Bio Chapter 10 Flashcards
Diploid (2n)
Carries 2 sets of genetic information, somatic cells (anything other than sperm and eggs)
Haploid (n)
Carries 1 set of genetic information, gamete (reproductive) cells
DNA organization in eukaryotes
DNA double helix
DNA wrapped around a histone - group of proteins
Nucleosomes (groups of histones) are coiled into a chromatin fiber
Further condensation of chromatin
Duplicated chromosome
*Eukaryotic chromosomes are much larger and more complex than prokaryotes
Genome
All the genes in one package, all the genetic information that defines an organism
DNA repair genes
Not repairing damage to control of proliferation, differentiation or apoptosis
Repair mechanisms check DNA and repair genes
Oncogenes
A normal cellular gene that is altered or deregulated in a way that directly contributes to the malignant transformation
Proto-oncogene is the gene before it undergoes mutations (potential of becoming cancer gene)
Tumor supressor genes
Encode negative regulators of cell proliferation (splitting) or survival
Loss of function to the gene allows for tumor formation
Sister chromatids
A chromosome usually consists of 2 sister chromatids
During cell division, the 2 sister chromatids of each chromosome are duplicated and then separated into 2 nuclei
Cohesion
Proteins that join 2-sister chromatids to one another, ring-like cells
During anaphase, cohesions are cleaved and sister chromatids separate
They move along kinetochore microtubules to opposite ends of the cell
Phases of the cell cycle
Mitotic (M) phase - includes mitosis (nuclear division) or cytokinesis (cytoplasmic division)
Interphase - cell growth and copying of chromosomes in preparation for cell division
Phases of interphase
Most of the cell’s time is spent here (90% of the cell cycle)
G1 phase (gap phase - cell growth)
S phase (synthesis - the cells replicates DNA here, number of molecules double but number of chromosomes stays the same, chromosomes are duplicated ONLY during S phase
G2 phase (gap phase - cell growth)
Cleavage furrow
Animal cells form a cleavage furrow
A contractile ring made from actin and myosin pinches the cell in two
As cytokinesis progresses, the contractile ring becomes smaller
It will disassemble completely once the cell has finished dividing in two
Stages of mitosis
Prophase
Prometaphase
Metaphase
Anaphase
Telophase
Prophase
The chromosomes were duplicated by the time prophase starts
Chromosomes condense
Mitotic spindle assembles between centrosomes
Nucleolus disappears
Prometaphase
Starts with breakdown of nuclear envelope
Chromosomes attach to spindle microtubules via kinetochores
Chromosomes start to move toward center of cell
Centrosomes (spindle pole) move to opposite poles of the cell
Metaphase
Chromosomes are aligned at the equator of the spindle (midway between spindle poles)
Kinetochore microtubules on each sister chromatid attach to opposite poles of the spindle
Anaphase
Sister chromatids separate
Pulled to opposite poles
Kinetochore microtubules get shorter and spindle poles move apart
Ends when the groups of chromatids have arrived at opposite ends of the cell
Telophase
Chromosome sets arrive at poles of spindle
New nuclear envelope forms around each set of chromosomes
End of mitosis
G1 checkpoint
If the cell doesn’t receive a go-ahead signal, it exits the cycle and switches to a non-dividing state called the G0 phase
M checkpoint
Cells will not begin anaphase until all chromosomes are properly attached to the spindle at the metaphase plate
Ensures that daughter cells have the correct number of chromosomes
Stop signal without full chromosomes attachment
Go-ahead signal with full chromosomes attachment
Binary fission in bacteria
Prokaryotes reproduce by binary fission (NO MITOSIS)
The chromosome replicates - starts at origin of replication
2 daughter chromosomes actively move apart
Plasma membrane pinches inward dividing cell in two
What are chromosomes composed of?
DNA and proteins
Be able to calculate number of chromosomes in different parts of cell cycle
