quiz- genetics Flashcards
what are the functions of cell division?
there are three:
- growth of the organism
- repair of tissues and organs that have been damaged
- maintenance to replace dying or dead cells.
how long does it take for a cell to complete the cell cycle
the time it takes for the cell cycle to complete depends on the cell, certain cells in flies take 8 minutes, liver cells take over a year, most healthy dividing cells take 12-24 hrs.
what are the three steps of cell division?
what are the three phases of interphase?
interphase->mitosis->cytokinesis
In interphase the cell devolps into a mature functioning cell copies its dna and prepares for division. the three phases- G1 (GROWTH-1); rapid growth and cell activity, S (SYNTHESIS); DNA Synthesis and replication, G2 (GROWTH-2); Cell prepares for division
what happens in all the phases of mitosis?
INTERPHASE - cell copied DNA, and prepares for cell division
PROPHASE - chromatin condenses into sister chromatids, the chromosomes are joined in the middle with the centromere. (if its connected its one chromosome. spindle fibers form, nucleus membrane disappears, spindle fibers organizes the chromosomes during mitosis.
METAPHASE - spindle fibers bring the chromosomes
(sister chromatids) to the equator of the cell. the spindle fibers from opposite poles attatch to the centromere of each chromosome.
ANAPHASE- the spindle fibers shorten, splitting the centromeres, seperating the sister chromatids, bringing them to opossite poles of the cell. the one chromatid is now referred to one chromosome (as they are no longer connected). one full set of chromosomes at each cell.
TELOPHASE- begins when the chromosomes have reached the opposite poles of the cell. They become less-visible chromatin, the spindle fibers breakdown, nucleus membrane reappears. nucleolus forms within each nucleus.
rmr it by I - P.M.A.T - C
what is cytokinesis?
division of the cytoplasm, cleaveage furrow occurs and they seperate and become 2 new daughter cells. It completes the creation of the two new daughter cells.
what is dna?
DNA is the molecule that carries genetic information for the devolpment and functioning of an organism.
what are genes?
a part of a chromosome that governs the expression of a trait and is passed on to offspring; it has a specific DNA sequence.
sequences of dna that contain genetic information for specific traits.
what are alleles?
a different form of the same gene
what are homologus chromosomes?
homologus pairs are not identical to each other, they contain the same sequence of genes as another chromosome. they carry different forms of the same gene.
what is spermatogensis?
spermatogensis is the production of sperm cells, it occurs in the testes. it starts off with a diploid cell named spermatogonium, the diploid cell goes through meiosis and in the end four gametes are formed, four haploid cells.
animal cells
what is oogenesis?
it is the production of egg cells, it happens in the ovaries. it starts off with a diploid cell called an oogonium. meiosis occurs and theres a production of a egg cell, the rest are polar bodies these are haploid cells but the polar bodies do not have the ability to be fertilized, this egg cell looks for fertilization each month, start of your period, when it doesnt find one it releases and gets flushed, what we call our period.
animal cells
what is independent assortment?
during metaphase 1, chromosomes are arranged in homologus pairs along the equatior. In each pair - materan origin is oriented toward one pole of cell. - paternal origin is oriented to the other. depending on how they line up, a # of different combinations may be found in gametes.
maternal and paternal chromosomes.
what is crossing over?
when homologus chromosomes are lined up during prophase 1, non sister chromatids of homologus chromosomes may exchange pieces of chromosomes.
synapsis
what is disjunction?
disjunction is the sister-chromatids/homologus pairs being able to seperate, the pulling apart in anaphase in meiosis 1/ meiosis 2. Normal disjunction results in four haploid cells.
what is non-disjunction?
the failure of one or more homologus pairs/ sister chromatids to seperate normally during nuclear division, usually resulting in an abnormal distribution of chromosomes. this results in disorders.
