Ch 2: Reproduction

For actively dividing cells, the cell cycle contains what 4 stages? Interphase is composed of what stages?

1. G1 2. G2 3. S 4. M interphase = G1, G2, and S

What are the two microtubule organizing centers of the cell?

1. centrosomes 2. basal body of a flagellum or cilium

what are the four phases of the menstrual cycle?

1. follicular phase 2. ovulation 3. luteal phase 4. menstruation

seminal fluid is produced from what three places?

1. seminal vesicles 2. prostate gland 3. bulbourethral gland

The testes have what two functional components? What do these do?

1. seminiferous tubules--> sperm are produced here! 2. interstitial cells (of Leydig)--> secrete testosterone and other androgens

oocytes are surrounded by what two layers?

1. zona pellucida--> surrounds oocyte and helps bind to sperm 2. corona radiate--> lies outside the zona pellucida and is a layer of cells that adhered to the oocyte during ovulation

By the end of the ___ trimester of pregnancy, progesterone is supplied by the ___, and the corpus luteum atrophies and ceases to function

1st placenta

T or F: crossing over occurs between sister chromatids not homologous chromosomes?

FALSE. it occurs during Prophase 1 with the homologous chromosomes...the sister chromatids are identical...therefore their crossing over would render NO change

During male puberty, what do FSH and LH each do?

FSH--> stimulates the Sertoli cells and triggers sperm maturation LH--> causes the interstitial cells to produce testosterone

Describe G1, S, and G2 stages

G1: PRESYNTHETIC GAP: cells create organelles for energy and protein production, while also increasing size. There is a restriction point!!!! S: synthesis--> each cell replicates its genetic material so that each daughter cell will have identical copies. After replication, each chromosome consists of two identical chromatids held by a centromere G2: POSTsynthetic gap: cell checks that DNA has been duplicated and that there are enough organelles for division

Meiosis I results in what vs meiosis II?

I: homologous chromosomes are separated, generating haploid daughter cells--this is known as reductional division II: results in separation of sister chromatids and is known as equational division.

What does testosterone do?

Influences sperm cell development and also produces the male secondary sex characteristics such as body hair and deep voice.

Pathway of sperm

Seminiferous Tubules in testes> Stored in epididymis> Vas Deferens> Ejaculatory duct-->Urethra

As sperm are formed, they are passed to the ____ where their ____ gain motility, and they are then stored until ejaculation.

epididymis flagella

Ovaries produce what?

estrogen and progesterone

In females, ____ are secreted in response to FSH. ____ is secreted by the ___ ____--the remnant follicle that remains after ovulation--in response to ____.

estrogens progesterone corpus luteum LH

Meiosis occurs in _____ and results in ___ nonidentical sex cells. It consists of one round of ____ and two rounds of ____.

gametocytes 4 replication division

Prior to puberty, the ____ restricts production of ___-____ hormone (___).

hypothalamus gonadotropin-releasing hormone (GnRH)

Sister chromatids are ____ strands of DNA connected at a ____.

identical centromere

describe the menstrual phase

if implantation does not occur, the corpus luteum loses its stimulation from LH, progesterone levels decline, and the uterine lining is sloughed off. the loss of high levels of estrogen and progesterone removes the block on GnRH so that the next cycle begins

What is the first main difference between prophase 1 in mitosis and meiosis?

in meiosis, the homologous chromosomes come together and intertwine in a process called synapsis. Chromatids may break at the point of contact, called the chiasma and exchange equivalent pieces of DNA--called crossing over.

What is the difference between mitosis and meiosis in metaphase I?

in mitosis, the chromosome is lined up on the metaphase plate by two spindle fibers; in meiosis, homologous chromosomes are lined up across from each other at the plate are held by ONE spindle fiber each.

between cell divisions in meiosis, _____ might occur, which is when the chromosomes partially uncoil.

interkinesis

what does hCG do? when do its levels decline and why?

is an analog of LH, and maintains the corpus leutum, which secretes estrogen and progesterone during the first trimester to keep the uterine lining in place. by the second trimester its levels decline because the placenta can secrete P and E itself

The secondary oocyte remains arrested in ____ II and does not complete the remainder of meiosis II unless ____ occurs.

metaphase fertilization

At he G1/S checkpoint, the restriction point, DNA is checked by this main protein: ____. This protein also checks between G2/M to ensure that there are enough organelles for daughter cells

p53

One of the most common mutations found in cancer is mutation of the genes that produces ___, called ____. when this gene is mutated, the cell cycle is not stopped to repair damaged DNA.

p53 TP53

Once a month, one ____ oocyte with complete meiosis ___ to produce a _____ oocyte and a polar body

primary 1 secondary

By birth, all the oogonia have already undergone DNA replication and are considered _______ _____. These cells are 2n, and like primary spermatocytes, are arrested in _____ 1.

primary oocytes prophase

Mitosis is the M stage, and divided into ____, ____, _____ and _____. _____ is the splitting of the cytoplasm and organelles into two daughter cells.

prophase, anaphase, metaphase, telophase ctyokinesis

What is the G0 phase?

the cell is simply living and serving its function, without any preparation for division

what is linkage?

the tendency for genes to be inherited together; genes that are located farther from each other physically are less likely to be inherited together and more likely to undergo crossing over relative to each other.

describe ovulation phase

too much estrogen causes GnRH, LH and FSH levels to spike. The surge in LH induces ovulation, the release of the ovum from the ovary into the abdominal cavity

T or F: estrogen causes the initial thickening of the endometrium, not progesterone.

true

In autosomal cells, division results in what?

two genetically identical daughter cells.

what triggers meiosis II in oocyte?

when the sperm penetrates the oocyte with its acrosomal enzymes

The ____ chromosome carries a sizeable amount of genetic info; mutations in these genes can cause ___-_____ disorders.

X sex-linked

The ___ chromosome contains v. little genetic info but does contain the ______ region.

Y SRY: sex-determining region Y, which codes for a transcription factor that initiates testis differentiation and, thus, the formation of male gonads

Sperm consist of what?

a head with an acrosome, mid piece, end piece, centriole connecting head and mid, and tail.

describe the Luteal phase

after ovulation, LH causes the ruptured follicle to form the corpus luteum, which secretes progesterone -progesterone levels rise, while estrogen levels remain high

Prototherians encase their developing embryos in ______ and metatherians do what? these are both mammals

amniotic hard shelled eggs outside of the protherians metatherians develop their babies inside the mother and then have live births

At the start of puberty, the hypothalamus release GnRH, which triggers the ___ ____ ____ to synthesize and release ___-___ hormone (___) and ____ hormone (__).

anterior pituitary gland follicle-stimulating hormone, FSH luteinizing hormone LH

Estrogen establishes and progesterone protects the ____.

endometrium

describe the follicular phase

begins with the menstrual flow to shed the uterine lining of the previous cycle. -GnRH secretion increases in response to decreased concentrations of E and P from last cycle, thus more FSH and LH are secreted. -these two hormones help develop several ovarian follicles which begin to grow and produce estrogen, which has negative feedbacks and causes the GnRH, LH and FSH concentrations to level off -estrogen regrows the endometrial lining

It fertilization has occurred, the resulting zygote with develop into a ____ that will implant in the uterine lining and secrete ___ ___ ___ (__).

blastocyst human chorionic gonadotropin (hCG)

During interphase, individual chromosomes are NOT visible because they are in their less condensed form call _____.

chromatin

The molecules responsible for the cell cycle are known as ___ and ____-dependent _____.

cyclins cyclin-dependent kinases these cyclins bind to CDKs, creating an activated CDK-cyclin complex, which can then phosphorylate transcription factors to promote the transcription of genes required during the next stages if the cell cycle

In animals, autosomal cells are ____ while sex cells are ____. what does this mean?

diploid--> 2n = 2 copies of the each chromosome. these are 2 chromosomes for each of the 23 chromosomes haploid--> 1n --> 23 homologous pairs. one from each parent...go on to meiosis and generate 1n gametes

During anaphase I, homologous pairs separate and are pulled to opposite poles of the cell. this process is called ____, and accounts for Mendel's first law of segregation.

disjunction -during disjunction, each chromosome of paternal and maternal origin are separated

Most X-linked disorders are _____ inherited, which is why females express these disorders far ____ than males

recessively less

The ___ ____ contribute fructose to nourish sperm. The _____ gland secretes a clear viscous fluid to clear out the urethra of acids and urine

seminal vesicles Cowper's

where are sperm produced? what nourishes them?

seminiferous tubules Sertoli cells

Spermatogenesis is the formation of haploid sperm through meiosis and occurs in the _____ _____. In males, the diploid sperm cells are known as _____. What do they become after that and when?

seminiferous tubules spermatogonia --> primary spermatocytes (after S stage) --> secondary spermatocytes (after Meiosis 1 division) --> spermatids (after meiosis II division)

Meiosis II is very similar to mitosis in that

sister chromatids rather than homologues are separated

Mitosis is the process by which two identical daughter cells are created from a single cell and occurs in ____ cells. describe each phase

somatic 1. prophase: condensation of chromatin into chromosomes, centriole pairs separate and move toward opposite poles of the cell and form spindle fibers 2. metaphase: centriole pairs now at opposite ends of cell, and the kinetochore fibers align chromosomes at the metaphase plate 3. anaphase: centromeres splits so that each chromatid has its own, thus sister chromatids separate 4. telophase: reverse prophase! spindle apparatus disappears, nuclear membrane reforms, and nucleoli reappear. (cytokinesis)--> actual separation of the cytoplasm and organelles

mature spermatids undergo maturation to become mature _____.

spermatozoa

What do FSH and LH do?

stimulate the gonads to produce sex hormones