Week 3 - Cellular Level of Organisation Flashcards

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1
Q

Question

A

Answer

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2
Q

What is the cell cycle?

A

The cell cycle is an orderly sequence of events in which a somatic cell duplicates its contents and divides into two identical cells.

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3
Q

What are somatic cells?

A

Somatic cells include all body cells except for germ cells (egg and sperm).

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4
Q

How many chromosomes do human somatic cells have?

A

Human somatic cells contain 23 pairs of chromosomes, totaling 46 chromosomes.

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5
Q

What are homologous chromosomes?

A

Homologous chromosomes are pairs of chromosomes, with one chromosome inherited from the mother and the other from the father.

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6
Q

What are the two major periods of the cell cycle?

A

Interphase and the mitotic phase.

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7
Q

What happens during interphase?

A

The cell prepares for division, including growth, replication of organelles and DNA, and synthesis of proteins and enzymes.

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8
Q

What occurs in the G1 phase of interphase?

A

The cell grows, replicates its organelles and cytosolic components, and the metabolic rate increases. Centrosome replication begins.

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9
Q

What happens during the S phase of interphase?

A

DNA is replicated, forming chromatids.

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10
Q

What occurs in the G2 phase of interphase?

A

The cell continues to grow, synthesizes proteins and enzymes, and completes centrosome replication.

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11
Q

What are the stages of the mitotic phase?

A

Prophase, Metaphase, Anaphase, Telophase.

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12
Q

What occurs during prophase in mitosis?

A

Chromatin fibers condense into paired chromosomes, the nucleolus and nuclear envelope disappear, and the mitotic spindle forms. Centrosomes move to opposite poles.

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13
Q

What happens during metaphase in mitosis?

A

Chromatid pairs line up along the metaphase plate.

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14
Q

What occurs during anaphase in mitosis?

A

Centromeres split, and identical sets of chromosomes move to opposite poles of the cell. Cytokinesis begins with the formation of a cleavage furrow.

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15
Q

What happens during telophase in mitosis?

A

Nuclear envelopes and nucleoli reappear, chromosomes revert to chromatin form, and the mitotic spindle disappears. The cytoplasm divides, resulting in two identical daughter cells.

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16
Q

What is meiosis?

A

Meiosis is a type of cell division in the gonads that produces four haploid gametes from a diploid cell.

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17
Q

What are the main stages of meiosis?

A

Meiosis I and Meiosis II.

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18
Q

What occurs during prophase I of meiosis?

A

Chromosomes condense, nuclear envelope and nucleoli disappear, the mitotic spindle forms, and homologous chromosomes pair up and exchange genetic material (crossing over).

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19
Q

What happens during metaphase I of meiosis?

A

Tetrads line up along the metaphase plate.

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20
Q

What occurs during anaphase I of meiosis?

A

Homologous chromosomes separate and move to opposite poles.

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21
Q

What happens during telophase I of meiosis?

A

Nuclear envelopes reappear, and the cytoplasm divides, resulting in two haploid cells.

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22
Q

What is interkinesis?

A

Interkinesis is a brief phase between Meiosis I and Meiosis II where no chromosome duplication occurs, but centrosomes duplicate.

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23
Q

What occurs during prophase II of meiosis?

A

The mitotic spindle forms, and the nuclear membrane disappears.

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24
Q

What happens during metaphase II of meiosis?

A

Chromosomes line up along the metaphase plate.

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25
Q

What occurs during anaphase II of meiosis?

A

Centromeres split, and sister chromatids separate, moving to opposite poles.

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26
Q

What happens during telophase II of meiosis?

A

Nuclear membranes reappear, and the cytoplasm divides, resulting in four haploid cells.

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27
Q

How do mitosis and meiosis differ in the type of cells they affect?

A

Mitosis affects somatic cells, while meiosis affects gametes.

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28
Q

How many divisions occur in mitosis and meiosis?

A

Mitosis has 1 division; meiosis has 2 divisions.

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29
Q

Do both mitosis and meiosis include interphase?

A

Yes, but in meiosis, interphase occurs only before Meiosis I.

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30
Q

Are tetrads formed in mitosis or meiosis?

A

Tetrads are formed in meiosis.

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31
Q

How many cells are produced at the end of mitosis and meiosis?

A

Mitosis produces 2 cells; meiosis produces 4 cells.

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32
Q

How many chromosomes are present in cells produced by mitosis and meiosis?

A

Mitosis produces cells with 46 chromosomes (diploid, 2n); meiosis produces cells with 23 chromosomes (haploid, n).

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33
Q

What is protein synthesis?

A

Protein synthesis is a crucial cellular function that determines physical and chemical characteristics of cells by assembling proteins for various roles such as forming the plasma membrane, cytoskeleton, organelles, and acting as hormones, antibodies, enzymes, and contractile elements in muscle tissue.

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34
Q

What is gene expression?

A

Gene expression is the process by which a gene’s DNA is used as a template to synthesize a specific protein.

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35
Q

What are the sets of three nucleotides in DNA and RNA called?

A

In DNA, they are called base triplets, and in RNA, they are called codons.

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36
Q

What do each triplet or codon correspond to?

A

Each triplet or codon corresponds to a specific amino acid.

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37
Q

What are the nucleotide bases in DNA?

A

Adenine (A), Thymine (T), Guanine (G), Cytosine (C)

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38
Q

What nucleotide replaces thymine in RNA?

A

Uracil (U)

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39
Q

What base pairs form in DNA?

A

Adenine pairs with thymine, and guanine pairs with cytosine.

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40
Q

What is transcription?

A

Transcription is the first step in gene expression, occurring in the nucleus, where genetic information from DNA is copied to a complementary RNA sequence.

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41
Q

What happens during the initiation step of transcription?

A

The enzyme RNA polymerase binds to a promoter sequence on the DNA, initiating transcription.

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42
Q

What occurs during the elongation step of transcription?

A

RNA polymerase reads the DNA strand and synthesizes a complementary mRNA strand using base pairing rules (A-U, T-A, G-C, C-G).

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43
Q

What happens during the termination step of transcription?

A

Transcription ends at a terminator sequence, and the newly formed mRNA strand detaches.

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44
Q

What types of RNA are produced during transcription?

A

Messenger RNA (mRNA), Ribosomal RNA (rRNA), Transfer RNA (tRNA)

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45
Q

What is the role of mRNA?

A

Directs protein synthesis.

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46
Q

What is the role of rRNA?

A

Assists in ribosome production.

47
Q

What is the role of tRNA?

A

Transfers amino acids to the ribosome during protein synthesis.

48
Q

What is translation in protein synthesis?

A

Translation is the process by which the nucleotide sequence in mRNA specifies the amino acid sequence of a protein, occurring in the cytoplasm at the ribosome.

49
Q

What happens during the initiation step of translation?

A

The mRNA binds to the small ribosomal subunit, and the initiator tRNA pairs with the start codon (AUG).

50
Q

What occurs during the elongation step of translation?

A

The large ribosomal subunit joins, and the ribosome moves along the mRNA. tRNA molecules bring amino acids to the ribosome, where they are added to the growing polypeptide chain.

51
Q

What happens during the termination step of translation?

A

The process ends when the ribosome reaches a stop codon, signaling the completion of the protein.

52
Q

What are tissues?

A

Tissues are groups of cells and surrounding materials that work together to perform specific functions.

53
Q

How many basic types of tissues are there in the body?

A

There are four basic types: epithelial, connective, muscular, and nervous tissues.

54
Q

What is the structure of epithelial tissue?

A

Composed of closely packed epithelial cells with minimal extracellular matrix.

55
Q

Where is epithelial tissue found?

A

Covers body surfaces, lines hollow organs, body cavities, ducts, and forms glands.

56
Q

What is the function of epithelial tissue?

A

Allows interaction with internal and external environments and provides protection.

57
Q

What is the structure of connective tissue?

A

Composed of various cell types surrounded by an extracellular matrix.

58
Q

Where is connective tissue found?

A

Found throughout the body.

59
Q

What are the functions of connective tissue?

A

Protects and supports the body, binds organs, stores energy as fat, and provides immunity.

60
Q

What is the structure of muscular tissue?

A

Composed of muscle cells (myocytes) surrounded by an extracellular matrix.

61
Q

Where is muscular tissue located?

A

Attached to bones, found in the walls of internal organs and blood vessels.

62
Q

What is the function of muscular tissue?

A

Facilitates contraction, generates force, and produces heat.

63
Q

What is the structure of nervous tissue?

A

Composed of neurons surrounded by an extracellular matrix.

64
Q

Where is nervous tissue found?

A

In the brain, spinal cord, and nerves throughout the body.

65
Q

What is the function of nervous tissue?

A

Detects changes, generates nerve impulses, and activates muscle contractions and glandular secretions.

66
Q

What is epithelial tissue composed of?

A

Cells arranged in continuous sheets, either in single or multiple layers, with minimal extracellular matrix.

67
Q

What is the apical surface of epithelial tissue?

A

The surface that faces the body surface, body cavity, lumen of an organ, or tubular duct.

68
Q

What is the lateral surface of epithelial tissue?

A

Contains cell junctions like tight junctions, adherens junctions, desmosomes, and gap junctions.

69
Q

What is the basal surface of epithelial tissue?

A

The deepest cells adhere to the basement membrane via hemidesmosomes.

70
Q

What is the basement membrane?

A

A structure composed of two layers: the basal lamina and reticular lamina, separating epithelial tissue from underlying connective tissue.

71
Q

Is epithelial tissue vascular?

A

No, epithelial tissue is avascular (lacks blood vessels) and relies on nutrients from adjacent connective tissues.

72
Q

What are the functions of epithelial tissue?

A

Acts as a selective barrier, secretory surface, protective surface, and helps move substances.

73
Q

What are the two main types of epithelial tissue?

A

Covering and lining epithelium, and glandular epithelium.

74
Q

What is covering and lining epithelium?

A

Forms the outer covering of the skin, internal organs, and inner lining of blood vessels, ducts, body cavities, and systems.

75
Q

What is glandular epithelium?

A

Makes up the secreting portion of glands like the thyroid, adrenal glands, and sweat glands.

76
Q

What are the three arrangements of cells in covering and lining epithelium?

A

Simple (single layer), pseudostratified (appears multilayered but all cells touch the basement membrane), and stratified (two or more layers).

77
Q

What are the four cell shapes in covering and lining epithelium?

A

Squamous, cuboidal, columnar, and transitional.

78
Q

What is simple squamous epithelium?

A

A single layer of flat cells involved in filtration, diffusion, and secretion.

79
Q

Where is simple squamous epithelium found?

A

Lines cardiovascular and lymphatic systems, serous membranes, air sacs of lungs, and kidneys.

80
Q

What is simple cuboidal epithelium?

A

A single layer of cube-shaped cells involved in secretion and absorption.

81
Q

Where is simple cuboidal epithelium found?

A

Covers the ovary surface, lines kidney tubules, and glands.

82
Q

What is non-ciliated simple columnar epithelium?

A

A single layer of non-ciliated, column-like cells involved in secretion and absorption.

83
Q

Where is non-ciliated simple columnar epithelium found?

A

Lines the gastrointestinal tract, ducts of many glands, and gallbladder.

84
Q

What is ciliated simple columnar epithelium?

A

A single layer of ciliated, column-like cells involved in movement.

85
Q

Where is ciliated simple columnar epithelium found?

A

Lines bronchioles, uterine tubes, uterus, spinal cord, and brain ventricles.

86
Q

What is pseudostratified columnar epithelium?

A

A single layer of cells that appears stratified, involved in motility and secretion.

87
Q

Where is pseudostratified columnar epithelium found?

A

Ciliated form lines airways; non-ciliated form lines ducts of glands, male urethra, and epididymis.

88
Q

What is stratified squamous epithelium?

A

Multiple layers with apical squamous cells, providing protection.

89
Q

What are the two types of stratified squamous epithelium?

A

Keratinized (contains keratin) and non-keratinized (lacks keratin).

90
Q

What is stratified cuboidal epithelium?

A

Two or more layers of cube-shaped cells involved in protection and limited secretion and absorption.

91
Q

Where is stratified cuboidal epithelium found?

A

Ducts of sweat glands, esophageal glands, part of the male urethra.

92
Q

What is stratified columnar epithelium?

A

Two or more layers of column-shaped cells involved in protection and secretion.

93
Q

Where is stratified columnar epithelium found?

A

Lines parts of the urethra, large ducts of glands, part of the eye’s conjunctiva.

94
Q

What is transitional epithelium?

A

Cells that vary in appearance, allowing for stretching.

95
Q

Where is transitional epithelium found?

A

Lines the urinary bladder, ureters, and parts of the urethra.

96
Q

What is glandular epithelium specialized in?

A

Secretion.

97
Q

What are the two main types of glands in glandular epithelium?

A

Endocrine and exocrine glands.

98
Q

What is the structure of endocrine glands?

A

Composed of hormone-producing epithelial cells, lacking ducts.

99
Q

Where are endocrine glands located?

A

Brain, thyroid, parathyroid glands, adrenal glands, pancreas, ovaries, and testes.

100
Q

What is the function of endocrine glands?

A

Secrete hormones into the bloodstream, regulating metabolic and physiological activities.

101
Q

What is the structure of exocrine glands?

A

Composed of secretory epithelial cells with ducts.

102
Q

Where are exocrine glands found?

A

Sweat, oil, wax, salivary glands, and pancreas.

103
Q

What is the function of exocrine glands?

A

Produce substances like sweat, oil, cerumen, saliva, and digestive enzymes.

104
Q

What are unicellular glands?

A

Single-celled glands like goblet cells that secrete mucus.

105
Q

What are multicellular glands classified based on?

A

Branching of ducts and shape of the secretory portion.

106
Q

What are the types of multicellular gland duct arrangements?

A

Simple (unbranched) and compound (branched).

107
Q

What are the types of secretory portion shapes in multicellular glands?

A

Tubular (tube-shaped) and acinar (rounded).

108
Q

How are exocrine glands classified functionally?

A

Based on their method of secretion: apocrine, holocrine, and merocrine glands.

109
Q

What is the secretion method of apocrine glands?

A

Accumulate product at the apical surface; the top part of the cell pinches off.

110
Q

What are examples of apocrine gland secretions?

A

Milk production in mammary glands, some types of sweat.

111
Q

What is the secretion method of holocrine glands?

A

The entire cell matures, ruptures, and releases the product.

112
Q

What is an example of a holocrine gland?

A

Sebaceous (oil) glands.

113
Q

What is the secretion method of merocrine glands?

A

Secretions are released in secretory vesicles via exocytosis.

114
Q

What are examples of merocrine gland secretions?

A

Saliva, clear sweat, digestive enzymes.