Complete Review - CR Chapter 12 and 13 Spring 2014 PDF

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Bio 1 Chapter 12 and 13 review -Spring 2018...

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BSC 2010 Review Sheet – Chapter 12 and 13

last updated Spring 2018

Chromosomes and Cell Division

Answer the following questions as completely as possible, referring to your class notes and textbook. They are designed to help you process and review course material. Questions on quizzes and exams will also deal with these topics, but will be specific and in a M/C and T/F format. Quiz and exam questions may not be limited to the topics covered here.

1. For what reason(s) do cells of single celled organisms divide?

How about

multicellular organisms? What type of cell division is involved in each case? 1. grow/development (differentiation) 2. repair/regeneration 3. reduction (only reason for single cell) b. Prokaryotes: All are single-celled organisms! i.Have ONE CIRCULAR chromosome. 1.copied by DNA Replication (Ch. 16) ii.Cells divide by BINARY FISSION. 1.NOT mitosis, NOT meiosis! 2.cells always divide with adequate nutrients c. Eukaryotes: more complicated i.membrane-bound organelles 1.mitochondria, chloroplasts 2.ER, Golgi, Nuclear Envelope a. Disintegrates (comes apart) and reconstructs in daughter cells ii.More chromosomes iii.Two Types of cell division 1. Mitosis 2. Meiosis 2. Summarize what occurs during each of the 4 phases of the cell cycle. What is G0 phase? At what point of the cycle can cells ‘decide’ to enter G 0? 1. G1-S-G2-M: 

G1 and G2: separate S/M; growth occurs; prep for next phase

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S： ： chromosome duplication; DNA synthesis

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M: cell divide：mitosis (division of the nucleus); cytokinesis (division of the cytoplasm)

2.G0: cell exit the cycle and exist in a Non-dividing state. G1 enter G0 3. Explain how the frequency of cell division varies in the tissues of an adult multicellular organism. How does G0 phase fit in? Give examples of human cell types from lecture. 1. Continuous (skin cells) 2. Based on need (liver) G0 3. Rare/never (muscle, nerve cell) G0 4. Most human cells are in G0 4. The terms gene, genome, DNA, chromosome, replicated chromosome, sister chromatids, and chromatin are distinct ways of referring to genetic material. What does each term mean? How do terms relate to one another other? Compose sentences such as “_____ is made out of _____,” or “_____ is composed of _____(a number)

_____.”

1. A repicated chromosome contain 2 sister chromatids (each contain 1 DNA) 2. Chromatin: DNA wrapped around proteins

3. Chromatin pack tightly to be chromosome 4. A genome is the whole group genetic information, contained in every cell 5. What are the two basic functions of histones? 1. Histones: DNA is wrapped around histone proteins. i.

help maintain chromatin structure

ii.

help to REGULATE genes (ON/OFF)

6. Comment on chromosomal structure and how it changes over the course of the cell cycle—particularly between interphase and M phase—and why. 

Interphase: The chromatin (coiled histones and DNA) condenses into chromosomes for efficient packing. The

chromosomes are then replicated and are known as sister chromatids. 

Prophase: chromosomes condense

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Metaphase: chromosomes in the middle

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Anaphase: the sister chromatids separate into individual chromosomes.

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Telophase: the chromosomes uncoiled and becomes less condensed.

7. Describe the appearance and the location of the chromosomes, the nuclear envelope, and the mitotic spindle during the five stages of mitotic cell division, as pictured in Figure 12.6. 

Prophase: –chromosomes CONDENSE –centrosomes begin moving to opposite ends –spindle begins to form

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Prometaphase: –nuclear envelope DISINTEGRATES –microtubules grab chromosomes by their centromeres

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Metaphase: –chromosomes in the MIDDLE

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Anaphase: –chromosomes are pulled APART –cell ELONGATES

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Telophase: –TWO nuclear envelopes REFORM –chromosomes DECONDENSE

8. Explain how two types of cytoskeletal fibers—discussed in Chapter 6—become reorganized during cell division to help pull apart chromosomes and pinch the cell in two. Include in your answer the terms mitotic spindle, kinetochore microtubule, nonkinetochore microtubule, centrosome, centromere, kinetochore, tubulin, actin, and cytokinesis.

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The mitotic spindle is a structure made of microtubules and proteins that controls chromosome movement during mitosis. In animal cells, assembly of spindle microtubules begins in the centrosome, the microtubule organizing center. 

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Microtubules bind to the kinetochores at the centromere and are now called kinetochore microtubules. Non-kinetochore microtubules are also involved in mitosis. They make contact with the plasma membrane opposite their respective poles. They push against each other, elongating the cell. During cytokinesis, the contractile ring formed by actin interacting with myosin forms a cleavage furrow that will split the cell into daughter cells.

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two types of cytoskeletal fibers: microtubules and microfilaments -microtubules: forms the spindle and pulls apart (made of

tubulin) -microfilaments: form cleavage and pinch (made of actin) -mitotic spindle begins to form in the cytoplasm during prophase (in animal cells, this start at centrosome – a subcellular region containing material to organize cell’s microtubules) -kinetochore – structure of proteins at the centrosome (two face in opposite directions) -kinetochore microtubules – when spindle microtubules attach to kinetochores (prometaphase)

9. Explain what homologous chromosome pairs are and why we have them. Then explain the difference between autosomes and sex chromosomes. Finally, comment on which are homologous and which are not. 

homologous chromosome pairs: pairs that carry the same genes BUT NOT IDENTICAL; same length, centromere position, and staining pattern; one from each parent

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-female (XX homologous) … male (XY small parts are homologous)-male have 22 homologous…female have 23 (all)

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-X and Y chromosomes = sex…..other chromosomes = autosomes

10.Contrast somatic cells and gametes with respect to their 1) ploidy (diploid v. haploid), 2) number of chromosomes in humans, and 3) locations in the body of organisms. -number of chromosomes represented in a single set = n

-somatic cells (body cells) – two chromosome sets = 2n = diploid -for humans, diploid number is 46 -zygote -gametes (sperm and eggs) – haploid – for humans, 23 (22 autosomes plus single sexchromo)…in the gonads 11. Summarize the events of the animal sexual life cycle. Include in your answer the terms meiosis, fertilization, gametes, the zygote, diploid cells and haploid cells. -side note: there are three sexual life cycles: animals, plants/algae, most fungi/some protists -animal sexual life cycle: -gametes are the only haploaid cells -meiosis occurs in germ cells during production of gametes -fertilization: union of gametes…result in zygote -after fertilization, the diploid zygote divides by mitosis -IF gametes were made by mitosis, normal chromosome number would be 92 instead of 46

12.As you did for #7 above, describe the appearance and location of the chromosomes, nuclear envelope, and spindle during the stages of meiotic cell division, as pictured in 13.8. -Meiosis I – separates the homologous chromosomes -Prophase I (PAIR) – chromosomes begin to condense; spindle formation; nuclear envelope breakdown -Metaphase I (ALIGN) – chromosomes align on metaphase plate -Anaphase I (SEPARATE) – guided by spindle -Telophase I and Cytokinesis – two haploid cells; each chromosome still have two sister chromatids -Meiosis II – separates the sister chromatids -Prophase II – spindle forms; chromosomes (still composed of two chromatids) move toward metaphase II plate -Metaphase II – chromosomes aligned on metaphase plate -Anaphase II – chromatids separate -Telophase II and Cytokinesis – nuclei form; chromosomes begin decondensing; four daughter cells (each with haploid set)

13.What occurs during synapsis, and which chromosomes does it involve? Include the terms tetrad, chiasma, and crossing over in your answer (refer to the textbook as needed). -Synapsis – when replicated homologs pair up and become physically connected along their lengths by a zipper-like protein structure… ends in mid-prophase-crossing over occurs here -Chiasma – X-shaped region – physical manifestation of crossing over

14.Create a table in which you compare and contrast mitosis and meiosis with regard to: 1) the number of cell divisions, 2) the number of daughter cells formed, 3) the number of chromosomes per cell before and after each process, and 4) the function(s) of each type of cell division in animals. 

Mitosis: All somatic cells, Produces a new cell for growth and repair, Pairing of homologous chromosomes does not occur, Crossing over does not occur, The chromosomes are arranged randomly, Sister chromatids separate to move to opposite poles Two daughter cellsSame number of chromosomes as the parent cells Genetically identical to the parent No genetic Variation

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Meiosis: Cells in the reproductive organ produces Gametes Homologous chromosomes pair up Crossing over occurs Homologous chromosomes line up side by side Homologous Chromosomes move to opposite poles Four daughter cell Half the number of chromosomes as the parent cell Deferent from parent cell There is a genetic variation from one generation to the next

15.Explain independent assortment of chromosomes, crossing over between homologous chromosomes, and random fertilization. How does each process increase genetic variation? When does each process occur during sexual reproduction? -Independent assortment: the chromosomes in gametes are a random mix of maternal and paternal chromosomes (2n)…number of combinations possible for daughter cells formed by meiosis -generates variation in two places (Metaphase I and II) -crossing over – occurs in prophase I…when homologous chromosomes are physically broken and rejoined…leads to chromosomes with new combinations of alleles -produces recombinant chromosomes – individual chromosomes that carry genes derived from two different parents-random fertilization – any sperm may fertilize any ova…70 trillion...