biology exam review

Identify different types of stem cells.

*Totipotent stem cells can grow into any other cell type. Only a fertilized egg and the cells produced by the first few divisions of an embryo are totipotent. • Pluripotent stem cells can grow into any cell type except for totipotent stem cells. • Multipotent stem cells can grow only into cells of a closely related cell family.

Differentiate between body cells and gametes.

- Body cells makeup organs and tissue and DNA of body cell can not be passed on to offspring. - Gametes are sex cells which are egg and sperm and DNA of gamete can be passed on to offspring

Identify factors that limit cell size.

- If cells were too small, they could not contain all of the necessary organelles and molecules. - Cells cannot grow beyond a certain size, even if surrounded by plenty of nutrients.The upper limit on cell size is due to the ratio of cell surface area to volume. - But as a cell increases in size, its volume increases faster than its surface area - further increase in size could result in a surface area too small for the adequate exchange of materials. - Some cells, however, must be large. A neuron running down a giraffe's neck to its legs may be several meters long, for instance. It is extremely long and thin. This structure gives the neuron a large surface area with a relatively small increase in volume. - Cell become too big than original size the next generation would be too big to live - Cell become too small than original size the next generation would be too small to live

Identify the three kinds of RNA and their functions.

- Messenger RNA (mRNA) is an intermediate message that is translated to form a protein. - Ribosomal RNA (rRNA) forms part of ribosomes, a cell's protein factories. - Transfer RNA (tRNA) brings amino acids from the cytoplasm to a ribosome to help make the growing protein.

Describe how natural selection acts on the distribution of traits in a population.

- When the frequency is highest near the mean value (middle) and decreases towards each extreme, it is called a Normal Distribution. The graphed result is a bell-shaped curve. - Directional selection favors phenotypes at one extreme. - Stabilizing selection favors the intermediate phenotype. - This chart may change over time due to the phenotype that best suits the environment.

Examine early ideas about evolution.

- animals arouse independently - the Earth is 6000 years old - proposed all loving things came from a common ancestor - proposed all organisms evolved toward perfection and complexity - species didn't become extinct: evolved into different species - environment caused organisms behavior to change

Summarize different types of evidence that support evolution.

- fossils - geography: different plants, animals, and predators - embryology: similarities in larvae - anatomy: homologous and analogous structures - vestigial structures homologous: same structure, different purpose analogous: same purpose, different structures

Describe how Darwin arrived at his idea about species variation.

- observed differences of species on the Galápagos Islands - led to the idea of adaptation - found fossil evidence - found fossils high up in the Andes Mts. ~ explained that land had previously been underwater

Examine the factors Darwin considered in forming his theory of natural selection.

- realized breeds aren't produced perfectly at once - knee it took many generations - struggle for survival: resources were natural limits to populations - variation seen in populations

Summarize Mendel's law of segregation.

-organisms inherit two copies of each gene, one from each parent -organisms donate only one copy of each gene in their gametes. Thus, the two copies of each gene segregate, or separate, during gamete formation.

Summarize the process of DNA replication.

1) Enzymes begin to unzip the double helix at numerous places along the chromosome, called origins of replication. That is, the hydrogen bonds connecting base pairs are broken, the original molecule separates, and the bases on each strand are exposed. Like unzipping a suitcase, the process of unzipping DNA proceeds in two directions at the same time. 2) One by one, free nucleotides pair with the bases exposed as the template strands unzip. DNA polymerases bond the nucleotides together and form new strands complementary to each template. On one template, DNA replication occurs in a smooth, continuous way in one direction. This continuous strand is called the leading strand. On the other template, replication occurs in a discontinuous, piece-by-piece way in the opposite direction. Replication of this strand, known as the lagging strand, is not shown or described in detail here. 3) Two identical molecules of DNA result, each with one strand from the original molecule and one new strand. As a result, DNA replication is called semiconservative because one old strand is conserved, and one new strand is made

Outline the three -step PCR process.

1) Separating The container with all of the reactants is heated to separate the double-stranded DNA into single strands. 2) Binding The container is cooled and the primers bind to their complementary DNA sequences. One primer binds to each DNA strand. The primers bind on opposite ends of the DNA segment being copied. 3) Copying The container is heated again and the polymerases begin to build new strands of DNA. Added nucleotides bind to the original DNA strands by complementary base pairing. The polymerases continue attaching nucleotides until the entire DNA segment has been copied.

Describe three types of symbiosis.

1) mutualism (both benefit) 2) commensalism ( one benefits one remains neutral) 3) paratism (one benefits one is harmed)

Summarize the levels of organization that ecologists study.

1) organism- is an individual living thing, such as an alligator 2) population- is a group of the same species that lives in one area, such as all the alligators live in a swamp 3) community- a group of various species that live in the same habitat and interact with each other such as alligator, turtles, birds, fish, and plants that live together in the Florida Everglades. 4) ecosystem- a community of organisms and their abiotic environment. Includes living and nonliving things in a given area. Ecosystem varies in size. an entire ecosystem may live within a decaying log which in turn may be part of a larger wetland ecosystem. 5) biome- is a major regional or global community of organism. DEF- is a large region characterized by a specific type of climate and certain types of plant and animal communities that thrive there.

Identify several methods for mapping human chromosomes.

1) pedigrees - help traces the phenotypes and genotypes in a family to determine whether people carry recessive alleles. 2) karyotypes -too many chromosomes -loss of part of a chromosome -scientists use them to estimate the distances between genes on a chromosome -can help show the possible location of a gene on a chromosome.

Describe how populations can become isolated.

1. Behavioral barriers (songs, dances)- includes differences in courtship or mating behaviors 2. Geographic isolation- isolation between populations due to physical barriers divide a population into two or more groups. 3. Reproductive isolation- a state in which a particular set of populations can no longer interbreed to produce future generations of offspring 4. Temporal isolation- isolation between populations due to barriers related to time, such as differences in mating periods or differences in the time of day that individuals are most active

Summarize the experiments of Hershey and Chase that confirmed DNA as the genetic material.

• Experiment 1 In the first experiment, bacteria were infected with phages that had radioactive sulfur atoms in their protein molecules. Hershey and Chase then used an ordinary kitchen blender to separate the bacteria from the parts of the phages that remained outside the bacteria. When they examined the bacteria, they found no significant radioactivity. • Experiment 2 Next, Hershey and Chase repeated the procedure with phages that had DNA tagged with radioactive phosphorus. This time, radioactivity was clearly present inside the bacteria. - From their results, Hershey and Chase concluded that the phages' DNA had entered the bacteria, but the protein had not. Their findings finally convinced scientists that the genetic material is DNA and not protein.

Explain how gene flow, genetic drift, and sexual selection can lead to the evolution of populations.

• Genetic drift Allele frequencies can change due to chance alone. • Gene flow The movement of alleles from one population to another changes the allele frequencies in each population. • Sexual selection Certain traits may improve mating success. Alleles for these traits increase in frequency.

Explain how Avery identified DNA as the transforming principle.

• Griffith experimented with the bacteria that cause pneumonia. • He used two forms: the "S" form (deadly) and the "R" form (not deadly). • A transforming material passed from dead S bacteria to live R bacteria, making them deadly. - Qualitative tests showed DNA was present. - Chemical tests showed the chemical makeup matched that of DNA. - Enzyme tests showed only DNA-degrading enzymes stopped the transformation.

Identify the conditions that define Hardy -Weinberg equilibrium.

• Very large population No genetic drift can occur. • No emigration or immigration No gene flow can occur. • No mutations No new alleles can be added to the gene pool. • Random mating No sexual selection can occur. • No natural selection All traits must equally aid in survival.

Explain three ways natural selection can change the distribution of a trait in a population.

•stabilizing selection-a type of natural selection in which the average form of a trait is favored and becomes more common. occurs when intermediate phenotypes are favored by natural selection. •directional selection- a natural selection process in which one genetic variation is selected and that causes a change in the overall genetic composition of the population. occurs when one extreme is favored by natural selection •disruptive selection- a type of natural selection in which two extreme forms of a trait are selected. When both extremes are favored by natural selection.

Explain how heredity can be illustrated mathematically.

◊ Describe how geneticists use Punnett squares. -a graphic used to predict the results of a genetic cross ◊ Explain how geneticists use the principles of probability. Probability =number of ways a specific event can occur / number of total possible outcomes ◊ Explain the principle of independent assortment. -the random distribution of the pairs of genes on different chromosomes to the gametes

Describe how sexual reproduction creates unique gene combinations.

1. The independent assortment of chromosomes during meiosis - homologous chromosomes pair up randomly along the cell equator during meiosis 1, it's a matter of chance which of the two chromosomes from any homologous pair ends up in a given gamete. 6 2. the random fertilization of gametes - 70 posibilities

Describe three basic types of survivorship curves in relation to reproductive strategies.

1. Type I Curve - Shows a life history common in large mammals, including humans. There is a low level of infant mortality and they survive longer. 2. Type II Curve - Organisms such as birds, small mammals, and some reptiles show a survivorship rate that is roughly equal at all ages of an organism's life. At all times they have an equal chance of dying. 3. Type III Curve - Organisms with type III survivorship have a very high birth rate and also a very high infant mortality rate. These are typically reptiles, amphibians and plants.

Identify three geological theories that influenced scientific debate over evolution.

1. catastrophism: natural disasters caused mass extinctions and formed all landforms 2. gradualism: changes on Earth occurred by small steps over long periods of time 3. uniformitarianism: the geological processes that shape Earth are uniform through time

Summarize the four principles of natural selection.

1. variation: heritable differences in populations result in different genetic material of the organism 2. overproduction: raises chance of survival and competition between offspring for resources 3. adaptation: variations that allow individuals to survive better in an environment 4. descent with modification: more individuals will have a favorable adaptation in every following generation

Trace the flow of energy through an ecosystem, using an energy pyramid.

10% RULE - 90% lost & 10% passed on to next tropic level

Describe how organisms are cloned.

Bacteria is cloned by binary fission, plants are cloned by their roots, simple animals, such as sea stars, can essentially clone themselves through a process called regeneration, and animals are cloned by nuclear transfer. First, an unfertilized egg is taken from an animal, and the egg's nucleus is removed. Then the nucleus of a cell from the animal to be cloned is implanted into the egg. The egg is stimulated and, if the procedure is successful, the egg will begin dividing. After the embryo grows for a few days, it is transplanted into a female.

Summarize how restriction enzymes cut DNA

Bacterial cells can be infected by viruses. As protection against these invaders, bacteria produce enzymes that cut up the DNA of the viruses. DNA molecule can be cut apart in several places at once by several molecules of a restriction enzyme, or endonuclease. Restriction enzymes cut DNA into smaller fragments, which are always made at specific nucleotide sequences. straight cuts leave blunt ends. Staggered cuts leave sticky ends.

Identify how technology helps compare and study genes and proteins.

Bioinformatics gives scientists a way to store, share, and find data. DNA microarrays are tools that allow scientists to study many genes, and their expression, at once. DNA microarrays can compare gene expression in cancer cells with gene expression in healthy cells. Proteomics allows scientists to learn about proteins involved in human diseases.

Compare and contrast a biomass pyramid and a pyramid of numbers.

Biomass pyramid- total dry mass of all organisms in a given area Number = the amount of living organisms in each trophic level (can be inverted)

Identify biotic and abiotic factors in an ecosystem.

Biotic factors- an environmental factor that is associated with or results from the activities of living organisms. (producer and autotroph, consumer and heterotroph, decomposer and detrivoies.) abiotic factors-an environmental factor that is not associated with the activities of living organisms. (rain, wind, pH, soil type, and sunlight)

Describe the interactions of biotic and abiotic factors in the biosphere.

Biotic factors- an environmental factor that is associated with or results from the activities of living organisms. (producer and autotroph, consumer and heterotroph, decomposer and detrivoies.) abiotic factors-an environmental factor that is not associated with the activities of living organisms. (rain, wind, pH, soil type, and sunlight)

Describe four factors that affect population size.

Birth, deaths, immigration, and emigration

Explain cancer in terms of the cell cycle.

Cancer cells come from normal cells that have suffered damage to the genes that help make proteins involved in cell-cycle regulation. Most cancer cells carry mutations, or errors, in two types of genes. One type, called oncogenes, accelerate the cell cycle. The second type act as cell-cycle brakes

Describe different types and rates of evolution.

Coevolution- the evolution of two or more species that is due to mutual influence, often in a way that makes the relationship more mutually beneficial divergent evolution- evolution of one or more closely related species into different species; resulting from adaptations to different environmental conditions convergent evolution- the process by which unrelated species become more similar as they adapt to the same kind of environment

Describe the structure of a chromosome.

DNA double helix-Each continuous,double-stranded DNA molecule makes one chromosome. DNA and histones- DNA wraps at regular intervals around proteins called histones,forming chromatin Chromatin- Interactions between parts of the histones further compact the DNA. Supercoiled DNA- The chromatin coils more and more tightly around organizing proteins. chromatid- One half of a duplicated chromosome Sister chromatids are held together at the centromere, a region of the condensed chromosome that looks pinched the ends of DNA molecules form structures called telomeres, which are made of repeating nucleotides that do not form genes.

Summarize how DNA fingerprints are used for identification.

DNA fingerprints are very uncommon to be identical, and you can easily assess who a person is by their DNA. Usually, DNA fingerprinting compares at least five regions of the genome. That way it is more certain that the pattern of DNA fragments in the fingerprint is unique. The more regions of DNA that are studied, the less likely it becomes that another person would have the same DNA fingerprint.

Describe the three -dimensional structure of DNA.

DNA is double helixal structure, made up of the monomer nucleotides linked together. Each nucleotide is composed of a backbone made of a phosphate group and sugar, and is ended by a nitrogenous base (A, T, G or C). The nitrogenous bases connect in the middle of the DNA, connecting the two strands making up DNA's double helix.

Describe the role of polymerases in copying DNA segments.

DNA polymerase further attaches the missing nucleotides in order to create a new, complete DNA molecule. Polymerase chain reaction (PCR) is a technique that produces millions—or even billions—of copies of a specific DNA sequence in just a few hours. As the name indicates, the DNA polymerase enzymes that help copy DNA play key roles in this process. DNA replication that occurs in every living cell into a method for copying DNA in a test tube. Under the right set of conditions, DNA polymerases copy DNA in a test tube just as they do inside cells. However, in cells several other enzymes are needed before the polymerases can do their job. Before a cell can begin to copy its DNA, enzymes called helicases unwind and separate DNA molecules. Instead of using these enzymes, he used bacterium with high temprature levels.

Follow chromosomes through the processes of mitosis and cytokinesis.

During prophase, chromatin condenses into tightly coiled chromosomes.Each consists of two identical sister chromatids. The nuclear envelope breaks down, the nucleolus disappears, and the centrosomes and centrioles begin to migrate to opposite sides of the cell. Organized microtubules called spindle fibers grow from the centrioles and radiate toward the center of the cell. In metaphase, the spindle fibers attach to a protein structure on the centromere of each chromosome and align the chromosomes along the cell equator, around the middle of the cell. During anaphase, sister chromatids separate from each other. The spindle fibers begin to shorten, pulling the sister chromatids away from each other and toward opposite sides of the cell. In telophase, a complete set of identical chromosomes is positioned at each pole of the cell. The nuclear membranes start to form, the chromosomes begin to uncoil, and the spindle fibers fall apart. Cytokinesis divides cytoplasm between two daughter cells, each with a genetically identical nucleus. The cells enter interphase and begin the cycle again. for animals it forms inwards which for plants it can't do that due to the cell wall so a cell wall is made.

Analyze feeding relationships in a food web.

Energy is stored within an organism and some energy is dissipated into the environment; It depends on the presence of producers as they form the base of the food web; Has multiple feeding relationships

Relate energy pyramids to food chains and trophic levels.

Energy pyramids show how from one organism to the next energy is lost (and each trophic level)

Describe the role of enzymes in DNA replication.

Enzymes help to unzip the original DNA into two strands. They also make up the DNA polymerase, which attach free-floating nucleotides to corresponding ones on the strands of DNA. They also check to make sure that nucleotides were attached to their corresponding parts.

Identify internal and external factors that regulate cell division.

External factors that help regulate the cell cycle include physical and chemical signals. One example of a physical signal is cell-to-cell contact. Example once a cell enters culture and touches another cell it stops dividing. Many cells also release chemical signals that tell other cells to grow. For Example, growth factors are a broad group of proteins that stimulate cell division. Growth factors bind to receptors that activate specific genes to trigger cell growth. In general, cells grow and divide in response to a combination of different growth factors, not just one. Internal factors involved in the eukaryotic cell cycle are kinases and cyclins. A kinase is an enzyme that, when activated, transfers a phosphate group from one molecule to a specific target molecule. This action typically increases the energy of the target molecule or changes its shape. Your cells have many types of kinases, and they are almost always present in the cell. Those kinases that help control the cell cycle are activated by cyclins. Cyclins are a group of proteins that are rapidly made and destroyed at certain points in the cell cycle.These two factors help a cell advance to different stages of the cell cycle when cells bind to each other

Describe the relationship between RNA and DNA.

First DNA copies itself in replication, then transcription converts a DNA message into RNA, finally, translation interprets RNA and makes polypeptide bond which can lonely or combining form protein.

Explain how new genes can be added to an organism's DNA.

First, a restriction enzyme is used to cut out the desired gene from a strand of DNA. Then plasmids are cut with the same enzyme. The plasmid opens, and when the gene is added to the plasmid, their complementary sticky ends are bonded together by a process called ligation. The resulting plasmid contains recombinant DNA.

Describe the patterns of inheritance that Mendel's data revealed.

Found genes are passed on from generation to generation. Ex. Noticed F1 generation had all purple flowers. F2 generation purple and white. Recessive traits were hidden or skipped generations.

Describe how haploid cells develop into mature gametes.

Gametogensis-process by which gametes are produced through the combination of meiosis and other maturational changes. gametogenesis includes both meiosis and other changes that produce a mature cell. The final stages of gametogenesis differ between the sexes.

Describe how gene therapy research seeks to replace faulty genes.

Gene therapy replaces defective genes, missing genes, or adds new genes to treat a disease. first get the new gene into the correct cells of a patient's body. Once in the body, the gene has to become a part of the cells' DNA. One method of gene therapy that scientists have tried is to take a sample of bone marrow stem cells and "infect" them with a virus that has been genetically engineered with the new gene. Then the stem cells are put back into the patient's bone marrow. Because they are stem cells, they divide and make more blood cells with the gene.

Describe how genes influence the development of traits.

Genes influence the development of traits by containing two alleles that are the code for the different traits. (homozygous and heterozygous)

Describe Griffith's discovery of a transforming principle.

He was investigating two forms of bacterium that causes pneumonia. One form is surrounded by a coating made of carbohydrates. This form is called the S form because its colonies look smooth. The second form of bacteria does not have a smooth coating and is called the R, or rough, form. First he injected the live S bacteria the mice died. When he injected the live R bacteria the mice survived. When he injected the heat-killed S bacteria the mice survived. When he inject both heat-killed S bacteria+live R bacteria the mice died surprisingly. Even more surprising, he found live S bacteria in blood samples from the dead mice. Griffith concluded that some material must have been transferred from the heat-killed S bacteria to the live R bacteria. Whatever that material was, it contained information that changed harmless R bacteria into disease-causing S bacteria. Griffith called this mystery material the "transforming principle.

Compare and contrast the two rounds of division in meiosis.

Homologous chromosomes are divided in meiosis 1 and sister chromatids aren't divided til meiosis 2 Prophase 1- The nuclear membrane breaks down. The centrosomes and centrioles begin to move, and spindle fibers start to assemble. The duplicated chromosomes condense, and homologous chromosomes begin to pair up. Metaphase I Spindle fibers align the homologous chromosomes along the cell equator. Each side of the equator has chromosomes from both parents Anaphase I The paired homologous chromosomes separate from each other and move toward opposite sides of the cell. Sister chromatids remain attached. Telophase I The spindle fibers disassemble, and the cell undergoes cytokinesis Prophase II The centrosomes and centrioles move to opposite sides of the cell, and spindle fibers start to assemble. Metaphase II Spindle fibers align the chromosomes along the cell equator. Anaphase II The sister chromatids are pulled apart from each other and move to opposite sides of the cell. Telophase II The nuclear membranes form again around the chromosomes, the spindle fibers break apart, and the cell undergoes cytokinesis.

Explain how isolation of populations can lead to speciation.

If a population is isolated, then there are less alleles in the population. Thus, beneficial mutations can lead to variation of species. The species will adapt to their environment, altering the characteristics of that species even more. Soon the speices are at the last stage of isolation which is reproductive isolation. Then soon the species don't produce together so they because two different species.

Compare and contrast interspecific and intraspecific competition.

Interspecific competition is competition between the members from the same species intraspecific completion is competition between members of different species

Describe patterns of inheritance in sex-linked traits.

Male are XY they only get one X from mother and the (X and Y) determine the sex while in X can also determine the phenotype. Female is XX.

Describe monohybrid and dihybrid crosses.

Monohybrid crosses-a cross between individuals that involves one pair of contrasting traits Dihybrid crosses- a cross between individuals that have different alleles for the same gene

Identify sources of genetic variation.

Mutation- changing in DNA sequence which many results in a new allele Recombination- during meiosis, new allele combinations result in each gamete formed. New allele combinations form in offspring through this process of recombination

Explain why mutations may or may not affect phenotype.

Mutations may effect if they are changing the entire amino acid makeup. The gene doesn't affect when one nucleotide changes but still represents the same amino acids.

Describe research methods ecologists use to study the environment.

Observation- is the act of carefully watching something over time. experimentation-a procedure that is carried out under controlled conditions to discover, demonstrate, or test a fact, theory, or general truth modeling- allows scientists to learn about organisms or ecosystems in ways that would not be possible in a natural or lab setting.

Relate dominant-recessive patterns of inheritance in autosomal chromosomes to genetic disorders.

Parents who have dominant disorders is very unique but a mother and father can pass on the disease to the daughter, but only the mother can pass on the disease to the son. A recessive disorder is common but there is less chance of inheriting it unless both the parent of heterzygous of homozygous recessive.

Describe how a pedigree is used.

Pedigree: help traces the phenotypes and genotypes in a family to determine whether people carry recessive alleles.

Compare photosynthesis to chemosynthesis.

Photosynthesis- the process by which plants, algae, and some bacteria use sunlight, carbon dioxide, and water to produce carbohydrates and oxygen Chemosynthesis- process by which ATP is synthesized by using chemicals as an energy source instead of light

Describe polygenic traits and the effect of environmental factors on phenotype

Polygenic traits: traits produced by two or more genes. Environment and genes can influence the phenotype by the different types of nutrients and health care they are given.

Explain how restriction maps show the lengths of DNA fragments.

Restriction maps register the restriction sites and they appear and can be measured. In gel electrophoresis, an electrical current is used to separate a mixture of DNA fragments from each other. DNA is loaded into a gel, which is like a thin slab of hard gelatin. A positive electrode is at one end of the gel. At the other end is a negative electrode. Because DNA has a negative charge the fragments move toward the positive electrode or the positively charged pole. The gel also has tiny pores running through it. The pores allow small molecules to move quickly. Larger molecules cannot easily move through the gel and they travel more slowly. Therefore, the length of a DNA fragment can be estimated from the distance it travels through a gel in a certain period of time. DNA fragments of different sizes appear as different bands, or lines, on a gel. The pattern of bands on the gel can be thought of as a map of the original strand of DNA.

Describe the interaction of the four nucleotides that make up DNA.

The DNA nucleotides of a single strand are joined together by covalent bonds that connect the sugar of one nucleotide to the phosphate of the next nucleotide. The alternating sugars and phosphates form the sides of a double helix, sort of like a twisted ladder. The DNA double helix is held together by hydrogen bonds between the bases in the middle. Individually, each hydrogen bond is weak, but together, they maintain DNA structure. They pair up according to certain base pairing rules, A pairs with T, C with G. Lastly, different sequences of the four nucleotides code for different variations of genes.

Explain how there can be many versions of one gene.

There can be homozygous or heterozygous alleles that make up one type of gene.

Summarize the process of protein synthesis.

Transcription 1) A large transcription complex made of RNA polymerase and other proteins recognizes the start of a gene and begins to unwind the segment of DNA. 2)RNA polymerase uses one strand of the DNA as a template. RNA nucleotides form complementary base pairs with the DNA template. G pairs with C, and A pairs with U. The growing RNA strand hangs freely as it is transcribed. Then the DNA strand closes back together. 3)The completed RNA strand separates from the DNA template, and the transcription complex falls apart. Translation Translation is the process that converts, or translates, an mRNA message into a polypeptide. One or more polypeptides make up a protein. 1) The exposed codon attracts a complementary tRNA molecule bearing an amino acid. The tRNA anticodon pairs with the mRNA codon. This action brings the new tRNA molecule very close to the tRNA molecule occupying the second site. 2) Next, the ribosome helps form a peptide bond between the two amino acids. The ribosome then breaks the bond between the tRNA molecule in the second site and its amino acid. 3) The ribosome pulls the mRNA strand the length of one codon. The tRNA molecule in the second site is shifted into the third site, which is the exit site. The tRNA leaves the ribosome and returns to the cytoplasm to be charged with another amino acid. The tRNA molecule that was in the first site shifts into the second site. The first site is again empty, exposing the next mRNA codon

Describe how mRNA codons are translated into amino acids.

Translation is the process that converts, or translates, an mRNA message into a polypeptide. One or more polypeptides make up a protein. The "language" of nucleic acids uses four nucleotides and codons is a three nucleotide sequence that codes for an amino acid.

Explain how crossing over during meiosis increases genetic diversity.

When homologous chromosomes form pairs during prophase I of meiosis I, crossing-over can occur. Crossing-over is the exchange of genetic material between non-sister chromatids of homologous chromosomes. It results in new combinations of genes on each chromosome.

Compare artificial selection to natural selection.

artificial selection: humans change a species by breeding it for certain traits - humans determine which traits are favorable natural selection: individuals that have inherited beneficial adaptations produce more offspring on average than do other individuals

Explain how food chains and trophic levels are related.

as the food chain starts the next level gets 10% of its energy

Describe the specialization in multicellular organisms.

budding forms a new organism from a small projection growing on the surface of the parent fragmentation is the splitting of the parent into pieces that each grow into a new organism vegatitve reproduction forms a new plant from the modification of a stem or underground structure on the parents plant

Relate cycling of matter to ecosystems.

carbon cycle-the movement of carbon from the nonliving environment into living things and back nitrogen cycle- the cycling of nitrogen between organisms, soil, water, and the atmosphere phosphorus Cycle- the cyclic movement of phosphorus in different chemical forms from the environment to organisms and then back to the environment

Differentiate between competitive exclusion and ecological equivalents.

competitive- the exclusion of one species by another due to competition ecological - organisms that share a similar niche but live in different geographical regions

Compare and contrast autosomes and sex chromosomes.

contrast: autosomes are involved in determining the body features and characters of an individual. any chromosome that is not a sex chromosome. 1-22 chromosome sex chromosomes are involved in determining the gender and one of the pair of chromosomes that determine the sex of an individual. 23 pair chromosome. x and y. Compare: they both contain a sexual determination

Identify factors that limit population growth.

density independent factors- a variable that affects a population regardless of the population density, such as climate. EX: unusual weather, natural disaster, and human activities density-dependent factors- a variable affected by the number of organisms present in a given area. EX: competition, predation, disease, and parasitism

Describe the stages of the cell cycle

first formed from another cell, then divides itself 1. Interphase: duplication of cell contacts(longest phase) G1- growth, increase cytoplasm S-duplication of chromosomes G2- growth, preparation for division 2. Mitotic phase: division Mitosis- division of the nucleus prophase- chromosomes condense and spindle fibers form metaphase- chromosomes line up in the middle of the cell anaphase- sister chromatids move to opposite sides of the cell telephase- new nuclei form and chromosomes begin to uncoil cytokinesis- splitting of the cytoplasm, division of cytoplasm

Describe the significance of genetic variation within a population.

genetic variation in phenotypes, the more likely it is that some individuals can survive in a changing environment. Evolution is driven by variation Allows new alleles to enter the population

List some factors that cause mutations.

germs cells a parents can pass it on to the child or the UV radiations can damage cells so much that they can't protect you anymore and they start to begin damaged and cause cancer.

Differentiate between habitat and niche.

habitat- the place where an organism usually lives niche- the unique position occupied by a species, both in terms of its physical use of its habitat and its function within an ecological community

Summarize Earth's hydrologic and biogeochemical cycles.

hydrologic cycle- pathway of water from the atmosphere to Earth's surface, below ground, and back biogeochemical cycle- movement of a particular chemical through the biological and geological or living and nonliving, parts of an ecosystem; water changes form solid form to liquid form or gaseous form

Describe different types of allele interactions.

incomplete dominance- in which a heterozygous phenotype is somewhere between the two homozygous phenotypes. Neither allele is completely dominant nor completely recessive. Red+white=pin Codominance- in which both traits are fully and separately expressed. If one parent has AB type and the other has O type than the offspring will have ABO blood type.

Describe what a DNA fingerprint represents.

is a representation of parts of an individual's DNA that can be used to identify a person at the molecular level

Compare exponential and logistic population growth.

logistic- population growth that starts with a minimum number of individuals and reaches a maximum depending on the carrying capacity of the region; described by an S-shaped curve exponential- logarithmic growth, or growth in which numbers increase by a certain factor in each successive time period both- they both have an increase in the population

Compare and contrast binary fission and mitosis.

mitosis- occurs in eukaryotes, and have more DNA then prokaryotic, division of nucleus into two daughter cells (nuclei) binary fission- occurs in prokaryotic dividing of cell into another copy of itself, They also do not have spindle fibers, have less DNA then eukaryotes. Similarities-Binary fission and mitosis have similar results. That is, both processes form two daughter cells that are genetically identical to the parent cell.

Explain the predictive value of the Hardy -Weinberg equation.

p2+ 2pq + q2= 1 p equals the frequency of the dominant allele and q equals the frequency of the recessive allele. Population biologists compare predicted genotype frequencies with actual frequencies. used for traits in simple dominant-recessive systems must know frequency of recessive homozygotes

Describe the process of primary succession.

primary- establishment and development of an ecosystem in an area that was previously uninhabited. The first organism that lives in a previously uninhabited area are called pioneer species.

Explain the difference between primary and secondary succession.

primary- establishment and development of an ecosystem in an area that was previously uninhabited. The first organism that lives in a previously uninhabited area are called pioneer species. secondary- reestablishment of a damaged ecosystem in an area where the soil was left intact. following a flood or a fire, a community is given a chance for new life. there are small disturbances.

Describe the roles of producers and consumers in ecosystems.

producer- an organism that can make organic molecules from inorganic molecules; a photosynthetic or chemosynthetic autotroph that serves as the basic food source in an ecosystem. (autotroph). Consumer- an organism that eats other organisms or organic matter instead of producing its own nutrients or obtaining nutrients from inorganic sources. (heterotroph)

Distinguish between different types of mutations

silent mutation- no amino acid change missense- change amino acid nonsense- change to stop codon frameshift- addition or deletion

Compare rates of division in different cell types.

skin cells- 2 weeks red blood cell- 4 months liver cells- 300-500 days intestine internal lining- 4-5 years intestine muscle and other tissue- 16 years

Describe the structure of a food chain.

the pathway of energy transfer through various stages as a result of the feeding patterns of a series of organisms Primary producer → primary consumer → secondary consumer → Tertiary consumer → Quaternary consumer → detritivores → decomposers

Describe genomics.

the study of entire genomes, especially by using technology to compare genes within and between species. Scientists compare genomes both within and across species to find similarities and differences among DNA sequences. Comparing DNA from many people at one time helps researchers to find genes that cause disease and to understand how medications work. Biologists who study evolution can learn when closely related species diverged from each other. Scientists can also learn about interactions among genes and find out how an organism's genome makes the organism unique.

Recognize how Darwin's discoveries supported Lyell's ancient -Earth theory.

this showed how the Earth was indeed over 6000 years old

Describe how some eukaryotes reproduce through mitosis.

when sperm meets egg their chromosomes start to mix, and the cells keep growing and dividing and work together to make fetus