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biol 235 > Chr. 3 - Organization of Cellular Level > Flashcards

Chr. 3 - Organization of Cellular Level Flashcards

1
Q

List the three parts of a cell.

A

Plasma membrane, cytoplasm, and nucleus.

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2
Q

Describe the fluid mosaic model.

A

The molecular arrangement of plasma membrane resembling a moving landscape of lipids with different attached proteins.

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3
Q

Describe the lipid bilayer.

A

Two layers of made of phospholipids, glycolipids, and cholesterol. Structured with hydrophilic phosphate facing outwards, and hydrophobic lipids in between forming the center.

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4
Q

What is an integral protein?

A

Proteins extending into or through lipid bilayer, firmly embedded.

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5
Q

What is a transmembrane protein?

A

Protrude from plasma membrane into extracellular fluid, found across the membrane.

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6
Q

What is a peripheral protein?

A

Proteins attached to polar heads of membrane lipids or integral proteins.

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7
Q

What are glycoproteins?

A

Integral proteins with carbohydrate groups extending into extracellular fluid.

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8
Q

What is the glycocalyx?

A

Sugary coating comprised of the carbohydrate groups of glycoproteins.

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9
Q

Describe ion channels.

A

Pores/holes formed by integral proteins allowing ions to flow in or out of a cell. Usually selective.

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10
Q

Describe a transporter in regards to integral proteins.

A

Integral proteins that selectively move a polar substance. AKA a carrier.

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11
Q

Describe a receptor in regards to integral proteins.

A

Integral proteins that recognize and bind a ligand.

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12
Q

Describe an enzyme in regards to integral proteins.

A

Integral proteins that catalyze chemical reactions inside or outside the cell.

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13
Q

Describe linkers in regards to integral proteins.

A

Integral proteins that anchor other proteins in the plasma membranes of neighbouring cells via protein filaments inside and outside the cell.

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14
Q

What are cell-identity markers and what are their functions?

A

Glycoproteins and glycolipids that signal information about that specific cell.

  1. They recognize other cells during tissue formation.
  2. Recognize and respond to potentially dangerous foreign cells.
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15
Q

Describe selective permeability.

A

The ability of the plasma membrane to be permeable to nonpolar molecules, moderately permeable to small uncharged molecules, and impermeable to large uncharged polar molecules.

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16
Q

What is a concentration gradient?

A

A difference in the concentration of chemicals across a distance.

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17
Q

What is an electrical gradient?

A

A difference in electrical charge between two regions, usually with a barrier separating charges.

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18
Q

What is a membrane potential?

A

A difference in electrical charge between the interior and exterior of a cell with the plasma membrane as a barrier.

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19
Q

Describe an electrochemical gradient.

A

The combined influence of concentration gradient and electrical gradient on the movement of a particular ion/molecule.

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20
Q

What are passive and active transport processes?

A

Passive processes are when a substance moves only using its own kinetic energy, usually derived from the electrochemical gradient.

Active processes are when a cell uses energy to drive substances against the electrochemical gradient.

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21
Q

What is diffusion, and what are the five factors affecting it?

A

Passive process in which a solute in solvent moves across concentration gradient.

  1. Steepness of concentration gradient.
  2. Temperature.
  3. Mass of diffusing substance.
  4. Surface area.
  5. Diffusion distance.
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22
Q

What is facilitated diffusion?

A

When an integral protein assists substances across the membrane without expending cellular energy.

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23
Q

Describe channel-mediated diffusion.

A

Diffusion where solutes unable to pass through the plasma membrane enter the cell via integral proteins acting as channels.

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24
Q

Describe carrier-mediated diffusion.

A

Diffusion where solutes bind to a protein, causing it to change shape where it releases the solute on the opposite side.

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25
Q

What is osmosis?

A

A type of diffusion where a solvent moves through a selectively permeable membrane, inversely across a concentration gradient of solute.

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26
Q

How does osmosis occur across the plasma membrane?

A

In two ways:

  1. Moving between neighboring phospholipid molecules via diffusion.
  2. Moving through integral proteins that function as water channels, called aquaporins.
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27
Q

Describe hydrostatic pressure.

A

Pressure exerted by a fluid at equilibrium at any point due to gravity.

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28
Q

Define osmotic pressure.

A

Pressure exerted by a difference in amounts of solutes between solutions that are separated by a semipermeable membrane.

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29
Q

What is tonicity?

A

The measure of a solution’s ability to change volume of cells.

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30
Q

What is an isotonic solution.

A

A solution in which a cell will maintain it’s normal shape and volume.

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31
Q

What is a hypotonic solution.

A

A solution with lower concentration of solutes than a cell, causing water molecules to enter the cell by osmosis.

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32
Q

What is a hypertonic Solution.

A

A solution with higher concentration of solutes, dehydrating a cell by osmosis.

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33
Q

What is primary active transport?

A

Transport of molecules using protein pumps driven by cellular energy derived from ATP.

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34
Q

Describe how a protein pump functions.

A

Sodium ions bind to a protein pump inside the cell, initiating hydrolysis of ATP into ADP + Phosphate. The phosphate ion attaches to the protein pump, changing its shape and expelling the sodium into extracellular fluid. After sodium is released, it binds potassium. This causes a release of the phosphate, reverting the protein to its original shape and bringing the potassium inside the cell.

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35
Q

What is secondary active transport?

A

When a carrier protein binds two substances and changes its shape to move both across the membrane, one with concentration gradient and one against. Usually harnesses sodium.

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36
Q

What is endocytosis and exocytosis?

A

Endocytosis is when materials move into a cell within a vesicle formed by the plasma membrane.

Exocytosis is when materials move out of a cell within a vesicle that fuses with the plasma membrane, releasing its contents.

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37
Q

List the three types of endocytosis, and give a short explanation of each.

A
  1. Receptor-mediated endocytosis - highly-selective endocytosis where specific ligands bind to plasma membrane in extracellular space and initiate formation of a vesicles towards inside of the cell.
  2. Phagocytosis - process where particles bind to proteins in the extracellular plasma membrane, causing the membrane to extend and engulfing the particle.
  3. Bulk-phase endocytosis - Inward folding of the plasma membrane to uptake extracellular fluid. This process does not require ligands.
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38
Q

What is transcytosis?

A

When a transport vesicle forms during intake of contents into a cell, transports it across the same cell, and releases it at another location.

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39
Q

List the components of the cytoplasm.

A
  1. Cytosol.
  2. Organelles.
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40
Q

What is the cytoskeleton?

A

A network of protein filaments that extend throughout the cytosol. Consists of microfilaments, intermediate filaments, and microtubules.

41
Q

What is a microfilament, and what are it’s functions?

A

Elements of the cytoskeleton comprised of actin and myosin. They generate movement and provide mechanical support.

42
Q

What are intermediate filaments, and what are its functions?

A

Structural elements composed of multiple proteins. Stabilize positions of organelles and attach cells to each other.

43
Q

What are microtubules, and what are their functions?

A

Structural components of the cell, comprised of tubulin. Determine cell shape and aid in organelle movement.

44
Q

What is a centrosome, and what is its function?

A

Comprised of two componenets: a pair of centrioles and a pericentriolar matrix.

Centrioles are comprised of 9 x clusters of 3 x microtubules.

Pericentriolar matrix is a collection of hundreds of ring-shapes complexes of tubulin.

Responsible for organizing growth of the mitotic spindle and microtubule formation in nondividing cells.

45
Q

What are cilia and flagella?

A

Organelles consisting of microtubules.

Cilia - short hairlike projections extending from cell surface. Moves fluid along cell’s surface.

Flagella - longer hairlike extensions responsible for movement of the entire cell.

46
Q

What are ribosomes?

A

Organelles responsible for protein synthesis, consist of two subunits (large + small). Located on RER, cytosol, and within mitochondria.

47
Q

What is the endoplasmic reticulum?

A

An organelle composed of a network of flattened sacs/tubules originating on the nuclear envelop. Two forms exist: rough endoplasmic reticulum, and smooth endoplasmic reticulum.

48
Q

What is the function of the rough endoplasmic reticulum?

A

Protein synthesis, including glycoprotein, and phospholipids.

49
Q

What is the function of the smooth endoplasmic reticulum?

A

Synthesize fatty acids and steroids.

50
Q

What is the golgi complex, and what is its function?

A

A small flattened organelle comprised of curved membranous sacs. Responsible for modifying, sorting, and packaging proteins.

51
Q

List the steps of the process proteins take through the golgi apparatus.

A
  1. Rough ER forms a vesicle around proteins formed by ribosomes.
  2. Vesicles transport protein to golgi apparatus.
  3. Proteins enter the lumen of cis-face of golgi apparatus.
  4. Protein moves through golgi apparatus as it is modified by enzymes.
  5. Protein enters lumen of exit-face.
  6. Further modification of protein.
  7. Proteins are discharged according to destination released via:
    • secretory vesicles into extracellular content
    • membrane vesicles to be incorporated in the membrane
    • transport vesicles to destinations with in the cell.
52
Q

What is a lysosome?

A

A membrane-enclosed vesicle that contains digestive and hydrolytic enzymes.

53
Q

Describe autophagy.

A

The process where an entire organelle is digested by a lysosome.

54
Q

Define autolysis.

A

The process whereby a lysosome destroy the containing cell.

55
Q

What is a peroxisome?

A

A smaller vesicle-like organelle containing enzymes to oxidize substances.

56
Q

What is a proteasome?

A

A tiny, barrell-shaped structure consisting of four stacked rings of protein around a core. Respinsible for breaking down proteins.

57
Q

Describe a mitochondrion.

A

A thread-like organelle that generates ATP. Consist of external and internal mitochondrial membrane, where the inner membrane contains folds called mitochondrial cristae. Within the internal membrane, the mitochondrial matrix exists.

58
Q

What is apoptosis?

A

Genetically programmed cellular death.

59
Q

[3.5] What is a nucleus?

A

A spherical/oval shaped structure directing cell activity and containing DNA.

60
Q

[3.5] What is the nuclear membrane?

A

A double lipid-bilayer membrane where the outside layer is continuous with the rough ER.

61
Q

[3.5] What are nuclear pores, and what is their function?

A

Circular arrangements of proteins creating openings in the nuclear membrane. Control movement of substances between nuclear and cytoplasm.

62
Q

[3.5] What are nucleoli?

A

Spherical bodies made of clusters of protein, DNA, and RNA, within the nucleus that create ribosomes.

63
Q

[3.5] What is chromatin?

A

A complex of DNA and proteins responsible for organizing DNA into compact structures. Many chromatin form chromosomes.

64
Q

[3.5] What is a genome?

A

The total genetic information of a cell/organism.

65
Q

[3.5] What is a nucleosome?

A

Bead-like structural units attached on a string of chromatin, consist of a double-strand of DNA wrapped around a core of eight histones.

66
Q

[3.5] What is a histone?

A

Collection of eight proteins that form a core in which DNA can wind around on, to form the structural unit of nucleosomes.

67
Q

[3.5] What is a chromatin fiber?

A

Large-diameter strings of chromatin folded into loops.

68
Q

[3.5] What is a chromatid?

A

Condensed chromatin fibers, found in pairs that form chromosomes.

69
Q

[3.6] What is a proteome?

A

A term referencing the collective of all proteins in an organism.

70
Q

[3.6] What is gene expression?

A

A process in which a genes DNA is used as a remplate for synthesis of a specific protein. Comprised of transcription and translation.

71
Q

[3.6] What is a base triplet?

A

A sequence of three nucleotides forming a set.

72
Q

[3.6] What is a codon?

A

A complimentary set of nucleotides that mirror the original base triplet, representing particular amino acids.

73
Q

[3.6] What is the genetic code?

A

A set of rules that define the relationship between base triplets and codons.

74
Q

[3.6] What is transcription?

A

A process where RNA is created from DNA, forming a blueprint for protein synthesis.

75
Q

[3.6] Describe the three types of RNA transcripted from DNA.

A
  1. Messenger RNA - directs synthesis of protein.
  2. Ribosomal RNA - Integrates with ribosomal proteins to create ribsosome.
  3. Transfer RNA - holds amimo acid in place on the ribosome while it is integrated into a protein. Binds to mRNA via codon/anticodon.
76
Q

[3.6] What is the function of RNA polymerase?

A

To catalyze the transcription of DNA, starting at the promotor sequence and ending at the terminator sequence.

77
Q

[3.6] What are the promotor and terminator sequences?

A

The promotor sequence is a codon marking the beginning of a gene.

The terminator sequence is a codon marking the end of a gene.

78
Q

[3.6] What are introns and exons?

A

Introns are regions of a gene that do not code - they are sequences that are meaningless to RNA polymerase.

Exons are regions of a gene that can be read and transcribed by RNA polymerase.

79
Q

[3.6] What is translation?

A

The process in which sequences of mRNA dictate to a ribosome the amino acid sequence of a protein.

80
Q

[3.7] What is cell division and describe the two types.

A

Cell division is the process by which cells reproduce.

Somatic cell division occurs when a somatic cell undergoes nuclear and cytoplasmic division (mitosis and cytokinesis).

Reproductive cell division produces gametes forming the next generation of sexually reproducing organisms.

81
Q

[3.7] What is a somatic cell?

A

Any cell in the body other than a germ cell.

82
Q

[3.7] What is a germ cell?

A

A gamete or any precursor cell destined to become a gamete.

83
Q

[3.7] What are homologous chromosomes?

A

Two individual chromosomes that make up a pair.

84
Q

[3.7] What is a diploid cell?

A

Any cell that contains two sets of chromosomes. For humans, a set of chromosomes is 23 different chromosomes, and two sets are 23 pairs of these chromosomes - 22 autosomes and one pair sex chromosomes.

85
Q

[3.7] What is interphase?

A

A period of time where DNA is replicated and additional organelles/cytosolic components are created. Defined into G1, S, and G2 phases.

86
Q

[3.7] Describe G1 phase.

A

G1 phase: first phase of interphase, occurs after mitotic phase. Cell is metabolically active, replicating organelles and cytosolic components. Centrosomes created. Cells remaining in G1 phase indefinitely by design are declared in G0 phase.

87
Q

[3.7] Describe S phase.

A

Interval between G1 phase and G2 phase. DNA replication occurs.

88
Q

[3.7] Describe G2 phase.

A

Interval between S phase and mitotic phase. Cell growth continues, enzymes and proteins are synthesized, replication of chromosomes is complete.

89
Q

[3.7] Describe DNA replication.

A

The helical structure of DNA uncoils at hydrogen bonds between base pairs. Enzymes flow up the uncoiled strands, pairing newly synthesized nucleotides with the uncoiled strands, creating twin DNA strands. These will compress into the sister chromosomes in mitotic phase.

90
Q

[3.7] What are the phases of the mitotic phase?

A

Prophase, metaphase, anaphase, and telophase.

91
Q

[3.7] What occurs in prophase?

A

Chromatin fibers condense and shorten into chromosomes. A centromere holds each chromatid at its center. Pericentriolar material forms the mitotic spindle from microtubules; these attach to the centromeres and push them to opposite sides of the cell, leaving the chromatid in the center. The nucleus disappears.

92
Q

[3.7] What occurs in metaphase?

A

Mitotic spindle aligns centromeres at exact center.

93
Q

[3.7] What occurs in anaphase?

A

Centromeres split, pulling one out of each pair of chromosomes to either side.

94
Q

[3.7] What occurs in telophase?

A

Chromosomes at each side uncoil and revert to thread-like chromatin form. Nuclear envelope forms around each, the mitotic spindle beaks up, and the nucleus is formed.

95
Q

[3.7] What does cytokinesis consist of?

A

Begins in late anaphase by formation of a “cleavage furrow”, and completes after telophase. The cleavage furrow occurs perpendicular to the mitotic spindle, ensuring each side of the old cell has a nucleus. Actin microfilaments from a contractile ring that draws the plasma membrane inwards and pinches the cell in two.

96
Q

[3.7] Describe meiosis I.

A

Meiosis I is the first phase of meiosis, consisting of prophase I, metaphase I, anaphase I, and telophase I.

Prophase I: Similar to prophase of mitotic phase. Two unique events occur: sister chromatids pair off, known as synapsis, and form tetrads (four chromatids). Second, crossing-over occurs, the exchanging of genes between chromatids. This leads to cells unlike the starting cell, resulting in genetic recombination, the genetic variation seen in species.

Metaphase I: Similar to mitotic metaphase.

Anaphase I: Similar to mitotic anaphase, except the tetrads split, leaving whole chromosomes to be pulled to each side.

Telophase I: Identical to mitotic telophase; cell pinches into two separate cells.

97
Q

[3.7] Describe meiosis II.

A

Prophase II: Identical to mitotic prophase; chromosomes attach to centromeres via mitotic spindles.

Metaphase II: Identical to mitotic metaphase: chromosomes line up in center of cell.

Anaphase II: Identical to mitotic anaphase; mitotic spindle separates chromosomes into chromatids and pulls towards each end of the cell.

Telophase II: Identical to mitotic telophase; cell pinches into two separate cells and nuclear envelope forms.

98
Q
A

biol 235 (29 decks)

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