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Mammalian Physiology > Lecture 5 > Flashcards

Lecture 5 Flashcards

1
Q

Central dogma of DNA.

A

DNA is our genetic blueprint; it dictates what we are.

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2
Q

Types of proteins in a cell will determine its…

A

Phenotype.

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3
Q

Characteristics of proteins.

A

Form enzymes, form transport proteins, form structural skeleton of cells and tissues, have variability and specificity.

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4
Q

Molecular genetics.

A

The study of how genes are turned on and off and how they affect phenotype.

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5
Q

Transcription.

A

DNA is enzymatically copied by an RNA polymerase to produce mRNA.

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6
Q

Translation.

A

RNA is converted into protein. Process: DNA is unwound by DNA helices, RNA polymerase binds and recognizes the start site; RNA nucleotides will base pair with DNA, which forms a chain of mRNA.

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7
Q

Transcription factors.

A

Assist RNA polymerase in recognizing promoters.

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8
Q

2 types of transcription factors.

A

Gene-specific transcription factors and general transcription factors.

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9
Q

Gene-specific transcription factors.

A

They can activate specific genes.

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10
Q

General transcription factors.

A

Required to activate all genes; they bind to DNA regions within promoters and deliver the RNA polymerase to their respective promoter sites.

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11
Q

CREM

A

cAMP responsive element modulator.

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12
Q

CREM is…

A

A transcription factor in the testes; binds to the cAMP response element. In the early haploid spermatid, CREM binds with ACT and removes it, causing the silencing of gene expression. CREM is activated in male germ cells.

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13
Q

Processing of mRNA.

A

Pre-mRNA is made before the transcription, leads to spliced mRNA, which can result in different isoforms of proteins.

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14
Q

Exons.

A

Portions of the gene that are expressed (encode for proteins).

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15
Q

Introns.

A

Portions of the DNA that are silenced.

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16
Q

3 types of RNA.

A

mRNA, rRNA, and tRNA.

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17
Q

mRNA characteristics.

A

Processed in the nucleus after it is made; removal of introns, addition of Poly A tail, and gunning cap. It then enters the cytosol to work with rRNA and tRNA to direct the translation of protein.

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18
Q

tRNA characteristics.

A

In the cytoplasm, mRNA associates with ribosomes. tRNA molecules transfer specific amino acids (anticodon) to the mRNA, which reads the triplet codon. Amino acids are brought and assembled in a polypeptide chain.

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19
Q

Why are introns important if they are not expressed?

A

They contain intergenic regions; play a huge role in transcription for determining what will be expressed and what will not be expressed.

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20
Q

Splicing of the introns.

A

mRNA can leave the nucleus and go to the cytoplasm to the ribonucleotides, which will make a protein. tRNA comes in at this stage.

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21
Q

rRNA form a large and small unit.

A

Interacts with tRNA during translation; it brings amino acids as needed. rRNA contains an enzyme that catalyzes the peptide bond between new amino acids that are being formed.

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22
Q

tRNA contains the…

A

Complementary sequence to the mRNA; formation of peptide bonds between the amino acids.

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23
Q

Processing of the protein to make it functional.

A

Chaperone molecules supervise protein folding. Other enzymes in the cytosol, ER,a nd Golgi apparatus fold polypeptides and make them into larger protein molecules.

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24
Q

Chaperone molecules supervise…

A

Protein folding.

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25
Q

Proteome.

A

All the proteins synthesized by the cell make up the proteome.

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26
Q

Post-translational modifications.

A

Chemical modification of a protein: addition of sugars, lipids, CH3, and phosphate; depends on the function of the protein.

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27
Q

House-keeping genes.

A

Genes that are active all the time.

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28
Q

siRNA.

A

Short-interfering RNA: to knocks down a gene, expression is reduced but nor eliminated completely.

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29
Q

Osmolarity.

A

Water and solute distribution.

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30
Q

Permeability of the cell membrane determines…

A

The chemical gradient.

31
Q

Homeostasis of the cell.

A

Chemical and electrical disequilibrium, but in osmotic equilibrium.

32
Q

Sodium in the cell.

A

Most is found in the extracellular fluid.

33
Q

Potassium in the cell.

A

Low in extracellular fluid; high in the intracellular fluid.

34
Q

Na+K+ pump.

A

3 Na+ out for 2 K+ in.

35
Q

Diffusion.

A

Uses the energy within the molecules themselves for transport.

36
Q

Simple diffusion.

A

Uses the concentration gradient in order to move.

37
Q

Facilitated diffusion.

A

Done by a carrier protein.

38
Q

Primary active transport.

A

Creates a gradient that leads to secondary active transport.

39
Q

ATP-requiring transport.

A

Endocytosis, exocytosis, and phagocytosis.

40
Q

Characteristics of passive diffusion.

A

Uses kinetic energy inherent the molecule, follows the gradient, rapid over short distances, directly related to temepratvureinversely related to molecular size.

41
Q

Structural proteins.

A

Connect the membrane to the cytoskeleton (integrity), creates cell junctions, and attaches cells to ECM.

42
Q

Enzymes.

A

Catalyze chemical reactions.

43
Q

Membrane receptor proteins.

A

Part of the body’s chemical signalling system.

44
Q

Transporters.

A

Channel proteins, carrier proteins (conformational change occurs); essential in maintaining osmolarity of many ions.

45
Q

2 properties of molecules influence its movement across the cell membrane.

A

Size and lipid solubility.

46
Q

Gated channels.

A

Spend most of their time closed; open only in response to a stimulus that can be electrical, mechanical, or chemical. They can also be open channels.

47
Q

Carrier proteins.

A

Solute binds to the carrier protein, which changes the conformation to allow it into the cell; they are never open channels. Can be uniport, symport, or anti port.

48
Q

Uniport.

A

A carrier protein that allows one solute to pass in one direction.

49
Q

Symport.

A

A carrier protein that allows 2 solutes to pass in the same direction.

50
Q

Antiport.

A

A carrier protein that allows one solute in and one solute out.

51
Q

Active transport.

A

transports substances against concentration gradient: requires energy. Can be primary or secondary active transport.

52
Q

Na+K+ATPase is an example of which type of transport?

A

Primary active transport. It is the single, most important transport protein in animal cells.

53
Q

Mechanism of Na_K+ATPase.

A

3 sodium ions from the intracellular matrix bind to the spots, causing a change in conformation so the 3 Na+ ions release into the ECM. Potassium is then released into the cell.

54
Q

Transport via pumps.

A

Requires ATP to move the substance against its concentration gradient.

55
Q

Transport via vesicles.

A

Allows substances to enter or leave the interior of a cell without actually moving through its plasma membrane.

56
Q

Advantage of vesicle transport.

A

Cells do not have to move through the plasma membrane.

57
Q

Example of a secondary active transporter: SGLT.

A

SGLT uses the potential energy stored in the Na+ concentration gradient to move glucose against its concentration gradient in the lumen of the intestine or kidney. Sodium binds, which causes glucose to bind with it, inducing a conformational change that allows both ions to pass through.

58
Q

What happens to anything in the lumen?

A

It is lost from the body.

59
Q

SGLT transporter in the kidney cell (diabetes example).

A

Block SGLT (sodium glucose link transporter) and glucose will not be reabsorbed into the body. Useful in diabetes: it will lower blood sugar levels.

60
Q

Vesicular transport.

A

They transport molecules that are too large to pass through protein channel or carriers. Phagocytosis: creates a vesicle using the cytoskeleton. Endocytosis: the membrane surface indents and forms vesicles.

61
Q

Receptor-mediated endocytosis uses…

A

Clathrin coated pits: spots on the plasma membrane. Ligands bind to these receptors, which causes the endocytosis.

62
Q

Exocytosis.

A

Releases molecules too large for transport proteins; opposite of endocytosis.

63
Q

Purpose of exocytosis and endocytosis.

A

Allows cells to transfer nutrients, communicate by importing signal molecules, mediate an immune response, and clean up cell debris left by inflammation.

64
Q

Example of a phagocytic cell.

A

Macrophage (WBC): binds to the membrane of a bacterium; the cytoskeleton forms arms around it, leading to the fusion of lysosomes. Lysosomes have the digestive enzymes needed to break down the bacteria.

65
Q

Receptor-mediated endocytosis.

A

Process: ligand binds to a receptor in the clathrin pit, lysosomes break down the vesicle. Both clathrin and lysosomes are recycled for re-use.

66
Q

2 types of endocytosis.

A

Phagocytosis and pinocytosis.

67
Q

Phagocytosis.

A

Cell-eating; large particles are engulfed y the plasma membrane and enter the cell. Vesicles fuse with lysosomes in the cell, where the particles are digested.

68
Q

Pinocytosis.

A

Cell-drinking; fluid with substances dissolved in it enter the cell. It is used for smaller substances.

69
Q

Epithelium.

A

Found on surfaces exposed to the external environment. 3 types: squamous, cuboidal, or columnar. Epithelial tissue in the small intestine are lined with villi and microvilli to maximize absorption. Can be leaky or tight. Capillaries in the epithelium allow dissolved molecules to pass through. Epithelium in the kidney is held by tight junctions that create a barrier.

70
Q

Epithelial cells attach where and how?

A

They attach to the basal lamina through adhesion molecules.

71
Q

Epithelium in the kidney.

A

Contains tight junctions to strictly regulate movement of substances. Responsible for absorption, secretion, and transport.

72
Q

Secretory epithelium.

A

Exocrine glands: release into the external environment, like ducts, skin, airways, etc. Endocrine glands: release hormones into the bloodstream.

73
Q

Example of secretory epithelium.

A

A goblet cell found int he small intestine, found in the integument (skin).

74
Q

Types of epithelia.

A

Exchange, transport, protected, and secretory.

Mammalian Physiology (10 decks)

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