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Biology Kaplan MCAT > Ch. 2: Reproduction > Flashcards

Ch. 2: Reproduction Flashcards

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1
Q

Diploid (2n)

A

Type of cell, has 2 copies of each chromosome, autosomal cells

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2
Q

Haploid

A

Type of cell, has 1 copy of each chromosome, germ cells

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3
Q

Cell Cycle: Interphase

A

G1, S, G2, DNA is uncoiled into the form of chromatin in this phase, longest part of cell cycle, even actively dividing cells spend 90% of their time in interphase

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4
Q

G1

A

Presynthetic gap, cells create organelles (mitochondria, ribosomes, and endoplasmic reticulum) for energy and protein production while also increasing their size. There is a restriction point where DNA is checked for quality to move onto S stage, if there is damage to DNA, cell cycle goes into arrest until DNA has been repaired

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5
Q

S

A

Synthesis, DNA is replicated, the 2 strands of DNA called chromatids are held together @ centromere w cohesin

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6
Q

G2

A

Postsynthetic gap, there is further cell growth and replication of organelles in preparation for mitosis, cell checks if there are enough organelles and cytoplasm for 2 daughter cells another quality checkpoint must be passed to go to mitosis (not sure if this is part of G2)

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7
Q

M

A

Mitosis, mitosis and cytokinesis occur: prophase, metaphase, anaphase and telophase

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8
Q

G0

A

The cell performs its function without any preparation for division

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9
Q

P53

A

Protein that plays a role in the 2 major checkpoints of the cell cycle (G1 to S and G2 to M)

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10
Q

Cyclins and Cyclin Dependent Kinases (CDKs)

A

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

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11
Q

Transcription factors

A

Promote transcription of genes required for the next step of the cell cycle

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12
Q

Cancer

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 escape their site and invade or metastasize elsewhere. One of the most common mutations is one where gene which produces p53 is mutated and produces TP53

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13
Q

Somatic cells

A

Undergo mitosis to form 2 genetically identical diploid daughter cells from a single cell

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14
Q

4 phases of Mitosis

A
  1. Prophase: chromosomes condense, nuclear membrane dissolves, nucleoli disappear, centrioles migrate to opposite sides of the cell, and the spindle apparatus (defines plane of division) begins to form. The kinetochore of each chromosome is contacted by a spindle fiber
  2. Metaphase: chromosomes line up along the metaphase plate (equatorial plate)
  3. Anaphase: sister chromatids are separated and pulled to opposite poles
  4. Telophase: nuclear membrane reforms, spindle apparatus disappears and cytosol and organelles are split between the two daughter cells through cytokinesis
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15
Q

Meiosis

A

Occurs in gametocytes (germ cells) and produces up to 4 non-identical haploid sex cells (gametes)
- 1 round of replication and 2 rounds of division

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16
Q

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

  1. Prophase I: same as prophase in mitosis except homologues come together and intertwine in a process called synapsis. The 4 chromatids are referred to as a tetrad and crossing over exchanges genetic material from one chromatid w material from a chromatid in the homologous chromosome (Mendel’s second law– independent assortment)
  2. Metaphase I: homologous chromosomes line up on opposite sides of the metaphase plate
  3. Anaphase I: homologous chromosomes are segregated to opposite poles of the cell. (Mendel’s first law– segregation)
  4. Telophase I: the chromosomes may or may not fully decondense, and the cell may enter interkinesis after cytokinesis
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17
Q

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 @ the centromere

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18
Q

What is biological sex determined by?

A

23rd pair of chromosomes in humans

XX is female and XY is male

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19
Q

X chromosome

A
  • carries sizable amt of genetic info

- mutations of X-linked genes can cause sex-linked disorders

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20
Q

Hemizygous

A
  • males have only 1 X chromosome so they will express sex-linked disorders, even if they only have one recessive disease-carrying allele
  • women w one copy of the affected allele are called carriers
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21
Q

Y chromosome

A

Carries little genetic info, but contains the SRY (sex-determining region Y) gene which causes the gonads to differentiate into testes which have 2 fuctional components: seminiferous tubules and interstitial cells of Leydig

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22
Q

Male Reproductive System:

A

Contains both internal and external structures

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23
Q

Sperm

A
  • develop in the seminiferous tubules in the testes

- nourished by Sertoli cells

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24
Q

Interstitial Cells of Leydig

A

Secrete testosterone and other male sex hormones (androgens)

25
Q

Scrotum

A
  • Testes are located here
  • hangs outside the abdominal cavity and has a temp 2-4* lower than the rest of the body– layer of muscle around vas deferens to raise and lower testis to maintain proper temp
26
Q

Epididymis

A

Once they form, sperm gain motility and are stored there until ejaculation

27
Q

Ejaculation

A

Sperm travel through the seminiferous tubules to epididymis to vas deferens to the ejaculatory duct to the urethra and out through the penis (SEVE(n)UP)

28
Q

Seminal Vesicles

A

Contribute fructose to nourish sperm and produce alkaline fluid

29
Q

Prostate Gland

A

Produces alkaline fluid

30
Q

Bulbourethral glands

A

Produce a clear viscous fluid that cleans out any remnants of urine and lubricates the urethra during sexual arousal

31
Q

Semen

A

Composed sperm and seminal fluid from the aforementioned glands

32
Q

Spermatogenesis

A

4 haploid sperm are produced from a spermatogonium (diploid stem cells)

33
Q

What are germ cells called through Spermatogenesis

A
  • Primary spermatocytes: after S stage
  • Secondary spermatocytes: after meiosis I
  • Spermatids: after meiosis II
  • Spermatozoa: after maturation
34
Q

Parts of a Sperm

A
  • Head: contains the genetic material and is covered w an acrosome– a modified Golgi apparatus that contains enzymes that help the sperm fuse o and penetrate the ovum
  • Midpiece: generates ATP from fructose and contains many mitochondria
  • Flagellum: promotes motility
35
Q

Female Reproductive System:

A

Contains only internal structures

36
Q

Ova

A

Eggs, produced in follicles in the ovaries

37
Q

follicles

A

Multilayered sacs that contain, nourish and protect immature ova

38
Q

Once each month

A

An egg is ovulated into the peritoneal sac and is drawn into the fallopian tube or oviduct lined w cilia to propel egg forward

39
Q

Fallopian tubes

A

Connected to the muscular uterus whose lower end is called the cervix

40
Q

Vaginal canal

A

Lies below cervix, site where sperm are deposited, birth occurs through this

41
Q

Vulva

A

External female anatomy

42
Q

Oogenesis

A

One haploid ovum and a variable number of polar bodies are formed from an oogonium

43
Q

Primary oocytes

A

At birth, all oogonia have already undergone replication and are considered primary oocytes– they are arrested in prophase I

44
Q

Secondary oocyte

A

Ovulated egg each month, arrested in metaphase II

45
Q

When does the oocyte complete meiosis II?

A

When it is fertilized to become a true ovum

46
Q

Cytokinesis in oogenesis

A

Uneven, the cell receiving little cytoplasm and organelles is called a polar body

47
Q

Zona Pellucida

A

Acellular mixture of glycoproteins that protect the oocyte and contain the compounds necessary for sperm binding and the corona radiata

48
Q

Corona radiata

A

Layer of cells that adhered to the oocyte during ovulation

49
Q

Gonadotropin-releasing hormone (GnRH)

A

Comes from the hypothalamus, causes release of follicle-stimulating hormone (FSH) and luteinizing hormone which stimulate the production of estrogen and progesterone

50
Q

FSH

A

Follicle stimulating hormone

  • Males: stimulates the sertoli cells and triggers spermatogenesis
  • Females: stimulates development of ovarian follicles
51
Q

LH

A

Luteinizing hormone

  • Males: causes the interstitial cells to produce testosterone
  • Females: causes ovulation
52
Q

Testosterone

A

Responsible for maintenance and development of the male reproductive sys and male secondary sex characteristics (facial and axillary hair, deepening of the voice, and changes in growth patterns)

53
Q

Menstrual cycle:

A

Periodic growth and shedding of the endometrial lining

54
Q

Follicular phase

A

GnRH secretion stimulates FSH and LH secretion which promotes follicle development. Estrogen is released, stimulating vascularization and glandularization of the decidua

55
Q

Ovulation

A

Stimulated by a sudden surge in LH– occurs bc estrogen stops having negative feedback effects @ a certain threshold and begins to have positive feedback effects

56
Q

Luteal phase

A

LH promotes 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

57
Q

Menstruation

A

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

58
Q

Human chorionic gonadotropin

A

If fertilization occurs, the blastula produces this LH analog, can maintain the corpus luteum. Near the end of the first trimester, hCG levels drop as the placenta takes over progesterone production

59
Q

Menopause

A

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

Biology Kaplan MCAT (12 decks)

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