mitosis
what are chromosomes?
They are nuclear units of genetic information that are divided and distributed during mitosis
chroma = colour (describing their strong staining by particular dyes)
soma = body
What are chromatids?
The replication of the DNA chromatids
It represents two identical molecules sister chromatids
What is a chromatid?
A small portion of DNA composed of
How do we define the number of chromosomes in a species?
By ploidy number
Diploid(2n): humains have 23 pairs of chromosomes, 46 in total . Half from one type(mom) and other from dad. Called homologue pais
Haploid(1n): gametes. Only have one copy of chromosomes of the same type
What is the longest phase of the cell cycle for eukaryotic cells?
Interphase
What happens in the G1 phase?
Cell caries its functions, grows. prepares ribosomes and enzymes. The DNA is not duplicated yet
What happened in the S phase?
DNA replication and chromosome duplication
What happens in G2 phase?
Cell growth continues and prep for mitosis. The DNA has replicated already.
Describe G0 phase?
Also called quiescence. Its a rest phase where it stops dividing
What are the five stages of Mitosis?
Prophase
Prometaphase
Metaphase
Anaphase
Telophase
What is this structure ( purple strings) ? What is its function ?
Spindle: It’s a structure of proteins and microtubules that forms during cell division that separates the sister chromatids
What is this structure (yellow)? What is its function ?
Centromere: region not an actual structure) in the middle of a chromosome where the spindles attach
What is this structure (green)? What is its function ?
Centrosome: organizes the microtubule cytoskeleton and positions organelles. It’s a pair of microtubules
What is the function of a kinetochore ?
Kinetochore: a large protein that connects chromosomes to the spindle fibers/microtubules. It is in the center of the chromosomes in the outside area.
Binds the centromere and chromosomes together
What is the structure of cleavage furrow? What is its function ?
It’s a contractile ring formed by microfilaments
What is the structure of cell plate? What is its function ?
It is made from cell wall and cell membrane components brought during telophase in plant cells.
What’s the different between animal cells and plant cells in cytokinesis
Animal cells:the cleavage furrow is a contractile ring formed by microfilaments
Plant cells: vesicles for a cell plate within the cell to form a cell plate. A new cell wall forms and THEN, the membrane separates the new daughter cells
What can be stored in plant cells vacuoles?
Plastids/ pigments
nutrients
water
What is the longest phase of the cell cycle?
Interphase
Explain supercoiling
Histones: proteins in packs of four that DNA wraps around
Nucleosomes: 4 histones units wrapped by DNA
Chromatin: 8 nucleosomes
Chromosomes: chromatids chilled together
What’s the structure of DNA?
Double stranded helix
What happens in prophase? CC,x2, ½,s
Chromosomes condense( become visible in microscope)
Chromosomes are doubled (after G2)
Centrosomes divide in two parts (go pop of cell)
Spindles form
What happens in prometaphase?
Nuclear envelope breaks down!
Microtubules form complete spindles
Microtubules attach to kinetochores
How do spindles form and connect to chromosomes?
They are extended microtubules that will connect to the chromosome’s centromere by attaching to a protein complex called kinetochore
What happens in Metaphase?
Spindles are fully fledged
Chromosomes align in the middle of the cell
Sister chromatids are held by two opp forces: kinetochores out and cohesins(protein complex) in
What happens during Anaphase?
seperase proteins splits the sister chromatids
spindles (myosin) bring chromatids to opposite poles
What happens during Telophase?
Chromosomes decondense
A new nuclear envelope forms around chromosomes (we still only have one cell!!!)
The cytoplasm divides by furrowing
Which of the following is not part of mitosis?
Anaphase
Cytokinesis
Prometaphase
Telophase
Metaphase
Anaphase
Cytokinesis
Prometaphase
Telophase
Metaphase
How do bacteria undergo cell division?
A pilus (surface of bacteria) leaves its body and enters the other’s membrane containing some genetic material (horizontal gene transfer)
Why would cells undergo cell division?
For cell development
Cell growth (natural)
Repair of organism
Need to compete external source
Note
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