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Biology 30 > Cell Division (Chapter 16) > Flashcards

Cell Division (Chapter 16) Flashcards

1
Q

What are the three main reasons for cell division?

A
  1. Growth/Differentiation:
    Mitosis enables organisms to grow from a single-celled zygote into a mature organism that might contain hundreds of trillions of specialized cells
  2. Maintenance:
    New cells produced to replace worn out/dead cells
  3. Repair:
    They can regenerate damaged tissues (finger cut → new skin). Some organisms can regenerate entire body parts.
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2
Q

True or False…

There is no new combination of cellular material as a result of single cell reproduction

A

True; all new cells contain same DNA as original cell

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3
Q

Where does asexual reproduction occur?

A

Occurs in all somatic (body) cells, unicellular organisms, and simple multicellular organisms (budding, runners)

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4
Q

What are the five levels DNA is organized into?

A
  1. DNA Molecule
  2. Histones (DNA wraps around histones forming a bead-like structure)
  3. Chromatin Strands (the bead-like structure is packed tightly, producing chromatin strands)
  4. Chromatin Fibres: Stands from loops which are attached to a supporting protein scaffold
  5. Chromosomes: Protein scaffold folds further to condense the genetic material into chromosomes (duplicate during replication)
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5
Q

True or False…

Chromosomes may be found as individual chromatids (during late stages of cell division) or as paired/sister chromatids (connected at the centromere)

A

True

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6
Q

Fill in the Blank:

Sister chromatids are _________ to each other

A

Sister chromatids are IDENTICAL to each other

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7
Q

How many pairs of chromosomes do humans have?

A

23 pairs (46 total)

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8
Q

Define: Homologs

A
  • Homologous chromosomes carry the same genes, in the same order
  • Despite this, homologous chromosomes often have slightly different DNA sequences resulting in different alleles (different form of the same gene)
  • Share several other characteristics including: length, centromere location, and banding pattern
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9
Q

What is the cell cycle?

A

Refers to the life cycle of a cell where it alternates between haploid and diploid form

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10
Q

What are the two MAIN parts of the cell cycle?

A
  1. Cell division (mitosis): division of genetic material & nucleus
  2. Interphase: cell growth and synthesis stages
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11
Q

What are the 3 stages of interphase?

A
  1. G1 (first cell growth stage): cell grows (organelle replication)
  2. S (synthesis phase): Cell DNA is replicated
  3. G2 (second cell growth stage): cell grows, rebuilds energy reserves, and prepares for mitosis
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12
Q

What are the five stages of cell division?

A
  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase
  5. Cytokinesis
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13
Q

What are the five stages of cell division?

A
  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase
  5. Cytokinesis
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14
Q

Define: mitosis

A

Cell division in somatic cells

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15
Q

True or False…

All of the cells produced by mitosis are identical in genetic makeup to the original cells

A

True

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16
Q

Define: alleles

A

A alternative form of the same gene caused by slight variations in DNA base sequences

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17
Q

The appearance and functionality of a cell is a result of…

a) difference in cellular content
b) difference in the way that content is expressed

A

Answer: B

The unique appearance and functionality found in different cells of the body is NOT due to difference in cellular content, but instead, a difference in the way that content is expressed (differentiation)

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18
Q

Define: differentiation

A

The process during which young, immature (unspecialized) cells take on individual characteristics and reach their mature (specialized) form and function

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19
Q

Explain the steps of prophase in cell division

A
  • Nuclear envelope breaks down and the contents of the cell’s nucleus becomes visible
  • DNA strands shorten and thicken, causing chromatin to condense into visible chromosomes
  • Centrioles move to opposite poles of cell and begin growing spindle fibres
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20
Q

Explain the steps of metaphase in cell division

A
  • Chromosomes move to center of cell
  • Centromeres align across equator
  • Spindle fibres attach to the centromeres
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21
Q

Explain the steps of anaphase in cell division

A
  • Spindle fibres shorten and start pulling the sister chromatids apart
  • Chromatids separate at centromeres
  • Chromatids move to opposite poles of cell (same number of single-copy chromosomes should be at each pole)
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22
Q

Explain the steps of telophase in cell division

A
  • Chromosomes at opposite ends of cell
  • Chromosomes un-condense to form chromatin
  • Nuclear envelope and nucleolus reappears
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23
Q

Explain the steps of cytokinesis in cell division

A
  • Division of the cytoplasm
  • In plant cells, a cell-plate forms first, separating two cells by forming cell wall
  • In animal cells, cell membrane pinches in at the cleavage furrow to form two distinct daughter cells
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24
Q

Define: Stomaic Cells

A
  • Somatic cells are found all throughout the body, except in cells that divide by meiosis to produce gametes (sperm and eggs)
  • Somatic cells are diploid cells
  • They have DNA from maternal and paternal sides combined
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25
Q

Define: Gamete Cells

A
  • Gametes (sperm or eggs) are haploid cells
  • They only hold half the DNA from somatic cells from which they came
  • When an ovum is fertilized by a sperm, the original number of chromosomes (46 = 2n) is restored, forming a zygote
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26
Q

Define: Zygote

A

A diploid cell that results from the fusion of two haploids gametes

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27
Q

What is the purpose of meiosis?

A

Creates gamete cells by reducing the number of chromosomes from 46 to 23 by copying chromosomes once, but dividing twice

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28
Q

What is separated during Meiosis I?

A

Homologous chromosome

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29
Q

What is separated during Meiosis II?

A

Sister chromatids

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30
Q

What is crossing over?

A

Paired homologous chromosomes overlap and occasionally break, exchanging identical sized segments of DNA

31
Q

Fill in the Blank:

Crossing over leads to more __________ ___________

A

GENETIC VARIATION

32
Q

When can crossing over occur?

A

Only during prophase I

33
Q

What is chromosome segregation?

A

Chromosome segregation is a process where chromatids (individual or sister chromatids) are separated from each other and migrate to opposite poles of the nucleus.

34
Q

When does chromosome segregation occur?

A

The process of chromosome segregation occurs during both mitosis and meiosis

35
Q

Define: Oocyte

A

A cell located in an individual’s ovary which may undergo meiotic division to form an ovum (egg cell)

36
Q

What type of cell puts meiosis I on hold after prophase I?

A

Oocyte cells

37
Q

When do oocytes cells complete meiosis I?

A

Once the female reaches puberty

38
Q

What is the G-0 phase of the cell cycle?

A

A resting phase where the cell is neither dividing nor preparing to divide.

39
Q

When do oocytes cells complete meiosis II?

A

If/when the oocytes is fertilized

40
Q

Define: Gametogenesis

A

The process by which gametes, or germ cells, are produced via meiosis

41
Q

How many sperm cells are produced from gametogenesis?

A

Four sperm cells are produced

42
Q

How many egg cells are produced per oocyte?

A

One egg cell; the other 3 haploid cells sacrifice their cytoplasm to produce one large egg

43
Q

Define: Karyotyping

A

A method of identification of chromosomes

44
Q

How are chromosomes matched up together during karyotyping?

A

Chromosomes are matched up based on:
- Size (largest to smallest)
- Centromere position
- G-banding

45
Q

What is an amniocentesis?

A
  • Procedure where a small amount of amniotic fluid is removed from the sac surrounding the fetus
  • The sample of amniotic fluid contains fetal cells and chemicals produced by the baby
  • Amniotic fluid is then taken for testing
46
Q

What is chorionic villi sampling?

A
  • A prenatal procedure where a sample of chorionic villi tissue is removed from the placenta
  • Sample is then tested for chromosomal abnormalities and certain other genetic problems
47
Q

What is chorionic villi sampling?

A
  • A prenatal procedure where a sample of chorionic villi tissue is removed from the placenta
  • Sample is then tested for chromosomal abnormalities and certain other genetic problems
48
Q

Define: Nondisjunction

A

When chromosomes fail to seperate correctly, resulting in daughter cells with abnormal numbers of chromosomes

49
Q

What is the impact of nondisjunction?

A
  • One daughter cell produced during separation will be lacking information, the other will have too much
  • The impact is usually so severe to zygote that miscarriage occurs very early in pregnancy
  • If the baby survives, the set of traits is called a syndrome (trisomy 21, 13 and 18 are the only trisomies that result in surviving offspring)
50
Q

What is a trisomy? How do they occur?

A

A condition in which an extra chromosome is present in the cell’s nucleus (forming a triplet) and occur as a result of nondisjunction

51
Q

What is a monosomy? How do they occur?

A

A condition where a chromosome is absent from the cell’s nucleus (forming a singlet) and occur as a result of nondisjunction

52
Q

What condition does trisomy 21 cause?

A

Down’s Syndrome

53
Q

What condition does trisomy 18 cause?

A

Edward’s Syndrome

54
Q

What condition does trisomy 13 cause?

A

Patau’s Syndrome

55
Q

True or False…

Nondisjunction of the sex chromosomes is usually fatal

A

False; They can be fatal, but most people survive just fine

56
Q

Fill in the Blank:

XXY sex chromosomes causes ___________

A

Klinefelter’s Syndrome
- Tall, sterile males
- Normal intelligence
- Has female characteristics

57
Q

What syndrome does XYY sex chromosomes cause?

A

Jacob’s Syndrome (super male)
- Somewhat taller than average
- Extra testosterone
- Slightly below normal intelligence
- Delayed emotional development
- Learning problems in school

58
Q

A set of XXX sex chromosomes would cause ____________

A

Triple X Syndrome (super female)
- Normal intelligence
- Fertile
- No physical problems

Note: There are some women who are XXXX and XXXXX (each increasing X results in lesser intelligence and fertility)

59
Q

What is Turner’s Syndrome (X sex chromosome)?

A
  • The ONLY surviving monosomy
  • Do not mature sexually at puberty
  • Sterile
  • Short stature
  • Short, broad neck
  • Broad chest
60
Q

What is chromosomal deletion?

A

A segment of the chromosome is missing/deleted

61
Q

What is chromosomal duplication?

A

A segment of the chromosome is duplicated

62
Q

Define: Polyploidy

A

The condition in which a normally diploid cell or organism acquires one or more additional sets of chromosomes.

63
Q

Describe cloning

A
  • A process in which identical offspring are formed from a single cell or tissue (clone = cutting)
  • All cells formed in this manner are identical (or almost – some small variations due to mutation are expected)
  • Used in some plants and animals for reproduction
64
Q

What is binary fission?

A
  • Equal division of the cytoplasm and nucleus of an organism resulting in two new organisms
  • Bacteria and other prokaryotes have a single, circular chromosome and no nucleus, therefore, a bacterial cell does not undergo mitosis.
  • Instead, it replicates via binary fission. In favourable conditions, bacteria can divide at exponential rates (creating huge populations in little amounts of time).
65
Q

What is budding?

A
  • When the nucleus of an organism’s cell divides equally but the cytoplasm divides unequally
  • The new cells formed may live as individuals or as colonies
66
Q

What is sporulation?

A
  • The production of spores; single, specialized cells which are released from the parent
  • Spores are enclosed in a protective case and develop when environmental conditions are favourable
67
Q

Define: Alternation of Generation

A

Refers to the alternation of diploid & haploid generations.

68
Q

Define: Vegetative Propagation

A

A process of regeneration in plants where new plants develop from part of the original plant.

69
Q

What are the seven methods of vegetative propagation?

A
  1. Bulbs
  2. Tubers
  3. Runners
  4. Rhizomes
  5. Layering
  6. Cutting
  7. Grafting
70
Q

What is cancer?

A

The abnormal/uncontrolled growth of cells

71
Q

Define: Metastasis

A

spreading of cancer cells throughout the body

72
Q

What are the advantages of sexual reproduction?

A
  • Offers population a way to adapt to changing environment.
  • Competition among siblings may be reduced if genetically diverse.
  • Pairing of homologous chromosomes and crossing over opportunities to replace or repair damaged chromosomes and increase variation.
73
Q

What are the advantages of asexual reproduction?

A
  • Proceeds quickly and does not require presence of second organism
  • Usually requires less energy than sexual reproduction
  • Many forms, such as budding, help to maximize the chances of survival (as daughter cell does not fully separate until capable of independence).

Biology 30 (10 decks)

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