COMPENDIUM REVIEWS & TABLE OF CONTENTS

Table Of Contents
Reproduction
Chapters 16 & 17
Compendium Review


I. Chromosomes, Cell Division, & Cell Cycle
A. The Cell Cycle
1. Interphase
B. The Chromosomes
1. Chromosomal Condensation
2. Chromatids & Chromosomes
C. Cell Division
1. Mitosis 4 phases
2. Cytokinesis

Cell division plays an important role in maintaining homeostasis and aids the body in repairing damaged tissues and organs. This division in cells is part of the cell’s life cycle of cell cycle. In consists of two parts; interphase and the cell division. During cell division the nucleus and cytoplasm divide and split the cell somewhat equally and this in turn makes two individual cells.
-Interphase is the period of time that displays intense metabolic activity between cell divisions and is divided into three phases; G1 (gap 1), S phase (synthesis phase), and G2 (gap 2).
G1 begins immediately and the cell carries on day-to-day activities. During this phase the cell makes RNA, proteins, and other molecules. S phase is where DNA replicates. After replication, each chromosome in the nucleus of the cell contains two chromatin fibers, or chromatids. The G2 phase is where the mitochondria divide and the precursors of the spindle fibers and the chromosomes begin to condense. This period of time is relatively inactive and is a shorter period of time.
-After interphase is when cell division begins. The cell replicates its organelles and molecules are needed by the two daughter cells. Nuclear division is commonly known as mitosis. Mitosis involves a series of dramatic structural changes in chromosomes. During this process the chromosomes becomes more compact structures clearly visible in ordinary light microscopic preparations.
-The human cell has 46 chromosomes or 23 pairs that contain all of the genetic information required to control cellular activity. Chromosomes are described as homogeneous. Homogeneous chromosomes contain genes that control the same inherited traits. Cells that contain the full number of chromosomes (46) are considered to be diploid (two fold) Germ cells (sperm and ovum) are called hapoid because they contain half the chromosomes of the somatic cells. Germ cells are produced by a special kind of cell division known as meiosis.
-Chromosomal condensation happens after replication and it facilitates mitosis usually during prophase. During this the cells begin to coil, compacting in much the same way that a stretched phone cord shortens and compacts when the tension is removed. While the chromosomes are in a condensed state they are inactive and unable to produce either DNA or RNA. Condensation allows chromosomal separation which makes it easier to study them. Chromosomes are arranged by size and other features form a karyotype. It is used to help geneticists count the chromosomes and to locate potential abnormalities. It is especially important to mothers-to-be because it allows for a process to be done called an amniocentesis. The is where the doctor will extract fluid that surrounds the baby through a needle that is inserted through the mother’s abdomen. This fluid contains the baby cells and they can be separated where they are then grown in cultures. They continue to divide and grow. After which a chemical substance is added and that aids in stopping the cell division. Then they are removed from the culture and placed on a glass slide, photographed and analyzed. Then with the help of computer software the chromosomes are arranged in pairs and then looked at to see if there are any obvious defects.
Here are some helpful terminology when talking about chromosomes.
*chromatin is a strand of DNA and associated histones (globular proteins).
*chromatin fibers are strands of chromatin.
*chromosomes consists of one or two chromatin fibers.
*chromatid is one of the chromatin fibers of a replicated chromosome
*centromere is a region of each chromatid to which a sister chromosome is attached.
-The number of chromatids in chromosomes varies depending on the stage of the cell cycle. Each chromosome is made of two chromatids that are held together at the centromere.
-Mitosis is divided into four stages called prophase, metaphase, anaphase, and telophase.
-Prophase begins just after interphase and the replicated chromosomes condense. The nucleoli are regions of active rRNA synthesis. In the cytoplasm, the cell’s centrioles separate. The mitotic spindle forms. The mitotic spindle is an elaborate array of microtubules. It is also responsible for the movement of the chromosomes. Late in prophase the nuclear envelope begins to break down. This permit’s the chromosomal fibers of the mitotic spindle to attach to the chromosomes, setting the stage for the next step, metaphase.
-Before chromosomes can be divided equally, they are lined up in the center of the cell with their centromeres located along the equatorial plane. This aids in the separation of chromatids.
-Anaphase is when the chromatids of each chromosome begin to separate. The chromatids of the homologous chromosomes are drawn toward opposite poles of the mitotic spindle.
-The final stage of cell division is called telophase. This is when the chromosomes complete their migration to the poles. This stage involved a series of changes in the nuclei that are basically the exact opposite of prophase. During telophase, membranes form around the chromosomes of each new (daughter) cell. This phase ends when the nuclei of the daughter cells appear to be in interphase.
-Cytokinesis is the division of the cytoplasm. This is possible by the contraction of the microfilaments beneath the cell membrane. This usually happens in the latter part of anaphase or early in telophase.
-Many factors appear to be a part of the cell cycle from hormones to growth-promoting and growth inhibiting factors. These factors may act directly on the cytoplasm but more likely stimulate changes in the genes in the nucleus that regulate the cell cycle.

Table of Contents

II. Principles of the Human Heredity
A. Meiosis & Gamete Formation
1. Meiosis I
2. Meiosis II
3. Gamete Production
B. Principles of Heredity
1. Blending of Traits
2. Principles of Segregation
3. Dominant and Recessive Genes
4. Principle of Independent Assortment
C. Mendelian Genetics in Humans
1. Autosomoal-Recessive Traits
2. Autosomal-Dominant Traits
D. Variations in Mendelian Genetics
1. Incomplete Dominance
2. Multiple Alleles
3. Polygenic Inheritance
4. Crossing Over
5. Human Genome Project
E. Sex-Linked Genes
1. Sex-Influenced Genes
F. Chromosomal Abnormalities & genetic Counseling
1. Defects in Chromosomal Structure
2. Genetic Screening

During gamete formation, germ cells, undergo a special kind of division called meiosis, which reduces the number of chromosomes in half.
-Meiosis I has the same four steps as mitosis; prophase, metaphase, anaphase, and telophase.
During prohase I, the chromosomes condese and the homogeneous chromosomes pair up.
During metaphase I homogeneous pairs line up in the equatorial plate.
During anaphase I the pairs separate with one member of the pair each going to each daughter cell. Each daughter cell ends up with half the number of chromosomes (23) of parent cells (46) Each chromosome contains two chromatids and since the chromosomes decrease in half while going through this process it is called reduction division.
-Mitosis II is like mitosis in many ways and this is the second cell division. The cells start out as haploid. The chromosomes of haploid cells condense during prophase II. Chromosomes disassociate during anaphase II and go to each pole.
-Gamete production in males meiosis produces four gametes, in females it produces only one. The diploid cell in the gamete-producing organ, the testis gives rise to four sperm cells. The single diploid cell gives rise to only one gamete the egg or the ovum.
-Much of the work in the early knowledge on heredity came from the work of Gregor Mendel.
-Blending of traits was first discovered by Mendel. When the traits he studied did not blend.
-When talking about the principles of segregation the parents contribute equally to the characteristics of their offspring. The gametes of the parents combine to produce an offspring and because each gamete contains one hereditary factor for each trait. Mendel also concluded that the contributions of the parents are equal.
-Mendel also figured out that either plants are recessive or dominant. A recessive factor is expressed only when the dominant factor is missing. An alternative form of the same gene is called an allele.
-Independent assortment principles say that genes on different chromosomes segregate independently during gamete formation.
-Autosomal-recessive traits are expressed only when both the alleles are recessive. Sex chromosomes are needed in determining the sex of the baby to be born.
-Albinism is one of the most common genetic defects known to science. Melanin is the brown pigment responsible in the coloration of the eyes, skin, and hair. The skin in an albino is pale and the hair is white. It is easier for the skin to be sunburned.
-Cystic fibrosis is an autonomic-recessive disease that leads to early death. Over time the pancreas begin to degenerate and fibrosis tissue replaces glandular tissue. The respiratory system of victims of cystic fibrosis produce copious amounts of mucus. It is also one of the most common genetic diseases.
-Autosomal-dominant traits are present in every one of us.
Incomplete dominance results in a kind of blending of traits. Incomplete dominance occurs in many human disorders and one being sickle cell disease. This disease effects the blood and affects mostly African Americans. By having this disease it does make them immune to the HIV virus. Which I think it very interesting.
-Some genes have multiple alleles. There are four possible blood types; A, B, AB, & O.
-Some traits are determined by more then one gene pair. Skin color is controlled by as many as 8 genes. This type of inheritance is called polygenic inheritance. It is also responsible for height, weight, intelligence, and many behavioral traits.
-Crossing over is a genetic swapping that occurs in meiosis. Those genes that are located on the same chromosome tend to be inherited together and are said to be linked. Crossing-over can occur anywhere along the length of the chromosome.
-Human genome project I find very interesting. It seeks to determine the sequence of bases in human DNA and the location of all of the genes. It started in 1991.
-Sex linked genes can determine baldness and women carry the gene that dominants in supplying that gene.
-Abnormal chromosome numbers generally result from a failure of chromosomes to separate during gamete production.
-One of the most common triomies is down syndrome. One out of every 700 babies born in the US has down syndrome.
-Nondisjunction of sex chromosomes can occur in both autosomes and sex chromosomes. Klinefelter syndrome occurs when an ovum with an extra X chromosome is fertilized by a y bearing sperm resulting in a XXY genotype.
-Genetic disorders may also result from variations in chromosome structure. Deletions which are a loss of a piece of chromosome. Translocations which is breakage and reattachment somewhere else.
-Genetic screening allows parents to determine whether they will have a genetically normal baby. Amniocentesis is usually recommended only if one or more of the following conditions are met
1) a woman that is over 25
2) she has already delivered a baby with a genetic defect
3) she is a carrier of an X-linked genetic disorder
4) she or the father has a known chromosomal or genetic abnormality

Human Development & Aging
Chpt 22

Table of Contents

I. Fertilization
1. Passage of female reproductive tract
Sperm mobility and penetration
2. Zygote formation
II. Pre-embryonic development
1. Implantation
2. Ectopic pregnancy
3. Placental hormones
4. Amnion
III. Embryonic Development
IV. Fetal development
1. Fetal Circulatory
V. Birth Defects
VI. Child Birth and Lactation
1. Stages of birth
2. Lactation
VII. Aging and Death
1. Decline of cell numbers and functions
2. Death

-The sperm and the egg of humans unite during fertilization. This usually takes place in the upper third of the uterine tube. Sperm is deposited in the vagina and it reaches the site of fertilization by swimming. Muscle contractions also aids in the wall of the uterine tube and uterus and it pushes the sperm on its way.
Sperm dissolve away the cells surrounding the oocyte and then they bore through the zona pellucida and the contact the plasma membrane. The first one to contact the membrane fertilizes the oocyte. Further sperm penetration is blocked. The chromosomes of the sperm and oocyte duplicate and merge in the center of the cell, where mitosis begins.
Human development is divided into three stages: pre-embryonic, embryonic, and fetal.
-During pre-embryonic development the zygote undergoes rapid cellular division forming a morula. The morula is then converted into a blastula, a structure with a hollow cavity, called a blastocyst in humans. The blastcyst consists of a clump of cells. The inner cell mass (ICM) becomes and embryo and the trophoblast gives rise to the embryonic portion of the placenta.
While the placenta is forming a layer of cells form the ICM of the blast cyst separates from it and forms an amnion. The amnion fills with fluid and enlarges during embryonic and fetal development, eventually surrounding the entire embryo and fetus protecting them during development.
-The ICM separates into three germ cell layers; ectoderm, mesoderm, and endoderm. The formation of the three primary germ layers marks the beginning of the embryonic development. The organs develop from these three primary tissues during organogenesis.
-Fetal development begins at 8 weeks after fertilization and is primarily a period of fetal growth because most of the organ systems have developed or are under development.
The placenta produces several hormones that play an important role in reproduction. HCG maintains the corpus luteum during pregnancy. Progesterone and estrogen stimulate uterine growth and the development of the glands and the ducts of the breasts. The placenta delivers oxygen and nutrients to the fetal blood nd removes waste products from it.
-The fetal circulatory system is very much like th adult circulatory system, except that it contains three pathways that allow blood to bypass the lungs and liver, which are developing but not functioning. At birth these bypasses close up and the adult pattern of circulation develops.
-Birth defects arise from chemical, biological, and physical agents. The effects of these agents is related to the time of exposure, the nature of the agent, and the dose. A defect is most likely to arise if a woman is exposed during an embryonic period when the organs are forming.
-Labor consists of intense and frequent uterine contractions believed to be caused by the release of small amounts of fetal oxytocin prior to birth. Fetal oxytocin stimulates the release of prostaglandins by the placenta. Oxytocin and prostaglandins stimulate contractions in the sensitized uterine musculature.
-Maternal osytocin is also released, augmenting muscle contractions. As uterine contractions increase, they cause more maternal oxytocin to be released, which stimulates stronger contractions and more oxytocin release, a positive feedback that continues until the baby is born. Labor consists of dilation, expulsion, and placental stages. The breast consist primarily of fat and connective tissue interspersed with milk-producing glandular tissue and ducts. During pregnancy, the glands and ducts proliferate under the influence of placental and ovarian estrogen and progesterone.
-Milk production is induced by maternal prolactin. Before milk begins, the breast produce a small quantities of a protein-rich fluid called colostrum. The baby usually consumes the fluid and it enriches their bodies as well as aiding in building up their immune system.
-Aging is a progressive deterioration of the body’s homeostatic abilities and the gradual deterioration of the function of the body’s organs. These changes result in at least two of the factors; a decrease in the number of cells in the organs and a decline in the function of existing cells. Death is the result.

Human Evolution
Chpt 23
Compendium review
I. The Evolution of Life
1. Chemical evolution
2. First cells and Eukaryotes
II. How Evolution Works
1. Natural Selection, Genetic Variation
III. Evidence Supporting Evolution
1. Fossils
2. Biochemical Similarities
IV. Early primate Evolution
V. Evolution of Australopithecines
VI. Evolution of Genes Homo
1. Human races

Scientists believe that the Earth and the sun and the rest of the system came from and enormous cloud of cosmic dust and gas that gave rise to the Earth and the sun. The Earth formed about 4.5 billion years ago.
-The evolution of life probably began in the sea and is divided into 3 phases: chemical evolution, cellular evolution, and the evolution of the multicultural organisms.
-Chemical evolutions scientists think that about 4 billion years ago. Simple inorganic chemicals that were dissolved in the seas combined to form small organic molecules. Over time, the organic molecules combine to form polymers, small proteins and nucleic acids. These polymers combined to from aggregates that may have been the precursors of cells.
-The first few cells arose from the primitive aggregates. They contained primitive enzymes and simple genes and may have derived nourishment from organic molecules they absorbed from the environment.
-Over time scientists believed that photosynthesis envolved further and the new photosynthetic organisms began to produce oxygen.
-Prokaryotes emerged in about 3.5 billion years ago. Eukaryotes evolved about 1.2 billion years ago. The evolution of the eukaryotes opened the door for the evolution of multicultural organisms.
-A variety of multicultural plants and animals evolved from the single celled eukaryotes in the oceans. The ozone layer developed and life on land became possible.
-Evolution has produced a great diversity of organisms. Evolution takes place because of the genetic variation and natural selection. Genetic variation in a species arises from many factors such as mutations and from new genetic combinations resulting from sexual reproduction. Genetic variations in traits that may offer some organisms an advantage over others, giving them a better chance of surviving, reproducing, and passing the genes on to future generations. Beneficial traits are preserved in a population by natural selection.
-The scientific knowledge in support of evolution is rich and varied. The fossil record, anatomical similarities in groups of organisms, the common biochemical makeup of organisms, similar embryological development among many groups of organisms. The experimental evidence all support the theory of evolution by natural selection.
-When talking about early primate evolution humans belong to this order. Primates are characterized by grasping hands, forward-looking eyes and large brains.
*Timeline*
Based on fossil evidence it appears that the primates evolved from a mammalian insectivore that resembled the modern-day tree shrew and lived about 80 million years ago. They think that humans evolved from early apelike creatures.
-The first human primate belonged to the genus Australopithecus. The oldest known skeleton was unearthed in Africa 3.5 million years old. It belongs to the group Australopithecus afarensis. It stood about 3 ft tall and its brain was just slightly bigger then an ape’s but they were thinking that it probably walked erect.
-3 million years ago A. afarensis was replaced by other species A. africanus which was slightly taller and it had even a bigger brain.
-2.3 million years ago A. robustus emerged. It was taller and heavier and had an even larger brain.
-2.2 million years ago the forth species emerged and it was called A. boisei.
-Many paleontologists believe that A. afarensis also gave rise to the genus Homo, and ancestors of the modern humans. Homo sapiens. Some people still think that it might had emerged from another ancestor all together. The earliest discovery of a human skull was 1.8 million years ago in Tanzania. It belonged to the homo habilis.
-200,000 years ago after the emergence of homo habilis the homo erectus arose. Homo erectus unlike it predecessors that remained in Africa these guys moved to Europe and Asia. They stood about 5 ft tall and used fire and many different kinds of tools but their brains smaller than ours and we are believed to have some from them directly.
-Homo sapiens emerged about 300,000 years ago and consisted of two subspecies: homo sapiens neanderthalensis and homo sapiens sapiens.
-The Neanderthals lived in caves and camps in Europe and Asia approximately 40,000 years ago. Some archaeologists believe that they were replaced by modern humans, the CroMagnons and earliest members of the homo sapiens sapiens. The Cro-magnons first appeared in Africa and then spread across Europe and Northern Asia and wiped out the Neanderthals or maybe even copulating with them.
-Other the course of many years, the human population moved and went far and wide. They inhabited many climate changes and became very good at adapting and overcoming the various complications that arose. With these travels the formation of different cultures began to form. Many adaptations that make up the different races are thought ot have happened due to the races and different population groups adapting to the environment.

Table of Contents
Ecology & the Environment
Chpt 24

I. Introduction to the Ecosystems
1. Biosphere
2. Biomes & Aquatic Life Zones
II. Ecosystem Function
1. Producers & Food Chains
2. Energy & Nutrient Flows
3. Trophic Levels
4. Nutrient Cycles
III. Overshooting the Earth’s Carrying Capacity
1. Polution
2. Resources
IV. Overpopulation: Problems and Solutions
V. Resource Depletion
1. Forest, Soil, & Water
VI. Pollution
1. Global Warming and its Impacts
2. Ozone layer

Humans survival is dependent on the resources that surround us today. It is vital to keep these resources available and not to exhaust them otherwise we could face extinction ourselves. Ecology is the study of ecosystems. It is the examination of organisms and their environment and many of the interactions between them. The living skin of the planet is called the biosphere. It goes from the bottoms of the oceans to the tippy top of the highest mountains. The only thing that is necessary for this process to take place is the addition of sunlight. Too much sun and heat can be detrimental to plants and animals as well as not enough sun. It is a proper balance between the environment and the dependency of sunlight.
-The biosphere is a closed system in which materials are recycled over and over again. I have heard this referred to as the circle of life. The Earth;s surface is divided into large biomes eah with a characteristic climate and characteristic to plant and animal life. The ocean is referred to as a biological region known as the aquatic life zones.
-The ecosystem consists of a community of organisms, its environments, and their interactions.A group of organisms with the same species living in a specific region constitutes a population. If you have two or more populations occupying a region it is called a community. The area that a species being human or animal is called a habitat. A Species’ niche is made up of its habitat and where they are on the ladder of the food chain.
-Virtually all life on Earth depends on plants and other producers, organisms that synthesize organic materials from sunlight, carry carbon dioxide, and water via photosynthesis. Organisms depending on producers for food are called consumers. Four types of consumers are present and they are herbivores, carnivores, omnivores, and detrivores.
-When talking about the food chain we are all a part of it.
The food chains begin at plants that are consumed by grazers (herbivores) and this is called the grazer food chain. Those that feed off of dead organisms or wastes are a part of the decomposer food chain. The position where an organism is located on the food chain is called the trophic level.
Nutrients are necessary for life growth and for life to flow through the nutrient cycles.
-The term secession refers to a series of changes in the ecosystem in which one community replaces another until a mature ecosystem is produced. Primary succession is where a community previously existed. Secondary succession occurs where a community was destroyed by natural or human events. I thought of Pompay.
-Although environmental problems vary from one nation to another they are all the result of human populations exceeding the carrying capacity of the environment. Carrying capacity is the number of organisms an ecosystem can support indefinitely and is determined by food and resource supplies and by the capacity of the environment to assimilate or destroy waste products of organisms.
Overpopulation occurs anytime a population exceeds it carrying capacity. This can be by looking at the food ratios available lack of resources, and excessive pollution. It can be all three or even one of the three that could be harmful.
-When talking huge numbers of population growth I think of Africa, Asia and Latin America. Resource shortages and food depletion are the main concerns or problems in this area. Many experts believe that industrialized areas are overpopulated . I thought of New York when immigrants were flooding the area and there were extreme pollutants and sickness due to the inhumane ways of discarding wastes and such. It was industrial and it suffered.
-Human population can be sumed up in 6 words; too many people, reproducing too rapidly, which results in resource shortages, excessive pollution, and poverty.
Resource depletion is a huge problem and concern. Humans use renewable and nonrenewable resources and all of which are depleting. Forest are being cut down faster then they can be replaced. That is why bamboo is a great option for building and such because it grows at a rapid rate. There are many things we can do to help in the environmental problems… GO green! Recycle, plant trees, soil conservation, population control, and drive energy efficient cars but there are many other stategies that need to be implemented in order for it to work or help! The soils are being eroded from rangeland and farmland. The effects of this will be food production later down the road. Many areas in the world suffer from water shortages. With the rise in population this will get far worse before it gets better. I saw on the news the other day about huge sin holes that were evident because of the underground streams being used and causing the ground to give out.
-Oil supplies are also finite. Global oil is expected to peak between the years of 2004 and 2010. Production may not be able to meet demand. An alternative to this catastrophy would be to use renewable fuels, and a sustainable energy supply.
-Pollution from human activities is overwhelming and it has a huge strain on the nutrient cycles and assisting is destroying homeostasis. One of the most serious threats of pollution is carbon dioxide. Carbon dioxide is a greenhouse gas that traps heat in the Earth's atmosphere. This increases the planet's surface temperature, altering this climate, shifting the rainfall patterns and agricultural zones, flooding low lying regions and destroying many species that cannot adapt to the sudden change in temperature. To slow the effects of global warming scientists recommend massive reforestation projects and dramatic improvements in the efficiency of the fossil-fuel combustion and development of alternative fuels. There are two gases that are the gaseous pollutants ans they are sulfur dioxide and nitrogent dioxide and they are released from power plants, factories, automobiles, and other sources.
-The ozone layer encircles the Earth, trapping unltraviolet light. It is being destroyed by CFC's and other pollutants.