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Feralis' Biology > Feralis Ch 1 > Flashcards

Feralis Ch 1 Flashcards

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1
Q

Ionic Bonds

A

Transfer of electrons from one atom to another where both atoms have different electronegativities

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2
Q

Non-polar covalent bonds

A

Equal sharing of electrons between two atoms of identical electronegativity

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3
Q

Polar covalent bonds

A

Unequal sharing of electrons between two atoms of different electronegativities, results in dipole formation

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4
Q

Hydrogen bonds

A

Weak bond between molecules with a hydrogen attached to a highly electronegative atom and is attracted to a negative charge on another molecule (F, O or N)

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5
Q

5 Properties of water

A

Excellent solvent, high heat capacity, ice floats, cohesion/surface tension, adhesion

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6
Q

Excellent solvent - water property

A

Dipoles of H2O break up charged ionic molecules, making it easy for water to dissolve substances

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7
Q

High heat capacity - water property

A

Water requires large amount of energy to change the temperature degree. Water also has high heat of vaporization

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8
Q

Ice floats - water property

A

Water expands when frozen and becomes less dense than liquid water. This is because the H bonds become rigid and form crystal that keeps the molecules separated

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9
Q

Cohesion/surface tension - water property

A

Water can be attracted to like substances because of its H bonds. There is strong cohesion between H2O molecules, producing a high surface tension

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10
Q

Adhesion - water property

A

Water can also be attracted to unlike substances. Capillary action is the ability of a liquid to flow without external forces (ex. up a vertical paper)

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11
Q

Organic molecules

A

Made of carbon atoms. Macromolecules from monomers, monomers form polymers

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12
Q

Hydroxyl

A

OH functional group, polar, hydrophilic

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13
Q

Carboxyl

A

COOH functional group, polar, hydrophilic, weak acid

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14
Q

Amino

A

NH2 functional group, polar, hydrophilic, weak base

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15
Q

Phosphate

A

PO4(3-) functional group, polar, hydrophilic, acid

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16
Q

Carbonyl

A

C=O functional group, polar, hydrophilic. Incorporated into aldehyde and ketone

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17
Q

Aldehyde

A

H-C=O functional group, polar, hydrophilic

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18
Q

Ketone

A

R-C=O functional group, polar hydrophilic

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19
Q

Methyl

A

CH3 functional group, non-polar, hydrophobic

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20
Q

Monosaccharide

A

Single sugar molecule (ex. glucose and fructose)

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21
Q

Disaccharide

A

Two sugar molecules joined by glycosidic linkage (occurs via dehydration reaction) (ex. sucrose, lactose, maltose)

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22
Q

Polysaccharide

A

Series of connected monosaccharides; polymer. Bonds form via dehydration synthesis and breakdown via hydrolysis

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23
Q

Sucrose

A

Disaccharide, glucose + fructose

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24
Q

Lactose

A

Disaccharide, glucose + galactose

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25
Q

Maltose

A

Disaccharide, glucose + glucose

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26
Q

Carbohydrates

A

Includes sugars, starches and fibres. Composed of the “-saccharides”

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27
Q

Starch

A

A carbohydrate, a polymer of alpha-glucose molecules, stores energy in plant cells

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28
Q

Glycogen

A

A carbohydrate, a polymer of alpha-glucose molecules, stores energy in animal cells

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29
Q

Cellulose

A

A carbohydrate, a polymer of beta-glucose, structural molecules for walls of plant cells and wood

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30
Q

Chitin

A

A carbohydrate, a polymer similar to cellulose, but each beta-glucose group has a nitrogen containing group (n-acetylglucosamine) attached to the ring, it is structural molecule in fungal cells and insect cytoskeletons

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31
Q

Lipids

A

Hydrophobic, for insulation, energy storage, make up structural components like cholesterol and phospholipids in membranes, participates in endocrine signalling

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32
Q

Triglycerides (Triacylglycerols)

A

A lipid, 3 fatty acid chains attached to glycerol backbone, can be saturated or unsaturated

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33
Q

Saturated triglycerides

A

A lipid, no double bonds, has straight chains, bad for health because straight chains stack densely and form fat plaques

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34
Q

Unsaturated triglycerides

A

A lipid, contains double bonds that cause kinks, better for health because chains can stack less densely, can be cis or trans

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35
Q

Phospholipids

A

A lipid, composed of 2 fatty acids and a phosphate group (+R) attached to a glycerol backbone. It is amphipathic

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36
Q

Steroids

A

A lipid, composed of three 6-membered rings and one 5-membered ring, includes (sex) hormones, cholesterol, corticosteroids

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37
Q

Waxes

A

A lipid, esters of fatty acids and monohydroxylic alcohols, used as protective coating or exoskeletons (lanolin)

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38
Q

Carotenoids

A

A lipid, fatty acid carbon chains with conjugated double bonds and 6-membered C-rings at each end. Includes pigments that produce colours in plants and animals. Subgroups are carotenes (orange) and xanthophylls (yellow)

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39
Q

Porphyrins (tetrapyrroles)

A

A lipid, 4 joined pyrrole rings that often complex with a metal (ex. porphyrin heme complexes with Fe in hemoglobin; chlorophyll with magnesium)

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40
Q

Adipocytes

A

A lipid, specialized fat cells, two categories are white fat cells and brown fat cells

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41
Q

White fat cells

A

An adipocyte, a lipid, composed primarily of triglycerides with a small layer of cytoplasm around it

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42
Q

Brown fat cells

A

An adipocyte, a lipid, have considerable cytoplasm, lipid droplets scattered throughout, and lots of mitochondria

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43
Q

Glycolipids

A

A lipid, similar to phospholipids but have a carbohydrate group instead of phosphate group

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44
Q

Lipoproteins

A

A lipid, transports the insoluble lipids in the blood, are lipid cores surrounded by phospholipids and apolipoproteins

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45
Q

Cell membrane fluidity

A

Part of lipids, cell membranes need to maintain certain degree of fluidity and are capable of changing membrane fatty acid composition to do so

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46
Q

Cell membrane fluidity in cold weather

A

Cell membrane becomes more rigid. To avoid rigidity, cholesterol, monounsaturated and polyunsaturated fatty acids are incorporated into the membrane, which increases fluidity

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47
Q

Cell membrane fluidity in warm weather

A

Cell membrane becomes more fluid and flexible. To avoid cell membrane collapse, cholesterol is added to restrict movement. Fatty acid tails are saturated so they become straight and pack tightly, which decreases fluidity

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48
Q

Protein

A

Polymers of amino acids joined by peptide bonds. Have alpha-carbon attached to side chain, H, amino group and carboxyl group. Functions include structure, storage, transport, defence (antibodies) and enzymes. RNA can act as an enzyme sometimes (ex. ribozymes)

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49
Q

Storage proteins

A

casein in milk, ovalbumin in egg whites, zein in corn seeds

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50
Q

Transport proteins

A

Hemoglobin carries oxygen, cytochromes carry electrons

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51
Q

Enzymes

A

Catalyze reactions based on substrate concentration, does not change spontaneity of a reaction. Enzyme efficiency determined by temperature and pH. Amylase catalyzes reactions that breaks the alpha-glycosidic bonds in starch

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52
Q

Cofactors

A

Non-protein molecule that assists enzymes by donating or accepting some component of a reaction (such as electrons or functional groups), can be organic (called coenzyme, ex. vitamins) or inorganic (ex. metal ions like Fe2+ and Mg2+)

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53
Q

Holoenzyme

A

Union of cofactor and enzyme

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54
Q

Apoenzyme/Apoprotein

A

Enzyme is not combined with a cofactor

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55
Q

Coenzyme

A

Organic cofactor, ex. vitamins, usually donate or accept electrons

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56
Q

Prosthetic group

A

Cofactor binds tightly or covalently bound to an enzyme

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57
Q

Simple protein

A

Formed entirely of amino acids

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58
Q

Albumins and globulins

A

Functional proteins that act as carriers or enzymes

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59
Q

Scleroproteins

A

Fibrous proteins, have structural function (ex. collagen)

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60
Q

Conjugated proteins

A

Simple protein + non-protein

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61
Q

Lipoprotein

A

Protein bound to lipid

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62
Q

Mucoprotein

A

Protein bound to carbohydrate

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63
Q

Chromoprotein

A

Protein bound to pigmented molecule

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64
Q

Metalloprotein

A

Protein complexed around metal ion

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65
Q

Nucleoprotein

A

Contains histone or protamine, bound to nucleic acid

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66
Q

Primary protein structure

A

Sequence of amino acids connected by peptide bonds

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67
Q

Secondary protein structure

A

3D shape resulting from hydrogen bonding between amino and carboxyl groups of adjacent amino acids (alpha helix or beta sheet). Hydrogen bonds, disulfide bonds and Van Der Waals forces

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68
Q

Tertiary protein structure

A

3D folding pattern resulting from non-covalent interactions between amino acid R groups (side chain interaction). Non-covalent interactions include H bonds, ionic bonds, hydrophobic effect (R groups push away from water), disulfide bonds, and Van Der Waals forces

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69
Q

Quaternary protein structure

A

3D shape of a protein that is a grouping of 2 or more separate peptide chains

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70
Q

Protein structure

A

All proteins have primary structure, most have secondary structure, larger proteins may have tertiary and quaternary structure.

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71
Q

3 main protein categories

A

Globular proteins, fibrous/structural proteins and membrane proteins

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72
Q

Globular proteins

A

A protein category, somewhat water soluble, mostly dominated by tertiary structure, diverse range of functions including: enzymatic, hormonal, intercellular and intracellular storage and transport, osmotic regulation, immune response

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73
Q

Fibrous/structural proteins

A

A protein category, not water soluble, mostly dominated by secondary structure, made of long polymers, function to maintain and add strength to cellular and matrix structure (ex. collagen or keratin)

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74
Q

Membrane protein

A

A protein category, includes proteins that function as membrane pumps, channels or receptors

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75
Q

Protein denaturation

A

Protein is reversed back to primary structure, usually irreversible. Denaturation may be reversed with removal of denaturing agent. Implies that all information needed for a protein to assume its native state (its folded functional form) is encoded in its primary structure

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76
Q

Protein denaturation vs protein digestion

A

Denaturation reverses protein to primary structure. Digestion eliminates all protein structure, including the primary structure

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77
Q

Nucleotides

A

Monomers that make up nucleic acids and consist of a nitrogenous base, a 5-carbon deoxyribose sugar and a phosphate group.

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78
Q

Nucleosides

A

Sugar and nitrogenous base

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79
Q

Nitrogenous base

A

Nitrogen-containing compound that makes up a nucleotide and can vary based on DNA or RNA.

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80
Q

Nitrogenous bases of DNA

A

A and T pair with 2 H bonds. C and G pair with 3 H bonds

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81
Q

Nitrogenous bases of RNA

A

A and U (uridine) pair with 2 H bonds. C and G pair with 3 H bonds

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82
Q

Pyrimidines

A

1 ring, cytosine, uracil, thymine

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83
Q

Purines

A

2 rings, adenine, guanine

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84
Q

DNA

A

Deoxyribose sugar, 2 antiparallel strands of a double helix

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85
Q

RNA

A

Ribose sugar, single stranded

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86
Q

Cell theory

A 
i. All living organisms are composed of
one or more cells
ii. The cell is the basic unit of structure,
function, and organization in all
organisms
iii. All cells come from preexisting, living
cells
iv. Cells carry hereditary information
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87
Q

RNA world hypothesis

A

Proposes that self-replicating RNA molecules were precursors to current life. States that RNA stores genetic information (similar to DNA) and catalyzes chemical
reactions (similar to enzyme). RNA may have played a major role in the evolution of cellular life. RNA is unstable, compared to DNA, due to its extra hydroxyl group that makes it more likely to participate in chemical reactions!

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88
Q

Central dogma of genetics

A

Information must travel from DNA -> RNA -> protein

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89
Q

Ranking Biological Scale

A

Relative sizes of different cell elements at structures

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90
Q

Stereomicroscope (light)

A

Uses visible light to view the surface of a sample.
Pro: can view living samples
Con: has low light resolution compared to a compound microscope

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91
Q

Compound Microscope (light)

A

Uses visible light to view a thin section of a sample.
Pro: can view some living samples (single cell layer)
Con: may require staining for good visibility

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92
Q

Phase Contrast Microscope

A

Uses light phases and contrast for a detailed observation of living organisms, including internal structures.
Pro: has good resolution and contrast
Con: not ideal for thick samples and produces a “Halo Effect” around perimeter of samples

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93
Q

Confocal Laser Scanning Microscope and Fluorescence

A

Used to observe thin slices while keeping a sample in tact; common method for viewing chromosomes during mitosis
Pro: can observe specific parts of a cell using fluorescent tagging
Con: can cause artifacts
Note: confocal laser scanning microscopes can be used without fluorescence as well, in which laser light is used to scan a dyed specimen and display the image digitally

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94
Q

Scanning Electron Microscope (SEM)

A

Pro: view surface of 3D objects with high resolution
Cons: can’t use on living samples, preparation is extensive as sample needs to be dried and coated, is costly

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95
Q

Cryo Scanning Electron Microscope (Cryo SEM)

A

Pro: sample is not dehydrated so you can observe samples in their more ‘natural form’
Cons: can’t use on living samples, samples must be frozen, which can cause artifacts

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96
Q

Transmission Electron Microscope (TEM)

A

Pros: can observe very thin cross- sections in high detail, and can observe internal structures with very high resolution
Cons: cannot be used on living samples, preparation of sample is extensive, and technique is costly

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97
Q

Electron Tomography

A

not a type of microscope, but a technique used to build up a 3D model of sample using TEM data

Pro: can look at objects in 3D and see objects relative to one another
Cons: cannot be used on living samples, preparation of sample is extensive, and technique is costly

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98
Q

Centrifugation

A

Common technique used to prepare a sample for observation or further experimentation. It spins and separates liquified cell homogenates into layers based on density.

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99
Q

Order of pellet in centrifugation

A

Cell parts separate with the most dense pelleting first and least dense separating last. We spin and extract the dense pellet, and spin again and repeat. In cells, starting from first component to pellet at the bottom and progressively spinning faster, the order is: nuclei layer -> mitochondria/ chloroplasts/lysosomes → microsomes/small vesicles → ribosomes/viruses/larger macromolecules

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100
Q

Differential centrifugation

A

Relies on density, shape, and speed at which macromolecule travels

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101
Q

Density centrifugation

A

Based on density, separates cell parts within the same pellet group created from differential centrifugation. Forms continuous layers of sediment: insoluble proteins can be found in the pellet, soluble proteins remain in the supernatant liquid above the pellet.

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102
Q

Reaction at equilibrium

A

The rate of formation of reactants and products is equal and there is 0 net production.

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103
Q

Anabolic reactions

A

Chemical reactions in which small molecules are assembled into larger molecules

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104
Q

Catabolic reactions

A

Chemical reactions in which large molecules are broken down into small molecules

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105
Q

Catalysts

A

Enzymes, lowers activation energy of a reaction, accelerates the rate of the overall reaction, enzymes are substrate specific, enzymes remain unchanged during reaction, catalyzes both forward and reverse directions of the reaction, varying function based on pH and temperature, has an active site that binds substrates via induced fit

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106
Q

ATP

A

Common source of activation energy, stores its potential energy in the form of chemical energy, formed via phosphorylation, ADP and Pi come together using energy from an energy rich molecule like glucose.

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107
Q

Allosteric enzymes

A

Enzyme that has both an active site for substrate binding and an allosteric site for the binding of an allosteric effector (can be an activator or inhibitor)

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108
Q

Competitive inhibition

A

A substance that mimics the substrate and inhibits the enzyme by binding at the active site. The effect of competitive inhibition can be overcome by increasing substrate concentration

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109
Q

Uncompetitive / anti-competitive inhibition

A

Occurs when an enzyme inhibitor binds only to the formed enzyme-substrate (ES) complex (and not to the free enzyme), preventing formation of product. Vmax and Km are lowered

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110
Q

Vmax

A

Maximum velocity of the enzyme

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111
Q

Km, Michaelis constant

A

Represents the substrate concentration at which the rate of reaction is half of Vmax.

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112
Q

Relationship between Km and binding affinity

A

Inverse relationship; higher Km equals worse
substrate binding, lower Km equals better substrate binding.
i. A small Km indicates that an enzyme only requires a small amount of substrate to become saturated. Hence, Vmax is reached at relatively low substrate concentrations.
ii. A large Km indicates the need for high substrate concentrations to achieve Vmax.

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113
Q

Cooperativity

A

Phenomenon that occurs where an enzyme becomes more receptive to additional substrate molecules after one substrate molecule binds to the active site

i. Example: hemoglobin is a quaternary protein with 4 subunits that each has an active site for binding oxygen. As the first oxygen binds, the other active sites become increasingly likely to bind oxygen.
ii. Note: hemoglobin is not an enzyme, but is used here as a simple example of biological cooperativity that you will encounter later.

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114
Q

8 types of membrane proteins

A

Channel proteins, recognition proteins, ion channels, porins, carrier proteins, transport proteins, adhesion proteins, receptor proteins

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115
Q

Channel proteins

A

A type of membrane protein, provide a passageway through the membrane for hydrophilic (water-soluble), polar, and charged substances

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116
Q

Recognition proteins

A

A type of membrane protein, type of glycoprotein (have an attached oligosaccharide) that is used to distinguish between self and foreign (e.g major-histocompatibility complex on macrophage)

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117
Q

Ion channels

A

A type of membrane protein, used to pass ions across the membrane and referred to as gated channels in nerve and muscle cells
i. Can be voltage-gated (respond to
difference in membrane protein), ligand-gated (chemical binds to open channel), or mechanically-gated (respond to pressure, vibration, pressure)

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118
Q

Porins

A

A type of membrane protein, allows the passage of certain ions and small polar molecules; increase the rate of water passing in kidney and plant root cells; tend to be less specific - if you can fit through the large passage, you can go through

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119
Q

Carrier proteins

A

A type of membrane protein, specific to movement across the membrane via integral membrane protein; changes shape after binding to specific molecule that enables it to be passed across (e.g glucose into the cell)

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120
Q

Transport proteins

A

A type of membrane protein, includes active transport that uses ATP (e.g sodium-potassium pump) and facilitated diffusion that does not use ATP

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121
Q

Adhesion proteins

A

A type of membrane protein, attach cells to neighboring cells and provide anchors for stability via internal filaments and tubules

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122
Q

Receptor proteins

A

A type of membrane protein, serve as binding sites for hormones and other trigger molecules

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123
Q

3 membrane properties

A

Phospholipid membrane permeability, cholesterol, glycocalyx

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124
Q

Phospholipid membrane permeability

A

A type of membrane property, allows small, uncharged, non-polar, hydrophobic molecules to freely pass the membrane. Polar molecules may cross if they are small and uncharged. Every other type of substance requires a transporter

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125
Q

Cholesterol

A

A type of membrane property, adds rigidity to animal cell membranes under normal conditions and maintains fluidity of the membrane at lower temperatures; sterols provide analogous function in plant cells
Note: prokaryotes do not have cholesterol in their membranes - use hopanoids instead

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126
Q

Glycocalyx

A

A type of membrane property, a carbohydrate coat that covers the outer face of the cell wall of some bacteria and the outer face of the plasma membrane in some animal cells; consists of glycolipids attached to the plasma membrane, and glycoproteins that may serve as recognition proteins. Functions include adhesive capabilities, barrier to infection, or markers for cell-cell recognition

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127
Q

Peripheral membrane proteins

A

Generally hydrophilic and are held in place by H- bonding and electrostatic interactions. Can disrupt/ detach them by changing salt concentration or pH

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128
Q

Integral proteins

A

Hydrophobic, can be destroyed using detergent

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129
Q

Chromatin

A

General packaging structure of DNA around proteins in eukaryotes; tightness in packaging depends on cell stage

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130
Q

Chromosomes

A

Tightly condensed chromatin when the cell is ready to divide

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131
Q

Histones

A

DNA coils around it into bundles called nucleosomes; these bundles are wrapped around 8 histone proteins

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132
Q

Nucleosomes

A

DNA coiled around 8 histone proteins

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133
Q

Nucleolus

A

Inside of the nucleus and serves as the site of ribosome synthesis

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134
Q

Ribosome synthesis

A

Synthesized using rRNA and ribosomal proteins, which are imported from the cytoplasm. Once ribosomal subunits form, they are exported to the cytoplasm for final assembly into a complete ribosome.

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135
Q

Nucleus

A

Bound by proteins like RNA polymerase and histones. There is no cytoplasm in the nucleus, there is nucleoplasm. Found only in eukaryotic cells, not in prokaryotic cells

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136
Q

Nuclear Lamina

A

Dense fibrillar network inside of the nucleus of eukaryotic cells that provides mechanical support; helps regulate DNA replication, cell division, and chromatin organization

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137
Q

Nucleoid

A

Irregular shaped region within prokaryote cells that contains all or most of the cell’s genetic material. Found only in prokaryotic cells

138
Q

Cytoplasm

A

This is an area, not a structure. All of the cell’s metabolic activity and transport occur here, and the area includes the cytosol and organelles

139
Q

Cytosol / Cytoplasmic Matrix

A

Unlike the cytoplasm, it doesn’t include the components suspended within the gel-like substance, it is JUST the gel-like substance.

140
Q

Ribosomes

A

Organelles made of rRNA, function to make proteins
i. Composed of two subunits, 60S + 40S
= 80S in eukaryotes and 50S+ 30S = 70S in prokaryotes; the two subunits are produced inside of the nucleolus and moved into the cytoplasm where they are assembled into a single 80S ribosome
ii. A larger S value (Svedberg unit) indicates a heavier molecule

141
Q

Rough ER

A

ER studded with ribosomes and creates glycoproteins by attaching polysaccharides to polypeptides as they are assembled by ribosomes; in eukaryotes, the rough ER is continuous with the outer nuclear membrane

142
Q

Smooth ER

A

ER without ribosomes that synthesizes lipids and steroid hormones for export. In liver cells, the smooth ER function to break down toxins, drugs, and toxic by- products from cellular reactions. Smooth and striated muscle have smooth ER’s called sarcoplasmic reticulum that store and release ions like Ca2+

143
Q

Lysosomes

A

Vesicles produced from the Golgi that contain digestive enzymes with low pH, and functions in apoptosis, and to break down nutrients, bacteria, and cell debris. Any enzyme that escapes from lysosomes remains inactive in the neutral pH of cytolysis

144
Q

Golgi

A

Transport of various substances in vesicles and has flattened sacs known as cisternae. The cis face is for incoming vesicles, while the trans face is for secretory vesicles

145
Q

Peroxisomes

A

Organelles common in the liver and kidney that function to breakdown substances (H2O2 + RH2 → R + 2H2O), fatty acids, and amino acids

i. In plant cells, peroxisomes modify by-products of photorespiration. In germinating seeds, peroxisomes are called glyoxysomes that break down stored fatty acids to help generate energy for growth
ii. Peroxisomes produce H2O2, which they use to oxidize substrates and can also break down H2O2 if necessary (H2O2 → H2O + O2)

146
Q

Microtubules

A

Made up of the protein tubulin and serves to provide support and motility for cellular activities; is a spindle apparatus which guides chromosomes during division; Can be found in flagella and cilia of all animal cells and lower plants like mosses and ferns in a 9+2 array (9 pairs of microtubules with 2 singlets in the center)

147
Q

Intermediate Filaments

A

Provides support for maintaining cell shape (ex: keratin)

148
Q

Microfilament

A

Made of actin and involved in cell motility; found in skeletal muscle, amoeba pseudopod, and cleavage furrows

149
Q

Microtubule Organizing Centers (MTOCs)

A

Structures that include centrioles and basal bodies and are found at the base of each flagellum and cilium. Found in a 9x3 array. Plant cells lack centrioles and divide via cell plates rather than cleavage furrows, but plants still do have MTOCs

150
Q

Transport Vacuoles

A

Moves materials between organelles or between organelles and the plasma membranes

151
Q

Food Vacuoles

A

Temporary receptacles of nutrients that merge with the cytoplasm in order to breakdown food

152
Q

Central Vacuoles

A

Large, occupy most of the plant cell interior, exert turgor when fully filled to maintain rigidity, store nutrients, carry out functions performed by lysosomes in animal cells, and have a specialized membrane called a tonoplast

153
Q

Storage Vacuoles

A

Location where plants store starch, pigments, and toxic substances such as nicotine

154
Q

Contractile Vacuoles

A

Found in single-celled Protista organisms like amoeba and paramecium; function to collect and pump excess water out of the cell via active transport to prevent bursting

155
Q

Cell Walls

A

Functions to provide support in plants, fungi, protists, and bacteria; sometimes in presence with a secondary cell wall that develops beneath the primary cell wall

156
Q

Cellulose

A

Makes up plant cell walls

157
Q

Chitin

A

Makes fungi cell walls

158
Q

Peptidoglycan

A

Makes bacteria cell walls

159
Q

Polysaccharides

A

Makes archaea cell walls

160
Q

Extracellular Matrix

A

Found in animals in area between adjacent cells; occupied by fibrous structural proteins, adhesion proteins, and polysaccharides secreted by cells

161
Q

Extracellular matrix functions

A

Provides mechanical support and helps bind adjacent cells. Collagen is the most common protein that binds adjacent cells, but, there is also integral and fibronectin, which is a network of collagen and proteoglycans connected to interns in the cell membrane via fibronectin or laminin. The ECM also functions in transmitting mechanical and chemical signals between the inside and outside of the cell

162
Q

2 methods for the cell to adhere to ECM

A

Focal adhesions and hemidesmosomes

163
Q

Focal adhesions

A

Method for the cell to adhere to ECM, involve connection of the ECM to actin filaments in the cells

164
Q

Hemidesmosomes

A

Method for the cell to adhere to ECM, connection of ECM to intermediate filaments like keratin

165
Q

Fibroblasts

A

Cells that produce collagen and other connective tissue elements

166
Q

Plastids

A

Organelles found in plant cells, includes chloroplasts leucoplasts and chromoplasts

167
Q

Leucoplasts

A

A plastid. Specializes to store starch, lipids, proteins, as amyloplasts, elaioplasts, and proteinoplasts, respectively

168
Q

Chromoplasts

A

A plastid. Stores carotenoids

169
Q

Mitochondria

A

Double-layered organelles that make ATP, and serve as the site of fatty acid catabolism, or Beta-oxidation; have their own circular DNA and ribosomes

170
Q

Cytoskeleton

A

Includes microtubules (ex. flagella and cilia), microfilaments, intermediate filaments; found in eukaryotic cells, aids in cell division, cell crawling, and the movement of cytoplasm and organelles

171
Q

Hypotonic solution, plant context

A

Normal state of plant cells; vacuole swells and becomes turgid. Fungal cells also remain turgid due to the cell wall

172
Q

Isotonic solution, plant context

A

Plant cell is flaccid

173
Q

Hypertonic solution, plant context

A

Cell is plasmolyzed — the cytoplasm is pulled away from the cell wall

174
Q

Cytolysis

A

Cell bursts due to an osmotic imbalance that has caused excess water to diffuse into the cell, occurs in animal cells

175
Q

Endomembrane System

A

Network of organelles and structures, either directly or indirectly connected, that function in the transport of proteins and other macromolecules into or out of the cell. Includes the plasma membrane,
endoplasmic reticulum, Golgi apparatus, nuclear envelope, lysosomes, vacuoles, vesicles, and endosomes, but not the mitochondria

176
Q

Cell movement

A

Occurs via flagella, which undulate like snakes, and via cilia, which beat in a rapid back and forth motion

177
Q

2 methods of circulation

A

Intracellular Circulation and extracellular circulation

178
Q

Intracellular Circulation

A

i. Brownian movement: random
particle movement due to kinetic energy, spreads small suspended particles throughout cytoplasm
ii. Cyclosis/streaming: circular motion of cytoplasm around cell transport molecules
iii. Endoplasmic reticulum: provides channel through cytoplasm, provides direct continuous passageway from plasma membrane to nuclear membrane

179
Q

Extracellular Circulation

A

i. Diffusion: if cells in close contact with external environment, can suffice for food and respiration needs. Also used for transport of materials between cells and interstitial fluid around cells in more complex animals
ii. Circulatory system: required by complex animals with cells too far from the external environment

180
Q

Junctions and types of junctions

A

Structures that consist of protein complexes that connect neighbouring cells: anchoring junctions, tight junctions, gap junctions, plasmodesmata

181
Q

Anchoring Junctions

A

Includes desmosomes, which are keratin filaments attached to adhesion plaques which bind adjacent cells together via connecting adhesion proteins, providing mechanical stability by holding cellular structures together. Present in animals cells in tissues with mechanical stress including cells in the skin epithelium and cervix/uterus

182
Q

Tight Junctions

A

Junction that completely encircles each cell, producing a seal that prevents the passage of materials between cells, characteristic of cells lining the digestive tract. Materials must actually enter the cells (by diffusion or active transport) in order to pass through the tissue in animal cells

183
Q

Gap Junctions

A

Narrow tunnels between animal cells (connexins) that prevent cytoplasms of each cell from mixing, but allow passage of ions and small molecules; essentially channel proteins of two adjacent cells that are closely aligned. Tissues like the heart include them to quickly pass electrical impulses

184
Q

Plasmodesmata

A

A type of junction. Narrow tunnels between plant cells (narrow tube of endoplasmic reticulum - desmotubule - that exchanges material through cytoplasm surrounding the desmotubule)

185
Q

Eukaryotes

A

Include all organisms except for bacteria, cyanobacteria, and archaebacteria

186
Q

Prokaryotes

A

Have a plasma membrane, circular DNA, ribosomes, cytoplasm, and cell wall. In prokaryotes, there is no nucleus, single circular naked double-stranded DNA (no chromatin), Ribosomes (50S + 30S = 70S), Cell walls (peptidoglycan), flagella

187
Q

Hypertonic

A

higher solute concentration

188
Q

Hypotonic

A

lower solute concentration

189
Q

Isotonic

A

equal solute concentration

190
Q

Bulk Flow

A

Collective movement of substances such as blood in the same direction in response to a force or pressure

191
Q

Passive Transport

A

Includes simple diffusion, osmosis, dialysis (diffusion of different solutes across a selectively permeable membrane), plasmolysis (movement of water out of a cell that results in its collapse), facilitated diffusion, countercurrent exchange (diffusion by bulk flow in opposite directions such as blood and water in fish gills)

192
Q

Active Transport

A

Movement of molecules against their concentration gradients requiring energy. Usually solutes like small ions, amino acids, monosaccharides

193
Q

Primary active transport

A

Energy (ATP) is directly used to move against concentration gradients

194
Q

Secondary active transport

A

Energy is indirectly used to move against concentration gradient (usually with an ion moving down its concentration gradient) - can be anti-port or co-transport

195
Q

Group translocation

A

Seen in prokaryotes when the substance being transported across the membrane is chemically altered in the process, which prevents it from diffusing back out

196
Q

3 types of endocytosis

A

These are 3 types of active transport: Phagocytosis, Pinocytosis, Receptor-mediated Endocytosis

197
Q

Phagocytosis

A

A type of endocytosis, undissolved material

(solid) enters cell; white blood cell engulfs the material as the plasma membrane wraps around the substance

198
Q

Pinocytosis

A

A type of endocytosis, plasma membrane invaginate around dissolved material (liquid)

199
Q

Receptor-mediated Endocytosis

A

A type of endocytosis, form of pinocytosis in which specific molecules called ligands bind to receptors. Proteins that transport cholesterol in blood (LDL) and hormones that target specific cells use this technique

200
Q

Gibbs Free Energy

A

Tells us whether a given chemical reaction can occur spontaneously: G = H - TS (H is enthalpy, T is temperature, and S is entropy). If △G is negative, the reaction can occur spontaneously. If △G is positive, the reaction is non-spontaneous.

201
Q

Gibbs Free Energy change

A

Chemical reactions can be “coupled” together if they share intermediates. The sum of the △G values for each reaction. An unfavorable reaction with a positive △G1 value can be driven by a second, highly favorable reaction (negative △G2 value where the
magnitude of △G2 > magnitude of △G1

202
Q

Spontaneous change

A

Gibbs free energy goes down, stability goes up, and work capacity goes down

203
Q

Exergonic (spontaneous) reactions

A

Free energy is released and △G is less than 0

204
Q

Endergonic (non-spontaneous) reactions

A

Free energy is required and △G is greater than 0

205
Q

Cellular Respiration

A

Overall oxidative, exergonic process (△G = -686 kcal/mol) that breaks down glucose to derive ATP energy. High energy H atoms are removed from organic molecules (dehydrogenation), aerobic process. Four major steps: glycolysis, pyruvate decarboxylation, the Krebs Cycle, and the electron transport chain. Equation: C6H12O6 + 6O2 –> 6CO2 + 6H2O + ATP

206
Q

External respiration

A

Entry of air into the lungs and subsequent gas exchange between alveoli and blood

207
Q

Internal respiration

A

Exchange of gas between blood and the cells.

208
Q

Glycolysis goal and location

A

Decomposition of glucose into pyruvate in the cytosol

209
Q

Glycolysis start and end products

A

Start with 1 glucose. 2 ATP added in the intermediate reactions. 2 NADH, 4 ATP, and 2 pyruvate formed (Net 2 ATP formed)

210
Q

Glycolysis ATP production

A

ATP produced via substrate level phosphorylation, which involves direct enzymatic transfer of a phosphate to ADP (no extraneous carriers needed)

211
Q

Hexokinase in glycolysis

A

Phosphorylates glucose, which is important as this step is irreversible and glucose can’t diffuse out of the cell

212
Q

Phosphofructokinase (PFK) in glycolysis

A

Adds second phosphate, forming fructose 1,6- bisphosphate, which is irreversible and commits the glucose to glycolysis. Major regulatory point of glycolysis and is a point of allosteric regulation that controls the overall rate of glycolysis (rate limiting step)

213
Q

Pyruvate Decarboxylation location, start and end products, enzyme

A

Mitochondrial matrix. Pyruvate and co-enzyme A combine and produce 1 NADH, 1 CO2 and 1 Acetyl CoA (Net: 2 NADH, 2 CO2 and 2 Acetyl CoA since 2 pyruvate formed in glycolysis). Reaction is catalyzed by PDC enzyme (pyruvate dehydrogenase complex)

214
Q

Krebs Cycle/Citric Acid Cycle/Tricarboxylic Acid Cycle location and start and end products

A

Occurs in the mitochondrial matrix. Acetyl CoA merges with oxaloacetate to form citrate, and
the cycle continues with 7 intermediates. 3 NADH, 1 FADH2, 1 ATP (via substrate level phosphorylation) and 2 CO2 are produced per turn. Net of 6 NADH, 2 FADH2, 2 ATP (technically GTP), 4 CO2 as the cycle occurs for each of the two pyruvate formed from one glucose molecule. The CO2 produced here is the CO2 animals exhale during breathing

215
Q

Electron Transport Chain (ETC) location

A

Inner membrane / cristae (the folds which increase surface area for more ETC action)

216
Q

Electron Transport Chain (ETC) goal

A

Oxidative phosphorylation occurs here, which is the process of ADP → ATP from NADH and FADH2 via passing of electrons through various carrier proteins; energy doesn’t accompany the phosphate group but comes from the electrons in the ETC establishing an H+ gradient that supplies energy to ATP synthase

217
Q

Electron Transport Chain (ETC): NADH vs FADH2

A

NADH makes more energy than FADH2, and more H+ is pumped across per NADH (both of which are coenzymes) (3:2 yield)

218
Q

Electron Transport Chain (ETC): final electron acceptor and final product

A

Final electron acceptor: Oxygen, which combines with native H+ to form water
Final product: Water and ATP

219
Q

Electron Transport Chain (ETC): ATP synthase

A

Makes ATP by using the pH and electrical gradient established by electron carriers that ‘extract energy from NADH and FADH2 while pumping protons into the intermembrane space’. It makes ATP as it shuttles H+ back into the inner matrix

220
Q

Electron Transport Chain (ETC): Coenzyme Q (CoQ) / Ubiquinone

A

Soluble carrier dissolved in the membrane that can be fully reduced/ oxidized as it passes electrons

221
Q

Electron Transport Chain (ETC): Cytochrome C

A

Protein carrier, common in many living organisms, used for genetic relations, have nonprotein parts like iron that donate or accept electrons for redox reactions

222
Q

ETC coupled mechanism

A

Couples flow of electrons with endergonic pumping of H+ across the cristae membrane

223
Q

Total energy from 1 glucose in eukaryotes vs prokaryotes

A

~36 ATP in eukaryotes and ~38 ATP in prokaryotes (not actual yield as mitochondrial efficacy varies)

224
Q

Reasoning for difference between ATP totals in eukaryotes and prokaryotes

A

Prokaryotes have no mitochondria so they, unlike eukaryotes, don’t need to transfer the two NADH molecules into the mitochondrial matrix - which is done via active transport thus costing 1 ATP each. Side note - pyruvate is also actively transported into the mitochondrial matrix (in eukaryotes) but its transport is secondary active (symport with protons) and doesn’t directly use ATP.

225
Q

Mitochondria

A

The outer membrane, intermembrane

space (H+ build up), inner membrane (ETC), and mitochondrial matrix (Krebs) are involved in cell respiration

226
Q

Chemiosmosis

A

Mechanism of ATP generation that occurs when energy is stored in the form of a proton concentration gradient across a membrane. Krebs Cycle produces NADH/FADH2 which are oxidized and cause H+ to be
transported from the mitochondrial matrix to the intermembrane space. A pH and electrical charge gradient is created and ATP uses the kinetic energy from the flow established by this gradient (proton motive force) to create ATP as protons flow through the channel.

227
Q

ATP (adenosine triphosphate)

A

An RNA nucleotide (due to its ribose sugar)
i. Is an unstable molecule because the 3 phosphates in ATP are negatively charged and repel one another
ii. When one phosphate group is
removed via hydrolysis, a more stable ADP molecule results
iii. The change from a less stable molecule to a more stable molecule always releases energy
iv. Provides energy for all cells by transferring phosphate from ATP to another molecule

228
Q

Anaerobic Respiration (cytosol)

A

Includes glycolysis and fermentation

229
Q

Reasoning for why fermentation occurs

A

Aerobic respiration regenerates NAD+ via O2, which is required for continuation of glycolysis. Without O2, there would be no replenishing of NAD+, so NADH accumulates and no new ATP can be made, so fermentation occurs

230
Q

Alcohol Fermentation: location

A

Occurs in plants, fungi (e.g yeasts), and bacteria (e.g botulinum)

231
Q

Alcohol Fermentation: start and end products

A

Pyruvate → acetaldehyde + CO2, then acetaldehyde → ethanol (and NADH → NAD+)

232
Q

Alcohol Fermentation: final electron acceptor and final product

A

Acetaldehyde is the final electron acceptor, thus forming the final product of ethanol.

233
Q

Lactic Acid Fermentation: location

A

Occurs in human muscle cells and other microorganisms

234
Q

Lactic Acid Fermentation: start and end products

A

Pyruvate → lactate (and NADH → NAD+)

Lactate is transported to liver for conversion back to glucose once surplus ATP available

235
Q

Facultative Anaerobes

A

Use oxygen when it’s present (more efficient) but switch to fermentation/anaerobic respiration if oxygen is not present

236
Q

Obligate anaerobes

A

Cannot live in presence of oxygen

237
Q

Similarity between fermentation and cellular respiration

A

Both use glycolysis and produce a pyruvate molecule.

238
Q

Alternative Energy Sources

A

When glucose supply is low, the body uses other energy sources, in the priority order of other carbohydrates (4 calories/gram), fats (10 calories/gram, Stores more energy than carbohydrates and proteins per carbon. Carbons in fat are in a more reduced state), and proteins (4 calories/gram).

239
Q

Alternative Energy Sources: Other carbohydrates

A

Carbohydrates are converted to glucose or glucose intermediates, and are then degraded in glycolysis or the Krebs cycle.

240
Q

Alternative Energy Sources: Other carbohydrates - Gluconeogenesis

A

Produce glucose in liver or kidney

241
Q

Alternative Energy Sources: Other carbohydrates - Insulin

A

After large meals, stores glucose as glycogen, activates PFK enzyme. All cells are capable of storing glycogen, but only muscle cells and liver cells store large amounts of glycogen

242
Q

Alternative Energy Sources: Other carbohydrates -Glucagon

A

Turns on glycogen degradation to get glucose, inhibits PFK enzyme

243
Q

Alternative Energy Sources: Other carbohydrates - Disaccharides

A

Hydrolyzed into monosaccharides, most of which can be converted to glucose or glycolytic intermediates

244
Q

Alternative Energy Sources: Fats

A

Triglycerides, in the lumen of the small intestine, are broken down via lipase into monoacylglycerides + fatty acids, which are then absorbed into the enterocytes (cell lining of the small intestine). There, they are reassembled into triglycerides, and then, along with cholesterol, proteins, or phospholipids, are packaged into chylomicrons which move on to the lymph capillary for transport to the rest of the body where they are stored as adipose tissue

245
Q

Alternative Energy Sources: Fats - Lipases in adipose tissue

A

Hormone sensitive (e.g to glucagon)

246
Q

Alternative Energy Sources: Fats - Glycerol

A

Glycerol → PGAL, enters glycolysis

247
Q

Alternative Energy Sources: Fats - fatty acid

A

When fatty acid → Acetyl CoA, every 2
carbon from fatty acid chain makes an Acetyl CoA. Fatty acids in blood combine with albumin, which carries them throughout the bloodstream

248
Q

Alternative Energy Sources: Fats - Beta oxidation

A

Fatty acids are broken down for energy, taking place in mitochondrial matrix

i. 2 ATP are spent activating the entire fatty acid chain
ii. Saturated fatty acids produce 1 NADH and 1 FADH2 for every cut into 2 carbons — not the same as for every 2 carbons, as an 18C chain contains 9 2-carbon pieces, but it is only cut 8 times, with each cut being a beta oxidation step
iii. Unsaturated fatty acids produce 1 less FADH2 for each double bond
iv. Results in a BIG yield of ATP, as it yields more ATP per carbon than carbohydrates, with more energy in fats than sugars
v. End product is acetyl-CoA

249
Q

Alternative Energy Sources: Fats - lipoproteins

A

Between meals, most lipids of plasma are in the form of lipoproteins (chylomicrons are large lipoproteins). In addition to chylomicrons, there are low and high density lipoproteins. LDLs have low protein density but high fat density, and are unhealthy. HDLs have high protein density and low fat density, and are healthy.

250
Q

Alternative Energy Sources: Protein

A

Most amino acids are deaminated in liver, then converted to pyruvate or acetyl CoA or other Krebs cycle intermediates, and enter cellular respiration at these various points, which varies by amino acid.

251
Q

Alternative Energy Sources: Protein - oxidative deamination

A

Removes ammonia molecule directly from amino acids. Ammonia is toxic to vertebrates, but most aquatic specific and invertebrates excrete it directly

252
Q

Alternative Energy Sources: Protein - Converting ammonia

A

Insects, birds, and reptiles convert ammonia to uric acid. While mammals, sharks, and most amphibians convert ammonia to urea for excretion

253
Q

Photosynthesis

A

Harness light energy in order to synthesize glucose: 6CO2 + 6H2O -> C6H12O6 + 6O2. Occurs in chloroplast

254
Q

Photosynthesis - light-absorbing pigments in plant cells

A

Chlorophyll a, chlorophyll b, and carotenoids (red, orange, and yellow) function to absorb energy from light. Light is incorporated into electrons, which causes electrons to be excited and become un-stable. These electrons re-emit the absorbed energy, which is then reabsorbed by electrons in nearby pigment molecules.

255
Q

Photosynthesis - Chlorophyll a structure

A

Porphyrin ring that consists of alternating double and single bonds. The double bonds are critical for light reactions. The porphyrin ring is also complexed with a Mg atom inside.

256
Q

Photosynthesis - two special chlorophyll a molecules

A

P680 and P700

257
Q

Photosynthesis - P680

A

Forms pigment cluster 2, PSII

258
Q

Photosynthesis - P700

A

Forms pigment cluster 1, PSI

259
Q

Photosynthesis - Antenna pigments

A

Chlorophyll b, carotenoids, phycobilins [red algae pigment], xanthophylls capture wavelengths that chlorophyll a does not, and pass energy to chlorophyll a where the direct light reactions occur.

260
Q

Chloroplast - thylakoid lumen

A

Location where H+ accumulates as a result of the ETC.

261
Q

Chloroplast - thylakoids

A

Suspended within the stroma and their membranes contain the two photosystems, cytochromes, and electron carriers

262
Q

Chloroplast - stroma

A

Fluid material that fills area inside the inner membrane and is the location of the Calvin cycle.

263
Q

Chloroplast - inner and outer membranes of the chloroplast

A

Consist of a phospholipid bilayer

264
Q

Chloroplast - thylakoid membrane

A

Absorbs light

265
Q

Non-cyclic photophosphorylation location

A

Thylakoid membrane

266
Q

Cyclic phosphorylation location

A

Stroma lamellae — the pieces connecting the thylakoids

267
Q

Photolysis location

A

Inside the thylakoid lumen, and passes electrons to the thylakoid membrane for non-cyclic photophosphorylation

268
Q

Calvin cycle location

A

Stroma

269
Q

Chemiosmosis location

A

Across the thylakoid membrane

270
Q

Photosynthesis steps

A

Non-cyclic photophosphorylation, Cyclic Photophosphorylation, Calvin Cycle

271
Q

Non-cyclic photophosphorylation equation and all steps

A

Light dependent reaction: H2O + ADP + Pi + NADP + light → ATP + NADPH + O2 + H+.

i. Electrons trapped by P680 in PSII are energized by light
ii. Two excited electrons are passed to a primary electron acceptor (first in the chain of acceptors) from PSII
iii. Excited electrons enter the electron transport chain which consists of PSII that contains cytochrome proteins and Fe2+ as a cofactor; is analogous to oxidative phosphorylation
iv. Two electrons move down the electron transport chain and lose energy, which is used to phosphorylate about 1.5 ATP
vi. Electron transport chain terminates with PSI/P700 where electrons are re- energized by sunlight and passed to another primary electron acceptor. From this point on, the electrons can enter the non-cyclic or cyclic path
vii. If continuing on the non-cyclic path, two electrons pass down a short electron transport chain with proteins like ferrodoxin to combine NADP+ & H+ & 2 electrons to form NADPH
viii. The two electrons lost in step 2 from PSII are replaced when water splits to form 2 electrons, 2 H+, and 1 oxygen molecule. The H+ is used for NADPH formation and the oxygen molecule is released as gas.

272
Q

Photosystems

A

There are a few hundred photosystems in each thylakoid and each has a reaction center containing chlorophyll and antenna pigments that funnel energy to it

273
Q

Cyclic Photophosphorylation

A

Alternate path that replenishes ATP when the Calvin cycle (next step) consumes it

i. 2 excited electrons from PSI join with protein carriers in the first electron transport chain and generate 1 ATP as they pass through this chain
ii. These 2 electrons are recycled into PSI and continue to have an option to enter the cyclic or non-cyclic path

274
Q

Calvin Cycle

A

Dark reaction that fixes 6 CO2 molecules through a cycle that repeats 6 times to ultimately synthesize glucose. Light-independent process, but requires ATP and NADPH produced from light-dependent reactions. Cannot occur without light because it is dependent on the high energy molecules (ATP and NADPH) produced from the light reaction. 6CO2 + 18ATP + 12NADPH + H+ → 18ADP + 18 Pi + NADP+ + 1 glucose (or 2 G3P). Carboxylation, Reduction, Regeneration, Carbohydrate synthesis

275
Q

Calvin Cycle: Carboxylation

A

6 CO + 6 RuBP join to form 12 PGA, and is catalyzed by the enzyme RuBisCo, or RuBP carboxylase

276
Q

Calvin Cycle: Reduction

A

12 ATP + 12 NADPH convert 12 PGA → 12 G3P or 12 PGAL; energy is incorporated; the by-products NADP+ and ADP go into non-cyclic photophosphorylation

277
Q

Calvin Cycle: Regeneration

A

6 ATP convert 10 G3P → 6 RuBP, which allows the Calvin cycle to repeat

278
Q

Calvin Cycle: Carbohydrate synthesis

A

Two remaining G3P are used to build glucose.

279
Q

Plant mitochondria vs Plant chloroplast

A

Plants do have mitochondria that make ATP, but the ATP from photosynthesis comes from the chloroplast and is used to drive photosynthesis further via the Calvin cycle. Photosynthesis primarily makes glucose for the plant’s own mitochondria to use as energy! We still need mitochondria for plant tissues but the organelle doesn’t make the ATP for photosynthesis, and photosynthesis ATP isn’t used for general cell function!

280
Q

Chemiosmosis in Chloroplasts

A

Uses H+ gradient to generate ATP

  1. H+ ions accumulate inside thylakoids: H+ are released into lumen when water is split by PSII. H+ is also carried into the lumen from stroma by cytochrome between PSII and PSI
  2. A pH and electrical gradient is created with an approximate pH of 5
  3. ATP synthase generates ATP: ADP is phosphorylated with Pi to form ATP, and 3 H+ are required to make 1 ATP
  4. Calvin cycle produces 2 G3P using NADPH, CO2, and ATP: at the end of the electron transport chain following PSI, the 2 electrons produce NADPH
281
Q

Alternatives to C3 Photosynthesis

A

Depending on climate, photosynthesis can occur as either photorespiration, C4 photosynthesis, or CAM photosynthesis.

282
Q

Photorespiration

A

An alternative to C3 Photosynthesis. Process that involves the fixation of oxygen, instead of CO2, by rubisco but produces no ATP or glucose. Rubisco is not efficient or fast because it will fix both CO2 and oxygen at the same time if both are present. Peroxisomes break down the products of this process.

283
Q

C4 Photosynthesis steps

A

An alternative to C3 Photosynthesis. Process that evolved from normal photosynthesis (C3 photosynthesis) and is a type of spatial separation.

i. When CO2 enters the leaf, it is absorbed by mesophyll cells and moved to bundle sheath cells
ii. Instead of being fixed by rubisco into PGA, CO2 combines with phosphoenol pyruvate (PEP) to form oxaloacetate (OAA) by PEP carboxylase in the mesophyll
a. OAA has 4C, therefore it follows C4 photosynthesis
b. OAA is converted to malate, and transferred through plasmodesmata into the bundle sheath cell, which requires conversion of 1 ATP to 1 AMP
c. Malate is converted into pyruvate and CO2. The CO2 can be used in the Calvin cycle and pyruvate is shuttled back into the mesophyll and converted back into PEP.

284
Q

C4 Photosynthesis purposes

A
  1. Move CO2 from mesophyll to bundle sheath cells.

2. Minimize photorespiration and water loss found from the stomata, or lead pores

285
Q

C4 Photosynthesis - Kranz anatomy

A

A specialized structure in C4 plants that has mesophyll cells clustered around bundle-sheath cells

286
Q

C4 Photosynthesis - Hatch-Slack pathway

A

Explains that little presence of oxygen reduces competition while rubisco is deciding to fix either carbon dioxide or oxygen.

287
Q

C4 Photosynthesis - climate

A

C4 photosynthesis is found in hot, dry climates as it allows for a faster fixation speed and is more efficient. Typically occurs in plants like corn and
sugarcane

288
Q

C4 Photosynthesis - drawback

A

The use of extra ATP to pump 4C compounds to bundle sheath cells

289
Q

CAM Photosynthesis steps

A

An alternative to C3 Photosynthesis. Crassulacean acid metabolism

i. PEP carboxylase fixes CO2 + PEP to OAA, forming malic acid
ii. Malic acid is shuttled into the vacuole of the cell
iii. At night, when stomata are open (opposite of normal), PEP carboxylase is active, causing malic acid to accumulate in the vacuole
iv. During the day, stomata are closed. Malic acid is out of the vacuole and converted back into OAA, which requires 1 ATP, and releases CO2 that moves onto the Calvin cycle with rubisco, and PEP

290
Q

CAM Photosynthesis advantage

A

Photosynthesis can proceed during the day while stomata are closed, thereby reducing water loss. Therefore, this process is beneficial in cacti and crassulacean plants.

291
Q

As leaves age

A

Chlorophyll breaks down to extract valuable components like Mg2+, and carotenoids become visible

292
Q

Splitting of water in the light reactions

A

Provides two electrons for non-cyclic photophosphorylation, and are incorporated into NADPH and the Calvin cycle

293
Q

Cell division

A

Nuclear division (karyokinesis), followed by cytokinesis

294
Q

In diploid cells

A

2 copies of every chromosome, which forms a pair of homologous chromosomes. Humans have 46 chromosomes, or 23 homologous pairs. One chromosome is made up of 2 sister chromatids. Humans have a total of 92 chromatids

295
Q

Mitosis

A

Cell division in somatic cells. Microtubule organizing centers (MTOCs), or centrosomes, are key players in cell division. A pair of MTOCs lay outside the nucleus in animal cells, and each MTOC contains a pair of centrioles. Plants have MTOCs called centrosomes, but they are not composed of centrioles. Prophase, metaphase, anaphase, telophase, cytokinesis

296
Q

Prophase

A

Nucleus disassembles, nucleolus disappears, chromatin condenses into chromosomes, and nuclear envelope breaks down. The mitotic spindle forms, and microtubules (composed of tubulin) begin connecting to kinetochores.

297
Q

Metaphase

A

Chromosomes line up single file along the center of the cell, forming a chromatid complete with a centromere and kinetochore. Karyotyping is performed when cells are in metaphase.

298
Q

Anaphase

A

Microtubules shorten and each chromosome is pulled apart into 2 chromatids. Once separated, the chromatid becomes a chromosome, and the chromosome number doubles. The microtubules pull the chromosomes to opposite poles of the cell, a process known as disjunction. At the end of this phase, each pole has a complete set of chromosomes, same as the original cell before replication. This is the shortest step of mitosis. 92 chromosomes in human because the sister chromatids are split, but the cell is not split yet.

299
Q

Telophase

A

Nuclear envelope develops. The chromosomes unravel into chromatin and the nucleoli reappears

300
Q

Cytokinesis

A

Begins during the later stages of mitosis, usually begins towards the end of anaphase. Involves the division of cytoplasm to form two cells

301
Q

Cytokinesis in animal cells

A

Cleavage furrow forms, which involves the shortening of actin and myosin microfilaments and the plasma membrane is pulled into the center of the cell

302
Q

Cytokinesis in plant cells

A

Cell plate forms, which involves vesicles from Golgi bodies migrating and fusing to form a cell plate. As the plate grows, it merges with the plasma membrane, eventually separating the two new cells. Formation of the cell plate doesn’t actually separate cells from each other; the middle lamella (cell plate) cements adjacent cells together

303
Q

G1

A

Cell increases in size and lots of proteins and ribosomes are made. The G1 checkpoint ensures that everything is ready for DNA synthesis, and the phase as a whole is the most variable in length of all phases depending on cell type

304
Q

S

A

DNA synthesis occurs where a new DNA molecule is replicated from the first, creating sister chromatids

305
Q

G2

A

Rapid cell growth occurs, organelles are replicated, and genetic material prepares for cell growth

306
Q

Interphase vs Mitosis

A

More time is spent in interphase (G1, S, G2) than in mitosis. Interphase comprises about 90% of the cell cycle.

307
Q

Interphase

A

Growth occurs in all 3 interphase phases (G1, S, G2), not just the G phases.

308
Q

Checkpoints

A

Occurs throughout the cell cycle to ensure that every phase is occurring to plan.

309
Q

First checkpoint - end of G1

A

Cell growth is assessed and favorable conditions are checked. If this checkpoint fails, the cell enters G0, which is a non-dividing state. Some cells (liver, kidney) can be induced out of G0, while others (nerve, muscle) permanently reside in G0

310
Q

Second checkpoint - end of G2

A

Checks for sufficient Mitosis Promoting Factor (MPF) levels to proceed to mitosis. The accuracy of DNA replication is also evaluated

311
Q

Third checkpoint - M

A

Occurs during metaphase and checks if all chromosomes are attached to kinetochores. This also triggers the start of G1.

312
Q

Cyclin-dependent kinases (CDK’s)

A

Activates ‘proteins that regulate the cell cycle’ via phosphorylation. Are activated by protein cyclins, which vary in type and concentration throughout each phase of the cell cycle

313
Q

Growth factors

A

Plasma membrane contains receptors for growth factors that stimulate cell division, such as in a damaged cell

314
Q

Density-dependent inhibition

A

Cells stop dividing when surrounding cells density is at a maximum

315
Q

Anchorage dependence

A

Most cells only divide when they are attached to an external surface such as neighboring cells or placed on a culture dish

316
Q

Transformed cells

A

Cancer cells that defy 4 conditions: CDK’s, growth factors, density-dependent inhibition, anchorage dependence. Cancer drugs also inhibit mitosis by disrupting the ability of microtubules to separate chromosomes during anaphase, thus stopping replication

317
Q

Meiosis I

A

Reduction division; homologous chromosomes pair at the plate, migrate to opposite poles, yet there is no separation of sister chromatids

318
Q

Prophase I

A

Nucleus disassembles, nucleolus disappears, nuclear envelope breaks down, chromatin condenses, and mitotic spindle develops. The microtubules begin attaching to kinetochores, and crossing over occurs, which allows for genetic recombination.

319
Q

Prophase I - Synapsis

A

Occurs during prophase I, which involves homologous chromosomes pairing up, forming a tetrad (group of 4 chromatids) or bivalents

320
Q

Prophase I - Chiasmata

A

Region where crossing over of non-sister chromatids occurs

321
Q

Prophase I - Synaptonemal complex

A

Protein structure that temporarily forms between homologous chromosomes; gives rise to tetrad with chiasmata and crossing over

322
Q

Prophase I - leptotene

A

Step 1/5 of prophase I. Chromosomes start condensing

323
Q

Prophase I - zygotene

A

Step 2/5 of prophase I. Synapsis begins, synaptonemal complex forms

324
Q

Prophase I - pachytene

A

Step 3/5 of prophase I. Synapsis complete, crossing over

325
Q

Prophase I - diplotene

A

Step 4/5 of prophase I. Synaptonemal complex disappears, chiasma still present

326
Q

Prophase I - diakinesis

A

Step 5/5 of prophase I. Nuclear envelope fragments, chromosomes complete condensing, and tetrads are ready for metaphase

327
Q

Metaphase I

A

Homologous pairs line up along the metaphase plate, and microtubules attach to kinetochores of one member of each homologous pair.

328
Q

Anaphase I

A

Homologues within tetrads uncouple and pulled opposite sides (disjunction)

329
Q

Telophase I

A

Nuclear membrane develops and each pole forms a new nucleus that has half the number of chromosomes (from homologous pair to each chromosome = 2 sister chromatids). The cell is now haploid. Interphase may occur after telophase I, depending on the species

330
Q

Meiosis II

A

Chromosomes lining up on the metaphase plate and sister chromatids separating and migrating to opposite poles; similar to mitosis

331
Q

Prophase II

A

Nuclear envelope disappears and spindle develops, but no chiasmata or crossing over occurs

332
Q

Metaphase II

A

Chromosomes align on metaphase plate like in mitosis, but now with half the number of chromosomes (no extra copy)

333
Q

Anaphase II

A

Each chromosome is pulled into 2 separate chromatids and migrate to opposite poles of the cell. 46 chromosomes total in humans because the cell is not yet split

334
Q

Telophase II

A

Nuclear envelope reappears and cytokinesis occurs → 4 haploid cells form, with each chromosome consisting of one chromatid

335
Q

Fertilization/syngamy

A

Fusion of 2 haploid gametes, resulting in a diploid zygote

336
Q

3 Genetic variation events

A
  1. Crossing over during prophase I
  2. Independent assortment of homologues during metaphase I; The entry of chromosomes into one cell does not affect entry of the other chromosome into the other cell
  3. Random joining of gametes, aka germ cells; The sperm randomly selects an egg to fertilize
337
Q

Alternation of Generations

A

In plants, meiosis in sporangia produces spores (haploid), which undergo mitosis to become multicellular haploid gametophytes. These gametes fuse together to form a diploid zygote that grows via mitosis into a sporophyte. Cells in the sporophyte (sporangia) undergo meiosis again to produce haploid spores that germinate and repeat the life cycle known as alternation of generations.

338
Q

2 Functional Limitations to Cell Division

A

2 main ratios that dictate if a cell will divide: Surface to volume ratio and Genome to volume ratio

339
Q

Surface to volume ratio

A

As cells grow, the volume grows much larger compared to the surface area. When SA:V is large, exchange across the cell becomes much easier. When SA:V is small, exchange is harder, leading to either cell death or cell division to increase SA

340
Q

Genome to volume ratio

A

Genome size remains constant throughout life, as cell growth leads to only an increase in volume. G:V will be small and thus exceed the ability of its genome to produce sufficient amounts of regulation of activities. Some large cells like paramecium and human skeletal muscle are multinucleate to deal with this.

341
Q

Joining of gametes

A

Random, but some sperm cells contain genetic material that gives them a competitive advantage - so they all aren’t “equally” competitive

Feralis' Biology (6 decks)

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