Unit 2 Test

Describe how linked genes produce inheritance patterns that do not appear to follow Mendel's laws.

"Linked genes" are located close together on the same chromosome. The inheritance of such genes does not follow the pattern described by the principle of independent assortment because the two genes are normally inherited together on adjoining portions of the same chromosome.

Compare and contrast genotype and phenotype.

A genotype refers to the genetic characteristics of an organism. A phenotype refers to the physical characteristics. For example, having blue eyes (an autosomal recessive trait) is a phenotype; lacking the gene for brown eyes is a genotype.

Compare and contrast sexual and asexual reproduction.

Asexual reproduction involves one parent and produces offspring that are genetically identical to each other and to the parent. Sexual reproduction involves two parents and produces offspring that are genetically unique.

Distinguish between autosomes and sex chromosomes.

Autosomes differ from sex chromosomes, which make up the 23rd pair of chromosomes in all normal human cells and come in two forms, called X and Y. Autosomes control the inheritance of all an organism's characteristics except the sex-linked ones, which are controlled by the sex chromosomes.

Describe the events of binary fission in prokaryotic cells.

Binary fission is when prokaryotic cells, such as bacteria, replicate by a type of simple cell division. They cell makes copies of its genetic material, before splitting into two daughter cells. ... Step two: the cell gets bigger and the circular DNA strands move to the opposite 'the poles' (ends) of the cell.

Explain what happens in a eukaryotic cell at each stage of the cell cycle.

Cell cycle, the ordered sequence of events that occur in a cell in preparation for cell division. The cell cycle is a four-stage process in which the cell increases in size (gap 1, or G1, stage), copies its DNA (synthesis, or S, stage), prepares to divide (gap 2, or G2, stage), and divides (mitosis, or M, stage).

Describe the role of chromosomes in inheritance.

Chromosomes are the carriers of genetic information. ... During cell division, each DNA helix in the cell coils up to form a chromosome which then acts as a package carrying genetic information from the parent cell to the daughter cell.

Compare and contrast incomplete dominance and codominance.

Codominance and Incomplete dominance are two types of genetic inheritance. Codominance essentially means that no allele can block or mask the expression of the other allele. On the other hand, incomplete dominance is a condition in which a dominant allele does not completely mask the effects of a recessive allele.

Describe how DNA folds into a visible chromosome.

DNA is tightly packed up to fit in the nucleus of every cell. As shown in the animation, a DNA molecule wraps around histone proteins to form tight loops called nucleosomes. ... Chromatin, in turn, loops and folds with the help of additional proteins to form chromosomes

Explain how DNA technology has changed science and medicine.

DNA technology is being used to help diagnose genetic diseases, such as sickle-cell disease and Huntington's disease. ... Therapeutic hormones, such as insulin and human growth hormone, are also the result of DNA technology in medicine.

Describe the general structure of viruses.

Describe the general structure of a virus. Nucleic acid (DNA or RNA) surrounded by a protein coat called a capsid. Virus may be naked or enveloped. ... they have DNA or RNA, unlike prokaryotic and eukaryotic cells, which have both.

Explain the relationship between dominant and recessive alleles of a gene.

Dominant refers to the relationship between two versions of a gene. Individuals receive two versions of each gene, known as alleles, from each parent. If the alleles of a gene are different, one allele will be expressed; it is the dominant gene. The effect of the other allele, called recessive, is masked.

Identify the components of double-stranded DNA.

Double-stranded DNA is composed of two antiparallel, interlocked nucleotide chains, each consisting of a sugar-phosphate backbone with bases hydrogen-bonded with complementary bases of the other chain.

List and explain three ways that meiosis generates genetic variability among offspring.

During meiosis, homologous chromosomes (1 from each parent) pair along their lengths. The chromosomes cross over at points called chiasma. At each chiasma, the chromosomes break and rejoin, trading some of their genes. This recombination results in genetic variation.

Explain how cells divide to give rise to identical cells.

During mitosis, a cell duplicates all of its contents, including its chromosomes, and splits to form two identical daughter cells. Because this process is so critical, the steps of mitosis are carefully controlled by a number of genes. When mitosis is not regulated correctly, health problems such as cancer can result.

Explain how the environment and polygenic traits can influence phenotype.

Effects of Environment on Phenotype. Genes play an important part in influencing phenotype, but genes are not the only influence. Environmental conditions, such as temperature and availability of nutrients can affect phenotypes. ... The mutated enzyme is heat-sensitive; it fails to work at normal body temperatures.

Explain how cells use information in DNA to produce proteins.

First, enzymes read the information in a DNA molecule and transcribe it into an intermediary molecule called messenger ribonucleic acid, or mRNA. Next, the information contained in the mRNA molecule is translated into the "language" of amino acids, which are the building blocks of proteins.

Explain what features of DNA allow semiconservative replication to occur.

For semiconservative replication to occur, the DNA double-helix needs to be separated so the new template strand can be bound to the complementary base pairs. Topoisomerase is the enzyme that aids in the unzipping and recombination of the double-helix.

Explain how genetic information is passed from one generation to the next.

Genetic information is passed from generation to generation through inherited units of chemical information (in most cases, genes). Organisms produce other similar organisms through sexual reproduction, which allows the line of genetic material to be maintained and generations to be linked.

Differentiate between haploid and diploid cells.

Haploid cells are those that have only a single set of chromosomes while diploid cells have two sets of chromosomes

Explain how genetic traits are passed from one generation to the next.

Heritable traits are known to be passed from one generation to the next via DNA, a molecule that encodes genetic information. ... Organisms inherit genetic material from their parents in the form of homologous chromosomes, containing a unique combination of DNA sequences that code for genes.

Describe the role of homologous chromosomes in sexual reproduction.

Homologous chromosomes are important in the processes of meiosis and mitosis. They allow for the recombination and random segregation of genetic material from the mother and father into new cells.

Differentiate between the terms gene, allele, locus, and chromosome.

Homologous chromosomes can have different alleles on them. Alleles are variants of the same gene that occur on the same place on a chromosome. ... A locus refers to the location on the chromosome where the gene is found. Loci is the plural form of locus.

Differentiate between homozygous and heterozygous.

Homozygous and heterozygous are terms that are used to describe allele pairs. Individuals carrying two identical alleles (RR or rr) are known as homozygous. While individual organisms bearing different alleles (Rr) are known as heterozygous.

Explain how hydrogen bonds contribute to the structure of DNA.

Hydrogen bonds are responsible for specific base-pair formation in the DNA double helix and a major factor to the stability of the DNA double helix structure. A hydrogen-bond donor includes the hydrogen atom and the atom to which it is most tightly linked with.

Explain how cell cycle checkpoints relate to cancer.

If the checkpoint mechanisms detect problems with the DNA, the cell cycle is halted, and the cell attempts to either complete DNA replication or repair the damaged DNA. ... This self-destruction mechanism ensures that damaged DNA is not passed onto daughter cells and is important in preventing cancer.

Use a template strand of nucleotides to create a complementary strand.

If the original is guanine the complementary is cytosine.

Explain how meiosis contributes to Mendel's law of segregation.

In essence, the law states that copies of genes separate or segregate so that each gamete receives only one allele. ... As chromosomes separate into different gametes during meiosis, the two different alleles for a particular gene also segregate so that each gamete acquires one of the two alleles.

Explain how viruses cause disease in animals.

In order to reproduce, a virus must infect a host cell and reprogram it to make more virus particles. The first key step in infection is recognition: an animal virus has special surface molecules that let it bind to receptors on the host cell membrane.

Describe the participants and events in transcription.

Initiation. The DNA molecule unwinds and separates to form a small open complex. ... Elongation. RNA polymerase moves along the template strand, synthesising an mRNA molecule. ... Termination. In prokaryotes there are two ways in which transcription is terminated. ... Processing.

Diagram how crossing over can separate linked genes.

Linked genes on a pair of homologous chromosomes. Replication take place at the beginning of meiosis.

Diagram and explain why males express X-linked recessive traits more than females.

Males are affected more often than females, because the gene is located on the X chromosome. Hemophilia A. Hemophilia A is a disorder where the blood cannot clot properly due to a deficiency of a clotting factor called Factor VIII.

Explain how meiosis contributes to independent assortment of alleles.

Meiosis and Genetic Variation. ... When cells divide during meiosis, homologous chromosomes are randomly distributed during anaphase I, separating and segregating independently of each other. This is called independent assortment. It results in gametes that have unique combinations of chromosomes.

Explain the roles of meiosis, gamete formation, and fertilization in sexual reproduction.

Meiosis and fertilization alternate in sexual life cycles. The process of meiosis produces genetically unique reproductive cells called gametes, which have half the number of chromosomes as the parent cell. Fertilization, the fusion of haploid gametes from two individuals, restores the diploid condition.

Explain how meiosis and the production of gametes are associated with inheritance.

Meiosis leads to the formation of gametes which have half the number of chromosomes in the somatic body cells. This means two gametes should fuse together for a new individual to form. ... This means the gamete formed has a mixture of chromosomes from the parent's parents, and this is the second source of variation.

Identify the roles of mitosis, meiosis, and fertilization in the human life cycle

Mitosis allows for growth and repair from the fertilized egg to the adult. In reproductively mature individuals, meiosis creates gametes with half the genetic material. The male gamete then fertilizes the female gamete during sexual reproduction, forming a zygote with a full set of genetic material.

Compare and contrast mitosis and meiosis.

Mitosis produces two diploid (2n) somatic cells that are genetically identical to each other and the original parent cell, whereas meiosis produces four haploid (n) gametes that are genetically unique from each other and the original parent (germ) cell.

Explain how viruses cause disease in plants.

Most plant viruses are transmitted by insect vectors that cause damage to the plant and create an entry point for pathogens, or that tap into the phloem to feed. Once inside, viruses use the handful of genes in their tiny genomes to orchestrate the plant cells' machinery, while evading the plant's defenses.

Compare and contrast how substitution, insertion, and deletion mutations can alter a protein.

Mutations are errors in codons caused by changes in nucleotide bases. ... The most common mutations occur in two ways: 1) a base substitution, in which one base is substituted for another; 2) an insertion or deletion, in which a base is either incorrectly inserted or deleted from a codon.

Describe how mutations arise.

Mutations arise spontaneously at low frequency owing to the chemical instability of purine and pyrimidine bases and to errors during DNA replication. Natural exposure of an organism to certain environmental factors, such as ultraviolet light and chemical carcinogens (e.g., aflatoxin B1), also can cause mutations.

Diagram and explain how polyploidy and nondisjunction can lead to missing or extra chromosomes in a gamete.

Nondisjunction can occur during either meiosis I or II, with differing results, If sister chromatids fail to separate during meiosis II, the result is one gamete that lacks that chromosome, two normal gametes with one copy of the chromosome, and one gamete with two copies of the chromosome.

Diagram and explain the relationship between codons and amino acids

Nucleic acid is a polymer that stores genetic information. It is also involved in the production of a functional protein. The monomer of nucleic acids is the nucleotide. Amino acid is a monomer that serves as a building block of a protein.

List some of the factors that increase the risk for developing cancer.

Older age. A personal or family history of cancer. Using tobacco. Obesity. Alcohol. Some types of viral infections, such as human papillomavirus (HPV) Specific chemicals. Exposure to radiation, including ultraviolet radiation from the sun.

Describe the participants and events in translation.

Once the mRNA has been exported from the nucleus it binds to a ribsome. The ribosome scans along the mRNA reading each codon, after reading the codon, the ribosome facilitates the correct tRNA to bring in the correct specific amino acid that is required. Anti codons and codons match up by forming correct complementary base pairs. This pairing allows a peptide bond to form and adjacent amino acids join together. This process continues along the mRNA which will create a polypeptide. Once a stop codon is reached, the mRNA falls off the ribsome and the polypeptode is finished.

Use the product rule to predict inheritance patterns for two or more genes.

One probability rule that's very useful in genetics is the product rule, which states that the probability of two (or more) independent events occurring together can be calculated by multiplying the individual probabilities of the events. ... We can use the product rule to predict frequencies of fertilization events.

Compare and contrast preimplantation genetic diagnosis, genetic testing, and gene therapy.

PGS analyzes biopsied cells from the embryo to screen for potential genetic abnormalities when there are no known potentially inherited disorders. PGD, on the other hand, uses the same process to detect a specific disorder that has a high probability of being passed down from parents to their offspring.

Analyze a pedigree to determine what pattern of inheritance a trait displays.

Pedigrees are used to analyze the pattern of inheritance of a particular trait throughout a family. Pedigrees show the presence or absence of a trait as it relates to the relationship among parents, offspring, and siblings.

Describe pleiotropy and explain how it occurs.

Pleiotropy occurs when one gene will code and control the phenotype or expression of several different and unrelated traits

Describe DNA sequencing, the polymerase chain reaction, and DNA profiling techniques.

Polymerase chain reaction (PCR) is a laboratory technique used to amplify DNA sequences. The method involves using short DNA sequences called primers to select the portion of the genome to be amplified.

Explain how cloning is different from sexual reproduction.

Reproductive cloning is a method used to make a clone or an identical copy of an entire multicellular organism. ... Sexual reproduction requires two cells; when the haploid egg and sperm cells fuse, a diploid zygote results. The zygote nucleus contains the genetic information to produce a new individual.

Compare and contrast stem cells and differentiated cells.

Stem cells have the potential to become any type of cell once they are further along in development. Differentiated cells, on the other hand, already have a set purpose and can only become one type of cell when they develop and mature.

Describe the steps of DNA replication and the function of enzymes in each step.

Step 1: Replication Fork Formation. Before DNA can be replicated, the double stranded molecule must be "unzipped" into two single strands. ... Step 2: Primer Binding. The leading strand is the simplest to replicate. ... Step 3: Elongation. ... Step 4: Termination.

Use the genetic code to translate a nucleic acid sequence into protein.

The first step in the process of producing proteins is to transcribe the DNA sequence into a template (called messenger ribonucleic acid, mRNA) that is sent into the cell. ... This protein binds tRNA tightly and will only release it when the genetic code has been accurately translated.

Explain how linked genes can be used to create a chromosome map.

The frequency of crossing-over between genes is used to construct linkage maps that show the locations of genes on chromosomes

Compare and contrast lytic and lysogenic replication pathways.

The lytic cycle involves the reproduction of viruses using a host cell to manufacture more viruses; the viruses then burst out of the cell. The lysogenic cycle involves the incorporation of the viral genome into the host cell genome, infecting it from within.

Describe the most common treatments for cancer.

The most common treatments are surgery, chemotherapy, and radiation. Other options include targeted therapy, immunotherapy, laser, hormonal therapy, and others. Here is an overview of the different treatments for cancer and how they work. Surgery is a common treatment for many types of cancer.

Explain how some mutations alter an organism's reproductive success.

The only mutations that matter to large-scale evolution are those that can be passed on to offspring. These occur in reproductive cells like eggs and sperm and are called germ line mutations. No change occurs in phenotype. Some mutations don't have any noticeable effect on the phenotype of an organism.

Explain the roles of DNA, RNA, and protein in gene function.

The synthesis of proteins occurs in two sequential steps: Transcription and Translation. Transcription occurs in the cell nucleus and uses the base sequence of DNA to produce mRNA. The mRNA carries the message for making a specific protein out to the cytoplasm where translation occurs.

List examples of applications of DNA technology.

There are many ways that DNA technology is used to make vaccines, such as altering the pathogen's genes and mimicking surface proteins of harmful pathogens. Therapeutic hormones, such as insulin and human growth hormone, are also the result of DNA technology in medicine.

Identify ethical issues associated with the use of DNA technology in medicine.

These issues include basic human error and human bias, linking innocent people to crimes, privacy rights, and a surge in racial disparities. In 2011, in their much-cited study, researchers Itiel Dror and Greg Hampikian found that DNA interpretation varied significantly among lab technicians and forensic experts

Describe the five stages of viral replication in a host cell.

These stages include attachment, penetration, uncoating, biosynthesis, maturation, and release. Bacteriophages have a lytic or lysogenic cycle. The lytic cycle leads to the death of the host, whereas the lysogenic cycle leads to integration of phage into the host genome.

Explain the roles of somatic cells and germ cells in sexual reproduction.

Unlike somatic cells which build the multicellular body of the organism through mitotic division, germ cells undergo cell division to produce gametes which are haploid and involved in sexual reproduction. ... On the other hand, they both differentiate into specific types of cells that serve specific roles in the body.

Use a Punnett square to diagram and explain the simultaneous inheritance of two genes.

Use Punnett squares to model the inheritance of two traits and predict probabilities of each offspring's allele combination. Use two Punnett squares to model each trait independently, then multiply the probabilities to find the probability of a given allele combination.

Describe how drugs and vaccines help fight diseases caused by viruses.

Vaccinated people produce antibodies that neutralize a disease-causing virus or bacterium. They are much less likely to become infected and transmit those germs to others.

Explain how prions and viroids cause disease

Viroids are plant pathogens that consist of a very short stretch of circular, single-stranded RNA that does not have a protein coat. They are essentially strands of naked RNA. They are much smaller than viruses. Prions are protein particles that can cause other proteins to form abnormal shapes, which causes disease.

Compare and contrast the effects of crossing over, random orientation, and random fertilization on variability among offspring.

When a male gamete and a female gamete finally meet, each is the result of an immense number of genetic possibilities created during independent assortment and crossing over

Explain why one X chromosome is typically inactivated in female cells.

X-inactivation ensures that females, like males, have one functional copy of the X chromosome in each body cell. Because X-inactivation is random, in normal females the X chromosome inherited from the mother is active in some cells, and the X chromosome inherited from the father is active in other cells.

Define apoptosis.

the death of cells which occurs as a normal and controlled part of an organism's growth or development.