outcome 3a: describe the relationship of dna, chromosomes...

Objective 3 1

Objective 3: To learn the role of genetic material in species’ survival and variation This objective is further broken down into 5 outcomes

• Outcome 3A: Describe the relationship of DNA, chromosomes, and genes • Outcome 3B: Distinguish between mitosis and meiosis and describe what

happens at fertilization • Outcome 3C: Compare advantages and disadvantages of sexual and asexual

reproduction • Outcome 3D: Distinguish between examples of natural and artificial selection • Outcome 3E: Describe technologies for recombining genetic material

• Outcome 3A: Describe the relationship of DNA, chromosomes, and genes Genetic material

Variation is a characteristic of life. It is an important part of ecosystems and a feature of human populations. Later you will learn more about the importance of variation in adaptations. How are all of these things linked? The answer is found in the cell's nucleus. In Grade 8 Science you learned that the nucleus is the control centre of the cell and contains the genetic material. But what does the control centre do, how does it work, and what is "the genetic material"? • DNA: The secret of life

Philosophers and scientists have searched for the secret of life for thousands of years. Genetically speaking, the answer is a molecule called deoxyribonucleic acid (better known as DNA). Swedish chemist Johann Miescher collected DNA from the nuclei of certain cells in 1868. It was not until later that scientists could explain how this seemingly simple substance could carry out all of the functions of the genetic material. The genetic material had to be able to reproduce itself, move from parent to offspring, and control all the structures and functions of cells. In addition, the structure of the genetic material had to be able to explain variation within and between species.

Once scientists worked out the structure of DNA, they were able to explain how the molecule could do everything the genetic material had to do. Structurally a molecule of DNA has the shape of a coiled ladder. The rungs of the ladder are pairs of nitrogen bases that come in four different forms: adenine (A), thymine (T), guanine (G), and cytosine (C). Nitrogen base “A” forms chemical bonds with “T”, and C bonds with “G”. It is the pattern of these 4 molecules along our DNA that give cells the instructions to build a human being. A nucleic acid, along with the side part it is attached to make up a nucleotide, which is the building block of DNA. There is a square box around one nucleotide in the diagram to the right. Many of these nucleotides together make up long strands of DNA. DNA contains all the instructions for an organism’s characteristic features. Because every organism has so many physical and chemical characteristics, there is a lot of DNA in a cell. If the DNA from a typical human body cell was stretched out, it would be about two meters long, more than a billion times longer than the cell it came from! To fit such a large amount of DNA into cells, the cell must arrange it into packages. These packages are called chromosomes.

Objective 3 2 • Chromosomes

Chromosomes are tightly coiled strands of DNA that are found in the nucleus of our cells. Generally, each human body cell has 46 chromosomes. These chromosomes are found in 23 pairs, with one copy of each chromosome coming from each parent. It is important that each cell in the body has a complete set of chromosomes. As a result, the formation and movement of a new set of chromosomes is an important part of cell division. The diagram in the top right hand corner of the page shows the 23 pairs of chromosomes that make a human. In each pair, one chromosome came from the mother and the other came from the father. Each cell in the human body will have 46 chromosomes (23 pairs) with the exception of the gametes (sperm and egg cells). Sperm and egg cells only have 23 chromosomes in total. When they combine, the 46 chromosomes necessary to make a human being are present (23 +23 = 46).

• Genes Current scientific knowledge shows us that genes are

responsible for the inheritance of an organism's characteristic features. A single gene is an uninterrupted segment of DNA, which contains coded instructions for a specific trait. Much of the early research into genes was carried out on the fruit fly. Fruit flies were good to study because their life spans were so short (about 1-2 months). Because of this short life span, inherited characteristics could be studied from one generation to the next in short periods of time. Researchers found:

! Genes are located on the chromosomes ! Each chromosome contains numerous genes (thousands) ! As shown in the diagram above, chromosomes come

in pairs (1 from each parent). As a result genes come in pairs.

! The gene pairs may not carry instructions for the same thing (one may be for brown eyes and the other for blue eyes.)

! Which gene is actually expressed to make up a trait may depend on which one is dominant.

The last point above goes back to dominant vs recessive genes. Remember that everyone has two genes for each trait. Chromosomes come in pairs and one gene for a certain trait will be on one chromosome and the other gene will be on the other chromosome. The code may be different and whichever one is dominant will be expressed (unless that trait shows incomplete dominance in which case both genes will partly contribute to make up a certain trait). To the right is an example of how chromosome pairs are split up into many genes. DNA strands are extremely long and are split up into thousands upon thousands of genes that each code for different parts of the organism it makes up.

Objective 3 3 • How nucleotides, DNA, chromosomes, and genes are linked.

1. What are the four functions of genetic material?

-Reproduce itself (for cell division) -Move from parent to offspring (through gametes) -Control all functions of cells -Explain variation (within and between species)

2. What is a chromosome?

A tightly wound strand of DNA

3. How many chromosomes are there in a human? How many come from the mother and how many come from the father?

46 chromosomes (23 from mother, 23 from father)

4. What is a gene?

An uninterrupted segment of DNA that codes for a trait

5. People can either bend their thumb back or they can’t and a single gene is responsible for this ability. How many genes for this ability did you inherit? Explain (this isn’t a trick question but you do need to think about it)

2, but only 1 is expressed (which ever gene was dominant)

6. Which of the following is false? A. There may be thousands of genes on each chromosome B. Chromosomes come in pairs, and therefore genes for each trait you have also comes in

pairs C. You have two genes for each trait, and the two genes always carry identical

instructions D. Chromosomes are bunched up strands of DNA

C (they may carry different instructions)

Objective 3 4

7. The gene for turning peas green is dominant while the gene for turning peas yellow is recessive. A plant that produces green peas is mated with one that produces yellow peas and results in a green pea producing plant. In this new plant, the gene for turning the peas yellow is

A. Still part of the DNA B. Not part of the DNA

A Use following pictures to answer next 6 questions

8. What is the part labeled as “I”

Nucleus 9. What is the part labeled as “II”

Chromosome 10. What is the part labeled as “III”

DNA 11. What is the part labeled as “IV”

Nucleotide 12. What is the part labeled as “V”

Gene 13. Which one is the individual

chemical molecule that forms the genetic code?

Nucleotide

……….

• Outcome 3B: Distinguish between mitosis and meiosis and describe what happens at

Objective 3 5 fertilization

You have learned that the outcome of asexual reproduction is the production of offspring genetically identical to the parent. You have also seen that the outcome of sexual reproduction is the production of offspring that are genetically different from their parents. Scientists have spent many centuries exploring the processes that result in these outcomes. Cell division • Mitosis

When a unicellular paramecium splits to form two new organisms during binary fission, its cell contents are divided equally between the two new cells. But if its DNA molecules were divided between the two organisms, each new individual would have only half the DNA of the parent cell, and half the genetic information it would need to function. To avoid this, the parent cell first makes an exact copy of its DNA, and each chromosome doubles. For a short time, the parent cell has twice the amount of DNA it usually has. When the cell eventually divides, each new cell gets one complete copy of the DNA.

In multicellular organisms, such as humans, roses, and fruit flies, the process that produces two new cells with the same number of chromosomes is called mitosis (which seems very similar to binary fission, except mitosis happens to cells that make up larger multi-celled organisms, such as ourselves whereas binary fission occurs to unicellular organisms such as the amoeba). Mitosis occurs in the body cells of multicellular organisms and is responsible for the growth and cellular repair of a multicellular organism. Mitosis is the process in which the zygote undergoes cell division to form the embryo and eventually a baby and then an adult. Basically, it is responsible for you growing from one single cell to an organism made up of trillions of cells. It is also the process that allows cells to be replaced when needed such as when you cut yourself. Just like binary fission, mitosis is a form of asexual reproduction that results in two new cells that are genetically identical to the “parent” cell.

Human cells have 46 chromosomes. Therefore when mitosis starts, the chromosomes must double to 92. When the cell splits into two cells, each identical cell is given 46 chromosomes.

• Meiosis

Objective 3 6 Which type of human cell has only 23 chromosomes? These cells are the sex cells (gametes); the

sperm and eggs. Only when an egg and sperm join to form a zygote does the new cell have a complete set of chromosomes. Meiosis, the process of forming the gametes (sex cells), begins in the same way as the division of body cells. Prior to cell division, each chromosome is copied. There are 2 major differences between mitosis and meiosis. One is that before the cell divides in meiosis, the genes are shuffled up so that the new cells are not identical. The other difference is that in meiosis, cell division occurs two times. The final result is that the gametes have only half the original number of chro-mosomes as the original parent cell. In humans this means that each sperm or egg has only 23 chromosomes. The process of randomly dividing 23 pairs of chromosomes in half creates the possibility of 8.4 million (223) different combination of chromosomes! Any one of these combinations may be passed on to a gamete. In the zygote, 23 chromosomes from each parent were combined to result in the 46 chromosomes needed for a human being. When the sperm and egg combine, the genes are shuffled up even more, which is why there can be so much variation in organisms that reproduce sexually. Since meiosis is only the process of sex cell (gamete) formation, it will not occur until an organism reaches the age at which it can reproduce (puberty in humans).

The process of meiosis can also lead to certain genetic abnormalities. Chromosomal conditions such as Down syndrome of Klinefelter syndrome where there is an extra sex chromosome are a result of mistakes during meiosis. Normally female humans have two “X” sex chromosomes (XX) while male humans have an “X” and a “Y” (XY). Chromosomal conditions can result in offspring having additional chromosomes such as (XXY), (XXXY) and other combinations that result in structural and/or cognitive differences. Chromosomal conditions are not usually inherited like many other conditions that are due to specific genes. For example, color blindness or Tourette’s syndrome are due to specific genes that can be passed from parent to offspring but most chromosomal conditions are due to a mistake during the production of a specific sperm or an egg (meiosis) so two parents without Down Syndrome can suddenly have a child that does have Down Syndrome. Therefore, conditions linked to specific genes are much more predictable as to if the offspring will inherit that condition. Note that the example chromosomal conditions above were talking about the sex chromosomes but abnormalities can happen on other chromosomes.

Chromosome

Objective 3 7 number throughout a human life

The diagram below traces the number of chromosomes through the human life cycle

14. What is the process in which body cells divide called?

Mitosis

15. What is the formation of sex cells (gametes) called?

Meiosis

16. Mitosis is the name of cell division found in multi-cellular organisms. What is this process called when it happens to a single celled organism such as the amoeba?

Binary fission

17. Fill in the number of chromosomes at each step of mitosis in humans

-Original parent cell has – 46 - chromosomes -Chromosomes double to – 92 - -Cell divides and both new cells have – 46 – chromosomes

18. Fill in the number of chromosomes at each step of meiosis in humans

-Original parent cell has – 46 - chromosomes -Chromosomes double to – 92 - -Cell divides and both new cells have – 46– chromosomes -These 2 cells split again. The 4 new cells (gametes) each have – 23 - chromosomes.

19. A cell undergoes meiosis and forms 4 gametes (either 4 sperm cells or 4 egg cells). Are any of the gametes the same? Explain

No. Because the genes are shuffled around during meiosis

20. What are chromosomal abnormalities and what causes them?

Abnormalities where the offspring receives at least one extra chromosome. A mistake during meiosis can cause them.

Objective 3 8 Use the following picture to answer the next question (assume this species only has 2 chromosome)

21. The above cells

A. are part of the mitosis process only B. are part of the meiosis process only C. are part of both mitosis and meiosis

C Use the following picture to answer the next question (assume this species only has 2 chromosome)

22. The above cells are cells that are in the process of either mitosis or meiosis. Which of the

following is true? A. The two cells are the final product of mitosis B. The two cells are the final product of meiosis C. The two cells are undergoing mitosis, but the process still has another step to go D. The two cells are undergoing meiosis, but the process still has another step to go

D Use the following picture to answer the next question (assume this species only has 2 chromosome)



A Use the following picture to answer the next question (assume this species only has 2 chromosome)



B 25. Worms have 50 chromosomes in their body cells. Which of the following correctly traces the

number of chromosomes in the production of their sex cells? A. 50 " 100 " 25 B. 50 " 100 " 50 C. 50 " 100 "50"25 D. 50 "100"200"100"50 C

Objective 3 9

Objective 3 10

• Outcome 3C: Compare advantages and disadvantages of sexual and asexual reproduction

Variation helps a species survive by giving it the ability to survive changes in its environment. You have seen that the way an organism reproduces (sexual vs asexual) affects how much variation will occur in its offspring. Asexual reproduction produces no variation in heritable characteristics. Could it ever help a species not to have variation?

Advantages and Disadvantages of Asexual Reproduction Asexual reproduction does not require any specialized cells or a way of bringing gametes together.

As a result, asexual reproduction can produce lots of individuals very quickly. For example, if conditions are right, a bacterium can reproduce asexually every 20 min. Over a 12-h period, a single bacterium can divide to produce 10 million copies of itself. This is a great advantage in environments that do not change very much. For example, bacteria that live in the gut of an animal will always have a warm, moist environment to live in while the animal is alive. Producing many copies of a bacterial cell that is suited to that environment is a safer bet for survival than producing a smaller number of bacteria with many variations that may never be needed. Species that reproduce asexually invest energy to produce as many identical copies of themselves as possible to build a large population quickly. Another advantage of asexual reproduction is the ability to reproduce without a partner. This is especially useful if the species has a low population of individuals that may never come into contact with each other.

The main disadvantage of asexual reproduction is that if conditions become unfavorable, an entire population (or perhaps an entire species) may be wiped out. For example, every single one of those 10 million identical bacteria could be killed if they have no resistance to a certain antibiotic that is applied to them.

Advantages and Disadvantages of Sexual Reproduction Sexual reproduction has the advantage of providing lots of variation, which helps species survive

environmental change. The main disadvantage of sexual reproduction is that it takes a lot of energy. A flowering plant, for example, has to produce all the parts of its flower, as well as pollen grains and ovules (eggs) in order to reproduce. The flower parts must provide a way for the gametes to meet, such as producing lots of pollen to be blown by the wind or by attracting pollinators. Also, once the pollen reaches an egg to form an embryo, the flower must protect and nurture the embryo in a seed until the seed is dispersed. And despite all this, not all seeds will actually grow into a plant as many get eaten by animals or destroyed in some other way. Therefore, an organism that reproduces sexually puts a lot of energy and time into producing a relatively small number of variable offspring. This is true not only for plants but animals that reproduce sexually as well. They too must invest a great deal of energy into having a relatively small number of offspring.

Another disadvantage of sexual reproduction is that it takes a lot of time to produce offspring, which results in less offspring being produced. Even in sexually reproducing species like the fruit fly that can reproduce relatively quickly, it would take weeks for them to double their population, whereas asexually reproducing bacteria could double their population within an hour.

Objective 3 11 26. An advantage of asexual reproduction is that it does not require gametes finding a way to

join. Name 2 other advantages and then one disadvantage of asexual reproduction Advantage: -Reproduce many individuals quickly

-Ability to reproduce without a partner Disadvantage: Entire species can be wiped out if environment changes

27. What types of environments would species that reproduce asexually most likely be found in?

Ones that don’t change very much 28. A population of 10 bacteria make their way onto a loaf of bread on the counter top. Draw a

graph that shows how their population will increase if the population doubles every hour through asexual reproduction.

29. Name one advantages and then two disadvantages of sexual reproduction Advantage: Offspring have variation Disadvantage: -Wasted energy -Takes a long time to produce offspring

30. Fruit flies reproduce sexually (and compared to other sexually reproducing species, they can reproduce very quickly). It takes about 6 days for their population to double. Draw a graph showing their population size over the course of 24 days, if the population started at 1000 on day zero.

Objective 3 12

• Outcome 3D: Distinguish between examples of natural and artificial selection

Organisms are selected for their traits • Artificial selection (selective breeding)

What did you have for breakfast this morning? Did you have cereal or toast? How about a glass of orange juice? The particular grains and fruits used in these and many other foods are probably a product of artificial selection. Artificial selection (selective breeding) is the process of selecting and breeding individuals with desirable traits to produce offspring that have these desired traits. Consider the example of horse breeding. By combining the genes of champion parents, breeders hope to create offspring that have the prized traits of both parents. If those horses are bred with other champion horses when they reach maturity, the chances of producing the desired traits in succeeding generations increase. The same is true of breeders of other animals such as livestock (cows, sheep, pigs) and domestic animals (dogs, cats, birds, guinea pigs, hamsters). In a breeder's population, however, every individual is selected in the same way. Only those with a trait the breeder wants, such as a particular feather color, in the case of domestic finches, will be allowed to breed. In contrast, natural selection "selects" traits that are useful for the survival of the individuals with those traits and allows them to breed.

Artificial selection can also be applied to both food and ornamental plants. For example, by taking the seeds of the healthiest or best producing plants and sowing them the following year, farmers can generally "weed out" less desirable traits and promote more desirable ones. Humans have practiced artificial selection since we first began to farm about 10 000 years ago. After so many generations of artificial selection, most of our plants no longer resemble the wild species from which they were bred. Corn, for example, was bred by native peoples from a species of grass called teosinte. Teosinte produced much smaller cobs and far fewer seeds than modern-day corn. Every generation of teosinte would have produced millions of small teosinte pods and perhaps a thousand large pods. There would be a few that would be born extraordinarily large every generation, perhaps due to some genetic mutation. Farmers would choose to use seeds from only the extraordinarily large pods to grow the next year. This pattern continued for thousands of years finally giving rise to what we know as corn today. Artificial selection has created nearly everything we eat today.

• Natural selection Charles Darwin was a scientist who lived in the 1800’s and realized that all species of life have evolved over time from common ancestors through a process known as natural selection. He traveled to the Galapagos Islands and found 14 different species of finches, each similar, but with certain adaptations which allowed them to live in their slightly different environments. For example, on islands that had food which was protected from a shell (such as walnuts), finches had thicker, stronger beaks. But on islands that had insects within tree bark, finches had longer, skinnier beaks. Darwin realized that as a species inhabits an area, the individuals with advantageous traits for that specific environment will more likely live long enough to reproduce. Those without advantageous traits for that environment would more likely die before reproducing. For example, on the island with walnuts, finches with thick beaks would reproduce more than ones with long thin beaks who would not be able to break into the walnuts. But on an island with insects that live within tree bark, the thick beaked finches would be more likely to starve to death, with the long, thin beaked finches living to reproduce. Natural selection “selected” differently in the two distinct environments.

Objective 3 13 You may have heard the term “survival of the fittest” before. This term was originally used to explain how the individuals within a species with the best traits for that environment will survive and pass on their genes while the ones with traits that aren’t as good for that environment will die.

The theory of natural selection can be summed up in four statements I. All organisms produce more offspring than can possibly survive

II. There is incredible variation within each species so each offspring will have some unique characteristics

III. Some of the variations of characteristics, by chance, help some of the individuals survive in the current environmental conditions. Some individuals are born with characteristics that do not help and sometimes are a disadvantage.

IV. The individuals that did NOT acquire helpful characteristics die off and do not pass on their genes. The ones that were born with helpful characteristics pass these on to their offspring. This is how a species’ genetic characteristics adapt to the current environmental conditions.

31. Put an “N” if the organism is due to natural selection and an “A” if it is due to artificial selection

bananas A

wolf…

N pit bull

A

rhino….

N

ant……. N

rat….

N wheat

A

cow

A

32. Dogs are an example of artificial selection

(selective breeding). Name two traits that humans have caused almost all dogs to have due to artificial selection

Cuteness, obedience

33. If you sell sheep fur and own ten female and ten male sheep, which two animals would you want to put in a pen together so they can make offspring?

Fluffiest male and fluffiest female

34. Purebred animals are sometimes very unhealthy. For example, Great Danes often have weak hearts and Dalmatians commonly become deaf. Would you expect to see similar health problems in wild animals? Explain your answer

No. Unhealthy animals in the wild die

35. Which of the following statements is TRUE? A. In artificial selection, humans select traits that

will help the species survive in nature B. In nature, a species will produce more

offspring than can possibly survive C. In natural selection, parents chose to give their

offspring traits that will help them survive

B

36. Summarize the four statements of natural selection (each sentence can be summarized with less than 8 words) 1 Species make lots of offspring

2 Offspring have great variation

3 Some, by chance, have helpful

variations 4 These offspring will more likely

reproduce

Use the following information to answer next question I. Durum wheat is very high in protein which is

why it’s used to make foods such as bread II. Gophers have front paws that are good for

digging holes in the ground III. The roots of pine trees are efficient at sucking

up water allowing them to live in times of little rainfall

IV. Lemon sharks grow a new set of teeth every two weeks

37. Which adaptation above is the result of artificial selection?

I

Objective 3 14 ------

• Outcome 3E: Describe technologies for recombining genetic material Biotechnology

Biotechnology is the use of living things to make agricultural or medicinal products. It includes artificial selection (which you learned about in the last outcome) but it also includes creating clones, artificial insemination, in vitro fertilization and genetic engineering. • Artificial selection (selective breeding)

You learned about artificial selection (selective breeding) in the last outcome. Artificial selection has been occurring for thousands and thousands of years. Early people who grew crops in the Middle East knew that using seeds of the largest plants would result in the next generation of plants to be larger than the generation before it. Artificial selection has successfully produced most of our world’s crops and livestock, but it takes a very long time (many generations of the plants and animals) to get an organism with the desired combination of traits. For instance, livestock breeders had to breed cows over hundreds of generations to get a whole herd that produces the large quantities of milk we see today. Scientists and breeders have, therefore, developed technologies that can speed up this process. These technologies described below can range from “low tech” to extremely “high tech.”

• Artificial insemination Artificial insemination

is a method of artificially joining a male and female gamete. Most livestock in Canada are produced by artificial insemination. An example of this is harvesting sperm from a bull with desired characteristics and inserting it into many female cows. The advantage of this technology is that the bull's sperm can be in several places at once and more cows can be inseminated. The disadvantage is that there is no way to guarantee that a sperm will actually fertilize an egg.

• In vitro fertilization Another method of artificially joining a

male and female gamete is in vitro fertilization in which a sperm is inserted directly into an egg. An example of in vitro fertilization would be taking sperm from a prize bull and eggs from a prize cow, and then (in a laboratory) using a very small needle to inject the sperm into the egg. This produces many more embryos than could be produced naturally. Each embryo is then implanted into a different cow. These cows will eventually give birth to many calves, all of which will be brothers and sisters. An advantage of in vitro fertilization over artificial insemination is that fertilization is guaranteed.

Objective 3 15 • Cloning

Cloning is the process of creating genetically identical copies of a plant or animal. Cloning in plants can be done easily by taking a cutting off a plant with desirable traits and then planting that cutting, which will grow into a genetically identical plant. This process of taking cuttings is done by people routinely and is a way of cloning many identical individuals from one plant that is deemed to have desirable traits.

Cloning in animals is a more difficult task. You learned earlier that very few animals can reproduce asexually, in which a genetically identical offspring is a “clone” of the parent. Most animals reproduce sexually and don’t create clones. However, humans have learned how to take the DNA out of a sexually reproducing organism and grow identical clones from that DNA. Scientists first cloned a sheep, but have now cloned other animals like rats, cats, horses, pigs and deer.

• Genetic engineering Genetic engineering refers to any technology that

directly alters the DNA of an organism. Genetic engineering is a rapidly developing science, and every new advance increases our ability to control the characteristics of organisms. Many of the genetic engineering techniques involve inserting a gene from one species into another species. When genes are inserted into DNA by humans it is called splicing.

Bacteria are genetically engineered to produce life-saving medicines such as insulin. Insulin is a substance that many diabetics use to control the level of sugar in their blood. Just 20 years ago, insulin had to be extracted from the pancreas of cattle, and it was expensive to produce. Today, the human insulin-producing gene is spliced into the bacteria's DNA. Because the bacteria reproduce so rapidly, bacterial colonies can produce insulin quickly and cheaply. Now most of the world's supply of insulin comes from genetically engineered bacteria.

Another example of genetic engineering has been used to help protect crops and decrease the use of pesticides. A micro-organism called Bacillus thuringiensis produces a toxin commonly called Bt, which is poisonous to many insects. Scientists have isolated the gene that contains the instructions for making Bt toxin and have spliced it into the DNA of plants. These genetically engineered plants now produce Bt toxin! Since the 1990s, cotton, corn, and potatoes have been engineered to produce Bt toxin. Because insects that eat the engineered plants die, growers never need to apply pesticides to the genetically engineered plants.

Objective 3 16 Questions regarding biotechnology

Using biotechnology raises many questions. Does biotechnology “tamper with nature?” Are there unknown harms to the environment, people, or other organisms that come with specific biotechnologies? Remember, DNA is extremely complex. Ecosystems are also extremely complex. If we start altering the DNA found in those ecosystems and creating organisms that wouldn’t naturally be found there, unforeseen things could take place. Ecosystems and the food chains within those ecosystems are in a natural balance. It is impossible to predict what will happen if one part of the food chain has its DNA tampered with in some way.

38. What is biotechnology? The use of living things to make agricultural or medicinal products

39. Which type of biotechnology has the longest history of use?

Artificial selection (has been used for thousands of years)

40. Below are 5 examples of biotechnology. Indicate which type of biotechnology belongs beside each example. Each type of biotechnology can be used more than once

The sperm is taken out of a male bee, and inserting it into a female bee Artificial insemination The sperm is taken out of a male bee, an egg is taken out of a female bee, and these sex cells are put together by a scientist.

In vitro fertilization Only female bees that produce a lot of honey are allowed to breed with male bees

Artificial selection A gene is taken from the DNA of a firefly, and spliced into a plant. The plant now produces light, just like a firefly does.

Genetic engineering Only the seeds of the brightest roses are used for growing more roses Artificial selection A sperm of a male sheep is combined with the egg of a female sheep inside a Petri dish. Once an embryo is formed, it is put inside a female sheep where it will grow until it is born.

In vitro fertilization

The branch of a strawberry plant is cut off, and then planted in a garden. A new strawberry plant then grows and it is identical to the original plant

Cloning

41. What is an advantage of in vitro fertilization over artificial insemination?

Fertilization is guaranteed

42. You see a raspberry plant that grows excellent raspberries and you want to have many more just like it. What should you do?

Clone it by taking several cuttings and then growing them

Objective 3 17 43. Which of the following about taking cuttings of a tomato plant is false?

A. There will be a better chance of survival in the next generation if the environment changes B. There would be no genetic variation in the next generation of individuals C. The next generation can be produced relatively quickly D. Taking the cuttings is an example of cloning

A

44. How is insulin produced today for people with diabetes? The gene for insulin is taken from a human and put into bacteria, which will then produce insulin

45. When a gene is inserted into a strand of DNA it is called – splicing -.

46. How can genetic engineering help farmers reduce the need to use pesticides to protect their crops from pests?

Taking a gene that produces a toxic substance and putting into the crops they want to protect. The insects then die when they eat the crop

47. Give one reason why humans should be carful when altering the DNA of an organism found in an ecosystem.

Could have unforeseen effects on rest of ecosystem

Objective 3 18

Objective 3 19 Plants (and animals) that reproduce sexually invest a lot of energy to have genetically variable offspring. Most gametes do not actually meet other gametes to form zygotes (in plants the zygote is found in the seed as seen in the dandelion seeds to the left.) And even once seeds are formed, not all of them will actually find conditions that will allow them to grow into an organism.

Objective 3 20

Objective 3 21

Objective 3 22

Objective 3 23

Objective 3 24

Objective 3 25

Objective 3 26 Parent cell. Only 2 chromosomes are shown but in humans there would be 46. Size of cell doubles. Chromosomes double in size. There are still only 2 chromosomes (46 for humans).

outcome 3a: describe the relationship of dna, chromosomes...

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