chapter twelve/thirteen Flashcards
regulatory molecules of mitosis
protein kinases and cyclins
checkpoints of mitosis
- G1
- M
- metaphase/anaphase
G1 checkpoint
restriction point, allows completion of G1, S, G2, M, and division phases
M checkpoint
between G2/M, checks for damaged/unreplicated DNA
metaphase/anaphase checkpoint
checks spindle attachment and tension
protein kinases
activate/inactivate other proteins by phsophorylating them
cyclins
protein that has cyclic fluctuating concentration in the cell
- attaches to kinase, cyclin-dependent kinases
G0 phase
non dividing state, if G1 checkpoint doesn’t receive “go-ahead” signal
external regulators of mitosis
growth factors, mitogen
growth factors
- epidermal
- fibroblast
- platelet-derived
growth factors
protein released by certain cells that stimulate other cells to divide
PDGF
required for division of cultured fibroblasts to heal wound, made by platelets
mitogen
small protein that induces cell to begin or enhance rate of division
cancer cells…
divide indefinitely/excessively, don’t depend on growth factors/normal signals
transformation
conversion of cells in culture to divide like cancer cells
- give new characteristics
tumor
mass of abnormal cells within otherwise normal tissue
benign
tumor that remains at original site if their genetic/cellular changes don’t allow them to move or survive at another site
malignant
tumor that becomes transformed, spreads to new tissues and impairs function of 1+ organs, near capillaries for nutrition and spread
metastasis
spread of cancer cells to locations distant from the original site
- enter blood/lymph vessels and travel throughout body
heredity
transmission of traits from one generation to the next
variation
no multicellular organisms completely identical (most of time)
genetics
study of both heredity and inherited variation
genes
hereditary units (coded information)
DNA
polymer of 4 dif nucleotides that contains genetic program
locus
gene’s specific location along the length of a chromosome
asexual reproduction
single individual is sole parent and passes copies of all its genes to offspring w/o fusion of gametes
- creates clones
- differences come from mutations
sexual reproduction
2 parents produce offspring w/ unique combinations of genes inherited from parents
- 2 gametes
- variation
karyotype
display of chromosome pairs of a cell arranged by size/shape
homologous chromosomes
2 chromosomes of a pair that have the same length, centromere position, and staining pattern
sex chromosomes
X/Y chromosomes that determine sex
- female - XX (homologous)
- male - XY (heterologous)
autosomes
chromosomes that aren’t sex chromosomes
somatic cells (diploid)
- 2 sets of 23 chromosomes (2n=46)
- even when DNA duplicated, cell still considered diploid
- 44 autosomes, 2 sex chromosomes
gametes (haploid)
- 23 chromosomes (n)
- transmit genes down generations
- 22 autosomes, 1 sex chromosome
fertilization (zygotę)
resulting fertilized egg (diploid)
- union of gametes culminating in fusion of nuclei
where do gametes develop from
germ cells in gonads
meoisis
cell division that reduces number of sets of chromosomes from 2 in parent cell to 1 in each gamete
sexual life cycle
n to fertilization to 2n (mitosis/development) to meiosis to n
tetrads
2 homologous chromsomes in synpasis
what do you have at the end of meiosis 1
haploid number of chromosomes
why does meiosis 2 occur
to get the right amount of DNA
prophase I
- synapsis, crossing over, synaptonemal complex, tetrad, chiasma
- spindle fibers form
- chromosomes condense
- nucleolus disappears
- centrosome movement
synapsis
2 homologs joined together by synaptonemal complex
crossing over
each chromosome pairs w/ homolog, DNA molecules of NONSISTER chromatids are broken by proteins + rejoined to each other
synaptonemal complex
zipper-like protein complex that attaches 1 homolog to the other, includes enzymes for crossovers
metaphase I
alignment of homologous chromosomes (tetrads) on metaphase plate
- 46 chromosomes
- 23 tetrads
- 92 sister chromatids
chiasma
X-shaped region in homologous pair where crossovers have occured
anaphase I
breakdown of proteins responsible for sister chromatid cohesion, homologs separate and move to opposite poles
- 92 chromatids
telophase I/cytokinesis
each resulting cell has complete haploid set of duplicated chromsomes
what does not occur between meiosis I and II?
DNA replication
second meiotic division
- prophase II
- metaphase II
- anaphase II
- telophase II/cytokinesis
mitosis overview
- identical cells/chromosomes
- genetic constancy
- variation by mutation
- 2N -> 2N
- somatic cells
- 2 cells produced
- 1 division sequence
meiosis overview
- different cells/chromosomes
- genetic variety
- vacation by mutation/recomb
- 2N -> N
- gametes
- 4 cells produced
- 2 division sequences
what leads to genetic variation in gametes?
independent assortment, crossing over, which sperm fertilizes which egg
independent assortment of chromosomes
- random orientation of pairs of homologous/ind chromosomes
- metaphase I
recombinant chromosomes
- crossing over (1-3 crossovers per pair)
- ind chromosomes that carry genes from 2 dif parents
how many different diploid combinations are there?
70 trillion
