M2 Lecture 15,18, part of 20 Flashcards
- What are some functions/roles of actively dividing cells?
o Increasing population of single-celled organism
o Growth of multicellular tissue
o Asexual reproduction + replacement of cells lost to wear and tear
7.2 The Cell Cycle in Prokaryotic Organisms
In the 3-period cycle newly formed prok. Cell must:
Increase in size
Replicate circular chromosome
Move each of two daughter chromosomes into progeny cell during cell division
7.2 The Cell Cycle in Prokaryotic Organisms
What is binary fission?
: division into two parts
7.2 The Cell Cycle in Prokaryotic Organisms
Exlapin the 3 periods of the 3 period cell cycle:
o B period:
Daughter cells are formed, they grow during B period, initiate DNA synthesis
When nutrients = abundant, prokaryotic cells = no need for B period (b/c can grow quickly enough for it to divide cytoplasm as soon as DNA replication is complete + chromosomes are separated
o C period:
Once chromosomes = replicated, they separate to opposite ends of cell (poles)
o D period:
Membrane pinches together between them and 2 daughter cells are formed via binary fission
- 2 a Replication occupies most of the cell cycle in rapidly dividing prokaryotic cells
- Bacteria + Archaea: use DNA as what?
… as hereditary info then packaged into circular chromosome
7.2 a Replication occupies most of the cell cycle in rapidly dividing prokaryotic cells
Where are chromosomes located, what are they?
o Compacted in central region called nucleoid
- A chromosome is a long DNA molecule with part or all of the genetic material of an organism.
- 2 b Replicated chromosomes are distributed actively to the daughter cells in binary fission
- Bacterial chromosomes separate ____ to membrane dynamics and is linked to DNA replication
independantly
7.2 b Replicated chromosomes are distributed actively to the daughter cells in binary fission
What is the Origin of replication (ori)?
o specific region in middle of cell where replication of bacterial chromosomes begins @ specific region of DNA sequence
7.2 b Replicated chromosomes are distributed actively to the daughter cells in binary fission
Where is Ori located?
o Ori = located where enzymes for DNA replicated are located
7.2 b Replicated chromosomes are distributed actively to the daughter cells in binary fission
o Completion of ori duplication results in what happening?
two new origins migrate towards opposite poles while replication continues for rest of chromosome
7.2 b Replicated chromosomes are distributed actively to the daughter cells in binary fission
o Division of cytoplasm is accomplished by what?
Inward constriction of ring of cytoskeleton proteins
7.2 c Mitosis has evolved from an early form of binary fission
Is Prokaryotic mechanism of cell division effective? If so, why?
o b/c most prokaryotic organisms have single chromosome
Means: daughter cell receiving minimum one copy of chromosome= genetic information = complete
7.2 c Mitosis has evolved from an early form of binary fission
Is Eukaryotic mechanism of cell division effective? Why or why not?
o b/c genetic info = divided amongst linear chromosomes, each chromosome has much greater length of DNA
o Daughter cell fails to receive a copy of chromosomes = lethal
o Most of cell cycle eukaryotic chromosomes = contained within nuclear membrane
7.2 c Mitosis has evolved from an early form of binary fission
o Bacteria + archaea have (an or no?) internal membrane around nucleoid
What does this mean for the organisms?
require different cellular and chromosomal machinery for distributing chromosomes to daughter cells (mitosis)
7.2 c Mitosis has evolved from an early form of binary fission
What is the evolutionary advancement of binary fission?
How does this benefit the cell?
• Evolutionary advancement: ability to hold two newly created molecules of double-stranded DNA (chromatids) following DNA synthesis
o Enables cells to keep track of chromosomes and orient them relative to cytoskeleton and ensure distribution to daughter cells
7.2 c Mitosis has evolved from an early form of binary fission
• Main components of cytoskeleton (are/aren’t?) present in ancestral prokaryotic cells, there (is/isn’t?) evolution
are, is
7.2 c Mitosis has evolved from an early form of binary fission
in higher eukaryotes what happens to the nuclear membrane at time when chromosomes are distributed
it disintegrates and reforms around daughter cells
7.2 c Mitosis has evolved from an early form of binary fission
What does variation in miotic apparatus result in?
What is a miotic apparatus?
evolution
a temporary structure in a dividing cell that enables the chromosomes to move to the poles of the cell
- 3 Mitosis and the eukaryotic cell cycle
- Eukaryotes require what to be genetic copies of parent
daughter cells
- 3 Mitosis and the eukaryotic cell cycle
- What are the 3 interrelated systems to eukaryotic mitosis?
o 1. Master program = orderly + timely progression through cell cycle
o 2. Process of DNA synthesis replicates each DNA chromosome into near perfect copies
o 3. Structural + mechanical web of interwoven cables + motors of cytoskeleton separates daughter cells
- 3 a Chromosmes are genetic units divided by mitosis
- The hereditary information of eukaryote chromosomes is distributed where? What does this enable?
= distributed among DNA molecules
= o DNA combines with proteins for stability
o Assist in packaging during cell division + expression of genes
7.3 a Chromosmes are genetic units divided by mitosis
Differnce between haploid, diploid, and ploidy?
Haploid:
- Haploid= n chromosomes not in pairs (singular)
o Yeast can be both haploid and diploid
Haploid organisms/cells have only one set of chromosomes, abbreviated as n.
Diploid:
- 2 copies of each chromosome 2n
Ploidy:
- # of chromosome sets = ploidy
- 3 a Chromosmes are genetic units divided by mitosis
- Waht occurs Before cell divides in mitosis?
replication of DNA provides in given chromosomes produces 2 identical copies of DNA = chromatids
- 3 a Chromosomes are genetic units divided by mitosis
- Eukaryotes contain copies of each chromosome in where?
Are humans haploid of diploid?
nucleus
diploid
- 3 a Chromosmes are genetic units divided by mitosis
- What are chromatids?
= held together by proteins called cohesins
7.3 a Chromosomes are genetic units divided by mitosis
o During mitosis what happens to the sister chromatids?
o Each daughter nucleus receives what from parent?
= separated
= same genetic info as parent