Question | Answer |
chromosomes v chromatin | some: threadlike, gene-carrying structure found in nucleus. Each has long DNA molecule & protein
tin:The complex of DNA & proteins make up chromosome When the cell isn't dividing, it exists as mass of long, thin fibers that aren't seen w/light microscope |
what is the cell cycle? | An ordered sequence of events in the life of a dividing eukaryotic cell, composed of the M, G1, S, and G2 phases. |
the genome of an organism is defined by | a complete set of organism genes |
somatic cells v gametes | somatic-Any cell in a multicellular organism except a sperm or egg cell
gamete-A haploid egg or sperm cell; gametes unite during sexual reproduction to produce a diploid zygote. |
what are sister chromatids? how are they held together? | Replicated forms of a chromosome joined together by the centromere & eventually separated during mitosis or meiosis II. |
what is a centromere? how many does a replicated chromosome have? unreplicated? | -The centralized region joining two sister chromatids, centromere is the region in the middle of each chromosome, replicated 2, i replicated 1 |
what is the separating point that determines whether you call a replicated chromosomes, chromatids or chromosomes? | chromatid is half of chromosome |
which parts of the cell cycle includes mitosis? | in mitotic (m) phase (prophase, prometaphase, metaphase, anaphase, & telophase) |
is cytokinesis in mitosis? | Cytokinesis is part of M-phase, but not part of Mitosis.
*M-phase consists of nuclear division (mitosis) & cytoplasmic division (cytokinesis) |
cell cycle events | Interphase:G1 (first gap, grows), S (synthesis,grows and copies chromosomes), G2 (second gap, prep for division)
& M (divides genetic material in nucleus), C(cytoplasm divides) |
purpose of mitotic spindle in cell division? what is it made of? where is from? | Spindle fibers form protein structure that divides genetic material in cell.
used to divide chromosomes in parental cell into 2 daughter cells during 2 types of nuclear division: mitosis & meiosis
form in cytoplasm(prophase),composed of microtubules |
aster, what does it include? | a radial array of short microtubules that extends from each centrosome |
what is the function of kinetochore? where is it located? | anchoring of chromosomes to MTs in the spindle, verification of anchoring, activation of the spindle checkpoint & participation in force generation to propel chromosome movement during division
located in or near the centromere |
kinetochore microtubules v polar microtubules | Chromosomes are attached to kinetochore microtubules via a multiprotein complex called the kinetochore.
Polar microtubules intersect @ spindle midzone & push spindle poles apart via motor proteins. |
function of enzyme separase | cleaves chromosome in anaphase |
hypothesis: chromosomes moved to opposite side of cell | move to diff sides cuz spindle fibers |
cytokinesis: plant v animal cells
(cleavage, cleavage furrow,actin filaments, golgi apparatus,cell plate,cell wall) | Animal cells divide by a cleavage furrow(shallow groove in cell surface near old metaphase plate)
Plant cells divide by a cell plate that eventually becomes the cell wall.
cytokinesis occurs by process called cleavage |
how do bacteria divide? what is the origin of replication? | Bacteria reproduce by binary fission.
In this process the bacterium,(single cell), divides into 2 identical daughter cells.
origin of replication |
what drives the cell cycle? | cyclins |
analogy: washing machine & cell cycle | washing machine functions in stages: it takes water, mixes it w/ detergent, washes clothes, rinses them, & spins dry.
These processes of the wash cycle are analogous to the essential processes of the cell cycle—DNA replication, mitosis, and so on |
3 major checkpoints, which is most important? | The integrity of DNA is assessed at the G1 checkpoint.
Proper chromosome duplication is assessed at the G2 checkpoint.
Attachment of each kinetochore to a spindle fiber is assessed at the M checkpoint. |
what may cause cell to enter G0 phase? | when cells reach their final mature state, they don't need to divide again.
The cells leave G1 and enter an alternative state called G0 where they stop dividing permanently*Neurons & red blood cells are examples of terminally differentiated cells. |
growth factor | -protein released by certain cells that stimulate other cells to divide |
anchorage dependency v density dependence inhibition | anchorage-most animal cells must be in contact with a solid (substratum)surface in order to divide
density-
If a cell is crowded it will not divide. Cells will stop dividing when they are in contact with others cells. |
cancer cells v non cancerous cells | don't regulate @ normal signals, divide excessively & invade other tissues |
transformation | process that converts a normal cell to a cancer cell |
apoptosis | the death of cells that occurs as a normal and controlled part of an organism's growth or development |
benign v malignant tumor | benign: non harmful, at site no genetic and cellular change
malignant: bad, spreads to tissues and impairs functions |
besides excessive proliferation, what other ways may change in malignant cells show up? | unusual numbers of chromosomes, metabolism may be disabled |
genes | coded info in form of heriditary units |
locus | a genes specific location along length of chromsome |
asexual v sexual reproduction | asexual-single individual in sole parent & passes copies of all genes to offspring w/o fusion of gametes
sexual-2 parents giver offspring that have unique combination of gene inherited from 2 parents |
karyotype | the number and visual appearance of the chromosomes in the cell nuclei of an organism or species. |
homologous chromosomes | Chromosome pairs of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding loci.
One homologous chromosome is inherited from the organism's father, the other from mother. |
sex chromosomes v autosomes | autosomes-A chromosome that is not directly involved in determining sex, as opposed to the sex chromosomes. |
diploid v haploid | diploid-A cell containing two sets of chromosomes (2n), one set inherited from each parent.
haploid-A cell containing only one set of chromosomes (n). |
zygote | The diploid product of the union of haploid gametes in conception; a fertilized egg. |
germ cells | Gametes or the cells that give rise to gametes. |
animal v plants v fungi life cycles | plant have spores and gametophytes and animals dont |
alteration of genes | plants and species of algae, both diploid and haploid stages that are multicellular |
3 events unique to meiosis | Synapsis & crossing over. -During prophase 1, duplicated homologs pair up & formation of synaptonemal complex between them holds them in synapsis
Homologous pairs at the metaphase plate.
Seperation of homologs. |
how do independent assortment, crossing over, & random fertilization lead to variation among offspring? | co-sections of dna on 2 chromosomes r cut out, then switch over to opposite chromosome
rf-sperm and egg |
disadvantages of sexual reproduction | Slower reproduction rate
Less reliable reproduction
Takes time and energy to find mate |
recombinant chromosomes | A DNA molecule made in vitro with segments from different sources. |
reductional division v equational division | Because the ploidy is reduced from diploid to haploid, meiosis I is a reductional division.
Meiosis II is an equational division analogous to mitosis, in which the sister chromatids are segregated, creating four haploid daughter cells |