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Biology chapter 8 exam 3 > Chapter 8 (cycle of the Cell) > Flashcards

Chapter 8 (cycle of the Cell) Flashcards

1
Q

Q: How do unicellular organisms reproduce?

A
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2
Q

Q: What process do multicellular organisms depend on for growth and repair?

A

A: Cell division.

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3
Q

Q: What are the two main processes of eukaryotic cell division?

A

A: Mitosis (division of the nucleus) and cytokinesis (division of the cytoplasm).

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4
Q

Q: What are chromosomes made of?

A

A: Chromatin, a complex of DNA and protein.

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5
Q

Q: What is binary fission?

A

A: It’s a type of cell division in bacteria, different from mitosis in eukaryotes.

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6
Q

Q: How do organisms reproduce asexually?

A

A: By producing genetically identical offspring through cell division.

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7
Q

Q: Why does sexual reproduction create more genetic variation than asexual reproduction?

A

A: Offspring inherit a unique combination of genes from two parents.

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8
Q

Q: How many chromosomes do human somatic cells have?

A

A: 46 chromosomes (two sets of 23).

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9
Q

Q: What type of cells are created by meiosis?

A

A: Haploid gametes (eggs and sperm) with 23 chromosomes each.

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10
Q

Q: What are the stages of the mitotic phase of the cell cycle?

A

A: Mitosis and cytokinesis.

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11
Q

Q: What are the phases of mitosis?

A

A: Prophase, prometaphase, metaphase, anaphase, and telophase.

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12
Q

Q: What happens during interphase?

A

A: The cell grows, and DNA is replicated during the S phase.

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13
Q

Q: What is the mitotic spindle?

A

A: A structure of microtubules that controls chromosome movement during mitosis.

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14
Q

What structure helps separate sister chromatids in anaphase?

A

A : The kinetochores move along shortening microtubules.

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15
Q

Q: What are the key roles of cell division?

A

A: Reproduction, growth, and repair.

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16
Q

Q: How does cytokinesis differ in animal and plant cells?

A

A: Animal cells form cleavage furrows, while plant cells form cell plates.

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17
Q

Q: What happens during fertilization?

A

A: An egg and sperm combine to form a diploid zygote with 46 chromosomes.

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18
Q

Q: What alternates in all sexual life cycles?

A

A: Diploid and haploid stages.

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19
Q

Q: What is found in the cytoplasm of a cell in late interphase?

A

A: Two centrosomes, each possibly containing a pair of centrioles.

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20
Q

Q: What is found in the nucleus during late interphase?

A

A: Chromosomes are replicated and dispersed as chromatin, with one or more nucleoli present.

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21
Q

Q: What happens to nucleoli and chromatin during prophase?

A

A: Nucleoli disappear, and chromatin coils to form chromosomes with two sister chromatids.

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22
Q

Q: What happens at the metaphase stage?

A

A: Chromosomes align at the metaphase plate, and the mitotic spindle is fully formed.

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23
Q

Q: What occurs during anaphase?

A

A: Sister chromatids separate into daughter chromosomes and move toward opposite poles.

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24
Q

Q: What changes occur in the cell during telophase?

A

A: Nuclear envelopes form, chromosomes uncoil, and nucleoli reappear in each new nucleus.

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25
Q: How does cytokinesis differ in animal and plant cells?
A: Animal cells form a cleavage furrow, while plant cells form a cell plate.
26
Q: How does binary fission differ from mitosis?
A: Binary fission occurs in bacteria and involves an unknown mechanism for chromosome separation.
27
Q: What drives the cell cycle?
A: A molecular control system involving cyclin-dependent kinases (Cdks) and cyclins.
28
Q: What are cyclins?
A: Proteins whose levels rise and fall with the cell cycle stages, including G1, S-phase, and mitotic cyclins.
29
Q: What are cyclin-dependent kinases (Cdks)?
A: Proteins that must bind with cyclins to be active and add phosphate groups to control the cell cycle.
30
Q: What are examples of specific Cdks?
A: G1 Cdk (Cdk4), S-phase Cdk (Cdk2), and M-phase Cdk (Cdk1).
31
Q: What does the anaphase-promoting complex (APC) do?
A: It triggers sister chromatid separation and degrades mitotic cyclins
32
Q: What does G1-cyclin do in the cell cycle?
A: G1-cyclin binds to Cdks to prepare chromosomes for replication.
33
Q: What is the role of S-phase promoting factor (SPF)?
A: SPF, which includes cyclin A with Cdk2, prepares the cell for DNA and centrosome duplication.
34
Q: What does M-phase promoting factor (MPF) do?
MPF initiates mitotic spindle assembly, nuclear envelope breakdown, and chromosome condensation.
35
Q: What is the anaphase-promoting complex (APC)?
A: APC allows sister chromatids to separate during anaphase and starts the synthesis of G1 cyclin for the next cycle.
36
Q: What is the main purpose of checkpoints in the cell cycle?
A: Checkpoints ensure cell cycle quality control, pausing if errors are detected.
37
Q: What is the G1 checkpoint’s role?
A: It checks for DNA damage before the cell enters S phase.
38
Q: What is the spindle checkpoint’s function?
A: It ensures spindle fibers attach to kinetochores before anaphase and prevents errors in alignment.
39
Q: What is density-dependent inhibition?
A: It is when crowded cells stop dividing due to a lack of growth factors.
40
Q: What is anchorage dependence?
A: Cells must attach to a surface (extracellular matrix) to divide.
41
Q: What is metastasis?
A: The process by which malignant tumor cells spread to other parts of the body.
41
Q: How do cancer cells differ from normal cells?
A: Cancer cells lack density-dependent and anchorage dependence, divide uncontrollably, and are often undifferentiated.
42
Q: What are carcinogens?
A: Agents that can cause cancer, like UV light, cigarette smoke, and certain chemicals.
43
What is an example of an “immortal” cancer cell line?
A: HeLa cells, derived from Henrietta Lacks, have been growing since 1951.
44
Q: What is heredity?
A: Heredity is the transmission of genes from parents to offspring.
45
Q: What is genetics?
A: Genetics is the study of heredity and variations based on genes.
46
Q: How does asexual reproduction occur?
A: Asexual reproduction involves a single parent passing all its genes to its offspring, creating genetically identical individuals through mitosis.
47
Q: What is sexual reproduction?
A: Sexual reproduction involves two parents, each contributing genes, leading to genetic diversity in offspring.
48
Q: What is meiosis, and where does it occur?
A: Meiosis is a type of cell division that occurs in ovaries and testes, producing haploid gametes (sperm and eggs) with 23 chromosomes each.
49
Q: What happens during fertilization?
A: Fertilization combines two sets of chromosomes from egg and sperm, forming a diploid zygote with 46 chromosomes.
50
51
52
Q: How many chromosome pairs do humans have?
Humans have 23 pairs of chromosomes: 22 pairs of autosomes and 1 pair of sex chromosomes.
52
Q: What are homologous chromosomes?
A: Homologous chromosomes are pairs of chromosomes with similar length, centromere position, and gene sequence, one inherited from each parent.
53
Q: What is a karyotype?
A: A karyotype is an ordered display of an individual’s 46 chromosomes in 23 pairs.
54
Q: How do male and female sex chromosomes differ?
A: Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY).
55
Q: What is the difference between haploid and diploid cells?
A: Haploid cells have one set of chromosomes (n=23), while diploid cells have two sets (2n=46).
56
Q: What are gametes, and how are they formed?
A: Gametes are sperm and egg cells, produced by meiosis, and contain one set of 23 chromosomes.
57
Q: What is the role of fertilization in the human life cycle?
Fertilization combines haploid gametes to form a diploid zygote, which will develop into a diploid adult capable of producing gametes.
58
Q: How does the sexual life cycle alternate between diploid and haploid stages?
A: Meiosis produces haploid gametes, and fertilization restores diploidy in the zygote.
59
Q: Are gametes haploid or diploid?
A: Gametes are haploid, containing only one set of chromosomes.
60
Q: What happens to gametes after they are formed?
A: Gametes do not divide themselves but fuse to form a diploid zygote, which divides by mitosis to develop into a multicellular organism.
61
Q: What life cycle is found in fungi and some protists?
A: In this life cycle, the zygote is the only diploid phase. After fusion to form a zygote, it undergoes meiosis to produce haploid cells, which then undergo mitosis to develop into a haploid multicellular adult.
62
Q: What is alternation of generations?
A: Found in plants and some algae, this life cycle includes both haploid (gametophyte) and diploid (sporophyte) multicellular stages. The sporophyte undergoes meiosis to produce haploid spores, which develop into the gametophyte. Gametophytes produce gametes that fuse to form a zygote, giving rise to a new sporophyte.
63
Q: How does sexual reproduction produce genetic variation?
A: Genetic variation arises from four main mechanisms: independent assortment, crossing over, random fertilization, and mutations.
64
Q: What is independent assortment, and how does it contribute to genetic variation?
A: Independent assortment is the random orientation of tetrads at the metaphase plate during meiosis, leading to diverse combinations of chromosomes. For humans, this allows for 2^23 or about 8 million possible chromosome combinations.
65
Q: How does crossing over contribute to genetic diversity?
A: Crossing over exchanges genetic material between nonsister chromatids, creating recombinant chromosomes. In humans, crossing over occurs two to three times per chromosome pair, or 66-99 times per meiotic event.
66
Q: What role does random fertilization play in genetic variation?
A: Random fertilization allows any sperm to fuse with any egg, resulting in unique genetic identities. Each human egg and sperm have around 8 million possible chromosome combinations, producing a zygote with about 1 in 70 trillion possible combinations.
67
Q: What is the role of mutations in genetic variation?
A: Mutations introduce new genetic differences within a population, increasing diversity.
68
Q: What is the primary purpose of meiosis?
A: Meiosis reduces the chromosome number from diploid to haploid.
69
Q: How many divisions occur in meiosis, and what do they produce?
A: Meiosis consists of two divisions—meiosis I and meiosis II—producing four haploid daughter cells.
70
Q: What distinguishes meiosis I from mitosis?
A: In prophase I, homologous chromosomes undergo synapsis and exchange segments through crossing over. These paired chromosomes, or tetrads, align on the metaphase plate, and during anaphase I, each homologous pair is separated into different cells.
71
Q: What occurs during meiosis II?
A: Meiosis II separates sister chromatids, resulting in four unique haploid daughter cells.
72
Q: What is the main event of Metaphase 1?
A: Homologous chromosomes align at the equatorial plate of the cell.
72
Q: What occurs during Prophase 1?
A: Each chromosome duplicates and remains closely associated with its copy, forming sister chromatids. Crossing-over, where genetic material is exchanged between homologous chromosomes, can occur in this stage.
73
Q: What happens during Anaphase 1?
A: Homologous chromosome pairs separate, with sister chromatids remaining together as they move to opposite poles.
74
Q: Describe Telophase 1.
A: Two daughter cells are formed, each containing only one chromosome from each homologous pair.
75
Q: What is unique about Prophase 2?
A: DNA does not replicate before this stage.
76
Q: What is the outcome of Telophase 2?
A: Cell division completes, producing four genetically unique haploid daughter cells with half the number of chromosomes as the parent cell.
76
Q: Describe Metaphase 2.
A: Chromosomes align again at the equatorial plate.
77
Q: What occurs in Anaphase 2?
A: Centromeres divide, and sister chromatids separate, migrating to opposite poles.
78
DIFFERENCES BETWEEN MITOSIS AND MEIOSIS
* Location: Mitosis occurs in body cells, while meiosis occurs in reproductive organs. * Number of Division Events: Mitosis has one division, while meiosis has two. * Outcome: Mitosis produces two diploid (2N) daughter cells, genetically identical to the parent. Meiosis produces four haploid (N) daughter cells, genetically different from the parent due to crossing-over.

Biology chapter 8 exam 3 (2 decks)

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