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Goal • Use this summary to review the concepts in Unit 2, Reproduction.
Chapter 4 The nucleus controls the functions of life. Chromosomes found within the nucleus contain the genes that store the information to make proteins. (4.1)
Proteins control the activities of cells. (4.1) RNA carries the message out of the nucleus to the ribosomes, which function to make proteins. (4.1)
A gene mutation is a change in the order of the A, G, C, and T bases. (4.2) Gene mutations can have a positive, negative, or neutral effect on the individual. (4.2) Mutations can occur when DNA is being made or can be caused by mutagens. (4.2) Gene therapy attempts to correct gene mutations. (4.2)
Chapter 5 Mitosis is the basis of asexual reproduction. There are three stages to the cell cycle: interphase, mitosis, and cytokinesis. (5.1) There are four phases to mitosis: prophase, metaphase, anaphase, and telophase. (5.1) Checkpoint proteins instruct the nucleus whether to proceed through the cell cycle. (5.1) An error in a checkpoint protein can cause diseases such as cancer, which is the result of uncontrolled cell division. (5.1)
Asexual reproduction requires only one parent, and the resulting offspring are genetically identical to the parent. (5.2)
Types of asexual reproduction include: binary fission, budding, fragmentation, vegetative reproduction, and spore formation. (5.2)
Human-assisted plant and animal cloning methods can be used to save the genetic information of endangered species or to produce an organism with a desired trait. (5.2)
Chapter 6 Meiosis is the basis of sexual reproduction. Meiosis produces gametes with half the number of chromosomes as body cells. (6.1) In meiosis I, homologous chromosome pairs line up at the equator, separate, and then move to opposite poles of the cell. (6.1)
In meiosis II, chromosomes move to the equator and sister chromatids move to opposite poles of the cell. (6.1)
The process of meiosis creates variation in organisms because genetic information is shuffled during meiosis I. (6.1)
Chromosome mutations can occur during meiosis and can cause genetic disorders. (6.1) The three stages of sexual reproduction are mating, fertilization, and development. (6.2) For sexually reproducing plants and animals, there are two ways for a sperm cell and an egg cell to meet—through either internal or external fertilization. (6.2)
The early development of an organism takes place during a stage called embryonic development. (6.2)
Assisted reproductive technologies enable infertile couples to have children. These technologies have an impact on society (6.3)
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Goal • Check your understanding of Chapter 4.
What to Do
Circle the letter of the best answer.
1. The function of the nucleolus is A. to protect the nucleus B. to protect the chromosomes C. to make ribosomes D. to make DNA
2. Which of the following organelles does not have a membrane? A. mitochondrion B. vesicle C. vacuole D. ribosome
3. Which one of the following statements is not true? A. A gene stores the information to make a particular protein. B. All the genes within the nucleus of a cell will be copied to make a protein at some time in the life cycle of a cell. C. Different types of cells in your body contain the same genetic information. D. Different proteins have different sequences of bases.
4. The function of the Golgi body is A. to receive vesicles from the endoplasmic reticulum B. to send vesicles to the endoplasmic reticulum C. to receive messages from the nucleus D. to send messages to the nucleus
5. Which of the following steps for the production of a protein is incorrect? A. The DNA message for a protein is copied into RNA. B. The nucleus receives a chemical signal to make a specific protein. C. The manufactured protein enters the endoplasmic reticulum. D. DNA leaves through the nuclear pore.
6. Chromatin is A. a substance that contains several molecules of DNA within each strand B. a substance within the nucleus that contains DNA and proteins C. a substance that unfolds before cell division D. a segment of DNA that codes for a particular protein
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7. A gene mutation is A. a change in the specific order of the A, G, C, and T bases that make up a particular protein B. a change in the specific order of the sugar and phosphates that make up a particular protein C. a substance that changes the DNA structure D. a substance that causes genes to be copied incorrectly
8. Gene therapy is not used as frequently as drug therapy or surgical therapies because A. the technique is too expensive B. viruses for the procedure are not easily available C. healthy genes are not easily available D. the healthy gene must be switched on in the correct cells
9. Cystic fibrosis is A. an example of a neutral mutation B. an example of a positive mutation C. an example of a negative mutation D. the result of the substitution for the base A for the T base in only one position on the gene
10. The white coat of the Spirit Bear is because of a A. positive mutation B. neutral mutation C. negative mutation D. gene therapy
Match the Term on the left with the best Descriptor on the right. Each Descriptor may be used only once.
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Goal • Use this page to record your observations of onion root tip cell cycle stages for Conduct an Investigation 5-1C, Observing the Cell Cycle in Plant Cells.
What to Do
Using high power on your microscope, find an onion root tip cell at each of the following stages and draw the cell in the appropriate box. Label the chromosomes and spindle fibres.
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Goal • Check your understanding of Chapter 5.
What to Do
Circle the letter of the best answer.
1. The three stages of the cell cycle in order are A. interphase, cytokinesis, and mitosis B. interphase, replication and cytokinesis C. cytokinesis, replication, and interphase D. interphase, mitosis, and cytokinesis.
2. The purpose of DNA replication is to
A. separate the DNA strands B. separate the contents of the cell’s nucleus C. pair new bases with bases on the original DNA D. make an identical copy of the DNA
3. Which of the following is the correct order of the stages of mitosis?
A. telophase, anaphase, metaphase, prophase B. anaphase, metaphase, prophase, telophase C. anaphase, prophase, metaphase, telophase D. prophase, metaphase, anaphase, telophase
4. How does the cell cycle differ in plants and animals?
A. In plants, the daughter cells are not identical to the parent. B. In plants, a cell plate forms between the daughter cells. C. In plants, there are no spindle fibres formed. D. In plants, the centrioles move to opposite poles.
5. Which of the following descriptions does not describe cancer cell growth?
A. Cancer cell growth is highly controlled. B. Cancer cell has large abnormal nucleus. C. Cancer cells move to new locations. D. Cancer cells are unspecialized.
6. Which of the following organisms is not matched with its method of asexual
reproduction? A. yeast, budding B. hydra, binary fission C. sea star, fragmentation D. bacteria, spores
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7. If one cell divided once every hour, how many cells would be produced after eight hours? A. 16 B. 32 C. 64 D. 256
8. Which of the following is a disadvantage of asexual reproduction?
A. Offspring are genetic clones. B. Many offspring are produced. C. Energy is not required to find a mate. D. Large colonies are produced.
9. Which of the following is not a method of vegetative reproduction?
A. forming bulbs B. forming sprouts C. forming runners D. forming spores
10. Which of the following are the correct steps in DNA replication?
A. 1, 2, 3, 4 B. 2, 4, 1, 3 C. 3, 2, 4, 1 D. 4, 2, 1, 3
1. Each side of the ladder is a template on which a new side forms. 2. Enzymes separate the DNA molecule. 3. New bases pair with bases on the original DNA strand. 4. The DNA molecule unwinds.
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Goal • Review your understanding of gametes.
What to Do
In the spaces provided, write the term from the list below that best completes the sentence. Terms may be used more than once. You will not need to use every term.
1. Organisms produce ___________________________ through mitosis. 2. The main job of ________________________ is to join together to produce a new organism. 3. In humans, _________________________ have 46 chromosomes. 4. Gametes are the only cells that are not produced by ___________________________. 5. ________________________________ are the female gametes. 6. ________________________________ are the male gametes. 7. __________________________________ contain the instructions that tell a cell how to develop.
In the space provided, answer the following question.
8. Describe the relationship between chromosome numbers in body cells and gametes.
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Goal • Review your understanding of mitosis and meiosis.
What to Do
Read the statements given below. If the statement is true, write “T” on the line in front of the statement. If it is false, write “F” and rewrite the statement to make it true. ____ 1. Gametes have twice as many chromosomes as other cells.
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Goal • Check your understanding of Chapter 6.
What to Do
Circle the letter of the best answer.
1. Which of the following is the correct order in sexual reproduction? A. meiosis, gamete, fertilization, embryo B. gamete, meiosis, fertilization, embryo C. fertilization, meiosis, gamete, embryo D. gamete, fertilization, meiosis, embryo
2. Mitosis is similar to meiosis II because
A. in both processes, the number of chromosomes is doubled B. in both processes, identical daughter cells are produced C. in both processes, sister chromatids separate and move to opposite poles D. in both processes, homologous chromosomes separate and move to opposite poles
3. Which of the following events occurs in mitosis only?
A. produces genetically different cells B. produces haploid cells C. cells divide two times D. produces genetically identical cells
4. Gamete formation in males is different than in females because
A. in males, meiosis begins before birth and stops until puberty B. in males, meiosis II occurs before meiosis I C. in males, there is equal distribution of cytoplasm into four cells D. in males, there is unequal distribution of cytoplasm into four cells
5. The difference between gene mutations and chromosomal mutations is that
A. a single gene mutation can affect many genes in the chromosomes B. gene mutations are the result of mutagens such as radiation C. chromosomal mutations affect the sequence of the bases D. chromosomal mutations can affect many genes in the chromosomes
6. A mutation that would be inherited must occur in a
A. skin cell B. egg cell C. muscle cell D. cancer cell
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7. Cow body cells have 60 chromosomes. How many chromosomes will be in a sperm cell following meiosis II? A. 30 B. 60 C. 120 D. 15
8. In the gastrula, cells in the mesoderm layer will become
A. kidneys B. skin C. lungs D. liver
9. What is the main advantage of sexual reproduction?
A. Very little energy is required to find a mate. B. Fewer offspring are produced. C. The embryo is protected from dehydration. D. The offspring are genetically different from the parents.
10. The procedure when a single sperm is injected into an egg cell is known as
A GIFT B. ICSI C. AI D. IVF
Match each Term on the left with the best Descriptor on the right. Each Descriptor may be used only once.
Term Descriptor
___ 11. prophase I
___ 12. telophase II
___ 13. anaphase I
___ 14. metaphase II
___ 15. anaphase II
___ 16. prophase II
A. the chromosomes form a single line at the equator
B. sister chromatids move to opposite poles of the cell
C. there is one chromosome of the homologous pair in each cell
D. homologous chromosomes pair up and non-sister chromatids exchange genetic material
E. a nuclear membrane forms around each set of chromosomes
F. independent assortment of chromosome pairs occurs
_____________________________________________________________________________ 18. Explain how sexual reproduction by internal fertilization provides advantages over external
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Goal • Test your understanding of Unit 2, Reproduction.
What to Do
Circle the letter of the best answer.
1. A skin cell functions differently than a muscle cell because A. there are different genes in each cell B. there are different DNA molecules in each cell C. different proteins are made in each cell D. different genes are made in each cell
2. RNA is an important molecule in the cell because it
A. carries information from one generation to the next B. carries information from the cell to the rest of the body C. carries information from the ribosome to the nucleus D. carries information from the nucleus to the cytoplasm
3. If one side of a DNA molecule had the bases ACGTTGACT, the order of the bases on the
other side of the strand would be A. ACGTTGACT B. TGCAACTGA C. GTACCAGTC D. CGCAACTA
4. Which is not a use for gene therapy?
A. to clone an organism B. to replace a mutated gene with a healthy gene C. to deliver healthy genes using inactive viruses to treat cystic fibrosis D. to alter the immune system
5. Which of the following is not a step in DNA replication?
A. The DNA molecule unwinds. B. The steps of the DNA ladder break apart to form a template. C. The RNA is copied from the DNA molecule. D. The new side forms and A pairs with T and G pairs with C.
6. In the DNA sequence GACTGACTGACT, a mutation occurred and the piece of DNA
then contained the letters GACTTGACTGACT. What type of mutation is this an example of? A. deletion B. addition C. substitution D. translocation
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7. People with Down syndrome have A. 47 chromosomes in their karyotype B. 45 chromosomes in their karyotype C. three copies of chromosome 18 D. one copy of chromosome 21
8. The embryonic stage where the embryo cells are arranged into a hollow ball is called a
A. morula B. blastula C. gastrula D. fetus
9. Which event in prophase of mitosis is incorrect?
A. The nucleolus disappears. B. Centromeres pull apart. C. Spindle fibres form. D. Individual chromosomes attach to spindle fibres.
10. Which of the following best describes the events of anaphase 1?
A. Homologous chromosomes pair up at the equator. B. One chromosome from each homologous pair is at each pole of the cell. C. The centromere pulls apart, and the sister chromatids separate and are pulled to opposite poles by the spindle fibres. D. Homologous chromosomes attached to centromeres separate and are pulled to opposite poles by the spindle fibres.
Match each Term on the left with the best Descriptor on the right. Each Descriptor may be used only once.
A. two sets of chromosomes B. formed from the process of fertilization C. produces genetically different offspring D. these cells will form the lungs and liver E. specialized cells needed for reproduction F. the process where duplicated chromosomes
divide in two G. produces variation H. these cells will form the brain I. have the potential to become any type of cell J. process that produces gametes K. only one parent is required to produce offspring
____________________________________________________________________________________________ 22. Explain how the gene message creates a protein in the cell. ____________________________________________________________________________________________
____________________________________________________________________________________________ 23. Why is interphase important for the cell and cell cycle? ____________________________________________________________________________________________
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27. Why may human-assisted plant and animal cloning methods be useful in the future? ____________________________________________________________________________________________
____________________________________________________________________________________________ 28. Describe how the process of fertilization takes place within a flower. ____________________________________________________________________________________________
____________________________________________________________________________________________ 29. What main events occur in fetal development within the first three months following fertilization? ____________________________________________________________________________________________
____________________________________________________________________________________________ 30. What are three societal issues involving reproductive technology? ____________________________________________________________________________________________
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BLM 2-5, Cell Organelles
Cell Part Function
Cytoplasm Gel-like material inside cells
Nucleus Directs cell activities
Endoplasmic reticulum Folded membrane that transports materials inside the cell
Ribosome Manufactures substances important for cell functions
Mitochondrion Releases energy in the cell
Chromatin Mass of dispersed genetic material
Chloroplast Contains chlorophyll, the pigment for photosynthesis
Vacuole Stores water, food, and waste products
Golgi body Stacks of sacs that package and transport proteins
Lysosome Digests wastes BLM 2-7, Extracting DNA from Strawberries
1. plastic bag 2. (a) 5 mL dish soap (b) 2.5 mL table salt (c) 25 mL tap water 3. 5 min 4. one-half 5. ice cold, graduated cylinder 6. layer, three-quarters BLM 2-8, Making Predictions about Mutations
Term Before Reading
What I Think the Term Means/Example
After Reading What the Term Means/Example
Positive mutation Students’ answers will vary.
A change in the DNA that produces a change that benefits the organism
Example: A few people are resistant to HIV infection.
Negative mutation
Students’ answers will vary.
A change in the DNA that produces a change that harms the organism
Example: Substitution of base A for T causes sickle cell anemia.
Neutral mutation Students’ answers will vary.
A change in the DNA that produces a change that neither benefits nor harms the organism
Example: Spirit Bear, since it has no natural predators
Mutagen Students’ answers will vary.
Substance that causes a mutation, such as asbestos, cigarette smoke, X rays
Gene therapy Students’ answers will vary.
Treatment used to correct gene mutations, such as treatment for cystic fibrosis
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BLM 2-9, Chapter 4 Quiz
1. C 2. D 3. B 4. A 5. D 6. B 7. A 8. D 9. C 10. B 11. D 12. C 13. F 14. E 15. A 16. B 17. The nucleus contains DNA, which carries the code to make and specific proteins, such as enzymes and
hormones that perform specific functions in the cell. 18. Three types of gene mutations are deletions, additions, and substitutions. 19. The chart should connect the terms in a similar way to the example below: DNA codes for a protein. The RNA message for a protein is copied from the DNA. RNA leaves through a nuclear pore. RNA goes to the ribosomes, and the protein is made. The protein enters the endoplasmic reticulum. A vesicle forms off the endoplasmic reticulum and goes to the Golgi body. The Golgi body repackages the protein for export out of the cell. BLM 2-11, Stages of the Cell Cycle
Name of Cell Cycle Stage Cell Activities Nucleus Activities
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Phase 2: Metaphase
Spindle fibres pull double-stranded chromosomes across the middle of the cell.
Phase 3: Anaphase
Spindle fibres pull centromeres apart. One of each of the replicated strands moves to opposite poles of the cell.
Phase 4: Telophase
One set of chromosomes is now at each pole of the cell. Spindle fibres disappear. A nuclear membrane re-forms around each set of chromosomes. BLM 2-14, Cell Growth and Division
1. anaphase 2. prophase 3. telophase 4. anaphase 5. interphase 6. cell division 7. prophase 8. cell division 9. metaphase 10. interphase 11. two cells BLM 2-15, The Cell Cycle and Cancer
Questions What I Think What I Learned
Why is it important that there be checkpoints in the cell cycle?
Students’ answers will vary. The cell will die if it divides without enough nutrients, or with too many DNA errors, or if the DNA did not replicate correctly.
What causes a cell to become cancerous?
Students’ answers will vary. A mutation can occur in a checkpoint protein, and then cell cycle control will be lost.
How does a cancerous cell look compared to a normal cell?
Students’ answers will vary. Cells grow in multilayers. The cells have large abnormal nuclei because the nuclei may be full of undivided chromosomes.
How might the cell cycle be related to cancer ?
Students’ answers will vary. With the loss of cell cycle checkpoints, the cell could undergo uncontrolled cell division.
BLM 2-23, Comparing Reproductive and Therapeutic Cloning
Reproductive cloning: produces a clone of an existing organism; the purpose is to clone an individual with desirable qualities
Both: types of human-assisted animal cloning; involve the transfer of a nucleus of one cell into enucleated egg cell Therapeutic cloning: produces a clone of an organ or tissue; the purpose is to correct health problems BLM 2-25, Chapter 5 Quiz
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3. D 4. B 5. A 6. B 7. D 8. A 9. D 10. D 11. D 12. A 13. F 14. C 15. B 16. E 17. Before a cell can continue through the cell cycle there must be enough nutrients to support cell growth, the DNA must be replicated, and the DNA should not be damaged. 18. (a) Binary fission and budding are both methods of asexual reproduction. (b) Differences are that binary fission occurs in unicellular organisms and budding can occur in both unicellular and multicellular organisms. Also, in binary fission one parent cell divides once into two same-sized daughter cells, whereas in budding there may be repeated cell divisions and an unequal-size outgrowth forms off the parent. 19. The main disadvantage of asexual reproduction is that the offspring are genetic clones. If the conditions change or a disease appears it could wipe out the whole population. BLM 2-26, Using DNA to Solve Crimes
1. Students’ answers may vary depending on their responses and those of other students. 2. The key pieces of evidence could have been materials left behind by the thieves that contained fingerprints or DNA, including tools, cigarette butts, and tire tracks. The tree stump leaves the tree ring pattern which could be matched to the stolen log; however, thieves are cutting a piece off the stump so this type of match is not simple. However, sawdust from the tree stump could be matched for DNA with sawdust from cut wood brought to a nearby sawmill. 3. A small sample from each log could be saved, and an inventory of the source of each log could be kept. BLM 2-27, How Variation Occurs in Meiosis
1. body cells 2. gametes 3. body cells 4. mitosis 5. egg cells 6. sperm cells 7. chromosomes 8. Gametes have half the number of chromosomes as body cells.
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BLM 2-29, Key Events in Meiosis
1. (a) 4 chromosomes (b) 8 chromatids 2. Across the centre of the cell 3. (a) To opposite ends of the cell (b) Different 4. Each cell has one chromosome from each pair. Each chromosome is composed of sister chromatids 5. Chromosomes are not paired. 6. Sister chromatids separate as they do in mitosis. 7. (a) 4 new cells (b) Half the number of chromosomes BLM 2-30, Compare the Events of Meiosis and Mitosis Key
Meiosis I Mitosis
Prophase I Prophase (early and late)
• nucleolus disappears • nuclear membrane disappears • spindle fibres form • homologous chromosomes pair up and each attach to spindle fibres • non-sister chromatids exchange genetic material (crossing over)
• nucleolus disappears • nuclear membrane disappears • spindle fibres form • individual chromosomes attach to spindle fibres
Metaphase I Metaphase
• homologous chromosomes pair up at the equator • chromosomes form a single line at the equator
Anaphase I Anaphase
• spindle fibres contract and shorten • homologous chromosomes attached to centromeres separate and are pulled to opposite poles by the spindle fibres
• spindle fibres contract and shorten • the centromere pulls apart, and the sister chromatids separate and are pulled to opposite poles by the spindle fibres
Telophase I Telophase
• one chromosome from each homologous pair is at each pole of the cell • the spindle fibres disappear • the nucleolus appears within each nucleus • the nuclear membrane forms
• one complete set of chromosomes is now at each pole of the cell • the spindle fibres disappear • the nucleolus appears within each nucleus • the nuclear membrane forms
Interkinesis Cytokinesis
• cell divides in two (not genetically identical to parent cell) • cell will grow and make proteins like interphase in mitosis • no replication of DNA in this stage
• cell divides in two (genetically identical to parent cell) • cell will grow and make proteins like interphase in mitosis • DNA will replicate later in interphase
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Meiosis II Mitosis
Prophase II Prophase (early and late)
• nucleolus disappears • nuclear membrane disappears • spindle fibres form • individual chromosomes attach to spindle fibres
• nucleolus disappears • nuclear membrane disappears • spindle fibres form • individual chromosomes attach to spindle fibres
Metaphase II Metaphase
• X-shaped chromosomes form a single line at the equator
• X-shaped chromosomes form a single line at the equator
Anaphase II Anaphase
• spindle fibres contract and shorten • the centromere pulls apart and the sister chromatids separate and are pulled to opposite poles by the spindle
• spindle fibres contract and shorten • the centromere pulls apart, and the sister chromatids separate and are pulled to opposite poles by the spindle
Telophase II Telophase
• half of a complete set of chromosomes is now at each pole of the cell (one chromosome for each pair)• the spindle fibres disappear • the nucleolus appears within each nucleus • the nuclear membrane forms
• one complete set of chromosomes is now at each pole of the cell • the spindle fibres disappear • the nucleolus appears within each nucleus • the nuclear membrane forms
Cytokinesis Cytokinesis
• cell divides in two (total four daughter cells not genetically identical to parent) • cell will grow and make proteins like interphase in mitosis
• cell divides in two (genetically identical to parent) • cell will grow and make proteins like interphase in mitosis
BLM 2-31, Compare the Results of Meiosis and Mitosis
Comparing Mitosis and Meiosis Meiosis Mitosis
1. Type of cell undergoing reproduction gamete body cell
2. Number of chromosomes before cell begins to divide 4 4
3. Number of chromosome pairs in original cell 2 2
4. Final number of chromosomes in each new cell at the end of division
2
4
5. Chromosome pairs in each new cell at end of division none
2
6. In mitosis, chromosomes are not paired, but they do line up along the cell centre. In meiosis, chromosomes first line up and then become arranged along the cell centre. 7. The locations are the same, but in meiosis, in each pair of sister chromatids, the original and copy are still attached to each other.
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8. Mitosis produces two cells identical to the original one. Meiosis produces four cells, each with half the chromosomes of the original one. 9. The resulting organism would have twice the normal number of chromosomes. BLM 2-32, Mitosis and Meiosis
1. D 2. F 3. A 4. E 5. C 6. B 7. G 8. Student answers should include the following points. • Mitosis produces diploid cells, or body cells. • Meiosis produces haploid cells, or gametes. BLM 2-33, Gamete Summary
1. Trait Sperm Cell Egg Cell Both Sperm Cells
and Egg Cells
Has a tail
Has 23 chromosomes
Involved in fertilization
Formed in testes
Contains cytoplasm
Motile
Produced by meiosis
Formed in ovaries
Has a food reserve
Forms a zygote
2. A zygote is produced by the union of sperm and egg; the sperm fertilizes the egg. BLM 2-36, Cell Reproduction
1. False. Gametes have half as many chromosomes as body cells. 2. T 3. T 4. False. Gametes are formed during meiosis. 5. T 6. T 7. False. There is one cell division during mitosis. 8. False. During sperm cell production, four haploid sperm cells are produced. 9. T
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BLM 2-38, Chapter 6 Quiz
1. A 2. C 3. D 4. C 5. D 6. B 7. A 8. A 9. D 10. B 11. D 12. E 13. F 14. A 15. B 16. C 17. Variation is produced through independent assortment and crossing over in meiosis and the meeting of egg and sperm in fertilization. 18. Sexual reproduction by internal fertilization provides advantages since there is more protection for embryos and more parental care of offspring, and offspring are genetically different. 19. Answers should include: Some infertile couples are able to have a child. Couples can select embryos to exclude embryos with genetic defects. Parents trying to help cure a sick child can screen and select embryos for tissue matches. Extra embryos can be made available for stem cell research. BLM 2-39, Unit 2 Test
1. C 2. D 3. B 4. A 5. C 6. B 7. A 8. B 9. B 10. D 11. E 12. F 13. H 14. I 15. B 16. J 17. A 18. C 19. D 20. G 21. The nucleus contains the genes that store the information to make proteins, and proteins have many different functions within the cell such as to function as enzymes and hormones.
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22. The gene message creates a protein in the cell when the DNA is copied into RNA message. Then RNA leaves the nucleus through the nuclear pores in the membrane and RNA travels to the ribosome, where proteins are made. If proteins are to be shipped out of the cell, proteins enter the endoplasmic reticulum for transport. Vesicles form off the endoplasmic reticulum and travel to the Golgi body for repackaging before they leave the cell. 23. Interphase is important for the cell and cell cycle because this is when DNA is replicated. New organelles and chemicals are made in preparation for cell division. 24. Types of asexual reproduction are binary fission seen in bacteria or amoebas, budding seen in sponges or yeast, fragmentation seen in algae or sea stars, and spore formation seen in ferns and mosses. 25 Differences between mitosis and meiosis are: two daughter cells result from mitosis, four daughter cell from meiosis; the chromosome number is diploid or 2n following mitosis and is haploid or n following meiosis, the genetic information is the same in the daughter cells following mitosis, the genetic information is different in daughter cells following meiosis 26. Mutations are errors in the DNA caused by errors when the DNA replicates or caused by environmental mutagens such as X rays and chemicals. They can be errors in the bases within a gene or can be large chromosomal errors where whole pieces of chromosomes are lost, duplicated, or moved to another chromosome. 27. Human-assisted plant and animal cloning methods will be useful in the future to produce a greater food supply with pest-and drought-resistant crops, to grow organs for transplant, and to help maintain endangered species. 28. A flower is fertilized when the pollen, the male gamete, lands on the stigma of the flower and a pollen tube forms which delivers the sperm to the ovule or ovary which contains the egg and where fertilization takes place. 29. The main events in fetal development that occur within the first three months following fertilization are the formation of the brain and spinal cord; fingers appear; and eyes, kidneys, lung, liver, and muscles develop. 30. Answers may vary, but may include: that they may cause a slightly higher number of birth defects: what to do with leftover embryos; the issue of inequity, since some couples cannot pay for the procedure; and who the parents are.
