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Biology > Topic 2 A: Cell Structure and Division > Flashcards

Topic 2 A: Cell Structure and Division Flashcards

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1
Q

What is the primary function of the nucleus in a cell?

A

It controls cell activities by regulating DNA transcription.

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2
Q

Describe the structure of the mitochondrion.

A

Mitochondria are oval with a double membrane; the inner membrane is folded into cristae, with a matrix inside containing enzymes for respiration.

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3
Q

What is the role of the Golgi apparatus?

A

It processes, modifies, and packages new lipids and proteins and produces lysosomes.

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4
Q

How does rough endoplasmic reticulum (RER) differ from smooth endoplasmic reticulum (SER)?

A

RER has ribosomes attached and folds proteins, while SER synthesizes and processes lipids without ribosomes.

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5
Q

What is the function of lysosomes in the cell?

A

Lysosomes contain digestive enzymes to break down waste materials and cellular debris.

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6
Q

Explain the structural adaptation of red blood cells for oxygen transport.

A

Red blood cells lack a nucleus, maximizing space for hemoglobin to carry oxygen.

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7
Q

How does the cell membrane control cellular activity?

A

It regulates movement of substances in and out and responds to chemical signals.

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8
Q

Describe the structure and role of chloroplasts.

A

Chloroplasts contain thylakoids stacked into grana for photosynthesis, surrounded by stroma.

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9
Q

What is the purpose of the cell wall in plants, algae, and fungi?

A

It provides structural support and prevents cells from changing shape.

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10
Q

Define the function of ribosomes.

A

Ribosomes are the sites of protein synthesis in cells.

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11
Q

What is the role of the cell vacuole in plants?

A

It maintains cell pressure, keeps the cell rigid, and stores chemicals.

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12
Q

How do prokaryotic cells differ structurally from eukaryotic cells?

A

Prokaryotes lack a nucleus and membrane-bound organelles; they have smaller ribosomes and a cell wall made of murein.

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13
Q

Describe the function of plasmids in prokaryotic cells.

A

Plasmids are small DNA loops that often carry genes, like antibiotic resistance.

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14
Q

Explain the structure and function of viral capsids.

A

The capsid is a protein coat surrounding viral DNA or RNA, with attachment proteins for host cell binding.

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15
Q

What is the purpose of cell fractionation?

A

It isolates organelles by breaking cells apart, filtering, and centrifuging at various speeds.

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16
Q

How is the magnification of a microscope calculated?

A

Magnification = size of image ÷ actual size of object.

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17
Q

Describe the differences between magnification and resolution.

A

Magnification enlarges an image; resolution distinguishes two close points as separate.

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18
Q

What is the maximum resolution of an optical microscope?

A

Approximately 0.2 micrometers.

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19
Q

How does a transmission electron microscope (TEM) work?

A

TEMs use electrons to pass through a specimen, creating detailed images of cell interiors.

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20
Q

Why are electron microscopes better suited for studying small structures?

A

They offer much higher resolution than optical microscopes.

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21
Q

What is a limitation of transmission electron microscopes (TEM)?

A

TEMs cannot observe living specimens due to the vacuum requirement and specimen preparation.

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22
Q

How does a scanning electron microscope (SEM) differ from a TEM in function?

A

SEMs scan the surface of specimens to produce 3D images rather than viewing internal structures.

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23
Q

What is cell division, and why is it important?

A

Cell division is the process of creating new cells, essential for growth, repair, and reproduction.

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24
Q

Describe the basic stages of the cell cycle.

A

The cell cycle includes interphase (cell growth and DNA replication), mitosis (nuclear division), and cytokinesis (cytoplasmic division).

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25
Q

What occurs during interphase?

A

The cell grows, replicates DNA, and synthesizes necessary proteins and organelles.

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26
Q

What happens in prophase during mitosis?

A

Chromosomes condense, the nuclear envelope dissolves, and spindle fibers begin to form.

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27
Q

What key events occur during metaphase?

A

Chromosomes align at the cell’s equator, attached to spindle fibers by their centromeres.

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28
Q

Describe what happens in anaphase.

A

Centromeres split, and spindle fibers pull sister chromatids to opposite poles of the cell.

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29
Q

What occurs during telophase in mitosis?

A

Chromatids reach the poles, the nuclear envelope reforms around each set, and chromosomes decondense.

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30
Q

Define cytokinesis and its role in cell division.

A

Cytokinesis is the final division of the cytoplasm, resulting in two separate cells.

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31
Q

How is the cell cycle regulated?

A

Through checkpoints controlled by proteins that ensure each stage is completed accurately.

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32
Q

What is a tumor, and how does it relate to cell division?

A

A tumor is an uncontrolled mass of cells due to mutations in genes that regulate the cell cycle.

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33
Q

How do cancer treatments target cell division?

A

Treatments often disrupt DNA replication or mitosis, slowing tumor growth but also affecting healthy dividing cells.

34
Q

Describe the process and purpose of mitosis.

A

Mitosis creates two genetically identical daughter cells, used for growth, tissue repair, and asexual reproduction.

35
Q

What is binary fission, and in which organisms does it occur?

A

Binary fission is cell division in prokaryotes, resulting in two genetically identical cells.

36
Q

How does DNA replication differ in prokaryotic cells?

A

Prokaryotes replicate DNA by copying a single circular chromosome before division.

37
Q

What role do attachment proteins play in viruses?

A

They allow viruses to bind to host cells, enabling entry for infection.

38
Q

Describe the process of ultracentrifugation.

A

Cells are fractionated, and organelles are separated by density through spinning at various speeds.

39
Q

How does the S phase of the cell cycle relate to cancer development?

A

Mutations during the S phase (DNA replication) can lead to errors in genes that control cell division, promoting cancer.

40
Q

What is an artefact in microscopy, and how can it affect observations?

A

Artefacts are distortions or misinterpretations in microscope images, which can be mistaken for real cell structures.

41
Q

What is mitosis?

A

Mitosis is a type of cell division that results in two genetically identical daughter cells from a single parent cell.

42
Q

In what type of organisms does mitosis primarily occur?

A

Mitosis occurs in eukaryotic organisms, used for growth, repair, and asexual reproduction.

43
Q

What are the main stages of the cell cycle in order?

A

Interphase, mitosis (prophase, metaphase, anaphase, telophase), and cytokinesis.

44
Q

What is the purpose of mitosis?

A

Mitosis ensures genetic consistency across cells, aiding in growth, tissue repair, and asexual reproduction.

45
Q

What occurs during interphase before mitosis begins?

A

The cell grows, duplicates its DNA, and prepares for division by synthesizing proteins and organelles.

46
Q

Describe prophase in mitosis.

A

Chromosomes condense and become visible, the nuclear envelope dissolves, and spindle fibers start to form from centrioles.

47
Q

What is the role of spindle fibers in mitosis?

A

Spindle fibers attach to chromosomes at their centromeres and help separate sister chromatids during cell division.

48
Q

What happens to chromosomes during metaphase?

A

Chromosomes align along the cell’s equator, with each centromere attached to spindle fibers from opposite poles.

49
Q

Describe anaphase.

A

Centromeres divide, and spindle fibers pull sister chromatids toward opposite poles of the cell.

50
Q

What changes occur during telophase?

A

Chromatids reach the cell poles, decondense into chromatin, and are enclosed by newly formed nuclear envelopes.

51
Q

What is cytokinesis?

A

Cytokinesis is the division of the cytoplasm, which completes the cell division process, resulting in two separate cells.

52
Q

How does cytokinesis differ between plant and animal cells?

A

In animal cells, a cleavage furrow forms and pinches the cell into two; in plant cells, a cell plate forms to separate the new cells.

53
Q

What are sister chromatids?

A

Sister chromatids are identical copies of a chromosome, joined together at a centromere, produced during DNA replication.

54
Q

What is the function of centromeres in mitosis?

A

Centromeres hold sister chromatids together and serve as attachment points for spindle fibers during mitosis.

55
Q

How does mitosis ensure genetic consistency in daughter cells?

A

Each daughter cell receives an identical set of chromosomes, maintaining the same DNA as the parent cell.

56
Q

What is the significance of G1, S, and G2 phases in relation to mitosis?

A

G1 (cell growth), S (DNA synthesis), and G2 (preparation for mitosis) are interphase stages where the cell readies for mitosis.

57
Q

How do cancer treatments target mitosis?

A

Some treatments disrupt stages of mitosis to slow or stop the rapid cell division in tumors.

58
Q

How long does mitosis typically take in comparison to interphase?

A

Mitosis is a shorter phase, with interphase taking up most of the cell cycle as the cell grows and prepares for division.

59
Q

Why is mitosis important for multicellular organisms?

A

It supports growth, tissue maintenance, and repair by creating identical cells for the organism’s development and functioning.

60
Q

What would happen if errors occurred during mitosis?

A

Errors can lead to abnormal chromosome numbers in cells, potentially resulting in conditions like cancer or genetic disorders.

61
Q

What is the purpose of investigating mitosis?

A

To observe and analyze cell division stages in rapidly growing tissues, like plant root tips.

62
Q

Describe the purpose of preparing a ‘root tip squash’ in mitosis experiments.

A

It spreads out cells thinly for easier microscopic viewing of mitotic stages.

63
Q

Why are plant root tips used to study mitosis?

A

Root tips have actively dividing cells, making mitosis more observable.

64
Q

What initial step is required in preparing a root tip squash?

A

Add 1 M hydrochloric acid to a boiling tube and heat it to 60°C in a water bath.

65
Q

Why must the root tip be placed in hydrochloric acid?

A

Acid treatment softens the cell walls, making it easier to spread the cells.

66
Q

What safety precautions should be taken during this experiment?

A

Wear safety goggles, a lab coat, and gloves when handling chemicals and stains.

67
Q

What is the purpose of staining in a root tip squash?

A

Staining helps visualize chromosomes during mitosis.

68
Q

Name common stains used for observing mitosis.

A

Examples include toluidine blue, ethano-orcein, and Feulgen stain.

69
Q

What is the next step after staining in the root tip squash method?

A

Cover the sample with a coverslip, and use filter paper to apply even pressure without sideways movement.

70
Q

Why is it essential to squash the tissue during slide preparation?

A

Squashing makes the tissue thinner, allowing light to pass through for clear microscopic imaging.

71
Q

Describe the setup for viewing cells under an optical microscope.

A

Secure the slide on the microscope stage, select a low-power lens, and use the coarse and fine adjustment knobs to focus.

72
Q

How do you calculate the mitotic index?

A

Divide the number of cells undergoing mitosis by the total number of cells observed.

73
Q

Why is the mitotic index important?

A

It indicates the proportion of dividing cells, useful for assessing growth rate or abnormal tissue activity.

74
Q

In what tissues would you expect a high mitotic index?

A

Rapidly growing tissues, like root tips, or tissues undergoing repair or cancerous growth.

75
Q

How do you calculate the actual size of a cell observed under a microscope?

A

Use the formula: actual size = image size ÷ magnification.

76
Q

What is an eyepiece graticule, and how is it used?

A

It’s a scaled ruler in the eyepiece that allows measurement of specimens by calibrating with a stage micrometer.

77
Q

How can the magnification of a microscope be calculated?

A

Multiply the magnifications of the objective lens and the ocular lens.

78
Q

What is the advantage of a high mitotic index in plant root tips?

A

Indicates active growth, which is vital for root expansion and nutrient absorption.

79
Q

What might an unusually high mitotic index in other tissues indicate?

A

It may suggest tissue repair or potential cancerous growth.

80
Q

How long does each stage of mitosis last in an experiment?

A

Duration varies by cell type; calculate specific times by observing cell cycle proportions under controlled conditions.

Biology (19 decks)

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