Chapters 12-15 Flashcards
Synthesis (S)
DNA replication (DNA replication is the only replication not involved in G1)
Gap 1 Phase
growth of cell and synthesis of cytoplasmic organelle
Gap 2 Phase
synthesis of structures involved in cell division. (Ex. microtubules)
Mitosis (M) = Karyokinesis
“chromosome splitting” chromosomes condense and separate into 2 nuclei
Cytominesis
“Cell splitting” the cytoplasm separates into 2 cells
Interphase
Gap 1, Synthesis and Gap 2 are collectively called this. The cell is very biologically active at this time.
how much time do cells spend in mitosis?
5-15% of lifetime but varies among organs.
how long do blood marrow cells spend in mitosis?
Divide rapidly to replace worn out blood cells (120 days = life of a red blood cell)
How long do neurons (nerve cells) spend in mitosis?
neurons divide very slowly, or not at all in adults. Cycle stops in gap 1 stage (at the Gap 1 checkpoint) and exits the cell cycle into G0 phase.
how long do liver cells spend in mitosis?
liver cells divide rapidly to replace missing tissue but slowly otherwise
chromosome
a strand of DNA that has wound up tightly causing it to be visible in the microscope
centromere
constricted region of the chromosome with associated proteins
sister chromatids
2 identical copies of the same chromosome
homologous chromosomes
chromosomes that are the same length, have centromeres in the same location, and carry genes for the same traits (e.g. eye color or blood type). One comes from your father, the other comes from your mother.
how do you count the number of chromosomes?
count the number of centromeres
Interphase role in Mitotic Division
no condensation of chromatin
cant tell the number of chromosomes through a microscope
nuclear envelope present
nucleolus present at nucleolar organizer region
centrosomes paired side-by-side (not found in plants)
Prophase
chromatin condenses into chromosomes
chromosomes massed in center of cell
nuclear envelope disappears
nucleolus disappears
spindle fibers, made of microtubules attached end-to-end, form between the migrating centrioles and attach to kinetochores of each sister chromatid.
kinetochore
disk-shaped proteins found on the centromere of the chromosome. allows spindle fibers to push and pull the chromosomes into place.
metaphase
chromosomes are fully condensed
chromosomes line up at metaphase plate by the spindle fibers in a 1X1 pattern
Anaphase
spindle fibers push and pull sister chromatids to separate poles of the cell.
Telophase
two nuclei are now forming
chromosomes unwind into chromatin
nuclear envelope reappears
nucleoli reappear
spindle fibers break down
Cleavage furrow
where the animal cell pinches off in cytokinesis. made of contractile ring of microfilaments that work like a draw string.
cell plate
cytokinesis of plant cells
- vesicles form
- vesicles fuse into cell plate
- cell plate fuses with cell wall
meiosis
nuclear division that produces 4 daughter cells that have half the number of chromosomes as the original parent cell.
Gametes
egg or sperm. result of meiosis and are haploid.
another name for Meiosis
reduction-division because chromosome numbers are reuced by half during Meiosis I, then sister chromatids are separated in Meiosis II.
Prophase I
homologous chromosomes (mom and dad) pair up during a process called synapsis
during synapsis some homologous chromosomes break and swap places. this is called recombination
chiasmata
location where homologous chromosomes touch. this is where recombination is occuring
metaphase I
homologous chromosomes line up at metaphase plate 2-by-2. these sets of homologous chromosomes are called tetrads.
Anaphase I
homologous chromosomes are pulled apart to opposite poles of the cell.
sister chromatids are STILL connected.
Telophase I
the two cells that will be formed by cytokinesis will have only half as many chromosomes as the original parent cell.
however there is still the same amount of DNA material as a somatic cell
Prophase II
meiosis II begins
Metaphase II
chromosomes line up 1 by 1 at metaphase plate
anaphase II
sister chromatids are pulled apart to separate poles
Telophase II
end result is four haploid gametes
spermatogenesis
formation of sperm via meiosis
First step of Spermatogenesis
Maturation. Diploid spermatogonium matures into a diploid primary spermatocyte.
second step of spermatogenesis
Meiosis I. Primary spermatocyte divides into two haploid Spermatocytes.
Third step of spermatogenesis
Meiosis II. Two haploid Secondary divide into a total of four haploid Spermatids.
final step of spermatogenesis
maturation. four haploid spermatids mature into four haploid sperm.
Three steps of Oogensis
Oogonium matures into diploid primary oocyte. Meiosis I splits primary oocyte into two haploid cells, the secondary oocyte and a polar body. Meiosis II splits the secondary oocyte into an ovum and a polar body and the one haploid polar body into two haploid polar bodies.
Zygote
the single cell resulting from fusion of the sperm with the ovum. is a diploid cell
embryo
result of zygote undergoing mitosis. the division is called cleavage and the cell gets smaller each time they divide so the overall size of the embryo doesn’t change
Morula
solid ball of cells resulting from embryonic mitosis
Blastula
hollow cell made by morula moving out to edges.
blastocoel
hollow center of the blastula
gastrulation
process of indenting the cell that forms a blastopore that will later become either a mouth or anus.
gastrula
end result of gastrulation. cell with two embryonic tissues, the endoderm (lining the inside) and the ectoderm (lining the outside)
ectoderm becomes
skin
endoderm becomes
lines the gut
mesoderm becomes
muscles
blastopore becomes
mouth or anus
blastocoel becomes
body cavity
Holandric Traits
Y-linked traits
example: maleness, hairy ear rims
principle of segregation
during meiosis, the 2 alleles for a gene separate into two different gametes
principle of independent assortment
how the alleles for one gene segregate does not affect how the alleles for another gene separate. PROVIDED they are on different chromosomes.
F2 Genotype dihybrid cross
1 homo for both same case 2 homo for one hetero for one 1 homo for both opposite case 2 homo for one hetero for one 4 hetero for both 2 hetero for one homo for one 1 homo for both opposite case 2 hetero for one homo for one 1 homo for both same case
incomplete dominance or partial dominance
neither is dominant so the result is blended
codominance
both alleles for a heterozygous individual ate fully expressed
example: blood type
quantitative traits
polygenic traits caused by the additive affects of various alleles. many genes affect one trait.
continuous distribution with a bell-shaped curve. also affecter by environmental factors
as more genes are included in a trait, the distribution shifts from _____ to ______
discrete (bar graph) to continuous (curve, all points are included)
Pleiotropy
one gene affects many traits
example: Phenylketonuria
Phenylketonuria
- lack enzyme to metabolize phenylalanine
- have elevated concentrations.
- have smaller headsize
- have reduced IQ
- have light hair color