? Physical exchange between chromosome pieces of the crossing bivalent
? May increase the genetic variation of a species
In eukaryotes cell division occure by?
Mitosis and Meiosis
Field of genetics involving microscopic examination of chromosomes and cell division.
When cells get ready to divide what happens to the chromosomes?
The become compact enough to be seen.
This reveals number, size, and form of chromosomes in an actively dividing cell. ( looks like the lab exercise)
How many sets of chromosomes do humans have?
23 pairs. (46 then in total since in pairs)
How many autosomes are there in the human chromosome?
Hoe many Sex chromosomes are in the human chromosome?
These are normal chromosomes. In pairs and go under mitosis. 23 pair of chromosomes.
These are gamete chromosomes. have 1 member from each pair and go under meiosis. so 23 total chromosomes.
In diplois species members of a pair of chromosomes are called?
Each homologoue nearly identical in size and genetic composition.
X and Y veryu different from each other in size and composition.
Interphase is made up of what stages?
G1, s, and G2
Synthesis of dna
Mitosis and cytokinesis
Substitutes for G1 for cells postponing division or never dividing again.
In this phase cell growth occurs. Signaling molecules can cause cells to accumulate molecular charges during that promote progression through the cells cycle.
What happens if the cell passes the restriction point, or G1 Checkpoint?
The cell can now enter S phase and replicate DNA
In this phase chromosomes replicate. After replication, teo copies stay joined to eachother and are called sister chromatids
After going through the S Phase how many pairs of sister chromotids are the in the G2 phase?
46 pairs ( 92 chromatids all together)
In this phase cell sythesizes proteins needed during mitosis and cytokinesis. Decision to divide happens here too.
What are the factors of cell division?
External: Eviromental coditions good and signaling molecules. Internal factors: Cell cycle control molecules and checkpoints
These are the checkpoint proteins and are responsible for advancing a cell through the phases of the cell cycle. the amount varies.
Cyclins or cyclin-dependent kinases (cdks)
There are three critical checkpoints in eukaryotes.
G1 (restriction point), Gs, and metaphase
What happens if there is a loss of checkpoints.
mutations or cancer
two identical copies with associated proteins.
Chromatids tightly associated at?
This serves as attachment site for kinetochore used in sorting chromosomes.
Ensures that each daughter cell will obtain the correct number and types of chromosomes. Is responsible for organizing and sorting the chromosomes during mitosis.
Mitotic spindles are made of?
What forms microtubules?
What are the three types of microtubules.
Astral, polar, and kinetochore
These microtubules position spindle in cell.
These microtubules separate two poles.
These microtubules attached to kinetochore bound to centromeres.
phase of the cell cycle during which the chromosomes are decondensed and found in the nucleus (G1, S, G2)
What are the stages to mitosis?
Prophase, Prometaphase, Metaphase, Anaphase, and Telophase
division into two daughter cells
Chromosomes have already replicated and are joined as pairs of sister chromatids. Nuclear membrane dissociates into small vesicles. Chromatids condense into highly compacted structures that are readily visible by light microscopy
Nuclear envelope completely fragments. Mitotic spindle is fully formed during this phase. Centrosomes move apart and demarcate the two poles. Spindle fibers interact with sister chromatids. Two kinetochores on each pair of sister chromatids are attached to kinetochore microtubules from opposite poles
Pairs of sister chromatids are aligned along a plane halfway between the poles. Organized into a single row.
What is the sister chromatids are aligned along a plane halfway between the poles is called?
Connections broken between sister chromatids. ? Each individual chromatid is linked to only one pole by kinetochore microtubules. Kinetochore microtubules shorten, pulling chromosomes toward the pole to which they are attached. The two poles move away from each other. as overlapping polar microtubules lengthen and push against each other
Chromosomes have reached their respective poles and decondense. Nuclear membranes now re-form to produce two separate nuclei
THis follows mitosis. Two nuclei are segregated into separate daughter cells
What is the differece in cytokinesis in animals and plants?
Animals hvae a cleavage furrow and plants have a cell plate
is the process by which haploid cells are produced from a cell that was originally diploid
What are the two key differences in meiosis?
Homologous pairs form a bivalent or tetrad. Crossing over
Homologous pairs of sister chromatids associate with each other, lying side by side.
Bivalent or tetrad
What is the process of bivalent called?
This is a protein structure that connects homologous chromosomes
Physical exchange between chromosome pieces of the crossing bivalent. May increase the genetic variation of a species
arms of the chromosomes tend to separate but remain adhered at a crossover site
Is there an S phase between Meiosis 1 and 2
What are the chromosomal mutations
Deletions, duplications, inversions, translocations, Euploid, Polyploid, aneuploidy, trisomic, and monosomic
Segment of chromosomemissing
Repeated segment of chromosome
A segment has a change in direction along a single chromosome.
One segment becomes attached to another chromosome. May be simple or reciprocal.
The normal number of chromosomes
3 or more sets of chromosomes. Triploid 3n and tetraploid 4n
Abnormal number of particular chromosome.
THis is downs. Normal 2 copies of a chromosome plus a 3rd.