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CENG | CMB | MI > Chapter 9 CMB Cell Division > Flashcards

Chapter 9 CMB Cell Division Flashcards

1
Q

Cellular reproduction is also known as?

A

Cell division

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2
Q

*What are the 2 types of reproduction?

A

1) Asexual reproduction
2) Sexual reproduction

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3
Q

What is asexual reproduction?

A

Asexual reproduction is reproduction that does not involve fertilization.
Common in bacteria, archae and protists, some plants and fungi

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4
Q

What is sexual reproduction?

A

Sexual reproduction is reproduction involving the fusion of gametes
1. Involve male & female individuals which may/may not look alike
2. Almost all living things

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5
Q

*How do prokaryotes reproduce? Explain the steps involved (DCD)

A

They reproduce asexually through Binary Fission.

  1. Duplication of chromosome and separation of copies
  2. Continued growth of the cell and movement of copies
  3. Division into two cells
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6
Q

How does an amoeba produce?

A

Amoeba produces genetically identical offspring through asexual reproduction.

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7
Q

What are the advantages of asexual reproduction?

A
  1. If isolated, produce without finding mates
  2. Produce many quickly as no time or energy is spent in gamete production or fertilization
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8
Q

What are the disadvantages of asexual reproduction?

A
  1. Genetically uniform population
  2. If the environment changes, all individuals will be affected equally & entire population will be wiped out
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9
Q

*What is the total length of human genome?

A

3 billion base pairs

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10
Q

*How many base pairs does each haploid cell contain?

A

3 billion base pairs

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11
Q

*How many base pairs does each diploid cell contain?

A

6 billion base pairs

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12
Q

What does the nucleus act as?

A

The NUCLEUS acts as the cell’s control center. It regulates growth, metabolism and reproduction

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13
Q

The heart of the control center is the ________________

A

the heart of the control center is the Human GENOME

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14
Q

*How many chromosomes does the human genome have?

A

Two sets of 23 CHROMOSOMES = 46 chromosomes

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15
Q

Function of genes?

A

GENES control how cells grow & interact with one another

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16
Q

*Why is the human genome sequenced? (4 steps) SUIM

A
  1. To store the information gathered for further biological and medicinal study
  2. To understand the nature of the proteins that genes code for
  3. To identify mutations in the gene which cause genetic disorders
  4. Molecular medicine; new approaches to
    - Improve Diagnosis of disease
    - Prevention; detect genetic predispositions to disease
    - Create pharmaco-genomics-customized drugs
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17
Q

*What is molecular medicine used for? (3 examples) IPC

A

1) Improve diagnosis of disease
2) Prevention; detect genetic predispositions to disease
3) Create pharmaco-genomics-customized drugs

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18
Q

What is a human genome?

A
  • The complete set of genes present in a cell or organism
  • All genetic information present in an individual
  • All of the hereditary material possessed by an organism
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19
Q

*How many autosomes and sex chromosomes does the genome contain?

A

44 autosomes + 2 sex (XY or XX) chromosomes

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20
Q

*What are chromosomes? (4 points)

A
  1. Physical carriers of genes
  2. Located in the nucleus of eukaryotic cells
  3. Composed of DNA wrapped around proteins called histones
  4. X-shaped; condensed chromatin
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21
Q

Sister chromatids are identical in the information they carry. How do sister chromatids form?

A

From the chromosome undergoing DNA replication just before cell division

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22
Q

What is a centromere for during mitosis?

A

Region with attachment sites for microtubules (spindle apparatus) that will move the chromosome during division

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23
Q

What is a chromatin?

A

Chromatin is DNA wound around globular proteins called histones > More compact structure, easier to manage during cell division

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24
Q

*What does the structure of chromosome consist of? (Diagram)

A
  1. p arm (shorter, always arranged at the top)
  2. q arm (longer, at the bottom)
  3. centromere (middle/centre)
  4. sister chromatids
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25
Q

Where is the kinetochore located?

A

At the centromere of chromosomes in eukaryotic cells

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26
Q

What is a human karyotype?

A

Human karyotype is a systemized array of the chromosomes of a single cell prepared either by drawing or by photography

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27
Q

What is a giemsa dye for in a human chromosome?

A

To show the G-bands of a human chromosome

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28
Q

What are the dark regions in a human chromosome?

A

Heterochromatic, late-replicating and AT rich

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29
Q

What are the bright regions in a human chromosome?

A

Euchromatic, early-replicating, and GC rich

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30
Q

What does a replicated chromosome consist of?

A

A replicated chromosome consists of two chromatids (which carry identical information), held together at the centromere.

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31
Q

What are homologous chromosomes made up of?

A

Two chromosomes in a pair – normally one inherited from the mother and one from the father.

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32
Q

Do chromosomes contain many genes?

A

Yes

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33
Q

What are genes?

A

Gene is a unit of information that
- Codes for a protein
- Codes for genetic traits that are heritable
e.g Height, Eye colour etc

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34
Q

*What is the structure of gene? (Diagram, 3 steps)

A
  1. 7mG cap
  2. Addition of Poly A tail
  3. Splicing of introns
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35
Q

What are alleles?

A

Controls the genes
Allele: alternative form of a gene (one member of a pair)
- Organisms have two alleles for each trait
- Located on homologous chromosomes

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36
Q

How is dosage compensation achieved? (in humans, for sexual)

Hint: By inactivating _____

A

It is achieved by inactivating either the maternal X chromosome or the paternal X chromosome early in development

37
Q

Dosage compensation is the process that leads to the formation of?

A

Barr bodies in female somatic cells

38
Q

*What are barr bodies?

A

(Inactivated X chromosome)
1. The condensed, darkly staining spot, inactive X-chromosome found in the nuclei of somatic cells of most female mammals
2. If one of the two X chromosomes is inactivated in female cells, then the dosage of genetic information that can be expressed in males and females is equivalent.

39
Q

*What are the 2 main parts of the cell cycle?

A

Interphase and mitosis

40
Q

*What are the 4 stages of mitosis?

A
  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase
41
Q

*What are the 3 stages of interphase?

A
  1. G1 (growth)
  2. S (Synthesis)
  3. G2 (growth)
42
Q

*What are the 4 main phases of cell cycle?

A
  1. G1 (First gap)
  2. S (Synthesis)
  3. G2 (Second gap)
  4. M (Mitosis)
43
Q

What happens during G1 (First gap) in the cell cycle?

A
  • Cell grows in size and carries out normal metabolism
  • The cell makes more ribosomes and proteins
  • Organelles duplicate
44
Q

What happens during S (Synthesis) in the cell cycle?

A

The cell copies its DNA, the proteins that package DNA, and more cell membrane material

45
Q

What happens during G2 (Second gap) in the cell cycle?

A
  • The organelles divide, cell grows and prepares for division (mitosis)
  • The last phase before mitosis begins
46
Q

What happens during M (Mitosis) in the cell cycle?

A
  • Nuclear (chromosomes separate) and cytoplasmic (cytokinesis) division occur
  • One parent cell divides into two daughter cells
  • Resulting daughter cells have exactly the same number of chromosomes as the parent cells. (if parent cell has 46 chromosomes, then daughter cells will also have 46 chromosomes.)
47
Q

*Mitosis (for non-sexual cells) occurs in ______

A

Somatic (body) cells

48
Q

What happens during prophase?

A
  • The chromatin condenses and the chromosomes become visible.
  • The nucleolus disappears, the nuclear membrane fragments (breaks into pieces), and
  • The spindle apparatus forms and attaches to the centromeres of the chromosomes.
49
Q

What happens during metaphase?

A

During metaphase, the nuclear membrane fragmentation is complete and the duplicated chromosomes line up along the cell’s equator

50
Q

What happens during anaphase?

A

During anaphase, diploid sets of daughter chromosomes separate and are pushed and pulled toward opposite poles of the cell.

51
Q

What happens during telophase?

A

During telophase, the nuclear membrane and nucleoli reform, cytokinesis is nearly complete, and the chromosomes eventually uncoil to chromatin.

52
Q

What happens during cytokinesis in both animal and plant cells?

A

During cytokinesis, the dividing cell separates into two diploid daughter cells.

  1. Not a phase of mitosis.
  2. It completes the entire process of cell division.
53
Q

How does cytokinesis happen in animal cells?

A
  • In animals, cytokinesis occurs by cleavage
  • This process pinches the cell apart
54
Q

What happens during cytokinesis in plant cells?

A

Cell plate forms at the equator, dividing the cell into 2 (develops into new cell wall)

55
Q

Meiosis (sexual cell division) occurs only in _________

A

Occurs only in reproductive cells (egg & sperm)

56
Q

Meiosis does not occur in archaea or bacteria because ___________

A

Meiosis does not occur in archaea or bacteria as they reproduce asexually (binary fission).

57
Q

*In animals, meiosis produces gametes such as ______ and _________

A

In animals, meiosis produces gametes like sperm and egg cells

58
Q

In fungus, meiosis generates _______

A

Spores

59
Q

During meiosis, one parent cell divides into ______. Resulting daughter cells have _________________

A
  • One parent cell divides into four daughter cells
  • Resulting daughter cells have half the number of chromosomes as the parent cell
    EG. If the parent cell has 46 chromosomes (2n = 46), then the daughter cell will have 23 chromosomes (n = 23).
60
Q

Meiosis begins with __________________ containing ____________________

A

Begins with one diploid cell containing two copies of each chromosome. One from the organism’s mother and one from its father

61
Q

Meiosis produces ___________

A

Produces 4 haploid cells containing one copy of each chromosome.

62
Q

What do the resulting chromosomes in the gamete cells contain?

A

Each of the resulting chromosomes in the gamete cells is a unique mixture of maternal and paternal DNA.

63
Q

TRUE OR FALSE?
Offspring are genetically distinct from either parent during meiosis.

A

True. Allows for genetic diversity.

64
Q

What are the 2 divisions of meiosis?

A

1st division (meiosis 1)
2nd division (meiosis 2)

65
Q

What are the phases of meiosis?

A

prophase 1/2, metaphase 1/2, anaphase 1/2 and telophase 1/2

66
Q

What happens during the 1st meiotic division?

A

In the first meiotic division (reduction stage), the number of cells is doubled but the number of chromosomes is not. This results in 1/2 as many chromosomes per cell (haploid)

67
Q

What happens during 2nd meiotic division?

A

The second meiotic division is like mitosis (division stage); the number of chromosomes does not get reduced.

68
Q

What is interkinesis?

A

Interkinesis is similar to interphase except DNA synthesis does not occur

69
Q

State the 5 differences between mitosis and meiosis**

A
  1. Mitosis occurs in somatic cells (autosomes) (Asexual division) while meiosis occurs in reproductive cells (Sexual or reductional division)
  2. During mitosis, the mother cell (2n) gives rise to two diploid (2n) daughter cells (46 chromosomes > 2 x 46 chromosomes) while during meiosis, the mother cell (2n) gives rise to four haploid (n) daughter cells (46 chromosomes > 4 x 23 chromosomes)
  3. During mitosis, homologous chromosome do not pair and chromosomes align themselves in single file along the equator during metaphase. On the other hand, during meiosis, homologous chromosome pair-up during prophase 1 and align themselves as homologous pairs along the equator during metaphase 1.
  4. During mitosis, no cross over occurs while meiosis does

5.Mitosis produce identical cells while meiosis produce variations in offspring.

70
Q

Remember to study the diagrams for mitosis and meiosis. How do they divide?

A

1) Mitosis is dividing into two diploid daughter cells (2x46)
2) Meiosis is dividing into four haploid daughter cells (4x23)

71
Q

What causes genetic diversity?
(Synapsis and Crossing over)

A

During meiosis, homologous chromosomes (1 from each parent) pair along their lengths. The chromosomes cross over at points called chiasma. At each chiasma, the chromosomes break and rejoin, trading some of their genes. This recombination results in genetic variation/diversity because the chromatids are genetically different from each other.

72
Q

*State the 3 types of chromosome structures
(study the diagram)

A

1) Metacentric
2) Submetacentric
3) Acrocentric/acentric

73
Q

What causes chromosomal mutation?

A
  1. Error in Meiosis cell division or separation of chromosomes
  2. Chromosomes fail to separate in Meiosis I or Meiosis II or in both.
  3. As a result, the individual born with less or more chromosomes.
74
Q

*What is a karyotype?

A
  • Study about the arrangement of chromosomes according to their size.
  • Helps in diagnosis of presence of chromosome disorders.
75
Q

*What is cytogenetics?

A

Study of chromosomes and their abnormalities

76
Q

What are the 3 Abnormalities in Chromosome Number called? (EPA)

A

1) Euploidy
2) Polyploidy
3) Aneuploidy

77
Q

What is euploidy?

A
  • Normal number of chromosomes, 23 pairs in the cell
78
Q

What is polyploidy?

A
  • Extra set of chromosome in all chromosomes (triploidy & Tetraploidy) of the cell.
  • Can be fatal in humans
79
Q

What is aneuploidy? (2 types)

A

Less or extra copy of a single chromosome
(i) Monosomy: 1 copy of a chromosome in the somatic cells
(ii) Trisomy: 3 copies of a chromosome in the somatic cells.
(Non-disjunction = Down syndrome)

80
Q

What happens in prophase I?

A
  • The chromosomes condense, and the nuclear envelope breaks down.
  • Pairing of homologous chromosomes
  • Synapsis occurs - homologous chromosomes switch their genes. The switching is called “crossing-over”, when the chromosomes separate, they end up with new gene combinations.
81
Q

What happens in metaphase I?

A
  • Pairs of homologous chromosomes move to the equator of the cell.
  • Spindle microtubules harness & orientate one chromosome of each pair towards opposite poles of the spindle
  • Random harnessing (independent assortment) of maternal and paternal chromosomes
82
Q

What happens in anaphase I?

A

Homologous chromosomes move to the opposite poles of the cell

83
Q

What happens in telophase I & cytokinesis

A

Chromosomes gather at the poles of the cells. The cytoplasm divides.

84
Q

What happens in prophase II?

A

A new spindle forms around the chromosomes.

85
Q

What happens in metaphase II?

A

Chromosomes line up at equator.

86
Q

What happens in anaphase II?

A

Centromeres divide, chromatids move to the opposite poles of the cells.

87
Q

What happens in telophase II & cytokinesis?

A

A nuclear envelope forms around each set of chromosomes. The cytoplasm divides

88
Q

What is synapsis?

A
  • The process of linking of the replicated homologous chromosomes
  • Homologous chromosomes stick together along their lengths
89
Q

What is crossing-over?

A

Two non-sister chromatids break at an identical site called a chiasma (chiasmata), and swap genetic segments at the break and may be reattached to a different homologous chromosome

CENG | CMB | MI (25 decks)

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