NUR 313 Lecture Notes - Lecture 2: Sister Chromatids, Reproductive System, Spindle Apparatus
Kevin DeLeon
A&P II
Dr. Lee
Intro to the Reproductive System
Reproduction
There is asexual and sexual
A: Replication of a diploid – you end up with genetically identical cells (Diploid – is one full
genetic material)
The pot is the same as the other one
Passes all of 46 chromosomes to the child
S: requires two individuals that allow for the union of the haploids – Haploids make the union
(1/2 of the genetic material)
Two haploid – each passes 23 chromosomes
Karyotyping – cell is chemically induced to undergo meiosis and become a chromosome
46 chromosomes – duplicate of 23 sets
1 set from mom and dad – they are similar genes b/c came from two different people
The first 22 are the somatic chromosomes – has to do with the survival of the cell
The 23rd set is the sex determining chromosome
Cell division for Mitosis (Asexual Reproduction)
1st phase: Interphase (G1, S, G2)
Growth – the cell is engaged in metabolic activity and prepares to divides (you have 46
chromosomes here)
find more resources at oneclass.com
find more resources at oneclass.com
S Phase – synthesis – you replicate the nuclear material (DNA) – copy of the cell
You have 46 chromosomes x 2 because you replicated the DNA at the S phase of mitosis
(46 x 2)
G2 – the cell keeps growing in size – b4 it enters Mitosis
THEN . . . .
Prophase: the chromatin begins to condense (Nucleolus disappears)(mitotic spindle forms) –
Metaphase: (Chromosomes are lined up at the middle of the cell: known as the metaphase plate)
Anaphase: (sister chromatids go onto their own ends of the cell and the chromatids are pulled
towards opposite ends of the cell
Telophase – normal structures are reestablished – nucleolus and the envelope; spindle fibers
disappear
Cytokinesis – is last step; (the cytoplasm divides and forms two new identical cells)
***If the cell enters G0 – the plant cell becomes dormant – the “cycle arrest.”
Chromosome – Nuclear material – It is the DNA condensed
Chromatin – is the uncondensed DNA material
When the chromosome duplicates and it is attached to the original chromosome = sister
chromatid
½ of the sister chromatid is the chromatid
1 exact copy of sister chromatid from dad will line up with the one that came from your mom –
Tetrad – there are 4 chromatid – found on the chromosome
Because they are similar chromosomes they can share chromatids – chromatids can detach and
stick to different places on the two chromosomes
Chromatid – is one half of the sister chromosome
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find more resources at oneclass.com
Cross over = – exchanges of pieces between the sister chromatids
Non disjunction – the chromosome pairs fail to separate during cell division
Spermatogenesis
Spermatogonia
Primary Spermatocyte
Secondary Spermatocytes
Spermatid (Chromatid – immature sperm)
Spermatozoa (Sperm)
The Cell Division Process for Sperm Development
STEM CELL has 46 x 1 (Spermatogonia)
Then it undergoes mitosis - the S Phase - DNA replicates
Final product: There are 2 cells that have 46 x 1 chromosomes
Spermiation – loses the cytoplasm and grows a tail known as the flagellum – only the
mitochondria is collected
At the end of the head is full of nuclear material – it does not carry glucose to swim – the
mitochondria gives the sperm energy
Oogenesis
Oogonia
Primary Oocyte and then Secondary Oocyte
Ovum
Polar Bodies
Three polar bodies die – the best egg is the one that survives – it gathers all of the material from
the polar bodies - the one that survives is known as the ovum – the best egg becomes mature and
it gathers information from the other polar bodies – the rest died in the process known as atresia
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
A: replication of a diploid you end up with genetically identical cells (diploid is one full genetic material) The pot is the same as the other one. Passes all of 46 chromosomes to the child. S: requires two individuals that allow for the union of the haploids haploids make the union (1/2 of the genetic material) Karyotyping cell is chemically induced to undergo meiosis and become a chromosome. 1 set from mom and dad they are similar genes b/c came from two different people. The first 22 are the somatic chromosomes has to do with the survival of the cell. The 23rd set is the sex determining chromosome. Growth the cell is engaged in metabolic activity and prepares to divides (you have 46 chromosomes here) S phase synthesis you replicate the nuclear material (dna) copy of the cell. You have 46 chromosomes x 2 because you replicated the dna at the s phase of mitosis (46 x 2)
