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week 2 Flashcards

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1
Q

The Cell Theory

A

A cell is the basic structural and functional unit of all organisms.
The biochemical reactions occurring in a cell are dictated by the subcellular structures present in the cell.

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2
Q

3 main parts of a cell

A

plasma membrane, cytoplasm, nucleus

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3
Q

What embedded in the lipid bilayer of the plasma membrane?

A

membrane proteins and cholesterol

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4
Q

Fluid Mosaic Model

A

Lipid bilayer exhibits fluidity, and the membrane proteins are in
constant flux - their shapes constantly change as in a kaleidoscope or a mosaic pattern.

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5
Q

Cholesterol importance in Plasma Membrane

A

Cholesterol inserts between the phospholipids tails to stabilize the
plasma membrane = “ cholesterol therefore maintains the integrity of the plasma membrane

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6
Q

Integral proteins

A

Span the plasma membrane exposed on one surface or both
surfaces of the plasma membrane.
Integral proteins exposed on both surface of the plasma membrane are called Transmembrane Proteins

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7
Q

Peripheral proteins

A

attached to integral proteins or the phospholipids’ heads on the
extracellular face of the plasma membrane

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8
Q

6 functions of membrane functions

A

Transport, enzymatic activity, receptors, intercellular joining, cell-cell recognition, attachment to cytoskeleton & extracellular matrix

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9
Q

Tight junction

A

Fusion of integral proteins in plasma
membrane of adjacent cells that prevent the transfer of substances
directly between adjacent cells hence, tight junctions are also
known “impermeable junctions”

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10
Q

Desmosome

A

linker proteins extending from plaques on the cytoplasmic surface of the plasma membrane of adjacent cells interdigitate to hold the cells together and prevent their
separation. Desmosomes are also known as “anchoring junctions”

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11
Q

Gap Junction

A

Formed by hollow cylinder called connexon; it allows for the rapid transfer of ions between cells; Gap junctions also known as “communicating junctions”. Cells connected by gap junctions are electrically-coupled

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12
Q

Passive processes
two types…

A

substances cross the plasma membrane without any energy input. There are two types: diffusion and filtration.

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13
Q

diffusion
3 subtypes..

A

movement of substances from area of higher concentration to area of lower concentration = down a concentration gradient
3 subtypes: simple diffusion
facilitated diffusion
osmosis

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14
Q

filtration

A

A passive process: no energy input. Movement of solution from area of higher pressure to area of lower
pressure = down a pressure gradient
Filtration occurs in the kidneys as the first process in urine formation

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15
Q

Active processes

A

the cell provides energy required to move substances across
the plasma membrane
two types: active transport & vesicular transport

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16
Q

Active transport

A

movements of solute from area of lower concentration to area of
higher concentration against a concentration gradient hence, active transport is also known as “solute pumping”
active transport exhibits saturation and specificity
Ex. sodium./potassium pump ( Na+/K+ pump)

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17
Q

Exocytosis

A

movement of substances enclosed
in vesicles from the interior of cells to the exterior.
Protein secretion such as enzymes and hormones released from
endocrine cells are released via exocytosis; metabolic wastes are
secreted via exocytosis.

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18
Q

Simple diffusion

A

nonpolar/hydrophobic/lipid-soluble substances
diffuse through the plasma membrane. Ex. Oxygen, carbon dioxide

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19
Q

Facilitated diffusion

A

transport of large/polar substances mediated by
carrier proteins embedded in the plasma membrane.
Facilitated diffusion exhibits saturation and specificity

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20
Q

Osmosis

A

movement of water from area of lower solute concentration
to area of higher solute concentration through a semi-permeable
membrane. Water moves through specific pores in the plasma
membrane called aquaporins

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21
Q

isotonic solution

A

concentration of solution inside and
outside of the cells is the same; the same amount of water
moves in/out of the cells and thus, the shape of cells
remain unchanged

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22
Q

hypotonic solution

A

cells are placed in a solution with
a lower concentration than solution inside cells; water moves via osmosis into the cells – cells swell and
eventually lyse (burst)

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23
Q

hypertonic solution

A

cells placed in solution with a
higher concentration than solution inside cells; water
moves via osmosis from the cells; cell crenate ( shrink)

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24
Q

Endocytosis

A

movement of substances enclosed
in vesicles from the exterior of cells to the interior.
Nutrients, fluids, hormones taken into target cells, pathogens are
taken from the exterior into the interior of cells

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25
Phagocytosis
movement of solid particles from the exterior into the cell; solid particles such as clumps of bacteria or cell debris, are enclosed in vesicles called PHAGOSOMES; Lysosomes fuse with the phagosomes to digest the phagosomes and its contents. ****Only cells called phagocytes can perform phagocytosis
26
Pinocytosis
movement of solution into cells by enclosing the solution in vesicles called pinocytic vesicles. That’s how cells take in nutrients in bulk and therefore all cells can perform pinocytosis
27
Receptor-mediated endocytosis
substances bind to specific receptors (carrier-mediated) on the surface of the cell and taken into the cell. ( LDL binds to LDL receptors on the surface of steroidogenic cells and taken in via receptor mediated endocytosis; cholesterol is released Receptor-mediated endocytosis exhibits saturation and specificity
28
Transcytosis
Movement of substances enclosed in vesicles into a cell via endocytosis, travels across the cell and released on the opposite side of the cell via exocytosis
29
Vesicular Trafficking
Intracellular movement of substances in vesicles from organelle to organelle within the cell
30
The resting membrane potential (RMP)
RMP is established by the partial/selective permeability of the plasma membrane to potassium ion (K+) diffusion over sodium ion ( Na+) diffusion.
31
K & Na
K+ concentration is higher inside the cell than outside the cell – K+ diffuses out of the cell down its electrochemical gradient * Na+ concentration is higher outside of the cell than inside the cell – Na+ diffuses into the cell down its electrochemical gradient * The plasma membrane is about 75 times more permeable to K+ than Na+ = more K+ diffuses out of cell than Na+ diffusing into the cell = more positive ions move out of the cell making the cytoplasmic surface of the plasma membrane negative compared to the extracellular surface
32
Cytosol
the viscous, semitransparent fluid in which the organelles are suspended
33
Cytoplasmic organelles
specialized subcellular compartments with specific functions i) Mitochondria = “power plants” ii) Ribosomes = sites of protein synthesis iii) Endoplasmic reticulum ( ER) Rough ER = “membrane factories” Smooth ER = lipid/drug metabolism iv) Golgi apparatus = “traffic director” of the cell v) Lysosomes = “demolition crew” vi) Peroxisomes = neutralize harmful free radicals vii) Cytoskeleton = “skeleton” of the cell
34
Membranous cytoplasmic organelles
organelles surrounded by membranes Mitochondria Endoplasmic Reticulum (ER) Golgi apparatus Lysosomes Peroxisomes
35
Non membranous cytoplasmic organelles
not surrounded by membrane Ribosomes Cytoskeleton
36
Mitochondria
Contain own DNA and are self-replicating organelles – when the energy demands of a cell increases, its mitochondria number increases by replication. * Composed of 2 membranes enclosing a fluid matrix * 2 mitochondrial membranes: -outer membrane which appears featureless - inner membrane consists of infoldings called cristae
37
Each ribosomal subunit consists of
protein and rRNA
38
Free ribosomes
float freely in the cytosol and synthesize proteins that stay in the cell
39
Bound ribosomes
bound to surface of rough ER and make proteins that are trasnported to the plasma membrane or for export out of the cell
40
Rough ER
these ribosomes synthesize the plasma proteins, enzymes enclosed in vesicles and secretory proteins. Rough ER is therefore abundant in secretory cells such as liver cells. Rough ER is referred to as the “Membrane factory” because the synthesis of plasma membrane proteins and phospholipids which form the plasma membranes is associated with the rough ER
41
Smooth ER
Its membrane-bound enzymes catalyze: - Synthesis of fats, cholesterol and the steroid hormones -- Detoxification of drugs and carcinogens in liver and kidney cells because, most drugs are lipid-based
42
Golgi Apparatus
Composed of stacked /flattened membranous sacs * Receives proteins and lipids from the rough ER * Golgi modifies, packages and tags proteins and lipids to their specific destinations hence, the Golgi apparatus is referred to as the “Traffic director” of the cell * 3 types vesicles are released from the Golgi (next slide): 1) secretory vesicles which contain proteins released from the cell via exocytosis 2) Vesicles that contain integral proteins and lipids destined for the plasma membrane to incorporated into the plasma membrane. 3) Vesicles which are cytoplasmic organelles called LYSOSOMES- contain powerful digestive enzymes called lysozymes (abundant in phagocytes)
43
lysosomes
Digest phagosomes hence, lysosomes are abundant in phagocytes - Digest worn-out organelles - Stimulate glycogenolysis - Involved in bone resorption to release calcium Hence, lysosomes are referred to as a cell’s “demolition crew”
44
Peroxisomes
Contain powerful enzymes that neutralize harmful free radicals
45
2 kinds of enzymes in peroxisomes
Oxidases and Catalases
46
Although free radicals are produced naturally in the body, lifestyle factors can accelerate their production. Those include
exposure to toxic chemicals, such as pesticides and air pollution *smoking *alcohol
47
What do peroxisomes do to free radicals
The enzymes in peroxisomes convert the harmful free radicals into the harmless compound, water. * In addition, the antioxidants, vitamins C and E neutralize free radicals by donating one of their own electrons to stabilize free radicals. * Free radicals have been involved in the pathogenesis of several diseases and in the aging process
48
Common Foods with the most antioxidants
Cranberries, blueberries, and blackberries ranked highest among the fruits studied. Beans, artichokes, and Russet potatoes were tops among the vegetables. Pecans, walnuts, and hazelnuts ranked highest in the nut category.
49
Cytoskeleton
he “Cell’s skeleton” – consists of non membranous rod-like structures that support other cytoplasmic organelles and allow for movements
50
Microtubules
Largest cytoskeleton – hollow tubes composed of the globular proteins called TUBULINS * Radiate from the CENTROSOME which acts as a microtubule organizing center
51
Function of Microtubules
Serve as “tracks” to transport intracellular substances - cytoplasmic organelles and secretory vesicles attached by motor molecules to microtubules for intracellular, vesicular trafficking
52
cilia
cellular extensions that occur in large numbers on the apical ( exposed ) surface of cells Several cells in the body are ciliated * Cilia beat to create a unidirectional current that moves substances across the surface of the cells
53
Flagellum
a single, longer cellular extension * Flagellum beats to propel the cell it extends from * The only flagellated cell in the human body is sperm
54
Intermediate Filaments
Composed of tough, insoluble fibrous fibers * Most stable type of cytoskeleton * Provide tensile strength to cells by resisting pulling forces placed on the cells * Given specific names in specific cell types: Tonofilaments in epidermal cells Neurofilaments in neurons
55
Microfilaments
Have the smallest diameter * Composed of the protein ACTIN * The arrangement of microfilaments is unique to each cell
56
Function of Microfilaments
Involved in changes in cell shape or cell motility as in contraction Involved in the formation of cleavage furrow during cytokinesis Involved in the changes of the plasma membrane during endocytosis and exocytosis
57
3 regions of nucleus
Nuclear envelope (membrane) * Nucleolus * Chromatin
58
Nuclear envelope
Double-layered selective membrane with nuclear pores * Nuclear pores allow molecules to enter /exit the nucleus – proteins translocate from the cytoplasm into the nucleus; RNA molecules move from the nucleus into the cytoplasm
59
Nucleolus
Dark spherical non- membranous structure in the nucleus Synthesizes ribosomal RNA ( rRNA) required for assembling the 2 ribosomal subunits – small and large Ribosomes are sites for protein synthesis hence, nucleoli are prominent in cells producing large amounts of proteins
60
Chromatin
Chromatin is composed of DNA and the histone proteins * Consists of structural units called NUCLEOSOMES * Each nucleosome is composed of 8 globular histone proteins connected by the thread-like DNA
61
Heterochromatin
condensed, inactive chromatin with DNA wrapped around the histone proteins Type of chromatin
62
Euchromatin
extended type of chromatin
63
Nucleic acids
2 Types of Nucleic Acids: Deoxyribonucleic Acids = DNA Ribonucleic Acids = RNA They consist of structural units called NUCLEOTIDES Each nucleotide is composed of – i) pentose sugar - deoxyribose or ribose ii) Nitrogen-containing base - A,G, C, T, U iii) Phosphate group
64
Purines
Adenine “A” Guanine “G
65
Pyrimidines
Cytosine “C” * Thymine “T” * Uracil “U”
66
SEMI- CONSERVATIVE REPLICATION
Each daughter DNA consists of a an old polynucleotide strand and a newly- synthesized polynucleotide strand
67
Interphase
consists of 3 sequential phases: G1, S, G2 G1 phase – longest phase; protein synthesis; cell growth S phase - DNA replication is the main event ( next slide) G2 phase – protein synthesis especially those required for the initiation/maintenance of mitosis
68
Cell division
sequential phases: mitosis and cytokinesis Mitosis – Nuclear division: 4 sequential subphases: Prophase, Metaphase, Anaphase, Telophase Cytokenesis – Cytoplasmic division
69
Hyperplasia
Growth by increase in cell number via mitosis
70
hypertrophy
Growth by increase in cell size
71
Neoplasm
excessive proliferation of cells considered abnormal
72
Benign Neoplasm
grows slowly and it’s confined to one location
73
transcription
DNA is transcribed into pre mRNA; pre-mRNA is edited, intros are removed leaving exons= mRNA
74
Translation
in cytoplasm, 3 base sequence on tRNA are called anti-codon

anatomy (8 decks)

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