Chpt. 2

Question 1

Diploid vs Haploid

Answer 1

diploid 2n cells have two copies of each chromosome while haploid cells only have one

Question 2

5 stages of cell cycle

Answer 2

G1(presynthetic gap): increase in size and resources: restriction point where DNA is checked.
S stage(synthesis): DNA replicated, strand of DNA called chromatids held together at centromere.
G2(postsynthetic gap): more cell growth and replication of organelles + another quality checkpoint.
M stage(mitosis): mitosis and cytokinesis occur.
G0 stage: cell performs functions without replicating

Question 3

p53

Answer 3

plays role in two major checkpoints of cell cycle. G1 to S, and G2 to M

Question 4

Cyclins and Cyclin-dependent kinases

Answer 4

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

Question 5

Cancer

Answer 5

occurs when cell cycle control becomes deranged, so damaged cells multiply. Cancerous cells may produce factors that allow them to delocalize and invade adjacent tissue or metastasize elsewhere.

Question 6

somatic vs germ cells

Answer 6

somatic undergo mitosis and produce identical daughter cells to the parent cell while germ cells undergo meiosis and produce gametes.

Question 7

Mitosis

Answer 7

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

metaphase: chromosomes line up along the metaphase plate(equatorial plate)

anaphase: sister chromatids are separated and pulled to opposite poles.

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

Question 8

Meiosis

Answer 8

Meiosis 1(reductional devision): homologous pairs of chromosomes are separated from each other. Homologues are chromosomes that are given the same number, but are of opposite parental origin.
Prophase 1: same events as mitosis, but homologues come together and intertwine in a process called synapsis where genetic material is exchanged between 4 chromatids. Accounts for Mendel’s second law of independent assortment.
metaphase 1: homologous chromosomes line up on opposites sides of the metaphase plate.
anaphase 1: homologous chromosomes are pulled to opposite poles of the cell. Accounts for Mendel’s first law of segregation
telophase 1: chromosomes may or may not fully decondense, and the cell may enter interkinesis after cytokinesis.

Meiosis 2: sister chromatids are separated from each other by same stages as meiosis 1

Question 9

Chromosomal sex

Answer 9

determined by chromosome 23 in humans. Male has XY, Female XX.

X chromosome carry lots of genetic material including sex-linked disorders. Most are recessive so Male show traits more often than females.
Y chromosome carry little genetic material but does contain SRY(sex-determining region Y). cause gonads to differentiate into testes.

Question 10

sperm

Answer 10

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

Question 11

Interstitial cells of Leydig

Answer 11

located in the testes. secrete testosterone and other male sex hormones(androgens)

Question 12

Testes

Answer 12

located in the scrotum which hang outside the abdominal cavity and has a temp of 2-4*C lower than the rest of the body

Question 13

During ejaculation

Answer 13

sperm travel through the vas deferens to the ejaculatory duct, then to the urethra and out though the penis

Question 14

Seminal vesicles

Answer 14

contribute fructose to nourish sperm and produce alkaline fluid

Question 15

prostate gland

Answer 15

also produce alkaline fluid

Question 16

bulbourethral glands

Answer 16

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

Question 17

Semen

Answer 17

composed of sperm and seminal fluid fro the glands above

Question 18

Spermatogenesis

Answer 18

production of 4 sperm cells from a spermatogonium.
Primary spermatocytes: after S stage
Secondary spermatocytes: after meiosis 1
spermatids: after meiosis 2
spermatozoa: after maturation

Question 19

Sperm structure

Answer 19

head: contains the genetic material and is covered with an acrosome(modified golgi apparatus)
midpiece: generates ATP from fructose and contains many mitochondria
flagellum: promotes motility

Question 20

Ova

Answer 20

gametes produced by females. Made in follicles in the ovaries.

Once a month an ova is ovulated into the peritoneal sac and is drawn into the fallopian tube or oviduct.

Question 21

female reproductive system

Answer 21

fallopian tubes are connected to the uterus, the lower end of which is the cervix. Vaginal canal lies below the cervix and is the site where sperm are deposited during intercourse. Vaginal canal is also can be the site at childbirth. External parts of female genital are known as vulva.

Question 22

Oogenesis

Answer 22

production of female gametes. 1 haploid and variable number of polar bodies are produced from an oogonium.
At birth, all oogonia have undergone replication and are considered primary oocytes, arrested at prophase 1.
The ovulated egg each moth is a secondary oocyte, arrested at metaphase 2. If the oocyte is ovulated in this stage, it will complete meiosis 2 become a true ovum.
Cytokinesis is uneven in oogenesis, so cells receiving little cytoplasm and organelles are called polar body.
Oocytes are surrounded by the zona pellucida, an acellular mixture of glycoproteins that protects the oocyte and contains the compounds necessary for sperm binding; and the corona radiata, which is a later of cells that adheres to the oocyte during ovulation.

Question 23

Gonadotropin-releasing hormone(GnRH)

Answer 23

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

FSH in males stimulates Sertoli cells and triggers spermatogenesis. FSG in females stimulates development of the ovarian follicles.

LH in males cause interstitial cells to produce testosterone. Testosterone is responsible for the maintenance and development of male reproductive system and secondary traits. LH in females causes ovulation and stimulate production of estrogens and progesterone

Question 24

Menstrual cycle

Answer 24

periodic growth and shedding of the endometrial lining.
Follicular phase - egg develops, endometrial lining becomes vascularized and glandularize. FH increase, LH equal, estrogen decrease then increase, progesterone decrease.
Ovulation - stimulate by surge in LH which is caused by threshold levels of estrogen(switch from negative to positive feedback)
Luteal phase - LH causes ruptured follicle to become the corpus leuteum, which secretes progesterone that maintains the uterine lining. High estrogen and progesteron leves cause negative feedback on GnRH, LH, and FSH.
Menstruation - occurs if there is no fertilization. As estrogen and progesteron levels drop, the endometrial lining is sloughed off, and the block on GnRH production is removed.
If fertilization occurs, blastula produces human chorionic gonadotropin(hCG) whihc can maintain the corpus luteum. Near the end of the first trimester, hCG levels drop as the placenta takes over progesterone production.
Menopause - occurs when the ovaries stop producing estrogen and progesterone, usually between 45-55. Mestruation stops and FSH and LH levels rise.