Chromosomes And Cell Reproduction Critical Thinking

Meiosis In Grasshopper Testis

Last Updated on Tue, 27 Feb 2018 | Critical Thinking


1. For each pair of terms, explain how the meanings of the terms differ.

a. autosome and sex chromosome b. synapsis and crossing-over c. haploid and diploid

2. Explain the relationship between the terms chromosome and homologous chromosomes.

3. Use the following terms in the same sentence: mitosis, meiosis, and cytokinesis.

4. Word Roots and Origins The word oogenesis is derived from the Greek oion, which means "egg," and geneia, which means "birth." Using this information, explain why the term oogenesis is a good name for the biological process it describes.

Understanding Key Concepts

5. Describe the structure of a chromosome.

6. Compare prokaryotic chromosomes with eukary-otic chromosomes.

7. State the number of chromosomes in normal human cells.

8. Identify the type of chromosome that determines the sex of an organism.

9. Distinguish between haploid cells and diploid cells.

10. Define the term binary fission. In what type of organism does this type of cell division occur?

11. Differentiate mitosis from cytokinesis.

12. Describe the events that occur in the G0, Gj, and G2 phases.

13. Summarize the phases of mitosis.

14. Describe the process of cytokinesis in plant cells.

15. List the three main checkpoints at which the cell cycle is controlled.

16. Identify the type of nuclear division that results in haploid cells.

17. Compare the phases of meiosis I with those of meiosis II.

18. Name the meiotic process that results in genetic recombination.

19. Summarize the major characteristics of spermato-genesis and oogenesis.

20. Identify the relationship between sexual reproduction and genetic variation.

21. Unit 4—Cell Reproduction

^¡«m^ Write a report summarizing how ttOLOCI « different cancer-fighting drugs kill cancer cells by interrupting the events of the cell cycle.

22. CONCEPT MAPPING Use the following □ □ □ terms to create a concept map that shows the connection between cellular division in prokaryotes and eukaryotes: binary fission, cell cycle, cytokinesis, eukaryote, mitosis, and prokaryote.

Critical Thinking

23. Predicting Results Can mitosis occur in the absence of cytokinesis? Support your answer. If your answer is yes, describe how the new cell would appear in the G1 phase.

24. Making Calculations If you consider the mass of DNA in a sperm (a haploid cell) to be 1, what would the relative value be for the DNA mass of a cell in the G2 phase of the cell cycle?

25. Applying Information Does a cell in metaphase II have the same mass of DNA as a diploid cell in the G1 phase? Assume that both cells are from the same animal. Explain your answer.

26. Analyzing Information The events of mitosis in plants and animals are very similar, with the exception of the absence of centrioles in plants. How has the absence of centrioles in plant cells influenced scientists' thinking about the function of centrioles in mitosis?

27. Interpreting Graphics The photograph below shows cell division in a grasshopper testis. The offspring cells are gametes. Do you think the photograph shows mitosis or meiosis? Explain your answer.

Ms/ Standardized Test Preparation

DIRECTIONS: Choose the letter of the answer choice that best answers the question.

1. Which of the following statements about prokary-otic chromosomes is true?

A. Prokaryotes have at least two chromosomes.

B. Prokaryotic chromosomes consist of a circular DNA molecule.

C. Prokaryotic chromosomes include histone and nonhistone proteins.

D. Prokaryotic chromosomes are made of DNA wrapped tightly around histone proteins.

2. Crossing-over occurs during which process?

F. mitosis

G. meiosis I

H. meiosis II J. interphase

INTERPRETING GRAPHICS: The graph below shows the relative mass of DNA and chromosome number for a cell undergoing mitosis. Use the graph to answer the questions that follow.


Presentation on theme: "Chapter Eight: Cell Reproduction"— Presentation transcript:

1 Chapter Eight: Cell Reproduction
8-1 Chromosomes8-2 Cell Division8-3 Meiosis


3 8-1 ChromosomesI. Chromosomal Structure (chromatin UNCOILED, chromosome compact)Rod-shaped, made of DNA and proteins, found in NUCLEUS as chromatin (numbers VARY between species).


5 (1) Histone ProteinROUND protein that DNA wraps tightly around to CONSERVE SPACE in nucleus (i.e., the core in a ball of yarn)

6 (2) Nonhistone proteinNuclear protein involved in REGULATING the ACTIVITY of specific REGIONS of DNA (i.e., genes).


8 (3) ChromatidForms as DNA CONDENSES and COPIES itself BEFORE cell division; (NOTE: Each half of a chromosome = 1 chromatid)


10 (4) Centromere (binding protein)
Holds TWO chromatids together UNTIL they separate during cell division.

11 II. Chromosome NumbersVARIES between species, although some SPECIES (not necessarily closely related) CAN contain the SAME number of chromosomes.

12 Critical Thinking(1) Do you suppose there is a correlation between the NUMBER of chromosomes and the COMPLEXITY of an organism? Support your answer.


14 (A) Sex Chromosomes and Autosomes
Chromosomes can be linked to SEX development (sex chromosomes  XX OR XY) OR can be responsible for NON-sex traits (autosomes)


16 (1) Homologous Chromosomes (1maternal, 1 paternal)
A PAIR of chromosomes that carry GENES for SAME traits (1 chromosome is inherited from EACH parent).


18 (2) KaryotypePhotomicrograph of chromosomes EXTRACTED from a dividing DIPLOID cell (2N); (typically derived from a white blood cell)


20 (B) Diploid and Haploid Cells
Can be IDENTIFIED by the NUMBER of chromosomes it contains; TWO types exist—(N, 2N)(1) Diploid (2N, Human Number is ?)Cell contains FULL set of chromosomes (including all NON –reproductive cells (body or somatic cells), produced via MITOSIS.(2) Haploid (N, Human Number is ?)Cell contains HALF set of chromosomes (including all REPRODUCTIVE cells (sperm or egg), produced via MEIOSIS.











31 8-2 Cell Division I. Cell Division in Prokaryotes (i.e., bacteria)
Simpler AND faster than eukaryotes (evolved cells).(1) Binary Fission (cell division of bacteria, i.e., prokaryotes)DNA is COPIED and bacterium DIVIDES with EQUAL DNA in each cell.


33 II. Cell Division in Eukaryotes (2 divisions: Nuclear AND Cytoplasmic)
Cells divide either through: (1) Mitosis, or (2) Meiosis

34 (1) Mitosis (M phase  NUCLEUS divides)
Results in DIPLOID cells IDENTICAL to original parent cell (i.e., growth, replacement of dead cells, 46  46)


36 (2) Meiosis (a.k.a. reduction division, 46  23)
Results in HAPLOID cells with GENETIC VARIATION from parent cell. (i.e., spermatogenesis and oogenesis)

37 (A) The Cell Cycle (5 PHASES  G1, S, G2, M, and Cytokinesis)
LIFESPAN of a cell (Cell division is a small phase of the life cycle)

38 (1) Interphase (80% of cell’s LIFE)
Divided into 3 phases (G1, S, and G2)  time BETWEEN cell divisions

39 (2) M phase (20% of cell’s LIFE is in M phase  precedes CYTOKINESIS)

40 (3) Cytokinesis (after NUCLEUS has completed its division)
Division of CYTOPLASM of a cell  END of CELL DIVISION.

41 Critical Thinking(2) What would you PREDICT may happen in a cell if CYTOKINESIS took place BEFORE mitosis?


43 (1) G1 Phase (G is for “Growth”)
1ST phase after division, characterized by VIGOROUS cell growth.

44 (2) S phase (S is for “Synthesis”)
Follows G1 phase, DNA is COPIED inside nucleus of cell (chromosomes are copied  UNDUPLICATED TO DUPLICATED)

45 (3) G2 Phase (2nd growth phase)
Follows S phase, SLOWED growth and more PREPARATION for DIVISION (i.e., M phase).


47 (4) G0 PhaseCells can EXIT the cell cycle (by entering G0), NO longer copying their DNA, NO longer preparing to divide.NOTE: Fully developed cells, including many NEURONS, stop dividing at MATURITY and will NEVER divide again.

48 Critical Thinking(3) If you consider the mass of DNA in a sperm (a haploid cell) to be 1, what would the RELATIVE VALUE be for the DNA mass of a cell in the G2 phase of the cell cycle?

49 (C) Mitosis (M PHASE  CYTOKINESIS)
Division of cell NUCLEUS is divided into 4 STAGES (P, M, A, T)

50 (1) Prophase (1st)CHROMATIN coils into compacted CHROMOSOMES; nuclear MEMBRANE disappears.


52 (2) Metaphase (2nd)Kinetochore FIBERS pull chromosomes toward CENTER of cell.

53 (3) Anaphase (3rd)Chromatids SEPARATE at CENTROMERE and migrate to OPPOSITE ENDS of cell.

54 (4) Telophase (4th)Chromosomes REACH opposite ends and return to chromatin, FIBERS disassemble; NUCLEUS reforms.


56 (5) Centrosomes (Centrioles, in Animal Cells)
Found at POLES, cast out SPINDLE FIBERS toward chromosomes.

57 (6) Spindle Fibers (Mitotic Spindle—2 TYPES of fibers)
EXTEND to EQUALLY DIVIDE chromatids between TWO offspring cells.

58 (7) Kinetochore Fibers (pull APART chromatids)

59 (8) Polar Fibers (extend from CENTROSOME to CENTROSOME)
Fibers extend ACROSS the DIVIDING CELL (pole TO pole).


61 (D) Cytokinesis (FOLLOWS telophase of M Phase)
CYTOPLASM pinches INWARD to yield TWO separate (daughter) cells.

62 (1) Cleavage Furrow (in Animal Cells)
CELL MEMBRANE pinches in (via microtubules) and separates into 2 cells.


64 (2) Cell Plate ( CYTOKINESIS in Plant Cells)
VESICLES formed by GOLGI fuse at MIDLINE of dividing PLANT CELL (produces a CELL WALL).












76 8-3 Meiosis (Gametogenesis)
I. Stages of Meiosis (Meiosis I AND II, reproductive organs)Sex cells undergo cell cycle, but DIVIDE 2x, requiring 2 phases. (i.e., to make haploid (N) gametes)


78 (A) Meiosis I (PHASE of tetrads ands synapsis)
1st set of meiotic phases, (PMAT); begin as DIPLOID cells.


80 (1) Synapsis (occurs during PROPHASE I)
Chromosomes PAIR up with HOMOLOGUES (NOTE: This pairing does NOT take place during MITOSIS).


82 (2) Tetrad (PAIR of homologues, during PROPHASE I)
Line so that GENES on 1st chromosome are adjacent to SAME GENES on 2nd chromosome.NOTE: During synapsis, CHROMATIDS may twist around one another (i.e., crossing-over).



85 (3) Crossing-Over (with TETRADS during SYNAPSIS)
Portions of genes may BREAK OFF 1 CHROMOSOME and ATTACH to PARTS of its HOMOLOGUE.NOTE: Allows for EXCHANGE of genes between MATERNAL and PATERNAL chromosomes, increasing genetic variation of SEX CELLS.

86 (4) Genetic Recombination (gives SEX CELLS variation)
RESULT of crossing-over of, increasing genetic diversity of OFFSPRING.


88 (5) Law of Independent Assortment (during Anaphase I)
EACH homologous chromosome can RANDOMLY move to an OPPOSITE side.NOTE: Independent Assortment results in a RANDOM COMBINATIONS of the maternal & paternal chromosomes, yielding genetic VARIATIONS.



91 (B) Meiosis II (separates CHROMATIDS into opposite poles)
Cell DOUBLED its DNA BUT was reduced (during Meiosis I) by the end to (2N);NOTE: Meiosis II takes the 2 DIPLOID (2N) cells and REDUCES them into FOUR HAPLOID (N) cells.


93 Critical Thinking(4) Explain why the CHROMSOMES in the haploid cells that are produced by Meiosis I APPEAR DIFFERENT from those produced by Meiosis II.

94 (C) Formation of Gametes (oogenesis AND spermatogenesis)
Meiosis II results in HAPLOID cells called GAMETES, and occurs in reproductive organs.

95 (1) Spermatogenesis (in testes, yields FOUR viable sperm)
A DIPLOID cell divides to form 4 haploid spermatids, each matures (following puberty) to become an active, swimming HAPLOID sperm.

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