Biology: Ch.2- Reproduction Flashcards
What are the five stages of the cell cycle and what happens in each of the stages?
- G1: Cell grows and performs normal functions. DNA is examined and repaired.
- S: DNA is replicated
- G2: Cell continues to grow and replicates organelles in preparation for mitosis. Cell continues to perform its normal functions
- M: Mitosis (cell division) occurs
- G0: The cell performs its normal functions and is not planning to divide
What are the four phases of mitosis and what happens in each of the phases?
- Prophase: xsomes condense, nuclear membrane dissolves, nucleoli disappear, centrioles migrate to opposite poles and begin forming the spindle apparatus
- Metaphase: xsomes gather along the metaphase plate in the center of the cell under the guidance of the spindle apparatus
- Anaphase: sister xtids separate, and a copy of each xsome migrates to opposite poles
- Telophase and Cytokinesis: xsomes decondense, nuclear membrane reforms, nucleoli reappear, spindle apparatus breaks down, cell divides into two identical daughter cells
What is the ploidy of the daughter cells produced from meiosis I? From meiosis II?
Meiosis I: two haploid daughter cells
Meiosis II: There are up to four haploid daughter cells
What is the difference between homologous xsomes and sister xtids?
Homologous xsome: related xsomes of different parental origin (such as maternal xsome 15 and paternal xsome 15)
Sister xtid: identical copies of the same DNA that are held together at the centromere.
After S phase, a cell contains 92 xtids, 46 xsomes, and 23 homologous pairs
How does prophase I of meiosis differ from prophase of mitosis?
Homologous xsomes come together as tetrads during synapsis; crossing over
How does metaphase I of meiosis differ from metaphase of mitosis?
Homologous xsomes line up on opposite sides of the metaphase plate, rather than individual xsomes lining up on the metaphase plate
How does anaphase I of meiosis differ from anaphase of mitosis?
Homologous xsomes separate from each other; centromeres do not break
How does telophase I of meiosis differ from telophase of mitosis?
chromatin may or may not decondense; interkinesis occurs as a cell prepares for meiosis II
What are the functions of the interstitial cells of Leydig and Sertoli cells?
The interstitial cells of Leydig secrete testosterone and other male sex hormones (androgens)
Sertoli cells nourish sperm during development
During which phase of meiosis is a primary oocyte arrested? During which phase of meiosis is a secondary oocyte arrested?
Primary oocyte is arrested in prophase I
Secondary oocyte is arrested in metaphase II
What is an acrosome? What organelle forms the acrosome?
The acrosome contains enzymes that are capable of penetrating the corona radiata and the zona pellucida of the ovum, permitting fertilization to occur. It is a modified Golgi apparatus
What are the four phases of the female menstrual cycle?
- Follicular
- Ovulation
- Luteal
- Menses
What are the key features of each phase of the female menstrual cycle
- Follicular-Egg develops, endometrial layer becomes vascularized and glandularized
- Ovulation- Egg is released from the follicle into the peritoneal cavity
- Luteal- Corpus luteum produces progesterone to maintain endometrium
- Menses- shedding of endometrial lining
What are the relative hormone concentrations of each phase of the female menstrual cycle (aka increase or decrease of FSH, LH, Estrogen and progesterone at each phase)
- Follicular- Increase FSH, same LH, decrease then increase estrogen, decrease progesterone
- Ovulation- increase FSH, double increase LH, increase estrogen, decrease progesterone
- Luteal- decrease FSH, same LH, increase estrogen, increase progesterone
- Menses- decrease FSH, LH, estrogen and progesterone
