REAL bio final TENNANT

The cells of an organism contain two alleles for every

gene

Traits are controlled by factors called

genes

Gametes, which contain only 1 set of chromosomes, are called _____________ (N) cells.

haploid

Codominance

occurs when both alleles are expressed equally in the phenotype of the heterozygote.

Incomplete dominance

occurs when the phenotype of the offspring is somewhere in between the phenotypes of both parents; a completely dominant allele does not occur.

One allele comes from each

parent

What is the difference between allopatric and sympatric speciation?

-Also known as geographic speciation, is speciation that occurs when biological populations of the same species become isolated due to geographical changes such as mountain building or social changes such as emigration. -The process through which new species evolve from a single ancestral species while inhabiting the same geographic region.

Name and describe three sources of genetic variation in the gene pool of a population.

-Mutations- changes in the DNA -Re-combine new genes from sexual reproduction- Mother and father's genes combining to create a new one/ introducing new genes/ genetic shuffling -gene flow- any movement of genes from one population to another one

Explain the difference between chromatin, chromosomes, and sister chromatids.

-the material of which the chromosomes of organisms other than bacteria (i.e., eukaryotes) are composed. It consists of protein, RNA, and DNA. -a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes. -pieces of identical DNA that are crucial in the process of cell replication and division

Name and describe the three types of substitution mutations.

1. change a codon to one that encodes a different amino acid and cause a small change in the protein produced. For example, sickle cell anemia is caused by a substitution in the beta-hemoglobin gene, which alters a single amino acid in the protein produced. 2. change a codon to one that encodes the same amino acid and causes no change in the protein produced. These are called silent mutations. 3. change an amino-acid-coding codon to a single "stop" codon and cause an incomplete protein. This can have serious effects since the incomplete protein probably won't function.

the haploid number of chromosomes is ________

23

In humans, the diploid number of chromosomes is ______

46

What is genetic drift? Describe the two types.

A change in a population's gene pool by chance Founders effect and Bottleneck effect

Why are sex-linked disorders more common in males than females?

A sex-linked disorder is any diseases or abnormality that is determined by the sex chromosomes (e.g. hemophilia). Most sex-linked disorders are carried on the X chromosome. Considering that the human males only possess one X chromosome, it seems plausible that recessive disorders (carried on the X chromosome) are more common in males than in female humans. This is the case because in females, a normal gene on their other gene masks the recessive disorder from being expressed. In order for a female to inherit a sex-linked disorder they would need to be homozygous for the disorder. That is why it is less likely for females to inherit sex-linked disorders compared to human males.

Fossil record

Because fossils that are dug up have shown similarities to common animals . This leads to supporting evolution.

Explain why smaller cells are more efficient than larger cells.

Because the surface area- volume ratio is better. Also, it helps it move around easier and quicker.

Homologous structures

Because they are skeletal elements that are found common in different animals. Because of their similarity, it leads scientists to believe that they were once a common ancestor/ supporting evolution.

What is cancer? What causes cancer?

Cancer is when abnormal cells divide in an uncontrolled way. Some cancers may eventually spread into other tissues. Cancer cells differ from normal cells in many ways that allow them to grow out of control and become invasive. One important difference is that cancer cells are less specialized than normal cells. That is, whereas normal cells mature into very distinct cell types with specific functions, cancer cells do not. This is one reason that, unlike normal cells, cancer cells continue to divide without stopping. This bunch of extra cells can make a tumor. Cancer is caused by changes to certain genes that alter the way our cells function. Some of these genetic changes occur naturally when DNA is replicated during the process of cell division. But others are the result of environmental exposures that damage DNA. Cancer is caused by accumulated damage to genes. Such changes may be due to chance or to exposure to a cancer causing substance. The substances that cause cancer are called carcinogens. A carcinogen may be a chemical substance, such as certain molecules in tobacco smoke. The cause of cancer may be environmental agents, viral or genetic factors. We should bear in mind, though, that in the majority of cancer cases we cannot attribute the disease to a single cause.

What is a mutation?

Changing of the structure of a gene, resulting in a variant form that may be transmitted to subsequent generations, caused by the alteration of single base units in DNA, or the deletion, insertion, or rearrangement of larger sections of genes or chromosomes.

Genes are found on DNA structures called ________________ within the nucleus of the cell.

Chromosomes

Molecular comparisons (DNA, protein)

Comparison between nucleic acid bases and amino acids. The natural base pair substitution can be put into a molecular clock. It supports the theory of evolution because it can go back and show a common ancestor.

Summarize Darwin's theory of evolution using the following terms: adaptation, fitness, natural selection, common descent.

Darwin defined evolution as "descent with modification," the idea that species change over time, give rise to new species, and share a common ancestor. The mechanism that Darwin proposed for evolution is natural selection. Because resources are limited in nature, organisms with heritable traits that favor survival and reproduction will tend to leave more offspring than their peers, causing the traits to increase in frequency over generations. Natural selection causes populations to become adapted, or increasingly well-suited, to their environments over time. Natural selection depends on the environment and requires existing heritable variation in a group. The central concept of natural selection is the evolutionary fitness of an organism.Fitness is measured by an organism's ability to survive and reproduce, which determines the size of its genetic contribution to the next generation. Darwin's theory of common descent is a basic theory in modern biology which states that different species of living organisms can ultimately be traced to a single common ancestor. Ultimately, at least in theory, it leads to the conclusion that all forms of life-bacteria, fungi, plants, and animals-can be traced back to a single universal common ancestor. Over hundreds of millions of years, life branches from a single species into multiple ones through natural selection.

For a new species to evolve (speciation), ____________________ isolation must occur between populations of organisms. Name and describe the three types of isolation that can cause this to occur.

Geographical-Features such as rivers or mountain ranges isolate groups. Movement of land-masses by continental drift led to geographical isolation millions of years ago. Ecological-Although groups are not geographically isolated from each other they may be isolated by such things as occupying different habitats or breeding areas, pH, salinity. Reproductive-Breeding between groups within a population may not be possible because of differences in courtship behaviour, physical differences which prevent mating, or failure of gametes to fuse.

Compare the gradualism and punctuated equilibrium theories about the pace of evolution.

Gradualism is selection and variation that happens more gradually. Over a short period of time it is hard to notice. Small variations that fit an organism slightly better to its environment are selected for: a few more individuals with more of the helpful trait survive, and a few more with less of the helpful trait die. Very gradually, over a long time, the population changes. Change is slow, constant, and consistent. Punctuated equilibrium is change comes in spurts. There is a period of very little change, and then one or a few huge changes occur, often through mutations in the genes of a few individuals.

Multiple alleles

Mendel's work suggested that just two alleles existed for each gene. Today, we know that's not always, or even usually, the case! Although individual humans (and all diploid organisms) can only have two alleles for a given gene, multiple alleles may exist in a population level, and different individuals in the population may have different pairs of these alleles. Blood Type is an example.Multiple alleles makes for many possible dominance relationships. Within a population, however, more than two alleles can exist (although any given individual still only has two alleles).

During which process do point mutations occur?

Normally, this type of mutation takes place during DNA replication. change within a gene in which one base pair in the DNA sequence is altered. Frequently the result of mistakes made during DNA replication, although modification of DNA, such as through exposure to X-rays or to ultraviolet radiation,.... Include______ mutations

Vestigial structures

Often homologous to structures that are functioning normally in other species. Therefore,_____________________ can be considered evidence for evolution, the process by which beneficial heritable traits arise in populations over an extended period of time.

Analogous structures

Pertain to the various structures in different species having the same function but have evolved separately, thus do not share common ancestor. HOwever, because they share the same function, this supports evolution

What are some potential benefits of stem cell research? Why is it controversial?

Regenerative medicine By directing stem cells to differentiate into specialised cell types, there is the exciting possibility to provide a renewable source of replacement cells for those suffering from diseases. Examples of diseases that could benefit:Parkinson's disease,Type I diabetes, Arthritis. Burn victims, Cardiovascular diseases Embryonic stem cells The main ethical objections are to human embryonic stem cell research, because early-stage human embryos are destroyed during the process of deriving their stem cells.

Asexual reproduction

Reproduction occurs when an organism makes more of itself without exchanging genetic information with another organism through sex.

How do mutations affect organisms?

Some mutations don't have any noticeable effect on the phenotype of an organism. This can happen in many situations: perhaps the mutation occurs in a stretch of DNA with no function, or perhaps the mutation occurs in a protein-coding region, but ends up not affecting the amino acid sequence of the proteins

What is the Hardy-Weinberg principle?

The Hardy-Weinberg equilibrium is a principle stating that the genetic variation in a population will remain constant from one generation to the next in the absence of disturbing factors. When mating is random in a large population with no disruptive circumstances, the law predicts that both genotype and allele frequencies will remain constant because they are in equilibrium.

Comparative embryology

The comparison of embryo development across species. All embryos pass from single cells to multi-celled zygotes, clumps of cells called morulas, and hollow balls of cells called blastulas, before they differentiate, creating the organs and systems of the body. Through the process of comparing all different embryos from different species, it shows that embryos of certain species look similar, supporting the theory of evolution.

What is non-disjunction? Explain how this type of mutation affects the gametes produced by meiosis.

The failure of homologous chromosomes or sister chromatids to separate properly during cell division. Results in trisomy or monosomy of certain chromosomes (ex: trisomy 21 = down syndrome)

In humans, which parent determines the sex of a child? Explain.

The father determines the sex of a child because the mom has two X chromosomes and the dad has a Y chromosome and an X chromosome. One from each parent determines the sex but since mom always gives an "x" then the chromosome from dad determines if it will be "XX" (girl) or "XY". (boy)

What is cell differentiation? How does this process relate to stem cells?

The process by which a less specialized cell becomes a more specialized cell type is called cell differentiation. This is a process which is seen in multicellular organisms. The organism changes from a single zygote to a complex system of tissues and cell types Common process in adults: adult stem cells divide to make fully-differentiated daughter cells during tissue repair and during normal cell turnover.

Sexual reproduction

The production of new living organisms by combining genetic information from two individuals of different types (sexes). In most higher organisms, one sex (male) produces a small motile gamete that travels to fuse with a larger stationary gamete produced by the other (female).

Name and describe the four types of chromosomal mutations.

These changes are most often brought on by problems that occur during meiosis (cell division process of gametes) or by mutagens (chemicals, radiation, etc.) This mutation can result in changes in the number of chromosomes in a cell or changes in the structure of a chromosome.

What is a karyotype?

What is the difference between an autosome and a sex chromosome? A karyotype is a chart including all the different chromosomes, including the 2 sex chromosomes. An autosomal chromosome is a chromosome that is any of the 22 top chromosomes on the karyotype chart. The last 2, the sex chromosomes, come from your mother and father.

Describe the Law of Segregation and the Law of Independent Assortment. Both are laws of heredity

When an organism makes gametes, each gamete receives just one gene copy, which is selected randomly. The principle, originated by Gregor Mendel, stating that during the production of gametes the two copies of each hereditary factor segregate so that offspring acquire one factor from each parent. The principle, originated by Gregor Mendel, stating that when two or more characteristics are inherited, individual hereditary factors assort independently during gamete production, giving different traits an equal opportunity of occurring together.

stabilizing

a type of natural selection in which the population mean stabilizes on a particular non-extreme trait value.

disruptive

also called diversifying selection, describes changes in population genetics in which extreme values for a trait are favored over intermediate values.

What is a mutagen? What are some examples of mutagens.

an agent, such as radiation or a chemical substance, that causes genetic mutation. -radioactive substances, x-rays, ultraviolet radiation, and certain chemicals.

directional

an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype.

Polygenic traits

are controlled by more than one gene, and each gene may have two or more alleles. The genes may be on the same chromosome or on nonhomologous chromosomes. If the genes are located close together on the same chromosome, they are likely to be inherited together. However, it is possible that they will be separated by crossing-over during meiosis, in which case they may be inherited independently of one another. If the genes are on nonhomologous chromosomes, they may be recombined in various ways because of independent assortment. For these reasons, the inheritance of polygenic characteristics is very complicated. Such characteristics may have many possible phenotypes. Skin color and adult height are examples of polygenic characteristics in humans.

What is polyploidy? How does this type of mutation affect plants? What about animals?

cells and organisms are those containing more than two paired (homologous) sets of chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two sets of chromosomes—one set inherited from each parent. is common among plants and has been, in fact, a major source of speciation in the angiosperms animals are far less common, and the process appears to have had little effect on animal speciation.

The zygote and somatic cells, which contain 2 sets of chromosomes (one set from each parent), are called ______________________ (2N) cells.

diploid

Which two mutations are considered "frameshift" mutations? Explain why.

insertions and deletions can alter a gene so that its message is no longer read correctly This is because a frameshift mutation is a mutation which alters the was someone sees the framework in DNA. The framework "Shifts" and this is caused by either taking out part of a gene, or adding an extra part of a gene.

These cells are produced by the process of ______________.

meiosis

What is genetics?

the study of heredity and the variation of inherited characteristics