Biology Notes
2694 cr points
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29 / F / NYC
Posted 5/17/10
So if any one is interested in some biology notes, here are some that my teacher gave me
• Evolution
o The changes that have occurred in living things since the beginning of life due to differential reproductive success
o Individuals reproduce better because they are better fit to the environment
o Fossils
 Remains and traces of past life or any other direct evidence of past life
 Consist of hard parts
• Bones, teeth, shells, etc
 Sometimes buried quickly thus
• Trails, footprints, burrows, worm casts, or even preserved droppings
 Are transition links between groups
 Geological Timescale
• Eras, periods, and epochs
• Dating fossils
o Radioactive dating
o Carbon 14 / Carbon 12
 Mass Extinctions
• Large percentage of species become extinct within a relatively short period of time
• 5 mass extinctions so far (at the end of each of these periods)
o Ordovician
o Devonian
o Permian
o Triassic
o Cretaceous
• Marine animals have a mass extinction about every 26 million years
o Biogeographical evidence
 Study of the distribution of species throughout the world
• Species evolved separately, and barriers prevented those species to join
• Barriers arose through a process called continental drift, continents have always been moving
o Anatomical evidence
 Homologous structures
• Anatomically similar because the structures are inherited from a common ancestor
• Analogous structures serve the same function but are not constructed similarly, nor is there a shared common ancestor
 Vestigial structures
• Anatomical features that are fully developed in one group of organisms but are reduced and may have no function in similar groups
• Homology shared by vertebrates extends to their embryological development
o Tail, gill slits
 Biochemical evidence
• Almost all living organisms use the same basic biochemical molecules, including DNA, ATP
o Evolution no longer considered a hypothesis

Dr. Nedwidek Mitosis & meiosis comparison; Starts March 12, 2010
Guided Lesson/filled in

Aim: What are the steps in mitosis versus meiosis?

DN: Can crossovers occur in mitosis? Why or why not?
Diagram chromosome anatomy from the board…this should be in your notebook.

A Fantastic Comparison of Mitosis versus Meiosis by Wilson Louie (Ned pd 7+8, 2008) Wow!! Please find attached.

Mitotic events (animal, assuming centrioles present): note that cell cycle includes synthesis and replication during interphase.
Interphase (between): Rest and replication
Prophase (before): chromosome copies condense and shorten; nuclear envelope breaks down; later on: alignment begins on spindle.
Metaphase (middle): Spindles recruit formal chromosomal alignment; in animals, centrioles control the “poles”; chromosomes stick to the spindles at chromosomal centromeres (kinetochore); plants have no centrioles.
Anaphase (after): sister chromatids separate at their centromeres and become individual chromosomes—tugged and reeled in by the spindle.
Telophase (end): one complete set of chromosomes reaches each pole.
Cytokinesis: cell splits into 2 daughters; chromosomes decondense and the nuclear envelope forms.
Humans have 23 pairs: maternal and paternal “halves” of the genetic complement.
Diagram (from the board) condition 2n=2 (1 maternal, 1 paternal) mitosis steps:
done in class!!

Meiotic events (animals):
Prophase I: chromosomes condense; spindle forms with centrioles; crossover occurs between maternal and paternal homologs of adjacent sister pairs
Metaphase I: paired homologs line up; attach to spindle
anaphase I: homologs separate and go to poles; they are still attached to the spindle; one doubled pair of each homolog goes to a pole.
Telophase I: spindles disappear; homologs are distributed to either pole as pairs of sisters (still attached)
Cytokinesis I occurs. First cell split. Sisters still attached. You took stuff below by dictation:
Prophase II: chromosomes recondense; spindles re-form.
Metaphase II: sisters realign at the spindle on the equator; poles are well-established.
Anaphase II: sister chromatid copies separate so that one homolog (paternal or maternal) is represented in each sex cell (males-4 sperm, females-1 egg and 3 polar bodies).
Telophase II: chromosomes finish moving; cells pinch off and split a second time.

Diagram (from the board) gamete (sperm) formation for condition 2n=2, 1n=1 meiosis steps: done in class!!!

We defined a nondisjunction even as when the chromosomes are not unconnected. While inefficient usage, this describes meiotic situations where sister chromosomes don’t separate, leading to faulty gametes having 1 too many/1 too few chromosomes. Some serious disorders associated with this are Downs, Klinefelters, Edwards, and Patau. More on this with genetics lessons in April.

Hws 5 and 6 were previously distributed as:

hw 5 is due thursday march 11; double side the written page:

kraus page 315 multiple choice 6 thru 15--write question and answer.; aud
pg 206 question 7; towle chapter 8 page 158 vocab 1 thru 5--on 2 sides of paper;

towle page 158 mc 6 thru 15--scantrons tbd;

aud page 206, do questions 3 and 6 each on the unlined side of a 3 x 5
index card with your name and section. that's two cards per assignment.
line drawings only; one side only. coloring allowed, no downloads. title
one, meiosis, and the other, mitosis.

you lose an hour this weekend.

algae and fungi lab is next tues (3/16) and thurs (3/18)

remember to get your green on on weds march 17...

Dr. Nedwidek BIO Reproduction, Development, STDs REV: March 17-22, 2010

Aim 1: How do animals and humans reproduce?

DN: We previously examined mitosis and meiosis verbally and visually. What happened to each paternal “brother” chromatid and maternal “sister” chromatid at the end of mitosis versus meiosis. Distinguish between homologs and sister chromatids.
We have 23 chromosomes in sex cells. Assuming crossovers do take place and all essential genes are represented, how many shuffle combinations are possible for the event that generates every human sex cell? Please hand in HW 5. Bartsch p 57 has good references on cell division.

Some notes about the genetic outcomes of meiosis. Recombination refers to both crossover events and different pairing of maternal and paternal homologs in the gametes. All sex cells originate from a 2n primary germ cell that ultimately yields 4 x 1n sex cells. Mutations can also introduce change in meiosis (but are basically the only way to introduce change in mitosis). Spontaneous mutations at some low frequency cannot be avoided; they are harmful, innocuous, or helpful, but most are innocuous.

In male animals, the testes make sperm via spermatogenesis:
-diploid primary spermatocytes give rise to spermatozoa cells (haploid).
-4 spermatids (1n) are made per meiotic event. Draw events from class notes: done

In female animals, ovaries make eggs via oogenesis:
-diploid primary oocytes give rise to three polar bodies plus an oocyte or egg, all haploid.
-only the egg can undergo fertilization. Draw the events below: done

Sexual reproduction: define terms below: Done in class
Monoecious: normally hermaphroditic

Diecious: requires separate male and female sexes

Procedure: Mechanism: Monoecious Diecious

External Fertilization Corals, Urchins, Amphibians, Fish

Internal Fertilization Flat/Tapeworms Mammals, Monotremes, birds,
Annelids &Snails Amphibs,Reptiles,bugs,snails, sharks

Parthenogenesis: aphids and some lizards do this form of asexual, haploid reproduction.

Steps for Sexual reproduction by internal fertilization include:
Courtship (in some species, stimulates ovulation): followed by sexual union
Copulation (see also aud p 725): this is insertion of the male sex organ into female
Intercourse: requires ejaculation for successful fertilization; followed by orgasm
Withdrawal: the pull out is necessary for obvious reasons.
Fertilization and development then occurs if successful page ref also aud 727

While I’d love to have you write all this in class, we need time for discussion, so here:
Know male sex organs: Audesirk 726: Testis (gonad), epididymis, vas deferens, urethra, penis, seminal vesicles. Prostate gland, bulbourethral glands. Important male hormones: GnRH, LH, FSH, testosterone controls secondary sex characteristics, which are? List:
->Body and facial hair-pubic, underarm too
->Muscle growth (connects to testosterone)
->Broadening chest-lower voice
->Larger voice box/larynx (Adam’s apple)
->Sperm cell production begins when testes enlarge or “drop”

Know sex organs in females: Audesirk 729: Ovary (gonad), fimbria (opening of Fallopian tubes), Uterine tube/fallopian tube/oviduct, uterus (womb/when pregnant), cervix, vagina. Important female hormones: progesterone, estrogen, FSH, LH, GnRH all regulate sex characteristics, which are.?.? List below.
->Pubic and underarm hair
->Breasts/Mammary glands develop and grow.
->Hips widen (to support fetus)
->Female Repro System; maturation of overy and uterus
->Egg cells mature

You must know and be able to articulate functions of each organ listed above.
Males, Table 36-1 Audesirk page 726
Females, Table 36-2 Audesirk page 729

Hormone (Type) Role in Females Role in Males

LH (pept) ovulation, CL, stims follicle, stims testosterone synth & secretion
secretion of E and P
FSH (pept) stims follicle growth, E stims Sertoli cells and sperm synth
secretion, ovulation
P: progesterone (ster) shuts down LH, FSH,forms ---------------
uterine lining (placenta)
E: estrogen (ster) female sec sex character’s, ---------------
eggs, uterus prep for fetus;
stims follicle
GnRH (pept) stims LH, FSH stims LH, FSH
Testosterone ------------------- male sec sex characteristics

You must know menstrual cycle control (you had a HW on this):
Copy the info from board that comes from 2 similar graph charts on Audesirk p 732 and Towle p 1052. Menstruation is a 4 week cycle; ovulation occurs at 2 weeks and menses flow at 4 weeks if fertilization has not occurred. Copy steps of the cycle into your notes:

1. GnRH stimulates AP to release FSH

2. Follicle grows, which takes 2 weeks.

3. Maturing follicle secretes more estrogen.

4. More estrogen stimulates LH, FSH at day 12. More LH: secondary oocyte and one polar body form due to meiosis I, follicle grows, corpus luteum forms.

5. Ovulation occurs (Day 14) due to follicle growth.

6. Corpus luteum (CL) secretes estrogen and progesterone.

7. FSH, LH production both shut down, E and P increase, and stimulate uterine lining to grow.

8. If no fertilization, no pregnancy-CL disintegrates (negative feedback).

9. E and P decrease endometrium is shed-this is the menstrual flow or period—day 28/day1; then follicles start over/process resumes. Mention moodswings/hormone changes.

Take notes on human reproduction and fertilization as needed in addition to below.

-If a fertilized egg implants in the uterus, no menstrual “period” occurs in females; hence, the colloqual term “late period” is used to describe the result of successful implantation.

Steps in human reproduction/fertilization:

-In humans, internal fertilization is accomplished by copulation.
-In human males, the erection of the penis occurs through visual or physical stimulus (masturbation) or both; the penis is then inserted into the female vagina. In animals, this union or insertion is called copulation.
-Upon ejaculation, semen (which contains sperm and glandular secretions providing nutrients and pH balance) is expelled, usually inside the female.
-300-400 million spermatozoa are made for every 3-4 milliliters of semen.
-The male orgasm follows ejaculation.
-In females, following penis insertion, the vagina/labia and the clitoris (which is anatomically and tissue-specifically like a female version of the penis) receive increased blood flow, and the clitoris becomes erect (usually stimulated by penis physically rubbing it and the “G spot”). This can but does not always lead to female orgasm.
-While the male orgasm requires ejaculation, which is mandatory for fertilization to occur, the female orgasm is totally unnecessary to successfully achieve fertilization. Alas, this is good and bad. Furthermore, because successful female orgasm is not apparent externally, it is possible for females to “fake it” with enthusiastic vocalizations during sexual intercourse.

The Union of Sperm and Egg: Fertilization: Pay attention to the timing of these events.

-Fertilization can succeed only if copulation occurs within a few days of—either before or after—ovulation of the secondary oocyte. Every female is born with a lifetime supply of primary oocyte eggs stalled at prophase I. Fertilization actually efficiently stimulates the completion of egg production, or development of the secondary oocyte, at meiosis II. The last division of meiosis II formally occurs at fertilization.
-The egg leaves the ovary, surrounded by a corona radiata of follicle cells, and a jellylike zona pellucida shell.
-The unfertilized egg travels down the oviduct toward the uterus where it is overwhelmed by many sperm, but a number less than the 300 million produced post-ejaculation; sadly, many sperm are killed by the acidic vaginal environment, which is why the semen is basic.
-“Head” enzymes in the lucky sperm carry out the acrosome reaction. These enzymes are specific for breaking down the corona and the zona. 1/100000 sperm reach the oviduct (also called fallopian tube or uterine tube), and 1/20 of those find the egg.
-When “the one” lucky sperm finds the egg, enters, and fuses with the plasma membrane of the egg, this triggers a true “shell” to be formed by the zona that keeps out further sperm.
-The two haploid nuclei (one from egg and one from sperm) fuse, forming a diploid nucleus. This is the zygote, which develops into an embryo (more complex), and ultimately a fetus (yet more complex). Identical twinning occurs in the first few divisions post fertilization. When the two “first division” cells separate, monozygotic identical twins result; very rarely, identical triplets or quadruplets can form if the second division cells separate as well. Monozygotic multiplets are true clones that occur naturally. Fraternal or dizygotic/multizyogotic twinning is the result of individual fertilization events and does not result in genetically identical offspring.
-The blastocyst stage (ES cells are derived from this tissue) is what implants in the uterus. If implantation occurs in the uterine tube, this is called “ectopic pregnancy” and is in-viable or not viable.
-In Vitro Fertilization (IVF) is when the above process of sperm-egg union is carried out external to the female body; the healthy embryos are successfully implanted in the uterus as blastocysts and monitored. Alas, IVF does not involve sexual intercourse, but for couples struggling with infertility, it may be the only natural way to conceive children. The first successful child resulting from IVF in the ‘80’s was called a “test-tube baby”. This technology has been combined with preimplantation genetic diagnosis (PGD) to eliminate harmful genetic diseases from certain families.

Take notes on animal embryonic development on separate sheets in addition to below. The parts of an animal embryo are the chorion, amnion, allantois, and yolk sac (aud/748). You should know the difference between egg, zygote, embryo, morula, blastula, gastrula.

Aim 1.5: What are the steps in Development?

The Stages of Development

-As the zygote moves from ovary to uterus, it undergoes a rapid series of MITOTIC cleavage events: 2-cell, 4-cell, 8-cell, morula. At day 7, the hollow-ball blastocyst, which is the human version of the ordinary mammal’s blastula, implants in the uterus. (aud 754)
-In humans, the blastocyst, which is near the embryonic disc, is a layer of cells separating the amnion from the yolk sac. The blastocyst is the best source for ES cells, which have great potential as undifferentiated cells—they can become/diffferentiate into any cell type. Stem cells can be harvested at this precise stage.
-At day 15 through week 3, early, mid- and late gastrula stages present/gastrulation occurs. A three-layered embryo is formed. When the ball of cells starts to fold in on itself, differentiation has begun. We are deuterostomes, meaning we (simply) have “2 holes” (mouth and anus), and undergo radial cleavage (around a central axis).
-Tissue fates (see Aud 749) are determined by their position as development and differentiation progress; fill in the chart below:

Name Location in Lay terms Forms Tissue type (differentiation)

Ectoderm “out” skin,hair,nails,nervous system

Mesoderm “middle” gonads, body cavity linings, outer
layers of digestive tract

Endoderm “in” organ linings, lungs, throat, inner
digestive tract

-Within a month of conception and early in the process of development (implantation through about week 12 of trimester 3), the fertilized zygote, now an embryo, “communicates” that it is “friendly” with many chemical signals (the most significant of which is believed to be human chorionic gonadotropin or hCG) that maintain the uterine lining and ward off an immune reaction to the baby, which is only part “self” relative to mom. Most standard pregnancy tests assay for large amounts of hCG in urine.
-These chemicals cause “morning sickness” which is essentially extreme nausea. It is a necessary inconvenience. About 50 years ago, women taking a drug called thalidomide to reduce primarily the nausea effects of morning sickness and some other side effects of pregnancy gave birth to “malformed” babies. Thalidomide had actually interfered with limb development in these children, and was subsequently banned. (see Aud 760)

Aim 2: What are the beauties and the risks of sexual intercourse?

DN: Please address the following: We previously mentioned the use of IVF (in vitro fertilization) for conception and harvesting of ES (embryonic stem) cells from blastulae or the human blastocyst. Name a pro and con for each technology.

Dolly, the cloned sheep , is discussed in detail on audesirk 194-195. In this case, the somatic DNA of a mammary cell was de-differentiated and inserted into a bona fide sheep egg “shell”. It is genetically better/more robust to have newborn sheep. Why?

The Beauties of sex: It provides pleasure and babies. More about the development of a baby human being, post-conception:

The Womb: Chorionic villi and the uterine lining form the placenta, and the developing embryo secretes hormones such as HCG (human chorionic gonadotropin--this is the indicator of pregnancy in most home dipstick tests like EPT). The placenta allows selective exchange of materials like oxygen, nutrients, and toxins between mom & fetus.

Human Pregnancy Trimesters, each 3 months.
Trimester 1: In the first 2 months of pregnancy, there is great risk for damage to the fetus due to the rapid rate of differentiation and dramatic change that occur during this time.
At three-weeks post-conception, gastrulation occurs and the neural tube including the brain, spinal cord, and nervous system form. At nine weeks post conception, toes, eyelids and major brain parts emerge. The structures that support the embryo are the amnion or amniotic sac, chorion consisting of chorionic villi, placenta also called the endometrium or afterbirth, and the umbilical cord or stalk, which is anchored to the uterus. Certain illnesses have critical effects upon the unborn fetus here. An example is rubella or german measles, for which people receive a childhood vaccine now.
Trimester 2: In these three months, the uterus enlarges, fetal heartbeat and movement can be detected via ultrasound.
Trimester 3: The fetus grows quickly and develops changes that facilitate its existence outside of the mother. At 8-9 months post-conception, the fetus is viable if born. At the end of pregnancy, prostaglandins initiate birth along with estrogen and oxytocin. Oxytocin stimulates breast milk production and uterine contraction (syntocin can be used to induce labor). At birth, the amniotic sac or “water” breaks, the baby is released head first through the cervix and vagina via a series of contractions, and the placenta or afterbirth follows. The mother’s mammary glands have already prepared to produce milk, and she starts lactating immediately upon baby beginning to suckle her breasts.

The Risks of Sex:

Humans have sex to fulfill a variety of emotional needs in addition to conceiving a baby. We share these behaviors with primates like bonobos, who have many “types” of sex with no intention of creating offspring, but instead to release emotional tension. Humans live more complicated lives, so precautions should be taken to prevent the transmission of Sexually Transmitted Diseases (see aud 734), also known as venereal diseases. They can be caused by bacteria, viruses, protists and arthropods, and they can be transmitted by the following forms of contact: penis to vagina (vaginal intercourse), mouth to penis (oral sex), penis to anus (anal sex). All of these activities are commonly expressed using a number of “colloquial”, sometimes vulgar, references, but you should know the proper simple verbal terms used to describe these acts, as it can enable you to communicate and gain extremely important information about sexual activity in a mature way as you grow.
Some examples of diseases:

Bacterial: Symptoms Treatment
Gonorrhea genitourinary pustular infection Antibiotics
Syphilis genital infectin advances to NS Antibiotics
Chlamydia inflammation of urethra Antibiotics

HIV/AIDS severe immunocompromise; die of sec. Infection None
Genital herpes genital blisters and cold sores Antiviral/no cure
Genital warts HPV is cause; lead to cervical cancer Antiviral/Vaccine

Trichomoniasis milky discharge at genitals Antibiotics

Crab lice pubic irritation and itching Antibiotics/hygeine

Most forms of contraception (see aud 737) are geared toward preventing pregnancy. The pill and Ortho Evra interfere with hormones thereby preventing ovulation, while IUD’S, sponges and diaphragms with spermicide interfere with the process of conception mechanically and/or chemically. The only barrier method currently available that interferes with both conception and STD transmission is the latex condom (for vaginal and anal sex) and/or dental dam (for oral sex). Their use is highly recommended for sexually active individuals who do not wish to conceive a child or to contract an STD. Aside from abstinence or celibacy, latex condoms are in fact the only truly effective HIV/AIDS & STD prevention method. Sadly, a broken condom is not at all effective, and only latex works, not porous materials like sheepskin. Most contraception does not protect against disease, only against pregnancy. HPV (human papilloma virus) is the leading cause of cervical cancer, even in monogamous relationships.

Other Topics: Drugs for arousal: This is for people who have difficulty achieving erection (commonly called ED or erectile dysfunction), usually due to groin injury or other malfunction. Drugs such as Viagra and Cialis should not be abused, and erections that go on indefinitely are dangerous! These drugs can cause hypertension and heart problems. Females entering menopause stop producing fertile eggs, at about age 50-60.

Ok if you ask me why me why did this.....i my reply would be because I was bored
well anyway i hope this can be useful to at least someone
61368 cr points
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25 / M / Canada
Posted 5/17/10
your forgetting MRNA and RNA. this is important because it ties into the whole mitosis meiosis. Remember you need then for your amino acids and ultimately for proteins
Kiki's Customer Support Service
100410 cr points
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F / Nova Scotia
Posted 5/17/10

Dear, god. Why on earth would you create this thread? @_@

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