1.2. Physical Basis of Heredity Flashcards
• Cell Structure and Genetic Function • Chromosomes • Major Processes Involved in the Genetic Continuity of Nucleated Cells
cell structure that houses the dna
nucleus
site of rRNA synthesis and the initial stages of ribosome assembly
nucleolus
site of translation
ribosome
site of atp synthesis; contains dna
mitochondria
site of photosynthesis; contains dna
chloroplast
coiled chromatin fibers
chromosome
extended form of the chromosome
chromatin fiber
centromere in the middle
metacentric
centromere between middle and end
submetacentric
centromere is close to end
acrocentric
centromere is at the end portion
telocentric
chromosomes that have the same size, shape, position of centromere, gene sites along their lengths, and characteristics
homologous chromosomes
homologous chromosomes all carry the same information. true or false?
false; not necessarily the same
major process in genetic continuity that leads to the production of two cells with the same number of chromosomes as the parent cells; involves somatic cells
mitosis
what are the roles of mitosis?
(1) growth and development
(2) regeneration and repair
(3) basis for asexual reproduction for unicellular organisms (i.e., protozoa, fungi, algae)
constitutes the events that occur from the completion of one division until the completion of the next division
cell cycle
what happens in the g0 stage?
cells are dormant; cells are viable and metabolically active but do not proliferate; reversible or irreversible
cells spend most of their time in interphase. true or false?
true. they spend 15 hours in interphase(5 for g1, 7 for s phase, and 3 for g2 phase. only one hour is spent for mitosis
g1/s checkpoint checks for
cell size and dna quality
g2/m checkpoint checks for
dna replication and quality
m checkpoint checks for
spindle assembly checkpoint
no visible chromosomes but visible nucleolus; nuclear membrane starts to disintegrate
interphase
interphase
(1) chromatin number
(2) chromosome number
(3) chromatid number
(1) 92 chromatins/cell
(2) 0 chromosome/cell
(3) 0 chromatid/cell
visible chromosomes; complete disintegration of nuclear membrane; asters/star-like arrangement of microtubules; spindle fiber assembly
prophase
cohesin is formed during what stage?
interphase
prophase
(1) chromatin number
(2) chromosome number
(3) chromatid number
(1) 0/cell
(2) 46/cell
(3) 92/cell
period of chromosome migration to the equatorial plane called the metaphase plate; migration is facilitated by the binding of spindle fibers to the chromosome’s kinetochore
prometaphase
an assembly of multilayered plates of proteins; associated with the centromere
kinetochore
degrades cohesin
separase
protects cohesin from degradation at the centromeric region
shugoshin
prometaphase
(1) chromatin number
(2) chromosome number
(3) chromatid number
(1) 0/cell
(2) 46/cell
(3) 92/cell
chromosome configuration following migration
metaphase
metaphase
(1) chromatin number
(2) chromosome number
(3) chromatid number
(1) 0/cell
(2) 46/cell
(3) 92/cell
degradation of shugoshin and cohesin; sister chromatids separate (disjunction)
anaphase
after anaphase, each migrating chromatid is referred to as ____.
daughter chromosome
anaphase
(1) chromatin number
(2) chromosome number
(3) chromatid number
(1) 0/cell
(2) 46 choromosomes/pole
(3) 0 chromatids/cell
final stage wherein there is one complete chromosome set per pole
telophase
chromosomes begin to uncoil; reformation of the nuclear envelope; spindle fibers disappear; nucleolus gradually reforms but not visible
late telophase
telophase + cytokinesis
(1) chromatin number
(2) chromosome number
(3) chromatid number
(1) 0 chromatin/cell
(2) 46 chromosomes/cell
(3) 0 chromatid/cell
cell division by which gametes or spores are produced; haploid set of chromosomes
meiosis
in meiosis, each haploid cell contain precisely one member of each homologous pair of chromosomes. true or false?
true
two sources of genetic variation
(1) many unique combinations of chromosomes from each parent
(2) crossing over
genetic exchange between members of each homologous pair of chromosomes, creating intact chromosomes that are mosaics of the paternal and maternal homologs
crossing over
how many rounds of dna replication take place in meiosis?
one; in meiosis I
localized condensations that resemble beads on a string
chromomeres
stage in prophase I wherein chromomeres appear and synapsis begins
leptonema
what is synapsis?
pairing of homologs
synapsed pair of homologs equal to the haploid number; what stage in prophase I do these appear?
bivalent; zygonema
two pairs of sister chromatids; what stage in prophase I do they appear?
tetrad; pachynema
stage in prophase I wherein crossing over happens
diplonema
site of crossing over/point where non-sister chromatids have undergone genetic exchange
chiasma/chiasmata
stage in prophase I wherein separation of chromosomes start; nucleolus and nuclear envelope break down; two centromeres of each tetrad attach to the recently formed spindle fibers
diakinesis
during diakinesis, what happens to the chiasmata?
they move toward the ends of the tetrad
prophase I
(1) chromatin number
(2) chromosome number
(3) chromatid number
(4) tetrad number
(5) bivalent number
(1) 0/cell
(2) 46/cell
(3) 92/cell
(4) 23/cell
(5) 23/cell
what happens during metaphase I?
chromosome are maximally shortened and thickened; tetrads are randomly aligned
metaphase I
(1) chromatin number
(2) chromosome number
(3) chromatid number
(4) tetrad number
(1) 0/cell
(2) 46/cell
(3) 92/cell
(4) 23/cell
what happens in anaphase I?
the dyads are pulled toward each pole of the dividing cell; disjunction: separation of chromosomes from one another
anaphase I
(1) chromatin number
(2) chromosome number
(3) chromatid number
(4) tetrad number
(5) dyad number
(1) 0/cell
(2) 23/pole
(3) 46/pole
(4) 0/pole
(5) 23/pole
what happens in telophase I?
nuclear membrane forms around the dyads; nucleus enters into a short interphase period but no dna synthesis (absent in other organisms)
telophase I
(1) chromatin number
(2) chromosome number
(3) chromatid number
(4) tetrad number
(5) dyad number
(1) 0/cell
(2) 23/pole
(3) 46/pole
(4) 0/pole
(5) 23/pole
in prophase II, each dyad is composed of one pair of sister chromatids attached by a common centromere. true or false?
true
prophase II
(1) chromatin number
(2) chromosome number
(3) chromatid number
(4) tetrad number
(5) dyad number
(1) 0/cell
(2) 23/pole
(3) 46/pole
(4) 0/pole
(5) 23/pole
what happens in metaphase II?
chromosomes align at the metaphase plate
metaphase II
(1) chromatin number
(2) chromosome number
(3) chromatid number
(4) tetrad number
(5) dyad number
(1) 0/cell
(2) 23/pole
(3) 46/pole
(4) 0/pole
(5) 23/pole
what happens in anaphase II?
sister chromatids of dyads are pulled to opposite poles
anaphase II
(1) chromatin number
(2) chromosome number
(3) chromatid number
(4) tetrad number
(5) dyad number
(1) 0/cell
(2) 23/pole
(3) 0/pole
(4) 0/pole
(5) 0/pole
what happens in telophase II?
one member of each pair of homologous chromosomes at each pole; each chromosome is called monad
telophase II
(1) chromatin number
(2) chromosome number
(3) chromatid number
(4) tetrad number
(5) dyad number
(6) monad numebr
(1) 0/cell
(2) 23/pole
(3) 0/pole
(4) 0/pole
(5) 0/pole
(6) 23/pole
cytokinesis
(1) chromatin number
(2) chromosome number
(3) chromatid number
(4) tetrad number
(5) dyad number
(1) 0/cell
(2) 23/cell
(3) 0/cell
(4) 0/cell
(5) 0/cell