Exam (elaborations)
BIO 344 CH 27 Questions answers latest update
- Course
- Bio 344
- Institution
- University Of Texas - Austin
BIO 344 CH 27 Questions answers latest update
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BIO 344 CH 272n cells
46 chromosomes (2 sets, 1 from each parent)
homologous chromosomes
Chromosomes that have the same sequence of genes and the same structure
22 pairs of autosomes
female
XX
Male
XY
gametes
1n cells -> 23 chromosomes (1 set)
Males: sperm (testes)
Females: oocytes (ovaries)
fertilization
sperm (1n) + egg (1n) -> forms zygote, restore 2n number
Meiosis I
Prophase I, Metaphase I, Anaphase I, Telophase I
goals of meiosis I
,divid chromosome number by 1/2
creates genetic recombination via synapsis and crossing over
end products of meiosis I
2 1n cells, DS chromosomes
Prophase I
The usual events
- Chromatin → chromosomes
- Nuclear envelope and nucleolus disappear
- Spindle apparatus forms
The not so usual events
- Homologous chromosomes pair up (synapsis)
- Non-sister chromatids can exchange genetic information (crossing over)
Metaphase I
- Homologous chromosomes align at the metaphase plate
- Maternal and paternal homologous align randomly
- 8 possible alignments with 6 chromosomes
Anaphase I
- Centromeres do not divide
- Homologous separate and migrate to opposite poles
- Each pole has 1 set of DS chromosomes
Telophase I
- Nuclear envelope reforms
- Cytokinesis occurs → cells are 1n with DS chromosomes
- Sister chromatids may not be identical
meiosis II
,Prophase II, Metaphase II, Anaphase II, Telophase II
goals of meiosis II
DS chromosome -> SS chromosome
End products of meiosis II
4 1n cells, SS chromosomes
**New combinations of genes with gametes
Prophase II
- Similar to mitosis
- Chromatin → X-somes
- Nuclear envelope and nucleolus disappear
- Spindle apparatus forms
- Cells are 1n
- Chromosomes are DS
Metaphase II
- Similar to mitosis
- Chromosomes aligning on metaphase plate
- Cells at 1n
- Chromosomes are DS
Anaphase II
- Similar to mitosis
- Centromere splits
- SS chromosomes migrate to opposite poles
Telophase II
- Similar to mitosis
- Nuclear envelope reforms
- Nucleolus reappears
- Chromosomes → chromatin
, - Cytokinesis
- 4 1n cells
- SS chromosomes
Overall Functions of the reproductive system
gamete production, nurture and/or transport of gametes, sexual intercourse,
nurture of offspring, production of sex hormones
gamete production
males/sperm (testes), females/oocytes (ovaries)
nurture and/or transport of gametes
Males: nurture and transport sperm via spongy urethra
Females: nurture and transport oocytes/ovum -> uterine tubes -> uterus
sexual intercourse
delivery of sperm into vagina via penis
nurture of offspring
throughout pregnancy by female body
production of sex hormones
testes and ovaries -> profound effects on the body
location of testes
lie outside abdominopelvic cavity within scrotum
embryonic development
- Begin development near kidneys
- Descend into scrotum during 7th month of development
- Scrotum maintains testes at 34 degrees celsius (93 degree fahrenheit; lower
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