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CHEE370 > Biomolecules + Cell Structure > Flashcards

Biomolecules + Cell Structure Flashcards

1
Q

Binary fission

A

Asexual separation into 2 cells for prokaryotes

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1
Q

Mycoplasma

A

Smallest known bacteria

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2
Q

3 basic bacterial cell shapes

A
  1. Cocci - spheroidal w/70 nm-thick cell membrane
  2. Bacilli - rodlike w/30-250 nm thick cell wall made from chemically cross-linked polysaccharides
  3. Spirilla (helicoidal) w/flagella for locomotion
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3
Q

Mitosis

A

Eukaryotic cells divide by this - each chromosome is duplicated + each copy sent to 1 daughter cell

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4
Q

Meiosis

A

Eukaryotic cells divide by this - reductive process where each daughter cell contains half the chromosomes of the mother cell

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5
Q

How do the metabolisms of mitochondria + chloroplasts function in opposite directions?

A

In mitochondria oxygen is used as electron acceptor to extract energy from organic molecules - in chloroplasts solar energy is invested to generate organic molecules + oxygen

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6
Q

Do both chloroplasts and mitochondria contain their own DNA?

A

Yuh - it’s replicated by binary fission

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7
Q

Glycosylation

A

Addition of sugar to secreted proteins that occurs in rough ER and then Golgi apparatus

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8
Q

Differences in prokaryotes + eukaryotes in terms of structure/size

A
  • P: 1 large circular chromosome, E: several long chromosomes in duplicate copies (diploid)
  • P: chromosome condensed in nucleoid, E: nucleus surrounded by nuclear envelope
  • P: plasmids (small circular DNA), E: nucleolus (synthesis of ribosomal RNA)
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9
Q

Differences in prokaryotes + eukaryotes in terms of genetic material

A
  • P: no organelles, E: organelles
  • P: no vesicles, E: vesicles
  • P: photosynthesis in chloroplasts, E: no photosynthesis
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10
Q

Difference in prokaryotes + eukaryotes in terms of sub cellular elements

A
  • P smaller than E
  • E longer doubling times than P
  • P unicellular, E multicellular
  • P: complex cell wall, E: simpler cell wall + no cell wall in animals
  • P: flagella made from single protein, E: flagella made from microtubule complex
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11
Q

Autotrophs

A

Use simple molecules + external energy source to synthesize organic molecules

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12
Q

Photoautotrophs

A

Use simple molecules + light via photosynthesis to synthesize organic molecule

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13
Q

Chemolithotrophs

A

Require organic compounds + oxidizing agents to generate energy via oxide-reduction reactions

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14
Q

Heterotrophs

A

Extract energy from pre-existing organic molecules

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15
Q

Obligate aerobes

A

Must use oxygen

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16
Q

Obligate anaerobes

A

Oxygen is toxic to these

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17
Q

Facultative anaerobes

A

Can grow in presence or absence of oxygen

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18
Q

Bacteria use in biotechnology products

A

Easy to introduce foreign genetic material + don’t secrete proteins (ex: food products + nucleic acids)

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19
Q

Fungi use in biotechnology products

A

Can secrete proteins + perform post-translational modifications but may be diff than those seen in animal cells (ex: food products + antibiotics)

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20
Q

Animal cells use in biotechnology products

A

Fragile + expensive + able to secrete proteins - post-transcriptional modifications of proteins similar to humans (ex: vaccines + hormones)

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21
Q

mRNA

A

Intermediate molecule that can be used to convert + amplify info stored in DNA into large amounts of proteins

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22
Q

Central dogma of molecular biology

A

DNA is transcribed into RNA which is translated into polypeptide sequences

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23
Q

Constitutional isomers

A

Molecules w/same chemical composition but dif bonds

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24
Q

Stereoisomers

A

Molecules w/same chemical composition + bonds but dif 3D organization

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25
Q

Beta anomer - when is it an alpha anomer

A

Used if OH and CH2OH groups are on same side - it’s an alpha when it’s not a beta lol

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26
Q

Glycosidic bond

A

Forms between 1 anomeric carbon and 1 non anomeric carbon on neighbouring saccharide monomer - condensation rxn of monosaccharide to polysaccharide results in its formation

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27
Q

Glycogen

A

Acts as energy-storage molecule in mammals - branched polysaccharide made from glucose monomers linked by beta-1,4 glycosidic bonds

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28
Q

Nucleotides

A
  • Nucleic acids are its polymers - comprise of pentose sugar (ribose in RNA, deoxyribose in DNA) + nitrogenous base on 1’ carbon of sugar + P group on 5’ carbon of sugar
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29
Q

Phosphodiester bonds

A

Bind together chains of nucleotides that make up strands - link each P group to 2 pentose sugars + form between nucleotide and 3’ carbon of another nucleotide so they’re created by linking 2 ribose/2 deoxyribose sugars via their 3’ and 5’ carbons

30
Q

How are the 2 DNA strands oriented towards each other?

A

They’re antiparallel - 5’ and 3’ ends of nucleotides face in opposite directions on 2 strands

31
Q

Where are nitrogenous bases found on the helix? What about the P residues?

A

Nitrogenous bases found inside as they’re hydrophobic - P residues found outside because they’re charged

32
Q

tRNA

A

Converts mRNA sequence into polypeptide chain

33
Q

rRNA

A

Involved in catalytic rxn required to produce proteins from mRNA strands

34
Q

Differences DNA and RNA

A
  • DNA is A T C G, RNA is A U C G
  • DNA carries genetic info that’s always present, RNA only expressed when needed
  • DNA has long stable double helices w/2 complementary antiparallel strands, RNA usually single-stranded + can form short/temp double helices + can form complex 3D structures
35
Q

Coding strand

A

DNA strand chosen to provide sequence info

36
Q

Template strand

A

Transcribed to produce complementary RNA strand

37
Q

Main interactions + effects that stabilize DNA double helix

A
  1. Hydrophobic effect
  2. Hydrogen bond formation between complementary base pairs
  3. Base stacking - pi stacking interactions between aromatic rings of nitrogenous bases
  4. Ionic interactions between negatively charged P backbone + ions present in sol’n
38
Q

What happens if pH of hydration shell in DNA/RNA is lowered below the pKa of the nucleic acid P groups?

A

P backbone becomes protonated + loses its charge - protonated nucleic acids are less polar so they ppt from sol’n

39
Q

Salting in

A

At low salt concentrations the addition of salt leads to cations helping to shield negative charges of P backbone which increases nucleic acid solubility

40
Q

Salting out

A

At high salt concentrations the salt molecules compete w/nucleic acids for interactions w/water to form salvation shells so nucleic acids ppt from sol’n

41
Q

Hybridizing short RNA or DNA sequences with long nucleic acid strands

A

Exploits the fact that shorter complementary strands anneal faster than longer ones -

42
Q

Hyperchromic effect

A

Extinction coefficient of single-stranded DNA is higher than extinction coefficient of double-stranded DNA

43
Q

DNA melting temperature

A
  • On a DNA melting curve this is the temperature at which slope of relative absorbance of temperature is steepest - molecules w/higher GC content + longer molecules + molecules w/surrounding solvent w/increased salt concentration have higher Tm
  • Very low/high pH decrease Tm
44
Q

Main roles of proteins

A
  1. Catalyzing bio rxns
  2. Cell structure + movement - scaffolding, contractility, motility
  3. Cell-cell communication
  4. Transport
  5. Immune functions w/in organisms
  6. Modulating gene expression
45
Q

Amino acids

A

Make up polypeptide chains

46
Q

Alpha-carbon of an alpha-amino acid

A

Surrounded by primary amine group, carboxylic acid group, H atom + side chains

47
Q

Do proteins consist of L or D enantiomers?

A

L

48
Q

O-linked glycosylation

A

Addition of sugars linked to hydroxyl groups (on amino acids) via glycosidic bonds

49
Q

N-linked glycosylation

A

Sugars added to amino acids that have reactive nitrogen atoms on their side chain

50
Q

Disulphide bonds

A

2 cysteine side chains react together in oxidizing conditions to form this

51
Q

Peptide bonds

A

Join amino acids in linear fashion to make polypeptide chains - form via dehydration rxn that creates covalent bond between amine group of 1 amino acid + carboxylic acid group of next

52
Q

How is sequence of polypeptide chains normally given?

A

From free amino/N terminus to free carboxy/C terminus

53
Q

Why is alpha helix formation favourable?

A

Their particular conformation allows for establishment of H bonds to stabilize the helix

54
Q

What’s the difference between the hydrogen bonds in alpha and beta sheets?

A

In beta the H bonds form between dif polypeptide segments rather than w/in 1 polypeptide segment - beta sheets involve at least 2 interacting beta sheet segments to allow H bonding

55
Q

Difference between parallel and anti-parallel beta sheets?

A

Parallel ones have N and C termini of interacting segments on same side - antiparallel have N and C termini of interacting segments opposite from each other

56
Q

Motifs

A

Secondary structure arrangement patterns

57
Q

Interactions that stabilize the tertiary structure of proteins

A
  1. Disulphide bonds - covalent bonds forming between side chains of cysteine residues
  2. Salt bridges - ionic interactions between 2 charged amino acids
  3. Coordination bonds
  4. Hydrogen bonds - between secondary structure elements
  5. Van der Waals interactions - dipole-dipole associations between neutral molecules
58
Q

Proteoglycans

A

Heavily glycosylated proteins that include core proteins and glycosaminoglycans

59
Q

Glycosaminoglycans

A

Unbranched polysaccharides consisting of repeating disaccharide units - viscous + elastic

60
Q

Difference saturated and unsaturated fatty acids

A

Saturated fatty acids have fully hydrogenated chains while unsaturated have double bonds

61
Q

Glycerophospholipids

A

Main component of biological membranes - similar to triglycerides but 1 hydroxyl group of glycerol is occupied by phosphatidic head

62
Q

Sphingolipids

A

Compose a hydrophilic head + hydrophobic body on glycerol backbone with its central carbon bound to an amine/amide group

63
Q

Liposomes

A

Self-sealing solvent filled vesicles bound by single lipid bilayer - also obtained by injecting ethanol-containing phospholipid solution into water/by dissolving phospholipids in detergent then removing detergent by dialysis + used as drug delivery methods

64
Q

What does the effect of cholesterol on membrane fluidity depend upon?

A

Test temperature - at body temps it decreases membrane fluidity due to its rigid structure but it broadens T of order-disorder transition by hindering packing of fatty acid side chains to form a paraffin-like crystalline structure

65
Q

Integral proteins

A
  • Completely/partially embedded in membrane via hydrophobic regions that interact w/hydrophobic region w/in bilayer - amphiphilic + contain transmembrane domains that expose hydrophobic surfaces to membrane
  • Relay signals from outside to inside of cell
66
Q

Peripheral proteins

A

Linked to membrane via lipid that anchors protein to membrane - presence/absence of diff lipid anchors controls localization of proteins to specific organelles + this impacts function of proteins and their interactions w/other proteins

67
Q

Peptidoglycan

A

Polymer consisting of polysaccharide chains cross-linked by peptide chains that composes cell wall

68
Q

What is cell wall flanked by?

A

2 permselective lipid bilayer membranes (cytoplasmic membrane + outer membrane)

69
Q

Lipopolysaccharides

A

Displayed on outer membrane surface - lipids that include polysaccharide chain + trigger strong immune response as defence against invasion by pathogenic bacteria

70
Q

Why may an outer membrane be problematic when over-expressing proteins of interest in bacteria using recombinant DNA tech?

A

Because proteins get trapped in the periplasm which complicates protein recovery

71
Q

How to distinguish gram positive and gram negative bacteria?

A

Gram staining - u apply a primary stain + then dehydrate/wash (which is when peptidoglycan layer condenses)

72
Q

How are gram positive bacteria distinguished from gram negative?

A

Bacteria w/thick peptidoglycan cell wall retain the primary stain so they’re gram positive

CHEE370 (6 decks)

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