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Grade 12 Biology (TRU ONLINE LEARNING) > Topic 3.1: Cell Division- Mitosis and Meiosis > Flashcards

Topic 3.1: Cell Division- Mitosis and Meiosis Flashcards

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1
Q

Describe the cell cycle and explain the maor events that occur during each stage.

A

G1: The organelles are doubled in the cell, collects the materials to be used for DNA synthesis.

G0: The cells take a break from cell division preparation and resume their normal functions. If DNA is damaged in the cell, they will also enter the G0 phase and apoptosis will occur if the DNA is not reparable.

S: Replication of DNA occurs. One chromatid turns into two (sister chromatids).

G2: The cell synthesizes proteins for cell division.
M: Mitotic stage; the process in which mitosis or cytokinesis occur.

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2
Q

Explain why apoptosis is a necessary process.

A

It removes unwanted tissue and abnormal cells.

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3
Q

Define somatic cells

A

Body cell; excludes cells that undergo meiosis and become sperm or eggs.

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4
Q

Define apoptosis

A

Programmed cell death; involves a cascade of specific cellular events leading to death and destruction of the cell.

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5
Q

Define cell cycle.

A

An ordered sequence of events in eukaryotes that involves cell growth and nuclear division; consists of the stages G1, S, G2, and M.

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6
Q

Define interphase

A

Stages of the cell cycle (G1, S, G2) during which growth and DNA synthesis occur when the nucleus is not actively dividing.

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7
Q

Define chromatid

A

Following replication, a chromosome consists of a pair of sister chromatids, held together at the centromere; each chromatid is comprised of a single DNA helix.

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8
Q

Define sister chromatids

A

One of two genetically identical chromosomal units that are the result of DNA replication and are attached to each other at the centromere.

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9
Q

Define Mitosis

A

The stage of cellular reproduction in which nuclear division occurs; process in which a parent nucleus produces two daughter nuclei, each having the same number and kinds of chromosomes as the parent nucleus.

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10
Q

Define cytokinesis

A

Division of the cytoplasm following mitosis or meiosis.

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11
Q

Explain what factors would cause a cell to stop at each of the three cell cycle checkpoints

A

Cells stop at the G1 checkpoint if conditions are not favorable for cell division and/or there is DNA damage. Cells stop at the G2 checkpoint if the DNA has not finished replicating and/or there is DNA damage. Cells stop at the M checkpoint if the chromosomes are not lined up correctly at the metaphase plate.

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12
Q

Summarize the importance of growth factors in regulating the cell cycle.

A

Growth factors are external signals that promote cell division of target cells.

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13
Q

Distinguish between the action of oncogenes and mutated tumor suppressor genes.

A

Oncogenes encode proteins that continuously promote the cell cycle, leading to unregulated cell division. Tumor suppressor genes function to inhibit the cell cycle. If mutated, the proteins they express would not be active and the cell cycle would continue, possibly leading to cancer.

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14
Q

Define growth factors

A

A hormone or chemical, secreted by one cell, that may stimulate or inhibit growth of another cell or cells.

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15
Q

Define proto-oncogenes

A

Gene that promotes the cell cycle and prevents apoptosis; may become an oncogene through mutation.

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16
Q

Define tumor suppressor genes

A

Gene that codes for a protein that ordinarily suppresses the cell cycle; inactivity due to a mutation can lead to a tumor.

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17
Q

Define oncogenes

A

Cancer-causing gene formed by a mutation in a proto-oncogene; codes for proteins that stimulate the cell cycle and inhibit apoptosis.

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18
Q

Distinguish between the number of chromatids each chromosome contains before and after replication

A

One chromatid before replication; two chromatids after.

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19
Q

Summarize the events that are ocurring in each stage of mitosis.

A

Prophase: The centrosomes move away from eachother toward the opposite side of the nucleus, spindle fibers appear between the separating centrosomes, the nuclear envelope begins to fragment, the nucleolus begins to disappear, the chromatin condenses and chromosomes are visible.

Prometaphase: Kinetochores appear on either side of the centromere and they attach sister chromatids to the kinetochore spindle fibers. The kinetochore fibers attach the sisters to opposite poles of the spindle.

Metaphase: The spindle is fully formed and consists of poles, asters, and fibers. The chromosomes attached to the spindle fibers line up at the metaphase plate.

Anaphase: The sister chromatids separe and become daughter chromosomes and move to opposite poles of the spindle.

Telophase: The spindle disappears and the nuclear envelope reassembles. Each daughter nucleus contains the same number/kinds of chromosomes as the parental cell.

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20
Q

Compare and contrast cytokinesis in plant and animal cells.

A

Both result in two daughter cells with identical genetic material. Animal cells form a cleavage furrow between the daughter nuclei, which is constricted by the action of a band of actin filaments. Plant cells build a new cell wall between the daughter cells by fusing together vesicles produced by the Golgi apparatus.

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21
Q

Define chromatin

A

Network of DNA strands and associated proteins observed within a nucleus of a cell.

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22
Q

Define diploid (2n)

A

Cell condition in which two of each type of chromosome are present

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23
Q

Define haploid (n)

A

Cell condition in which only one of each type of chromosome is present.

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24
Q

Define centromere

A

Constriction where sister chromatids of a chromosome are held together.

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25
Q

Define spindle

A

Collection of microtubules that assist in the orderly distribution of chromosomes during cell division.

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26
Q

Define prophase

A

First phase of mitosis; characterized by the condensation of the chromatin; chromosomes are visible, but scattered in the nucleus.

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27
Q

Define prometaphase

A

Phase of cell division that occurs between prophase and metaphase and is characterized by attachment of the spindle fibers to the kinetochores of each sister chromatid.

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28
Q

Define metaphase

A

Third phase of mitosis; chromosomes are aligned at the metaphase plate.

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29
Q

Define anaphase

A

Fourth phase of mitosis; chromosomes move toward the poles of the spindle.

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30
Q

Define telophase

A

Final phase of mitosis; daughter cells are located at each pole.

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31
Q

Define cleavage furrow

A

Indentation in the plasma membrane of animal cells during cell division; formation marks the start of cytokinesis.

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32
Q

Define cell plate

A

Structure across a dividing plant cell that signals the location of new plasma membranes and cell walls.

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33
Q

Outline the major events that occur during meiosis I and II, focusing on the activities of the chromosomes

A

Meiosis I: Following DNA replication, each chromosome is duplicated. During meiosis I, the homologous chromosomes pair during synapsis and then separate.

Meiosis II: During meiosis II, the centromeres divide and the sister chromatids separate, becoming daughter chromosomes that move into the daughter nuclei.

34
Q

Explain why there are two divisions in meiosis and why the DNA is not replicated between meiosis I an meiosis II

A

In order to divide the DNA content in half; because the DNA was already replicated before meiosis began.

35
Q

Explain how crossing-over and independent assortment introduce genetic variation.

A

During crossing-over, genetic material is exchanged between nonsister chromatids. This produces a different combination of genes. Independent assortment mixes the whole chromosomes donated by both parents. The end result of both processes is cells that do not have genetic material identical to either parent.

36
Q

Define meiosis

A

Type of nuclear division that reduces the chromosome number from 2n to n; daughter cells receive the haploid number of chromosomes in varied combinations; also called reduction division.

37
Q

Define homologous chromosomes

A

Member of a pair of chromosomes that are alike and come together in synapsis during prophase of the first meiotic division; a homologue.

38
Q

Define synapsis

A

Pairing of homologous chromosomes during meiosis I.

39
Q

Define gamete

A

Haploid sex cell; e.g., egg or sperm.

40
Q

Define fertilization

A

Fusion of sperm and egg nuclei, producing a zygote that develops into a new individual.

41
Q

Define crossing-over

A

Exchange of segments between nonsister chromatids of a bivalent during meiosis.

42
Q

Define independent assortment

A

Alleles of unlinked genes segregate independently of each other during meiosis so that the gametes can contain all possible combinations of alleles.

43
Q

Define interkinesis

A

Period of time between meiosis I and meiosis II during which no DNA replication takes place.

44
Q

Describe the differences in the activity of the homologous chromosomes in prophase and metaphase of meiosis I and mitosis.

A

Meiosis I

Prophase I: Pairing of homologous chromosomes
Metaphase I: Homologous duplicated chromosomes at metaphase plate
Anaphase I: Homologous chromosomes separate
Telophase I: Two haploid daughter cells

Mitosis

Prophase: No pairing chromosomes
Metaphase: Duplicated chromosomes at metaphase plate
Anaphase: Sister chromatids separate, becoming daughter chromosomes that move to the poles
Telophase/ Cytokinesis: Two diploid daughter cells, identical to the parental cell.

45
Q

Compare and contrast the outputs of meiosis and mitosis with regard to the number of cells and the chromosome complement of each cell.

A

Meiosis II

Prophase II: No pairing of chromosomes
Metaphase II: Haploid number of duplicated chromosomes at metaphase plate
Anaphase II: Sister chromatids separate, becoming daughter chromosomes that move to the poles
Telophase II: Fur haploid daughter cells, not identical to parental cell

Prophase: No pairing of chromosomes
Metaphase: Duplicated chromosomes at metaphase plate
Anaphase: Sister chromatids separate, becoming daughter chromosomes that move to the poles.
Telophase/Cytokinesis: Tw diploid daughter cells, identical to the parental cell.

46
Q

Summarize the cells in the human body that are haploid and the role these cells play in the life cycle.

A

Sperm and egg cells are haploid. They function in sexual reproduction..

47
Q

Contrast the number of sperm produced from on primary spermatocyte with the number of eggs produced from on oocyte.

A

Four sperm; one egg.

48
Q
  1. Apoptosis
    a) decreases the number of cells in the body
    b) is programmed cell death
    c) is controlled by enzymes in the cell
    d) all of the above
A

d) all of the above

49
Q

At which of the following checkpoints is the DNA checked for damage and, if damage is present, the cell is placed in G0 phase?
a) M
b)G1
c) G2
d) None of the above

A

b)G1

50
Q

This checkpoint determines if the DNA has been replicated properly prior to cell division.
a) G1
b) S
C) G2
d) M

A

C) G2

51
Q

Which of the following act as the brakes of the cell cycle and prevents cells from dividing too quickly?
a) oncogenes
b) proto-oncogenes
c) cyclins
d) tumor suppressor genes

A

d) tumor suppressor genes

52
Q

Which of the following terms is describes incorrectly?
a) prometaphase-the kinetochores become attached to spindle fibers
b) anaphase- daughter chromosomes migrate toward spindle poles
c) prophase- the chromosomes condense and the nuclear enelope disintegrates
d) metaphase- the chromosome are aligned at the metaphase plate
e) telophase- a resting phase between cell division cycles

A

e) telophase- a resting phase between cell division cycles

53
Q

If a parent cell has a diploid of 24 chromosomes before mitosis, how many chromosomes with the daughter cell have?
a) 12
b) 24
c) 30
d) 36
e) 64

A

b) 24

54
Q

Cytokinesis in animal cells involves the formation of a/an
a) oncogene
b) cell plate
c) cleavage furrow
d) sister chromatid

A

c) cleavage furrow

55
Q

If a parent cell has 22 chromosome, the daugter cells following meiosis II will have
a) 22
b) 44
c) 11
d) all of the above

A

c) 11

56
Q

Crossing-over occurs between
a) sister chromatids of the same chromosome
b) chromatids of nonhomologous chromosomes
c) nonsister chromatids of a homologous pair
d) non of the above

A

c) nonsister chromatids of a homologous pair

57
Q

Which of these helps provide genetic diversity?
a) independent alignment during metaphase I
b) crossing-over during prophase I
c) random fusion of sperm and egg nuclei during fertilization
d) all of the above

A

d) all of the above

58
Q

The pairing of homologous chromosomes occurs during which of the following?
a) mitosis
b) meiosis I
c) meiosis II
d) all of the above

A

b) meiosis I

59
Q

Sister chromatids separate during anaphase of which of the following
a) mitosis
b) meiosis I
c) meiosis II
d) Both a and c

A

d) Both a and c

60
Q

Polar bodies are produced during
a) DNA replication
b) mitosis
c) spermatogenesis
d) oogenesis
e) none of the above

A

d) oogenesis

61
Q

Following fertilization, the somatic cells of humans divide by
a) apoptosis
b) meiosis
c) mitosis
d) DNA replication

A

d) DNA replication

62
Q

BPA is a chemical compound that has historically been used in the manufacture of plastic products. However, cells often mistake BPA compounds for hormones that accelerate the cell cycle. Because of this, BPA is associated with an increased risk of certain cancers.
a) How might BPA interact with the cell cycle of its checkpoints?
b) Why do you think very small concentrations of BPA might have a large effect on the cell

A

a) BPA could increase or decrease the production of cyclins, which would affect cell cycle progress through the checkpoints

b) Because BPA acts like a hormone, its effects are amplified within the cell

63
Q

Describe the characteristics of a pedigree for an autosomal dominant and an autosomal recessive trait.

A

Autosomal dominant:
- Affected children will usually have an affected parent
- Heterozygotes (Aa) are affected.
- Two affected parents can produce an unaffected child
- Two unaffected parents will not have affected children
- Both males and females are affected with equal frequency

Autosomal recessive:
- Most affected children have unaffected parents
- Heterozygotes (Aa) have an unaffected phenotype
- Two affected parents will always have affected children
- Closer relatives who reproduce are more likely to have affected children
- Both males and females are affected with equal frequency

64
Q

Distinguish between autosomal recessive and autosomal dominant genetic disorders.

A

Autosomal recessive disorders result from the inheritance of two recessive alleles. The child is affected and is homozygous recessive, but neither parent is because they are heterozygous. In autosomal dominant disorders, both parents are affected but the child can be unaffected.

65
Q

Define pedigree

A

Chart of genetic relationship of family individuals across generations.

66
Q

Interpret the genotype of the heterozygote if the inheritance pattern for a genetic disorder is shown to be incompletely dominant.

A

With incomplete dominance, the heterozygote exhibits a phenotype that is intermediate between the homozygous recessive and the homozygous dominant.

67
Q

Determine the genotype of the child, the mother, and the possible genotypes of the father for a child with type O blood who is born to a mother with type A blood.

A

The mother has to be heterozygous for type A blood, and the second allele for type O blood would have come from the father. He could have been heterozygous for type A, type B, or type O blood.

68
Q

Define incomplete dominance

A

Inheritance pattern in which an offspring has an intermediate phenotype, as when a red-flowered plant and a white-flowered plant produce pink-flowered offspring.

69
Q

Define codominance

A

Inheritance pattern in which both alleles of a gene are equally expressed in a heterozygote.

70
Q

Define familial hypercholesterolemia

A

Genetic disorder that causes an accumulation of cholesterol in the blood due to defects in the LDL receptors on the cell surface.

71
Q

Define multiple alleles

A

Inheritance pattern in which there are more than two alleles for a particular trait; each individual has only two of all possible alleles.

72
Q

Define polygenic inheritance

A

Pattern of inheritance in which a trait is controlled by several allelic pairs.

73
Q

Summarize the environmental factors that may influence polygenic traits such as height and skin color

A

Environmental factors include nutritional status, diet, temperature, and exposure to sunlight.

74
Q

Discuss how studies using identical twins may help determine how much f a phenotype is based on genetics and how much is environmental.

A

Identical twins have identical genomes and have developed from identical oocytes containing the same cytoplasmic composition. However, the expression of their genes is influenced by environmental inputs. Variation between identical twins is attributed to the inputs from the environment on their development.

75
Q
  1. Which of the following does not have an autosomal recessive pattern of inheritance?
    a) cystic fibrosis
    b) Huntington disease
    c) phenylketonuria
    d) sickle-cell disease
    e) none of the above
A

c) phenylketonuria

76
Q

Which of the following does not describe the pedigree analysis of an autosomal dominant disorder?
a) heterozygotes are affected
b) two affected parents will always have affected children
c) affected children usually have an affected parent
d) two unaffected parents will not have affected children

A

b) two affected parents will always have affected children

77
Q

If a child has type O blood and the mother is type A, then which of the following might be the blood type of the child’s father?
a) A only
b) A or O
c) B only
d) A, B, or O
e) O only

A

a) A only

78
Q

A trait in which the heterozygotes have a phenotype that is intermediate between the dominant and recessive phenotypes is an indication of
a) codominace
b) pleiotropy
c) a sex-linked trait
d) incomplete dominance
e) none of the above

A

d) incomplete dominance

79
Q

In the analysis of a genetic disorder, you notice that the phenotypic distribution follows a bell-shaped curve, and that multiple genes are probably involved. This suggests what pattern of inheritance?
a) autosomal dominant
b) autosomal recessive
c) incomplete dominance
d) polygenic inheritance
e) none of the above

A

d) polygenic inheritance

80
Q

Which of the following does not have an environmental factor that affects the distribution of the phenotype?
a) phenylketonuria
b) skin color
c) height
d) Marfan syndrome

A

d) Marfan syndrome

81
Q

You are working with the fruit fly Drosophila and want to determine whether a newly found characteristic is dominant or recessive. Design and experiment that will help you determine the dominance of the trait.

A

Grade 12 Biology (TRU ONLINE LEARNING) (17 decks)

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