Cell division Flashcards
Largest structure to smallest
Organism, Organ, tissue, cells, nucleus, chromosome, gene, DNA
How many chromosomes does a human have?
46
How many chromosomes does an egg/sperm have?
23
How many chromosmes does a fertilized egg have?
46
Avantages of reproducing sexually
Diversity/variability
Avantages of reproducing asexually
Quicker, no energy finding a mate, produce more.
Normal process of cell division where one cell divides in such a way as to produce 2 identical daughter cells with same chromosome # as parent cell.
Mitosis
When cell does its job,preparing for cell division, uncondensed chromatin. 90% of life cycle of cells. Replication of DNA.
Interphase
immediately follows mitosis; cells grow in size; cytoplasmic molecules & structures increase in number(organelles double)
G1 (gap/growth phase)
Chromosome DNA is replicated
S (synthesis phase)
final preparation for cell division
G2 (gap/growth phase)
Chromatin shortens/thickens to form chromosomes.chromosomes composed of 2 chromatids attached by centromere. nuclear mem. disappears. centrosomes migrate to opposite poles & form spindle fibers
prophase
made up of genes. A thread like structure made up of DNA & proteins
chromosomes
uncondensed chromosomes, complex of DNA & protein that make up chromosomes
chromatin
Half of a duplicated chromosomes
Chromatids
Made up of 2 centrioles. produce spindle fibers that move the chromosomes
Centrosome
Individual part that make centrosomes
centriole
Structure that holds chromatids together
Centromere
chromatids are highly visible and align themselves along the middle of the cell (equatorial plate)
Metaphase
Centromere split, and chromatids seperate (now have 2 single stranded, unduplicated chromosomes) spindle fibers pull seperated chromosomes to opposite poles
Anaphase
Nuclear membrane/nucleoli reforms. chromosomes become chromatin, spindle fibers dissolve, chromosomes become longer & thinner(chromatin)
Telophase
Cytoplasm divides, not a phase in mitosis
Cytokinesis
a term to describe the number of chromosomes sets in a nucleus and is represented by the letter n
Ploidy
refers to two sets of chromosomes (full complement) and is found in body cells.
Diploid
are organismes with three or more complete sets of chromosomes. if diploid is 2n, then triploid is 3n, tetraploid is 4n,etc
Polyploids
process in which sex cells (gametes) are formed, occur in gonads(ovaries, fallopian tube 7 testes) not identical haploid to parent cell. one replication.
meiosis
chromatin becomes visible chromosomes with chromatids joined by centromere, nuclear mem. fades, centrioles move to opp. poles, spindle appear. Homologous chromosomes pair up forming tetrad
Prophase I
2 homologous/4 chromatids
tetrad
tetrads line up on the equatorial plate
metaphase I
Homologous pairs/tetrads seperate & move to opposite poles(segregation) diploid mother becomes 2 haploid daughters
Anaphase I
Division of cytoplasm forming 2 cells that are not identical
Telophase I
Centrioles in the two new cells move to opposite poles, nuclear mem. dissapears, spindle reappear
prophase II
Chromatids line up on equatorial plate
Metaphase II
Sister chromatids seperate and move to opposite poles
Anaphase II
Nuclear membrane reforms. haploid daughter cells forming.
Telophase II
Resulting in 4 haploid daughter cells (all nonidentical) each with half the chromosomes of the original parent cell. Then chromosomes unravel & turn back into chromatin
Cytokinesis (miosis)
chromosomes similar in length,location of centromere & order of genes. One is received from each parent
Homologous chromosomes (homologues)
homologous chromosomes pair up, forming tetrads during prophase I in meiosis I
Synapsis
breaking and rejoining homologous non-sister chromatids (increases genetic variation); results in recombinants (new gametes with new gene combinations)
crossing over
the process by which 2 sister chromatids formed because DNA replicaiton, or paired homologous chromosomes, separate from each other & migrate to opp. poles. process occurs in mitosis & meiosis
segregation
the haploid (n) stage of a plant that produces gametes by mitosis, which fuse and produce the sporophyte generation
Gametophyte
The diploid stage of a plant that produces spores by meiosis
Sporophyte
the gamete joins with 24 chromosomes joins with a normal gamete (230 to form zygote with 47 chromosomes
trisomy
The gamete with 22 chromosomes joins with a normal gamete (23) to form zygote with 45 chromosomes
Monosomy
results in trisomy or monosomy which results in down syndrome, Klinfelter syndrome, & turners syndrome
Nondisjunction
A group of signs and symptoms that occur together and characterise a particular abnormally or condition, however not all symptoms may be present in each patient & not the same degree of severity
Syndrome
47 chromosomes (extra 21-also called trisomy 21)
Down syndrome
XXY-47 (extra X chromosomes;but will be male due to presence of Y chromosome)Calico
Klinefelter syndrome
XO-45 chromosomes, individuals only have one X chromosome (will have 45 chromosomes and be female)
Turners syndrime
Picture of chromosomes arranged in homologous pairs
karyotype
