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Biology > Chapter 2 Reproduction > Flashcards

Chapter 2 Reproduction Flashcards

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1
Q

Diploid (2n) cells have

haploid (n) cells have

A

-two copies of each chromosome

-one copy
Ex: egg and sperm

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2
Q

In humans we have how many chromosomes ?

A

*In humans we have 46 chromosomes and 23 respectively; we inherit 23 chromosomes from each parent.

*Eukaryotic cells replicate through the Cell Cycle
-Derangement of the cell cycle can lead to unchecked cell division and may play a part in formation of cancer.

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3
Q

The cell cycle contains 4 stages. What are they?

A

The G1, S, and G2 stages are collectively called interphase, during which the DNA is uncoiled in the form of chromatin.

*****

*G1, S, G2, M
*Cell cycle consist of 4 stages: G1, S, G2, and M.
-First 3 stages (G1, S, and G2) are called: Interphase.
-Interphase: longest part of cell cycle; even actively dividing cells spend about 90% of their time in interphase. Cells that don’t divide spend all of their time in an offshoot of G1 called G0.
-G0 stage: cell is living and carrying out its functions w/o any preparation for division.
-during Interphase, chromosomes are not visible w/ light microscopy bec less condensed form known as chromatin. During mitosis it is preferred to condense the DNA into tightly coiled chromosomes to avoid losing genetic material during cell division.

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4
Q

G1, S, and G2 stages are collectively called

A

interphase

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5
Q

In the G1 stage (presynthetic gap)

A

During this stage cells create organelles for energy and protein production (mitochondria, ribosomes, and ER) while increasing their size also. The restriction point, during which the DNA is checked for quality, must be passed for the cell to move into the S stage.

-Passage into S(Synthesis) stage is govern by restriction point. Cell must contain the proper complement of DNA to enter synthesis stage.

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6
Q

In the S stage (synthesis)

A

DNA is replicated. The strands of DNA, called chromatids, are held together at the centromere.

  • S Stage: Synthesis of DNA:
  • During this stage cell replicated it’s genetic material so that daughter cell has identical copies. After this, each chromosome consist of two identical chromatids that are bound together at a region called centromere.
  • Remember: Humans have 46 chromosomes, even though 92 chromatids are present.
  • Cells entering G2 have 2X as much DNA as cells in G1.
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7
Q

In the G2 stage (postsynthetic gap)

A

G2 Stage: Postsynthetic Gap:

  • During this stage cell passes thru another quality checkpoint.
  • DNA has already been duplicated. The cell just checks to make sure there are enough organelles and cytoplasm for 2 daughter cells. Cell also checks that DNA replication proceeded correctly to avoid passing on an error to daughter cells that may further pass on the error to their progeny.
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8
Q

In the M stage (mitosis) what occurs? Both what?

A

mitosis and cytokinesis occur

******

M Stage: Mitosis: (P-MAT)

  • M stage consist of mitosis along w/ cytokinesis.
  • Mitosis is divided into 4 phases:
    1. Prophase
    2. Metaphase
    3. Anaphase
    4. Telophase
    Cytokinesis: is the splitting of the cytoplasm and organelles b/t the 2 daughter cells.
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9
Q

In the G0 stage

A

the cell performs its functions without preparing for division

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10
Q

p53 plays a role in the

A

two major checkpoints of the cell cycle (G1 to S, and G2 to M).

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11
Q

About Cyclins and cyclin-dependent kinases (CDK)

A

rise and fall during the cell cycle. Cyclins bind to CDKs, phosphorylating and activating transcription factors for the next stage of the cell cycle.

  • Molecule responsible for the cell cycle are known as cyclins and cyclin dependent kinases (CDK).
  • CDK: Cyclin Dependent Kinases

********

In order to be activated, CDKs require the presence of the right cyclins. Cyclin levels increase and decrease during specific stages. Cyclins bind to CDK creating an activated “CDK-cyclin complex”. The complex can then phosphorylate transcription factors. Transcription factors then promote transcription of genes required for the next stage of the cell cycle.

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12
Q

Cancer occurs when cell

A

occurs when cell cycle control becomes deranged, allowing damaged cells to undergo mitosis without regard to quality or quantity of the new cells produced.

Cancerous cells may begin to produce factors that allow them to delocalize and invade adjacent tissues or metastasize elsewhere.

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13
Q

Mitosis produces what?

A

two genetically identical diploid daughter cells from a single cell and occurs in somatic cells.

********

Process by which 2 identical daughter cells are created from single cell.
4 phases: prophase, metaphase, anaphase, and telophase; occur in somatic cells or cells that are not involved in sexual reproduction.

******

Key Concept:

  • PROPHASE: Chromosomes condense, spindle forms
  • METAPHASE: Chromosomes align
  • ANAPHASE: Sister chromatids separate
  • TELOPHASE: New nuclear membranes form
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14
Q

Mitosis has four phases:

A

P-MAT
1 prophase
2 Metaphase
3 anaphase
4 telophase

• In prophase,
the chromosomes condense,
the nuclear membrane dissolves,
nucleoli disappear,
centrioles migrate to opposite sides of the cell, and the
spindle apparatus begins to form.
The kinetochore of each chromosome is contacted by a spindle fiber.
• In metaphase, chromosomes line up along the metaphase plate (equatorial plate).
• In anaphase, sister chromatids are separated and pulled to opposite poles.

• In telophase, the nuclear membrane reforms, spindle apparatus disappears, and cytosol

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15
Q

In prophase

A

the chromosomes condense, the nuclear membrane dissolves, nucleoli disappear, centrioles migrate to opposite sides of the cell, and the spindle apparatus begins to form. The kinetochore of each chromosome is contacted by a spindle fiber.

******
Prophase:
- Condensation of the chromatin into chromosomes.
- Centriole pairs separate and move towards opposite poles of the cell.
- Centrosome are responsible for the correct division of DNA. Once the centrioles migrate to opposite poles of cell, they begin to form spindle fibers, which are made of microtubules.
- Kinetochores which appear at the centrosome, are protein structures located on the centromeres that serve as attachment points for specific fibers of the spindle apparatus (called kinetochore fibers).

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16
Q

In metaphase

A

******

Metaphase:
-Centriole pairs are at opposite ends of the cell. Kinetochore fibers interact w/ the fibers of the spindle apparatus to align the chromosomes at the metaphase plate (equatorial plate).

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17
Q

In anaphase

A

Anaphase:
Centromeres split so that each chromatid has its own distinct centromere, allowing the sister chromatids to separate. Sister chromatids are pulled towards opposite poles of the cell by the shortening of the kinetochore fibers.

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18
Q

In telophase

A

the nuclear membrane reforms, spindle apparatus disappears, and cytosol and organelles are split between the two daughter cells through cytokinesis.

*******
Telophase and Cytokinesis:
- Reverse of prophase
- Spindle apparatus disappears. A nucleus membrane reforms around each set of chromosomes and the nucleoli reappear.
-Cytokinesis: Happens at the end of telophase. Is the separation of cytoplasm and organelles, giving each daughter cell enough material to survive on its own.

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19
Q

In humans how many chromosomes do we have?

A

46 chromosomes and 23respectively; we inherit 23 chromosomes from each parent.

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20
Q

Meiosis occurs in

A

gametocytes (germ cells) and produces up to four nonidentical haploid sex cells (gametes).

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21
Q

Meiosis has how many round or replication and division?

A

Meiosis has one round of replication and two rounds of division (the reductional and equational divisions).

1 round of replication ——-> 2 round of division

******

PMAT
Prophase I: “Before”. Line up w/ their homologous pairs and intertwine in a process called synapsis. Chromatids are referred to as a tetrad, and crossing over exchanges genetic material b/t one chromatid and material from a chromatid in the homologous chromosome. This accounts for Mendel’s 2nd law (of independent assortment).

Metaphase I: Homologous chromosomes line up on opposite sides of the metaphase plate.

Anaphase I: Humongous chromosomes are pulled to opposite poles of the cell. Mendel’s 1st law ( of segregation).

Telophase I: The chromosomes may or may not fully decondense, and the cell may enter interkinesis after cytokinesis.

Meiosis II: sister chromatids are separated from each other in a process that is functionally identical to mitosis. Sister chromatids are copies of the same DNA held together at the centromere.

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22
Q

In meiosis I

A

homologous pairs of chromosomes (homologues) are separated from each other. Homologues are chromosomes that are given the same number, but are of opposite parental origin.

2n = (n) and (n)

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23
Q

In prophase I

A

the same events occur as in prophase of mitosis, except that homologues come together and intertwine in a process called synapsis. The four chromatids are referred to as a tetrad, and crossing over exchanges genetic material between one chromatid and material from a chromatid in the homologous chromosome. This accounts for Mendel’s second law (of independent assortment).

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24
Q

In metaphase I

A

homologous chromosomes line up on opposite sides of the metaphase plate.

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25
Q

In anaphase I

A

homologous chromosomes are pulled to opposite poles of the cell. This accounts for Mendel’s first law (of segregation).

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26
Q

In telophase I

A

the chromosomes may or may not fully decondense, and the cell may enter interkinesis after cytokinesis.

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27
Q

In meiosis II

A

sister chromatids are separated from each other in a process that is functionally identical to mitosis. Sister chromatids are copies of the same DNA held together at the centromere.

28
Q

Sister chromatids

A

are copies of the same DNA held together at the centromere.

29
Q

Biological sex is determined by the

A

23rd pair of chromosomes in humans, with XX being female and XY being male.

30
Q

The X chromosome carries a

A

The X chromosome carries a sizeable amount of genetic information; mutations of X-linked genes can cause sex-linked disorders. Males are hemizygous with respect to the unpaired genes on the X chromosome, so they will express sex-linked disorders, even if they only have one recessive disease-carrying allele. Women with one copy of the affected allele are called carriers.

31
Q

The Y chromosome carries

A

carries little genetic information, but does contain the SRY (sex-determining region Y) gene, which causes the gonads to differentiate into testes.

32
Q

The male reproductive system contains both

A

internal and external structures

Testes- have 2 fuctions: seminiferous tubules and interstitial cells of Leydig.

  • Sperm develop in the seminiferous tubules in the testes. They are nourished by Ser-to-li cells.
  • Interstitial cells of Leydig(laydies tig testosterone), in the testes, secrete testosterone and other male sex hormones (androgens).
  • The testes are located in the scrotum, which hangs outside of the abdominal cavity and has a temperature 2°C to 4°C lower than the rest of the body.
  • Once formed, sperm gain motility in the epididymis and are stored there until ejaculation.
  • During ejaculation, sperm travel through the vas deferens to the ejaculatory duct, and then to the urethra and out through the penis.
  • The seminal vesicles (looks like a sponge) contribute fructose to nourish sperm and produce alkaline fluid.
  • The prostate gland also produces alkaline fluid.
  • The bulbourethral glands produce a clear viscous fluid that cleans out any remnants of urine and lubricates the urethra during sexual arousal.
  • Semen is composed of sperm and seminal fluid from the glands above.

******

  • The primitive gonads develop into testes.
  • Testes 2 functional components:
    1. Seminiferous tubules
    2. Interstitial of Leydig
  • Sperm produced: in highly coiled seminiferous tubules (where they are nourished by Sertoli cells).
  • Cells of Leydig secrete testosterone and other male sex hormones (androgens).
  • Testes located: in the scrotum (an external pouch that hangs below penis) a position that allows it to maintain 2-4 degree C lower than the body.
  • As sperm are formed they are passed to the epididymis, where their flagella gain motility, and they are then stored until ejaculation. During ejaculation sperm travels thru the vas deferens and enters the ejaculatory duct. The 2 ejaculatory ducts then fuse to form the urethra, which carries sperm through the penis as they exit the body.
  • As sperm pass thu reproductive tract they are mixed w/ seminal fluid, which is produced thru a combined effort by:
  • *1. Seminal vesicles, 2. prostate gland, and 3. bulbourethral gland.**

1.Seminal vesicle: contribute fructose to nourish sperm and both the vesicles and prostate gland give the fluid mildly alkaline properties so the sperm can survive in the acidity of the female reproductive tract.

Bulbourethral (Cowper’s) glands: produce a clear viscous fluid that cleans out any remnants of urine and lubricates the urethra during sexual arousal.

-Sperm+ Seminal fluid: Semen

***
MNEMONIC:
Pathway of sperm thu the male reproductive system:
SEVE(N)UP
• Seminiferous tubules
• Epididymis
• Vas deferens (also called the ductus deferens)
• Ejaculatory duct
• Nothing
• Urethra
• Penis

33
Q

Sperm develop in the

A

seminiferous tubules in the testes. They are nourished by Sertoli cells.

34
Q

Interstitial cells of Leydig, in the testes, does what?

A

secrete testosterone and other male sex hormones (androgens).

35
Q

The testes are located in the scrotum, and why?

A

The testes are located in the scrotum, which hangs outside of the abdominal cavity and has a temperature 2°C to 4°C lower than the rest of the body.

36
Q

In spermatogenesis, four haploid sperm are produced from a spermatogonium.

A
  • After S stage, the germ cells are called primary spermatocytes.
  • After meiosis I, the germ cells are called secondary spermatocytes.
  • After meiosis II, the germ cells are called spermatids.
  • After maturation, the germ cells are called spermatozoa (sperm cell)
37
Q

Sperm contain a

A

Sperm contain a head, midpiece, and flagellum.

  • The head contains the genetic material and is covered with an acrosome—a modified Golgi apparatus that contains enzymes that help the sperm fuse with and penetrate the ovum.
  • The midpiece generates ATP from fructose and contains many mitochondria.
  • The flagellum promotes motility.
38
Q

The female reproductive system only

A

internal structures

  • Ova (eggs) are produced(made) in follicles in the ovaries.
  • Once each month, an egg is ovulated into the peritoneal sac and is drawn into the fallopian tube or oviduct.
  • The fallopian tubes are connected to the uterus, the lower end of which is the cervix.
  • The vaginal canal lies below the cervix and is the site where sperm are deposited during intercourse.
  • The vaginal canal is also the site of natural childbirth.
  • The external female anatomy is known as the vulva.
39
Q

In oogenesis, one haploid ovum (egg) and a variable number of polar bodies are formed from an

A

oogonium

  • At birth, all oogonia have already undergone replication and are considered primary oocytes. They are arrested in prophase I. • The ovulated egg each month is a secondary oocyte, which is arrested in metaphase II.
  • If the oocyte is fertilized, it will complete meiosis II to become a true ovum.
  • Cytokinesis is uneven in oogenesis. The cell receiving very little cytoplasm and organelles is called a polar body.
  • Oocytes are surrounded by the zona pellucida, an acellular mixture of gly-coproteins that protect the oocyte and contain the compounds necessary for sperm binding; and the corona radiata, which is a layer of cells that adhered to the oocyte during ovulation.
40
Q

Gonadotropin-releasing hormone (GnRH) from the hypothalamus causes the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), the functions of which depend on the sex of the individual.

A

• In males, FSH stimulates the Sertoli cells and triggers spermatogenesis, while LH causes the interstitial cells to produce testosterone. Testosterone is responsible for the maintenance and development of the male reproductive system and male secondary sex characteristics (facial and axillary hair, deep-ening of the voice, and increased bone and muscle mass). • In females, FSH stimulates development of the ovarian follicles, while LH causes ovulation. These hormones also stimulate production of estrogens and progesterone.

41
Q

The menstrual cycle is a periodic growth and shedding of the endometrial lining.

A
  • In the follicular phase, GnRH secretion stimulates FSH and LH secretion, which promotes follicle development. Estrogen is released, stimulating vas-cularization and glandularization of the decidua.
  • Ovulation is stimulated by a sudden surge in LH. This surge is triggered when estrogen levels reach a threshold and switch from negative to positive feedback effects.
  • In the luteal phase, LH causes the ruptured follicle to become the corpus luteum, which secretes progesterone that maintains the uterine lining. High estrogen and progesterone levels cause negative feedback on GnRH, LH, and FSH.
  • Menstruation occurs if there is no fertilization. As the estrogen and proges-terone levels drop, the endometrial lining is sloughed off, and the block on GnRH production is removed.
  • If fertilization does occur, the blastula produces human chorionic gonad-otropin (hCG) which, as an LH analog, can maintain the corpus luteum. Near the end of the first trimester, hCG levels drop as the placenta takes over progesterone production.
42
Q

Menopause occurs when the

A

• Menopause occurs when the ovaries stop producing estrogen and progesterone, usually between ages 45 and 55. Menstruation stops and FSH and LH levels rise. Physical and physiological changes accompanying menopause include flushing, hot flashes, bloating, headaches, and irritability.

43
Q

Control of the Cell Cycle:

A

************
- Checkpoints: b/t G1 and S phase, and G2 and M phase
- G1 and S checkpoint cell determines if condition of DNA is good enough
- The main protein in control of this is p53.
- Checkpoint: btw G2 and M checkpoint cell makes sure that it has achieved size and the organelles have been properly replicated to support 2 daughter cells. P53 also plays a role in the G2 checkpoint.
- Molecule responsible for the cell cycle are known as cyclins and cyclin dependent kinases (CDK).
In order to be activated, CDKs require the presence of the right cyclins. Cyclin levels increase and decrease during specific stages. Cyclins bind to CDK creating an activated “CDK-cyclin complex”. The complex can then phosphorylate transcription factors. Transcription factors then promote transcription of genes required for the next stage of the cell cycle.

44
Q

Cancer:

A

*****************
- Cell cycle control is important to ensure that cells that are damaged or inadequately sized do NOT divide. When cell cycle control become deranged, and damaged then damaged cells undergo mitosis, the cancer may result.
- Common mutation found in cancer: gene that produces p53, called TP53. When gene is mutated cell isn’t stopped to repair damaged DNA. This allows mutations to accumulate, eventually resulting in a cancerous cell that divides continuously.
Often cancer cells undergo rapid cell division, creating Tumors. Local invasion as well as distant spread of cancerous cells thru the bloodstream or lymphatic system. The latter result is known as metastasis.

45
Q

Spermatogenesis:

A

Spermatogenesis:

  • In spermatogenesis, four haploid sperm are produced from a spermatogonium.
  • In Males, the diploid stem cells are known as spermatogonia.
    • After S stage, the germ cells are called primary spermatocytes.
    • After meiosis I, the germ cells are called secondary spermatocytes.
    • After meiosis II, the germ cells are called spermatids.
    • After maturation, the germ cells are called spermatozoa.
  • Sperm contain a head, midpiece, and flagellum.
    • The head contains the genetic material and is covered with an acrosome—a modified Golgi apparatus that contains enzymes that help the sperm fuse with and penetrate the ovum.
    • The midpiece generates ATP from fructose and contains many mitochondria.
    • The flagellum promotes motility.
46
Q

Female Reproductive Anatomy:

A

· The gonads, known as ovaries, produce estrogen and progesterone.
· Ovaries are located in the pelvic cavity; each consist of thousands of follicles, which are multilayer sacs that contain, nourish, and protect immature ova (eggs).

  • The female reproductive system only contains internal structures.
  • Ova (eggs) are produced in follicles in the ovaries.
  • Once each month, an egg is ovulated into the peritoneal sac and is drawn into the fallopian tube or oviduct.
  • The fallopian tubes are connected to the uterus, the lower end of which is the cervix.
  • The vaginal canal lies below the cervix and is the site where sperm are deposited during intercourse.
  • The vaginal canal is also the site of natural childbirth.
  • The external female anatomy is known as the vulva.
47
Q

Oogenesis:

A

Oogenesis:

  • Production of female gametes known as: Oogenesis
  • In oogenesis, one haploid ovum and a variable number of polar bodies are formed from an oogonium.
  • At birth, all oogonia have already undergone replication and are considered primary oocytes. They are arrested in prophase I. Once a woman reaches menarche (her 1st menstruation cycle) one primary oocyte per month will complete meiosis I producing secondary oocyte and a polar body.
  • The ovulated egg each month is a secondary oocyte, which is arrested in metaphase II.
  • If the oocyte is fertilized, it will complete meiosis II to become a true ovum.
  • Cytokinesis is uneven in oogenesis. The cell receiving very little cytoplasm and organelles is called a polar body.
  • Oocytes are surrounded by the zona pellucida, an acellular mixture of glycoproteins that protect the oocyte and contain the compounds necessary for sperm binding; and the corona radiata, which is a layer of cells that adhered to the oocyte during ovulation.
48
Q

Sexual Development:

A
  • The ability to reproduce is under hormonal control.
  • Before puberty the hypothalamus restricts the production of Gonadotropin-releasing hormone (GnRH).
    When puberty starts: the restriction is lifted as the hypothalamus releases pulses of GnRH, which then triggers the anterior pituitary gland to synthesize and release follicle-stimulating hormone (FSH) and luteinizing hormone (LH). These hormones trigger the production of other sex hormones that develop and maintain the reproductive system.
49
Q

Male Sexual Development:

A

Male Sexual Development:

  • During fetal period (9(like 2 Months) weeks after fertilization until birth) presence of Y-chrommosome leads to production of androgens resulting: in male sexual differentiation.
  • From infancy and childhood: androgen production is low.
  • Testosterone: produced by the testes increase dramatically during puberty & sperm production begins. In order to achieve this:
  • FSH stimulates the Sertoli cells and triggers spermatogenesis, while
  • LH causes the interstitial cells to produce testosterone. Testosterone is responsible for the maintenance and development of the male reproductive system and male secondary sex characteristics (facial and axillary hair, deepening of the voice, and increased bone and muscle mass). Testosterone production is high in adulthood and declines as men age. This hormone exerts negative feedback on the hypothalamus and anterior pituitary so that production is kept within an appropriate range.
50
Q

Female Sexual Development:

2 hormones that are secreted and by what part of the brain?

What part produces estrogen and progesterone?

What does FSH do?

What does LH do?

A
  • Ovaries, which are derived from the same embryonic structures as the testes, are under control of FSH and LH secreted by the anterior pituitary.

► Ovaries produce:

  1. Estrogen
  2. Progesterone.
  • Estrogens are secreted in response to FSH and result in the development and maintenance of the female reproductive system and female secondary sexual characteristics (breast growth, widening of the hips, change in fat distribution).
  • Progesterone is secreted by the corpus luteum–the remains of the ovarian follicle following ovulation– in response to LH.
  • Both estrogen and progesterone are req for generation, development, and maintenance of an endometrium capable of supporting a zygote.

In adults estrogen leads to the thickening of the lining of the uterus (endometrium) each month in preparation for the implantation of zygote.

51
Q

The Menstruation Cycle:

A

*From menarche to menopause, estrogen and progesterone levels rise and fall in a cyclic pattern. In response the endometrial lining will grow and be shed, this is known as the menstrual cycle and can be divided into 4 events:

  • *a. The follicular phase
    b. Ovulation
    c. Luteal phase
    d. Menstruation**

****The menstrual cycle is a periodic growth and shedding of the endometrial lining.****
A. Follicular phase:
- In the follicular phase begins w/ menstrual flow (which shed the uterine lining of the previous cycle, begins. GnRH secretion from hypothalamus increases in response to the decrease concentrations of estrogen and progesterone, which fall off towards end of each cycle.
- The higher concentration of GnRH cause increase of both FSH and LH.
The follicles begin producing estrogen which has negative feedback effect and causes the (GnRH, LH, and FSH) concentrations to level off. Estrogen stimulates regrowth of endometrial lining, stimulating vascularization and granularization of the decidua.

  1. Estrogen:(decreases –> increase)
  2. Progesteron: decrease
  3. FSH: increase
  4. LH: stays the same
  • *B. Ovulation:**
  • Estrogen can have negative and positive feedback effects. Later in follicular phase, the developing follicles secrete higher and higher concentrations of estrogen and eventually, estrogen concentrations reach a threshold that results in positive feedback and GnRH, LH, and FSH levels spike.
  • The surge in LH is important; Ovulation is stimulated by a sudden surge in LH. This surge is triggered when estrogen levels reach a threshold and switch from negative to positive feedback effects.
  1. Estrogen: increases
  2. Progesterone: decreases
  3. FSH: increase
  4. LH: increase… increase L LOT!!

C. Luteal phase:
In the luteal phase, LH causes the ruptured follicle to become the corpus luteum, which secretes progesterone that maintains the uterine lining. High estrogen and progesterone levels cause negative feedback on GnRH, LH, and FSH.
*remember that estrogen helps regenerate the uterine lining, but progesterone maintains it for implantation. Progesterone levels begin to rise, while estrogen levels remain high. The high level of progesterone causes negative feedback on GnRH, FSH, and LH preventing the ovulation of multiple eggs.

  • *D. Menstruation:**
  • Menstruation occurs if there is no fertilization. As the estrogen and progesterone levels drop, the endometrial lining is sloughed off, and the block on GnRH production is removed. The loss of high levels of estrogen and progesterone removes the block on GnRH so that the next cycle can begin.

Pregnancy:

  • If fertilization does occur, the blastula produces human chorionic gonadotropin (hCG) which, as an LH analog, can maintain the corpus luteum. Near the end of the first trimester, hCG levels drop as the placenta takes over progesterone production.
  • hCH is critical during first trimester development because the estrogen and progesterone secreted by the corpus luteum keep the uterine lining in place.

Menopause:
• Menopause occurs when the ovaries stop producing estrogen and progesterone, usually between ages 45 and 55. Menstruation stops and FSH and LH levels rise. Physical and physiological changes accompanying menopause include flushing, hot flashes, bloating, headaches, and irritability.

52
Q

DNA is uncoiled in the form of

A

chromatin.

53
Q

less condense chromosomes___ and why?

A

chromatin

beacuse the DNA must be available to RNA polymerase so that genes can be transcribed.

54
Q

how many chromosomes vs chromatids?

A

46 chromasomes vs 92 chromatids

centromere is what keeps the chromosomes together

55
Q

cytokinesis

A

is the splitting of the cytoplasm and organelles between the two daughter cells

56
Q

chromosomes may be refer to either

A

a single chromatid before S phase OR the pair of chromarids attached at the centromere after S phase.

57
Q

in autosomal cells?

A

division results in two genetically identical cells

58
Q

oncogenes vs tumor suppressor genes

A

oncogenes: genes that, when mutated, actively promote cell division

tumor suppressor genes: genes that, when mutated, lose their ability to regulate or arrest the cell cycle

An oncogene is a mutated gene that contributes to the development of a cancer. In their normal, unmutated state, onocgenes are called proto-oncogenes, and they play roles in the regulation of cell division. Some oncogenes work like putting your foot down on the accelerator of a car, pushing a cell to divide.

59
Q

one of the most common mutations found in cancer is

A

mutation of the gene that produices p53 protein, called TP53

when this gene is mutated, the cell cycle is not stopped to repair damaged DNA

60
Q

Metaphase I the diff b/t mitosis and meosis

A

in mitosis(us), each chromosome is lined up on the metaphase plate by two spindle fibers (one from each pole)

in meosis, homologous chromosomes are lined up across from each other at the metaphase plate and are held by one spindle fibers.

61
Q

KEY CONCEPTS of the mesntruation cycle:

A
  • Follicles mature during the follicular phase (FSH, and LH). during this phase FSH increases and LH stays the same. Estrogen decreases and then increased (in preparation for Ovulation) and Progesterone decreases.
  • LH surge at midcycle triggers ovulation.
  • Ruptured follicle become corpus luteum, which secretes estrogen and progesterone to build up uterine lining in preparatio for implantation; LH and FSH are inhibited both decrease.
  • If fertilization does not occur, corpus luteum atrophies, progesterone and estrogen levels decrease, menses occurs, and LH and FSH levels being to rise again.
61
Q

Telophase I:

b/t cell division, there may be a short rest period called___, during which?

A

interkinesis, during which the chromosomes partially uncoil

62
Q

meiossis II is similar to mitosis in that ?

A

sister chromatids- rather than homologues are separated from each other

63
Q

MNEMONIC

A

Estrogen establishes and progesterone protects the endometrium

64
Q

OCP:

What it stands for?

What are OCP’s made out off?

How does it work?

A

OCP stands for Oral Contraceptive Pills

its made up of Estrogen and Progesterone (or progesterone only)

This pills work by inhibiting LH and FSH realease thru negative feedback thereby inhibiting Ovulation. Remember that during Ovulation all levels rise except Progesterone.

Biology (13 decks)

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