Biology Test 2

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Explain what evolution is at a population level:
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Terms in this set (104)
Explain what evolution is at a population level:
Biological evolution refers to the cumulative changes that occur in a population over time. These changes are produced at the genetic level as organisms' genes mutate and/or recombine in different ways during reproduction and are passed on to future generations.
Describe the process of natural selection, and how it leads to adaptations, such as antibiotic resistance in bacteria.
Natural selection is: the process whereby organisms better adapted to their environment tend to survive and produce more offspring. The theory of its action was first fully expounded by Charles Darwin and is now believed to be the main process that brings about evolution.
Antibiotic resistance is a consequence of evolution via natural selection. Theantibiotic action is an environmental pressure; those bacteria which have a mutation allowing them to survive will live on to reproduce. They will then pass this trait to their offspring, which will be a fully resistant generation.
Explain what fitness is in an evolutionary context and why fitness is environmentally dependent
fitness is the quantitative representation of natural and sexual selection within evolutionary biology. It can be defined either with respect to a genotype or to a phenotype in a given environment, as the environment influences whether it is defined by a genotype or phenotype
Identify the different patterns of natural selection.
Directional Selection. Phenotypes at one extreme are eliminated. Thus, alleles for the phenotype at one extreme becomes less common.
Stabilizing Selection. Phenotypes at both extremes are eliminated. Thus, alleles for both extremes become less common.
Disruptive (dispersive) Selection. Average phenotypes are estimated.
Genotype: the genetic constitution of an individual organism.
Phenotype: the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.
Explain how bacteria acquire genetic variation and how this is similar and different from sexual reproduction
(horizontal vs. vertical gene transfer).
It is different as the production is asexual
Horizontal gene transfer (HGT) or lateral gene transfer (LGT) refers to transfer ofgenes between organisms other than through sexual or asexual reproduction(referred to as vertical gene transfer VGT). ... And in this regard, in the simpler organisms, it has played an important role in evolution.
What structural features are shared by all cells, and what are the key differences between prokaryotic and eukaryotic cells?
Shared features: DNA, the genetic material contained in one or more chromosomes and located in a nonmembrane bound nucleoid region in prokaryotes and a membrane-bound nucleus in eukaryotes.
DNA, the genetic material contained in one or more chromosomes and located in a nonmembrane bound nucleoid region in prokaryotes and a membrane-bound nucleus in eukaryotes
Plasma membrane, a phospholipid bilayer with proteins that separates the cell from the surrounding environment and functions as a selective barrier for the import and export of materials
Cytoplasm, the rest of the material of the cell within the plasma membrane, excluding the nucleoid region or nucleus, that consists of a fluid portion called the cytosol and the organelles and other particulates suspended in it
Ribosomes, the organelles on which protein synthesis takes place
Eukaryotic cells contain membrane-bound organelles, including a nucleus. Eukaryotes can be single-celled or multi-celled, such as you, me, plants, fungi, and insects. Bacteria are an example of prokaryotes. Prokaryotic cells do not contain a nucleus or any other membrane-bound organelle.
How do antibiotics target bacteria, and in what situations is antibiotic therapy indicated?
Many antibiotics, including penicillin, work by attacking the cell wall of bacteria. Specifically, the drugs prevent the bacteria from synthesizing a molecule in the cell wall called peptidoglycan, which provides the wall with the strength it needs to survive in the human body.
Thearpy is indicated when the the cell can be broken down and the dissolve the material of bacterial cells
How do solutes and water cross membranes, and what determines the direction of movement of solutes and water in different situations?
Because the solutes cannot move across the membrane, the water molecules must. ... If solute molecules can move freely across the cell membrane, the movement of water by osmosis is not as important, because the solute molecules themselves will diffuse across the membrane to create an equal concentration on both sides.
Evolution (allele frequency perspective)
Evolution. In biology, evolution is the change in the inherited traits of a population from generation to generation. ... In contrast, genetic drift produces random changes in the frequency of traits in a population. Genetic drift arises from the role chance plays in whether a given individual will survive and reproduce.
Population
In biology, a population is the number of all the organisms of the same group or species, which live in a particular geographical area, and have the capability of interbreeding.
Allele frequencyAllele frequency, or gene frequency, is the relative frequency of an allele (variant of a gene) at a particular locus in a population, expressed as a fraction or percentage. Specifically, it is the fraction of all chromosomes in the population that carry that allele.Gene poolthe stock of different genes in an interbreeding population.FitnessBiologists use the word fitness to describe how good a particular genotype is at leaving ... The brown beetles have a greater fitness relative to the green beetles.Natural selectionthe process whereby organisms better adapted to their environment tend to survive and produce more offspring. The theory of its action was first fully expounded by Charles Darwin and is now believed to be the main process that brings about evolution.AdaptationFirstly, it is the dynamic evolutionary process that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the population during that process.Antibioticsantibiotics. Antimicrobial agent made from microorganisms, and can kill and inhibit the growth of microorganisms, especially those that are infectious or disease-causing. adjective. Of, relating to, or pertaining to antibiotic.Binary fissionBinary fission ("division in half") is a kind of asexual reproduction. It is the most common form of reproduction in prokaryotes such as bacteria. It occurs in some single-celled Eukaryotes like the Amoeba and the Paramoecium. In binary fission DNA replication and segregation occur simultaneously.Gene transfer (Horizontal vs. Vertical)Horizontal gene transfer (HGT) or lateral gene transfer (LGT) is the movement of genetic material between unicellular and/or multicellular organisms other than by the ("vertical")transmission of DNA from parent to offspring (reproduction). HGT is an important factor in the evolution of many organisms.Organellesany of a number of organized or specialized structures within a living cell.Cell membranesthe semipermeable membrane surrounding the cytoplasm of a cell.Cell theoryCell Theory is one of the basic principles of biology. Credit for the formulation of this theory is given to German scientists Theodor Schwann, Matthias Schleiden, and Rudolph Virchow. The Cell Theory states: All living organisms are composed of cells.Gram+ vs. Gram-: This is due to the difference in the structure of their bacterial cell wall. Gram-positive bacteria do not have an outer cell membrane found in Gram-negative bacteria.This is due to the difference in the structure of their bacterial cell wall. Gram-positive bacteria do not have an outer cell membrane found in Gram-negative bacteria.What shows in the outer cell wall?If you were to look into the outer cell wall of a membrane you would see phospholipid heads and parts of proteinsDiagram how meiosis produces gametes Meiosis makes sperm and eggs.During meiosis in humans, 1 diploid cell (with 46 chromosomes or 23 pairs) undergoes 2 cycles of cell division but only 1 round of DNA replication. ... The halving of the number of chromosomes in gametes ensures that zygotes have the same number of chromosomes from one generation to the next.Describe how meiosis causes genetic diversity in humans.Genetic variation is increased by meiosis. During fertilisation, 1 gamete from each parent combines to form a zygote. Because of recombination and independent assortment in meiosis, each gamete contains a different set of DNA. This producesa unique combination of genes in the resulting zygote. Apply understanding of inheritance and dominance patterns to evaluate risk for genetic disease given a family history.Describe the biology behind why it is important to match blood types in transfusions.When conducting a blood transfusion, it is important to carefully match the donor and recipient blood types. ... People with type O blood are universal donors because there are no molecules on the surface of the red blood cells that can trigger an immune response.Explain Laws of Inheritance and how they relate to genetic variation.deduced that genes come in pairs and are inherited as distinct units, one from each parent. Mendel tracked the segregation of parental genes and their appearance in the offspring as dominant or recessive traits, this relates to genetic variation as the inherited units are split from the parents and can change based on each parent's pairsBriefly outline the history biological understanding of inheritance.is the process by which an offspring cell or organism acquires or becomes predisposed to characteristics of its parent cell or organism.Describe how chromosomes determine sex and how this, in turn, influences the inheritance of sex-linked traits:A particularly important category of genetic linkage has to do with the X and Y sex chromosomes. These not only carry the genes that determine male and female traits but also those for some other characteristics as well. Genes that are carried by either sex chromosome are said to be sex linked.Multifactorial inheritance means that "many factors" (multifactorial) are involved in causing a birth defect.The factors are usually both genetic and environmental, where a combination of genes from both parents, in addition to unknown environmental factors, produce the trait or condition.Describe how some traits are the product of multifactorial inheritance.Multifactorial inheritance means that "many factors" (multifactorial) are involved in causing a birth defect. The factors are usually both genetic and environmental, where a combination of genes from both parents, in addition to unknown environmental factors, produce the trait or condition.Describe how genetics + environment = phenotype.An organism's phenotype is usually the result of both genetic factors, environmental factors, and the interactions between them.Understand how linked genes influence patterns of inheritance.Females carry no copies of Y-linked genes. Diseases caused by mutated geneslocated on the X chromosome can be inherited in either a dominant or recessive manner. ... Because females have two copies of X-linked genes, they will not be affected by inheriting of a single recessive mutation on an X-linked gene.Explain the consequences of abnormal chromosome counts due to nondisjunctions.Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during cell division. It causes a mutation in the number of chromosomes, either extra chromosomes or missing chromosomes.Nondisjunction during meiosis can causechromosomal disorders, such as trisomy 21 (Down syndrome), Turner's syndrome, and Klinefelter's syndrome. ... It is a monosomy of the X sex chromosomemeiosisa type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores.single-gene inheritenceSingle gene-pair inheritance occurs when a trait is linked to one gene-pair that consists of two alleles. This is also referred to as Mendelian inheritance. An allele is one part of the gene-pair. One allele is inherited from the father, and one is inherited from the mother.dominance patterns (dominance, incomplete, codominance)In both codominance and incomplete dominance, both alleles for a trait aredominant. In codominance a heterozygous individual expresses both simultaneously without any blending. ... An example of incomplete dominance is the pink snapdragon, which receives a red allele and white allele.List ways people can reduce their risk of developing cancer.Get regular cancer screening tests. Regular screening tests can catch some cancers early, when they're small, have not spread, and are easier to treat. ... Get to and stay at a healthy weight. ... Exercise regularly. ... Eat a healthy diet. ... Avoid tobacco. ... Limit alcohol.Compare the differences between cancer treatments and antibiotics in how they affect healthy human cells.Chemotherapy: using toxic chemicals to kill cancer cells Radiation therapy: focusing radiation on the tumor Both of these can often hurt the other cells in the process causing vomitting, hair loss, bruising, and susceptibility to infection Targeted therapy: designed to kill cancer cells specifically through a mutation or other items Immunotherapy: drugs that stimulate our own immune system to find the cancer and fight in it our own bodiesDescribe how new cancer drugs are developed.Cancer drugs are developed through creating studies and use: Preclinical research, which is when the drug is found and first tested Clinical research, which is when the drug is tested in people Post-clinical research, which takes place after the drug is approvedExplain when, where and how mutations occur.Acquired (or somatic) mutations occur at some time during a person's life and are present only in certain cells, not in every cell in the body. These changes can be caused by environmental factors such as ultraviolet radiation from the sun, or can occur if an error is made as DNA copies itself during cell divisionExplain how both inherited and non-inherited mutations occur.Inherited mutations: Hereditary mutations are inherited from a parent and are present throughout a person's life in virtually every cell in the body. These mutations are also called germline mutations because they are present in the parent's egg or sperm cells, which are also called germ cells. Non-inherited mutations: Somatic mutation, genetic alteration acquired by a cell that can be passed to the progeny of the mutated cell in the course of cell division.Distinguish between cancer risk factors and the causes of cancer.Cancer risk factors: smoking, radiation, viruses, cancer-causing chemicals (carcinogens), obesity,hormones, chronic inflammation and a lack of exercise causes : Gene mutations that occur after birth. Most gene mutations occur after you're born and aren't inheritedCanceris a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread.Mitosis/cell divisionMitosis is a process of nuclear division in eukaryotic cellsthat occurs when a parent cell divides to produce two identical daughter cells. During cell division, mitosisrefers specifically to the separation of the duplicated genetic material carried in the nucleus.Cell cycle (Interphase, mitosis, cytokinesis)The cell cycle. Actively dividing eukaryote cells pass through a series of stages known collectively as the cell cycle: two gap phases (G1 and G2); an S (for synthesis) phase, in which the genetic material is duplicated; and an M phase, in which mitosis partitions the genetic material and the cell divides. G1 phase.Sister chromatids and centromeresThe two identical chromosomes that result from DNA replication are referred to as sister chromatids. Sister chromatids are held together by proteins at a region of the chromosome called thecentromere. Chromosomes undergo additional compaction at the beginning of mitosis.Cell cycle checkpointA checkpoint is one of several points in the eukaryotic cell cycle at which the progression of a cell to the next stage in the cycle can be halted until conditions are favorable (e.g. the DNA is repaired). These checkpoints occur near the end of G1, at the G2/M transition, and during metaphase.Apoptosisthe death of cells which occurs as a normal and controlled part of an organism's growth or development.Metastasisthe development of secondary malignant growths at a distance from a primary site of cancer.TumorA tumor is an abnormal growth of cells that serves no purpose. A benign tumor is not a malignant tumor, which is cancer. It does not invade nearby tissue or spread to other parts of the body the way cancer can. In most cases, the outlook with benign tumors is very goodMutationmutation is a change that occurs in our DNA sequence, either due to mistakes when the DNA is copied or as the result of environmental factors such as UV light and cigarette smokeMutagenan agent, such as radiation or a chemical substance, which causes genetic mutationCarcinogenA carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis, the formation of cancer. This may be due to the ability to damage the genome or to the disruption of cellular metabolic processesProto-oncogeneA normal gene which, when altered by mutation, becomes an oncogene that can contribute to cancer. Proto-oncogenes may have many different functions in the cell. Someproto-oncogenes provide signals that lead to cell division. Otherproto-oncogenes regulate programmed cell death (apoptosis).Tumor suppressor geneA tumor suppressor gene, or antioncogene, is a gene that protects a cell from one step on the path to cancer. When thisgene mutates to cause a loss or reduction in its function, the cell can progress to cancer, usually in combination with other genetic changesBenign vs. malignant tumorOne is known as benign and the other as malignant. A benign tumor is a tumor that does not invade its surrounding tissue or spread around the body. A malignant tumor is a tumor that may invade its surrounding tissue or spread around the body.BRCA mutation and breast cancerBRCA Mutation Risks. ... However, women with certain genetic mutations have a higher lifetime risk of the disease. It's estimated that 55 - 65% of women with the BRCA1 mutation will develop breast cancer before age 70. Approximately 45% of women with a BRCA2 mutation will develop breast cancer by age 70. A BRCA mutation is a mutation in either of the BRCA1 and BRCA2 genes, which are tumour suppressor genes. Hundreds of different types of mutations in these genes have been identified, some of which have been determined to be harmful, while others have no proven impact.Describe how genetics + environment = phenotype.An organism's phenotype is usually the result of both genetic factors, environmental factors, and the interactions between them.Understand how linked genes influence patterns of inheritance.Females carry no copies of Y-linked genes. Diseases caused by mutated geneslocated on the X chromosome can be inherited in either a dominant or recessive manner. ... Because females have two copies of X-linked genes, they will not be affected by inheriting of a single recessive mutation on an X-linked gene.Explain the consequences of abnormal chromosome counts due to nondisjunctions.Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during cell division. It causes a mutation in the number of chromosomes, either extra chromosomes or missing chromosomes.Nondisjunction during meiosis can causechromosomal disorders, such as trisomy 21 (Down syndrome), Turner's syndrome, and Klinefelter's syndrome. ... It is a monosomy of the X sex chromosome.Meiosisa type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores.single-gene inheritanceSingle gene-pair inheritance occurs when a trait is linked to one gene-pair that consists of two alleles. This is also referred to as Mendelian inheritance. An allele is one part of the gene-pair. One allele is inherited from the father, and one is inherited from the mother.dominance patterns (dominance, incomplete, co dominance)In both co dominance and incomplete dominance, both alleles for a trait are dominant. In co dominance a heterozygous individual expresses both simultaneously without any blending. ... An example of incomplete dominance is the pink snapdragon, which receives a red allele and white allele.recessive alleleA recessive allele is a version of a gene which must be homozygous when inherited in order to be expressed in the phenotype.dominant alleleDominance in genetics is a relationship between alleles of one gene, in which the effect on phenotype of one allele masks the contribution of a second allele at the same locusHeterozygoushaving two different alleles of a particular gene or genes.Homozygousis a word that refers to a particular gene that has identical alleles on both homologous chromosomes. It is referred to by two capital letters (XX) for a dominant trait, and two lowercase letters (xx) for a recessive trait.Gametesa mature haploid male or female germ cell which is able to unite with another of the opposite sex in sexual reproduction to form a zygote.haploid / diploidDiploid cells contain two complete sets (2n) of chromosomes. Haploid cells have half the number of chromosomes (n) as diploid - i.e. a haploid cell contains only one complete set of chromosomes. Cell Division and Growth. Diploid cells reproduce by mitosis making daughter cells that are exact replicas.zygote / embryoA zygote is a single-celled organism resulting from a fertilized egg. The zygotedivides to become a ball of cells that eventually implants in the wall of the uterus. This ball of cells, known as a blastocyst, develops into the embryo and placenta.Laws of Inheritance (segregation, independent assortment)Mendel tracked the segregation of parental genes and their appearance in the offspring as dominant or recessive traits. ... 2) The Law of Independent Assortment: Genes for different traits are sorted separately from one another so that the inheritance of one trait is not dependent on the inheritance of another.Punnett squareThe Punnett square is a square diagram that is used to predict the genotypes of a particular cross or breeding experiment. It is named after Reginald C. Punnett, who devised the approach. The diagram is used by biologists to determine the probability of an offspring having a particular genotype.Simple genetic diseases / carrierA hereditary carrier (or just carrier), is a person or other organism that has inherited a recessive allele for a genetictrait or mutation but usually does not display that trait or show symptoms of the disease.PedigreeA pedigree is a diagram that depicts the biological relationships between an organism and its ancestors.GonadsThe development of the gonads is part of the prenatal development of the reproductive system and ultimately forms the testes in males and the ovaries in females. The gonads initially develop from the mesothelial layer of the peritoneumAndrogens / EstrogensAndrogens and estrogens are hormones. Estrogens are produced by the body in greater amounts in females. They are necessary for normal sexual development of the female and for regulation of the menstrual cycle during the childbearing years.Androgens are produced by the body in greater amounts in males.Autosomesany chromosome that is not a sex chromosome.Sex-chromosomesa chromosome involved with determining the sex of an organism, typically one of two kindsX-linked traitsX-linked inheritance means that the gene causing the trait or the disorder is located on the X chromosome. Females have two X chromosomes; males have one X and one Y. Genes on the X chromosome can be recessive or dominant.Y-chromosome analysisAnalysis of the Y-Chromosome is used to research the paternal line. The DNA contains the genetic information for every person. The DNA is packaged in chromosomes. The DNA encodes e.g. whether we have blue or brown eyes. Every person has 23 chromosome pairs.Continuous variationVariation within a population in which a graded series of intermediate phenotypes falls between the extremesPolygenic (quantitative) traitsA quantitative trait locus is a locus which correlates with variation of a quantitative trait in the phenotype of a population of organisms. QTLs are mapped by identifying which molecular markers correlate with an observed trait.Multifactorial inheritanceDiseases such as diabetes, high blood pressure, or cancer are multifactorial. Some cancers cluster in families as the result of a combination of genetic and shared environmental factors (multifactorial influences).Pleiotropythe production by a single gene of two or more apparently unrelated effectsLinked genesLinked genes are genes that are likely to be inherited together because they are physically close to one another on the same chromosome. During meiosis, chromosomes are recombined, resulting in gene swaps between homologous chromosomes.Crossing over / recombinationCrossing Over in Meiosis. Genetic recombination that involves crossing over occurs during prophase I of meiosis in sex cell production. ... Crossing over occurs when the chiasma breaks and the broken chromosome segments get switched onto homologous chromosomesDihybrid crossDihybrid cross is a cross between two different lines/genes that differ in two observed traits. According to Mendel's statement, between the alleles of both these loci there is a relationship of complete dominance - recessive.Aneuploidy (e.g., trisomy 21)Aneuploidy is the presence of an abnormal number of chromosomes in a cell, for example a human cell having 45 or 47 chromosomes instead of the usual 46. ... Most cases of aneuploidy result in miscarriage and the most common extra autosomal chromosomes among live births are 21, 18, and 13.Amniocentesis / KaryotypeKaryotype (amniocentesis) Chromosome analysis can detect balanced and unbalanced rearrangements, and numerical changes of autosomes and sex chromosomesExplain the physiological (proximate) explanations for aging.Damage-based theories propose that injury to DNA, telomeres, and tissues due to normal toxic by-products of metabolism (e.g. free radicals) or inefficient repair or defense accumulates throughout the lifespan and causes senescence.[3] Circulating levels of superoxide dismutase, uric acid, and other antioxidants are linked to lifespan across speciesChromosomal shortening / telomeresTelomere shortening in humans can induce replicative senescence, which blocks cell division. ... Uncapped telomeres also result in chromosomal fusions. Since this damage cannot be repaired in normal somatic cells, the cell may even go into apoptosis. Many aging-related diseases are linked to shortened telomeres.Metabolic damage to DNA / free radicalsFree radicals are produced in cells by cellular metabolism and by exogenous agents. These species react with biomolecules in cells, including DNA. The resulting damage to DNA, which is also called oxidative damage to DNA, is implicated in mutagenesis, carcinogenesis, and aging.DNA repair (P53)The cells in the human body are continuously challenged by a variety of genotoxic attacks. ... p53 plays a prominent role as a facilitator of DNA repair by halting the cell cycle to allow time for the repair machineries to restore genome stability.Mutation accumulationmutation accumulation theory is based on Medawar's Hypothesis, which suggests that the evolutionary effect of adverse events declines following the age at which an organism is initially capable of reproduction.Apoptosis and senolyticssenolytic is among the class of small molecules under basic research to determine if they can selectively induce death of senescent cells. The goal of those working to develop senolytic agents is to delay, prevent, alleviate, or reverse age-related diseases through apoptosisAntagonistic pleiotropy (testosterone)Antagonistic pleiotropy is when one gene controls for more than one trait, where at least one of these traits is beneficial to the organism's fitness and at least one is detrimental to the organism's fitness.Extrinsic mortalityIntrinsic and extrinsic mortality are often separated in order to understand and measure aging. Intrinsic mortality is assumed to be a result of aging and to increase over age, whereas extrinsic mortality is assumed to be a result of environmental hazards and be constant over ageSenescenceDeterioration with ageDescribe how trade-offs between survival and reproduction can result in the evolution of aging.Life history patterns evolve by natural selection, and they represent an "optimization" of tradeoffs between growth, survival, and reproduction. One tradeoff is between number of offspring produced and the amount of energy (both physical resources and parental care) put into each offspring. Timing of first reproduction is another tradeoff. Early reproduction lowers the chance of dying without offspring, but later reproduction may allow organisms to have more or healthier offspring or to provide better care. Members of some species reproduce only once (semelparity), while members of other species can reproduce multiple times (iteroparity).Explain the evolutionary (ultimate) explanations for aging.Cancer or other environmental causesExplain the evolution of different life-history strategies.collections of life history traits (number of offspring, timing of reproduction, amount of parental care, etc.), that are well-adapted for their role and environment. The optimal life history strategy may be different for each species, depending on its traits, environment, and other constraints: Parental care and fecundity Many offspring and low investment or parental care Few offspring and high investment or parental care Timing of reproduction Single vs multiple events of reproductionLife-history (iteroparity, semelparity)Semelparity and iteroparity are two classes of possible reproductive strategies available to living organisms. ... An annual is a plant that completes its life cycle in a single season, and is usually semelparous. Perennials live for more than one season and are usually (but not always) iteroparous.Life-history related traitsLife history characteristics are traits that affect the life table of an organism, and can be imagined as various investments in growth, reproduction, and survivorship. The goal of life history theory is to understand the variation in such life history strategies.