How does the cell control the cell cycle?
Check points and cyclins:
What checkpoints occur
-G1: end of phase, it checks if the cell is big enough to divide
-G2: end of phase, it checks if the DNA has been copied properly
-M checkpoint: end of metaphase, makes sure chromosomes are lined down metaphase plate
homologous chromosomes:
chromosomes that are corresponding. Have the same value but are not identical.
chromosomes that are corresponding. Have the same value but are not identical.
homologous chromosomes:
chromosomes
same:
Same traits (n)
Same length
Centromere in same location
Diff:
Same traits but they could be different, (ex; eyecolor)
Diploid
2 full of chromosomes 46, or 2 sets of 23
Haploid
1 set of chromosomes 23.
Somatic cells:
msot cells, general name for any cell that is diploid
what’s the only haploid cell?
gametes
Compare/contrast: Goal of mitosis to the goal of meiosis
Mitosis is for growth and repair=used to preduce somatic cells
Meiosis is a precursor for sexual reproduction. Cells have one set of 23 chromosomes=used to produce gametes
what is the same for meiosis/mitosis
INTERPHASE
Meiosis creates what
using haploid cells creates gametes, Produce four cells that are haploid
when do cells become haploid in meiosis
Haploid by miosis 1
What is the name of the process in which mom and dads chromsomes mix
independent assortment
similarities and differences of meiosis in PROPHASE ONE:
SIMILARITIES:
-Much of it same as prophase in mitosis
-Nucleus/nucleolus disappears
-Chromosomes coil
-Centrioles and spindle fibers
DIFFERENCES:
–homologous chromosomes pair up
-synapsis= homologous chromosomes physically connect
-Tetrad is the result of synapsis= (refers to four)
-crossing over -> WHen, non sister chromatids of
-homologous chromosomes break off and exchange pieces. (first chance at genetic variation/exchange pieces)
Metaphase 1 similarities, and differences:
similarities:
-Line up on metaphase plate
DIFFERENCES
-Line up in pairs, therefore there are two chromosomes paired up that are in a line.
-Line up at metaphase plate at random. (moms or dads could be on the top or the bottom.
Anaphase=
separation of chromosomes INDEPENDENT ASSORTMENT: The separation of one pair of homologous chromosomes does not affect the separation of another pair of homologous chromosomes. (happens officially in anaphase one.)
What is different about telephase one?
Do not reform nuclei
what is the end result of meiosis one?
two haploid cells
purpose of meiosis 1 and 2
1: separate chromosomes
2: separate chromatids
what is different between meiosis one and two
same process just with two cells simaltaniously, also this time the chromosomes line up the same as in mitosis, and the nucleus reforms
result of meiosis
Meiosis results in four genetically unique haploid cells from ones diploid parent cell
synapsis
homologous chromosomes physically connect
Tetrad
refers to the four chromatids
