Unit 3 Flashcards
G1 Phase (Interphase)
Cell accumulating building blocks of chromosomal DNA and the associated proteins as well as accumulating sufficient energy reserves to complete the task of replicating each chromosome in the nucleus
S Phase (Interphase)
DNA is replicated into identical paris of DNA (sister chromatids), that attach to centromeric region, centrosome duplicated in S phase
G2 Phase (Interphase)
cell replenished energy stores, and synthesizes proteins necessary for chromosome manipulation. Cell organelles duplicated, cytoskeleton dismantled
Prophase
chromosomes condense and become visible, spindle fibers emerge, nuclear envelope breaks down, nucleolus disappears
Prometaphase
- kinetochores appear at the centromeres
- mitotic spindle microtubules attach to kinetochores
- centrosomes move toward opposite poles
Metaphase
- mitotic spindle is fully developed, centrosomes are at opposite poles of the cell
- chromosomes lined up
- each sister chromatid attached to spindle fiber originating from opposite poles
Anaphase
- cohesion proteins binding sister chromatids together break down, sister chromatids (now called chromosomes) are pulled toward opposite poles, spindle fibers lengthen longing the cell
Telophase
- chromosomes arrive at opposite poles and begin to decondense, nuclear envelope material surrounds each set of chromosomes, mitotic spindle breaks down
Cytokinesis
animal cells - cleavage furrow
plant cells - cell plate
G1 Checkpoint
regulated internally and externally
most important
check DNA damage, cell size, adequate reserves, etc
G2 Checkpoint
regulated internally
cell size and reserves re-checked, and new DNA from s phase
G0 Phase
non-dividing state
M checkpoint
Regulated internally
when kinetochores not attached to spindle microtubles send a molecular singal delaying anaphase, prevents division with unequal chromosomes
Cyclins respondible for progress of cell through variuous checkpoints
D - all across
E - G1 - S
A - G1 - Mitosis
B - S - Mitosis (later)
negative regulators
halt the cell cycle
- retinoblastoma protein (Rb), p53 and p21
Proto-Oncogens
promote cell growth
Tumor Suppresor Genes
inhibit cell growth
sister chromatids
each duplicated chromosome consists of two identical sister chromatids
Synapsis and Crossing Over
prophase 1 of meiosis, homologous chromosomes physically connect and exchange genetic information
paired homologous chromosomes (tetrads)
metaphase plate
homologous chromosomes separate instead of sister chromatids
anaphase 1
Law of Segregation
alleles segregate during Meisos
law of independent assortment
allele pairs of different genes segregate independently
linked genes
genes located on the same chromosome that tend to be inherited together
Aneuploid
having too few or too many chromosomes
Trisomy
individual has three copies of one of their chromosomes
Monosomy
individuals have only one copy of one of their chromosomes
Down Syndrome
Trisomy of chromosome 21
Edwards Syndroms
trisomy of chromosome 18
Turner Syndrome
X0, only known viable monosomy
Klinefelter Syndrome
XXY
Polyploidy
individual with more then the correct number of chromosome sets
Structural Rearrangments
Deletion - segment removed
Duplication - segment duplicates
Inversion - reverses segment within a chromosome
Translocation - moves segment from one chromosome to another
