Evidence for evolutions

What is the genome

complete set of DNA in each cell of an organism. *examination of the genome of our closest living relatives, the chimpanzees show that they share more than 98% of our DNA.

What is often referred to as 'junk DNA ' and why

non-coding sequences of bases in the DNA. They have no apparent function and appear to serve no purpose

Embryology

comparing the very early stages of the development of organisms

How many genes does Mitochondria DNA have. And briefly outline what they do.

37 genes, all of which are essential for the mitochondrion to function normally. 24 of the genes contain the code for making transfer RNA molecules, which are involved in protein synthesis. The other 13 genes have instructions for making some of the enzymes necessary for the reactions of cellular respiration. *Some rare diseases may be caused by mutations in mitochondrial DNA.

What has comparative genomics revealed

A high level of similarity between closely related organisms e.g. humans and chimpanzees. It has also been used to reveal the diversity of the gene composition in different evolutionary lineages.

Why are endogenous retroviruses good examples of non-functional DNA that is relevant to evolution

A retrovirus only becomes endogenous if it inserts into a cell whose chromosomes will be inherited by the next generation. (ovum or sperm cell) The offspring of the infected individual will then have a copy of the ERV in the same place, in the same chromosome, in every single one of their cells. All subsequent generations will also have a copy of the ERV at the same location. What scientists have found is that ERVs make up 8% of the human genome, and that other primates also possess some of the same ERVs in exactly the same locations in their genomes. *So when it is found that 16 instances of human ERVs match exactly with the chimpanzee's. It is compelling evidence that humans and chimpanzees share a common ancestor.

Transfer RNA (tRNA)

A small RNA molecule that transfers the correct amino acid to the ribosome for inclusion in the protein molecule being made.

Pyramidalis muscles , vestigial

About one fifth of the population don't develop the muscles that lie above the pubic bone, the pyramidalis muscles. Even if they are present, do not make any difference to muscular performance.

Inheritance of mitochondrial DNA

After a sperm has penetrated the egg at fertilisation, the mitochondria in the sperm are rapidly destroyed. This means that our nuclear DNA comes from the nucleus of the egg and the sperm, but our mitochondrial DNA comes only from the egg. *We inherit nuclear DNA from both parents but we inherit mitochondrial DNA only from our mothers.

Ubiquitous proteins

Amino acid coding has been done for a number of proteins that appear to be in all species and they are referred to as ubiquitous proteins. Such proteins perform very basic but essential tasks that all organisms require for life. They are found in all organisms from bacteria to humans and are completely independent of an organism's specific function or the environment in which it lives. Such proteins carry out the same functions no matter where they are found.

How do primates today provide evidence of geographical distribution happening

As a result of shared ancestry and geographical isolation, lemurs are limited to the island of Madagascar, New World monkeys are only found in the Americas, and Old World monkeys in African and Asia. Interestingly, Darwin's knowledge of geographical distribution, and the work of other scientists suggest that humans most resemble chimpanzees and gorillas, led him, in 1871, to predict that Africa was the most likely place to find fossils of human ancestors. Which was correct.. The earliest ancestors of modern humans were found there.

How does mtDNA help with the study of evolutionary relationship

Because of these mutations human mtDNA has been slowly diverging from the mtDNA of our original female ancestor, and the amount of mutation is roughly proportional to the amount of time that has passed. Scientists are able to use the similarity between the mtDNA of any two individuals to provide an estimate of the closeness of the relationship through their maternal ancestors.

Why is it easy to find and extract mtDNA rather than nucleus DNA

Most cells contain large numbers of mitochondria and therefore usually have 500-1000 copies of the mtDNA molecule, making it easier to find and extract and so smaller samples can be used.

What is mitochondrial DNA or mtDNA

Most of a cell's DNA is located in the nucleus but a small amount is in the mitochondria. Thats mtDNA

Classic example of homologous structure

Classic example - the forelimbs of vertebrates. The same bones appear in various forms throughout the vertebrates - the feet of amphibians and reptiles, the wings of bats and birds, the leg of a horse, the flipper of a whale or seal and the human hand. *The bones are arranges in a similar way, even though some have developed different functions.

What is Mitochondrial DNA (mtDNA)

DNA found in the mitochondria

Rate of mitochondria mutations

DNA found in the mitochondria has a higher rate of mutation than nuclear DNA.

What is nuclear DNA (nDNA)

DNA found in the nucleus of cells

How dose DNA sequencing help with studying evolution

DNA sequencing facilitated by gel electrophoresis and bacterial enzymes (restriction e) can be used to establish a DNA profile. - It helps trace ancestry and relationships between individuals and groups.

Darwin's finches - the observations

During Darwin's time in South America, he encountered finches on the South American mainland but when he visited the Galapagos Islands, he found the finches there were quite different. One species of finch had managed to fly to these islands, while many other species of birds had not. With no competition, the finches of the Galapagos Islands had evolved by taking advantage of the range of food sources on offer. In this way, their beaks had gradually changed over time to better enable the different populations to survive. Eventually they evolved into 13 separate species.

What does the gill slits in human embryos develop into

Eustachian tube, and tissue surrounding other gill slits develops into the thyroid gland and tonsils.

Geographical distribution

Further evidence for evolution is found in the natural geographic distribution of related species. Isolated land areas and island groups have frequently evolved their own distinctive plant and animal populations

Idea of evolution

Gradual change in the characteristics of species over many generations

Tail , vestigial

Humans still have the vertebrae for a tail, fused to form the coccyx and an appendix

The religious view of the creation of the universe

Most religions include the concept of a god as the creator of the universe and of life on Earth. The Jewish and Christian idea of God as creator is described in the book of Genesis, the first book of the Bible, where there is a beautiful account of the creation of the Earth and it's life forms.

Muscles at the base of hairs , vestigial

In mammals with fur or spines, and in birds with feathers, these tiny muscles pull the hair or feature upright, creating a layer of insulating air to protect against the cold. However, human hair is so fine that it is not capable of such a function and the contractions of the muscles is seen as goose bumps

How can PCR help with studying evolution

It can be used to amplify minute amounts of DNA so that it can be used to facilitate the sequencing of the genome. Because significant amounts of a sample of DNA are necessary for molecular and genetic analysis, studies of isolated pieces of DNA are nearly impossible without PCR amplification. - especially important with fossil evidence as only very small amounts of DNA may be available

How has bioinformatics helped with evolutionary studies

It has been particularly useful in assisting evolutionary biologists to trace the evolution of a large number of organisms by measuring changes in their DNA rather than through traditional techniques of physical taxonomy and physiological observations.

How does comparative genomics contribute to the study of evolution

It helps to identify genes that are preserved among species, as well as genes that give each organism its unique characteristics.By analysing the genomic features that have been preserved in a number of species over millions of years, researchers are beginning to tease apart the often subtle difference between animal species.

What is comparative anatomy

It involves comparing the structural features of related animals to ascertain the degree of similarity between them. Similarities in structure often suggests that species have a common ancestor

What is comparative genomics

It is a relatively new field of biological research in which the genome sequences of different species are compared. By comparing the sequence of the human genome with genomes of other organisms, able to identify regions of similarity and difference.

What are endogenous retroviruses (ERVs)

It is a viral sequence that has become part of an organism's genome. Retroviruses store their genetic information as RNA, not DNA.

How does Cytochrome C help with evolution evidence.

It is a well-researched example of a ubiquitous protein that shows how protein sequences can provide evidence for evolution. *Human cytochrome C contains 104 amino acids. Regardless of the species tested, 37 of these have been found at the same positions in every sequenced cytochrome C molecule. This strongly suggests that these proteins have descended from an ancestral cytochrome C molecule found in a primitive microbe that existed more than 2000 million years ago.

How does Darwin's finches show natural selection and speciation

It is an example of natural selection and speciation because mainland species go to different islands and diverge into new species as natural selection adapted them to the local environment. - The first finches to reach the Galapagos Islands would have shown variation in beak shapes. These would have been part of the natural variation that exists in all species. - All different beaks would have an advantage on feeding on different types of food. - On islands with a lot of a specific food source, natural selection would have favoured a particular shape of beak - favourable characteristics would be passed on to offspring - beaks of other shapes would have been favoured on another island with that corresponding food source. - Over many generations, natural selection would favour those characteristics that aid survival on a particular island. - the populations of finches on the various islands would have gradually become diverse enough to be regarded as different species.

What is bioinformatics

It is the use of computers to describe the molecular components of living things. It is a multidisciplinary field that combines all areas of biological science with computer science, statistics and applied mathematics to help understand biological processes.

What is comparative embryology and how does it help with evolution study

It provides evidence for evolutionary change over time by comparing the early stages in the development of organisms.In vertebrates, comparing the embryonic stages reveals a remarkable similarity between different species at different times. They are all similar in the early stages, having embryonic gill pouches and arches. The presence of such structures is significant if the vertebrates are viewed as an evolutionary series that began with fish hundred of millions of years ago. *evidence of common ancestry with later evolution along different pathways

Nicitating membrane, vestigial

Its a transparent third eyelid, found in cats, birds, frogs and other vertebrates, is only represented in humans by a pinkish membrane located at the inner corner of each eye.

Ribonucleic acid (RNA)

Large molecule composed of a single strand of nucleotides

Male nipples, vestigial

Males also have nipples on their chests, although some would argue that these should not be termed vestigial, as they had no function in the first place, they appear to be retained in males because all human foetuses develop from the same basic genetic form, and nipples do have an important function in females.

Comparative protein studies provide evidence for evolution

Modern biochemical techniques enable the sequence of amino acids in a protein to be determined, and as the particular amino acids in a precise sequence is determined by DNA, by comparing the type and sequence of amino acids in similar proteins from different species, the degree of similarity can be established. *Animals of the same species have identical amino acid sequences in their proteins, and those from different species have different amino acids or they are arranged in a different order. *the longer period of time involved, the greater the number of amino acids that are different

Biological scientists view of the theory of evolution

Most accept the theory of evolution as fact due to the evidence that supports it. There are also many scientists, including many eminent biologists, who have strong religious convictions and don't find the symbolic interpretation of the creation to be incompatible with biological evolution.

Homologous organs

Organs that are similar in structure but are used in different ways

Vestigial organs

Organs that may once have been important but have lost or changed their function.

Other ubiquitous proteins

Other alpha and beta chains of the blood protein haemoglobin are identical in humans and chimpanzees, but the same protein sequences in gorillas differ by one amino acid. When the same chains are examined in gibbons, there are 3 amino acid differences. A comparison of the delta chain indicates that humans differ from chimpanzees and gorillas by one amino acid, and from gibbons by 2. It provides more support for the evolutionary relationships between primates than DNA comparisons.

Why does the sequence of bases in the DNA vary

because new genes are gained by mutation; others are lost by natural selection, genetic drift or some other process.

What do proteins consist of

Proteins consist of long chains of amino acids and some proteins may contain as few as a hundred amino acid units while other contain thousands

Messenger RNA (mRNA)

RNA molecules that carries the code for protein synthesis from the DNA in the nucleus to the ribosomes where the protein is made

The miscibility of religion and theory of evolution

Science doesn't have the answer to every question, it has limitations such as questions relating to the meaning of life, are beyond the scope of scientific investigation. It is the task of each of us to ponder and perhaps eventually arrive at our own answer to these questions. The important thing to remember is that acceptance of the theory of evolution doesn't preclude a belief and faith in a god.

How is DNA related to evolution

Scientists have determined that all living things use the same DNA code, adding weight to the hypothesis that all living things are related to each other and have evolved from a common ancestor.

How do homologous structures contribute to evolution

The forelimb bones are described as homologous organs because they possess a similar structure. Organisms possessing organs that are similar in structure are likely to have a common ancestor. Therefore the arrangement of the bones of the forelimb in such a range of vertebrates is convincing evidence that they have all evolved from a common ancestor.

Anthropoids, legs, homologous structures

The human like primates anthropoids have a similar arrangement of muscles in their legs compared to the humans. These 2 species share a common ancestor and are therefore closely related.

Ears, vestigial

The muscles that move the external ears of many mammals are reduced to such an extent in humans that, in most individuals they will not move the years at all

Wisdom teeth, vestigial

The third molars in humans or wisdom teeth erupt abnormally and cannot be used in mastication, frequently they are removed before eruption so that they don't become painful. About 1/5 of the population are spared any discomfort because the third molars do not develop at all.

Christianity and their views on creation of life

They believe that the Bible is the word of God, and for some groups they believe that the Bible is literally true in every detail so they think the account in Genesis is a description of the actual events of creation so these people don't believe in biological evolution. *Other Christians see the Bible story of creation as symbolic; a story written to explain the origins of life to people lacking the scientific knowledge that we have today.

What is Cytochrome C

This protein performs an essential step in the production of cellular energy. It appears to have changed very little over millions of years of evolution.

How does restriction enzymes help in DNA sequencing

To sequence DNA it is necessary to cut it into smaller fragments. Many DNA-digesting enzymes can do this, but no use in sequencing as they cut each molecule randomly. Where as restriction enzymes can slice the DNA at few precisely located sites so that a small set of homogeneous fragments are produced.

Single letter codes for amino acids

Usually amino acids are represented by a three letter code, frequently the first three letters of their name. To make comparison of amino acid chains easier, scientists have also adopted a system of coding whereby one letter is used to represent one particular amino acid. By listing the amino acids for a particular protein in sequence, a comparison can be made with other species.

How does vestigial organs help with evidence for evolution

Vestigial structure are largely or entirely functionless when their original role is being considered. Some may retain lesser functions or develop new ones. so they contribute to an understanding of how different species may be related to one another. *evolutionary mechanisms can be used to explain the existence of many of these no function structures. They are what remain of organs that were functional in ancestral forms. Over time, and with changing environmental conditions, such organs were no longer essential to survival and were gradually reduced to vestigial remnants. *As these remnants are not harmful in any way they haven't been completely eliminated. *Natural selection has reduced the organs to non-functional remnants because it would have been a waste of the organism's energy and resources to maintain useless structures. *Such organs will probably disappear altogether as there is no selection pressure to retain them.

When has the use of mtDNA found to be of most value

When comparing individuals within a species and for species that are closely related. In this way it has allowed scientists to track the ancestry of many species back hundred of generations. *Analysis of mtDNa has become an important tool in mapping the relationships between species

Retrovirus entering a cell

a retrovirus copies its RNA genome into DNA - a process known as reverse transcription. The DNA then becomes inserted into one of the host cell's chromosomes.

How many DNA molecules in mtDNA

about 5 to 10 of these molecules is each mitochondrion

How does natural geographical distribution in Australia contribute to evolutionary studies

before humans arrived in Australia, there were more than 100 species of kangaroos, koalas and other marsupials but none of the more evolutionarily advanced terrestrial placental mammals. Also the living representatives of the primitive egg-laying mammals, the echidna and platypus, are found only in Australia with one exception, the echidna that is found in New Guinea, an island very close to Australia, the most likely explanation is that the unique species found in Australia had been evolving in isolation fro the rest of the world for millions of years.

DNA

deoxyribonucleic acid is the chemical compound that makes up the genes and it is DNA that determines the type of proteins a cell can make. It is a very large molecule made of 2 strands of nucleotides that are joined by bonds between the nucleotide bases. The two strands are twisted into a double helix. Found in the nucleus and mitochondria of cells.

What are the common embryonic features in vertabrates

embryonic gill pouches and arches, absence of paired appendages and the presence of a well-developed tail. 2 chambered hearts and similar brain development.

Amount of mitochondria in the eggs and sperm cells

human eggs and sperm both have mitochondria, but while an egg has many hundred, a sperm has only about 100- just enough to provide the energy for the sperm to swim to the egg.

The chromosome number in humans and chimpanzees

humans have 23 pairs of chromosomes while chimpanzees have 24 pairs. *Scientists believe that this can be explained by two small chromosomes found in chimpanzees having fused to form one of the human chromosomes at some time in the past.

What is annotation

identifying the genes and other biological features in a DNA sequence. It needs to be computerised as most genomes are far too large to be annotated by hand. Annotation is made possible by the fact that genes have recognisable start and stop codons.

Comparisons of junk DNA

it provides similar results as those for other parts of the genome-more closely related species have more junk sequences in common. This observation only makes sense if related species have evolved from a common ancestor

What is the structure of mtDNA

it's in the form of small circular molecules. Not like the very long strands of DNA in the nucleus

When speciation occurs, how would the DNA variation be?

the new species would have very similar DNA. However, as the new species gradually change through the evolutionary processes, they accumulate more differences in their DNA. *Species that are more distantly related have more differences in their DNA, whereas species that are more closely related share a greater portion of their DNA.

What is mitochondria

they are the organelles in the cell where the aerobic phase of respiration occurs to release energy for use by the cell.

How to compare cytochrome C sequences

they need to be aligned so that the maximum number of positions containing the same amino acids can be determined. The more similarity there is between 2 molecules, the more recently they have evolved from a common ancestor. By doing such comparisons, scientists have determined that the cytochrome C of chimpanzees and gorillas is the same as that for humans.

What has more recent developments in bioinformatics enabled researchers to do

to compare entire genomes. The genes and other biological features in a DNA sequence need to be identified, a process termed annotation.