bio worksheet 1

4 components shared by ALL cells

Plasma membrane, cytoplasm, DNA, ribosomes

Prokaryote: nucleus? membranous organelles?

No and no

Prokaryote DNA (number & shape)

One circular chromosome (plus plasmids), in the nucleoid

Eukaryote DNA (number & shape)

Multiple linear chromosomes, inside the nucleus

Prokaryote vs eukaryote size

Prokaryotes small (~1-10 um); eukaryotes large (~10-100 um)

Which domains are prokaryotic? Eukaryotic?

Bacteria + Archaea are prokaryotic; Eukarya is eukaryotic

As a cell grows, which increases faster: volume or surface area?

Volume (surface area falls behind)

3 benefits of compartmentalization

Separates incompatible reactions; concentrates enzymes/substrates; allows different conditions (pH) + adds membrane surface area

Plasmid

Small circular, supercoiled extra DNA

Fimbriae

Needle-like projections for attachment to surfaces/cells

Prokaryotic flagellum

Long filament that rotates to propel the cell

Prokaryotic cell wall (general role)

Rigid "exoskeleton" that protects shape

Bacteria cell wall material

Peptidoglycan

Archaea cell wall material

Protein S-layer (no peptidoglycan)

Plant cell wall material

Cellulose

Nucleus / nucleolus: function, # membranes, A/P/B

Holds DNA, controls gene expression; nucleolus makes rRNA/ribosome subunits; 2 membranes; both

Ribosome: function, # membranes

Builds proteins; 0 membranes; both

Mitochondrion: function, # membranes

Cellular respiration, most ATP; 2 membranes; both

Chloroplast: function, # membranes, A/P/B

Photosynthesis; 2 membranes (+ thylakoids); plant/algae

Peroxisome: function, # membranes

Breaks down fatty acids, detoxifies H2O2; 1 membrane; both

Rough ER: function

Makes, folds, glycosylates secretory and membrane proteins; 1 membrane

Smooth ER: function

Lipid synthesis, detox, calcium storage; 1 membrane

Golgi apparatus: function

Modifies, tags, sorts, packages proteins into vesicles; 1 membrane

Lysosome: function, A/P/B

Digests/recycles with acid hydrolases; 1 membrane; animal

Central vacuole: function, A/P/B

Storage, turgor pressure, waste; 1 membrane; plant

Centrioles (centrosome): function, A/P/B

Organize microtubules / spindle; 0 membranes; animal

Mitochondria came from an engulfed ___ bacterium

Aerobic bacterium

Chloroplasts came from an engulfed ___ bacterium

Photosynthetic bacterium (cyanobacterium)

2 lines of endosymbiosis evidence

Own circular DNA; own ribosomes; double membrane; divide like bacteria (any two)

Secretory pathway: steps 1-7

1 Ribosomes on RER make protein; 2 folded + glycosylated in RER lumen; 3 vesicle buds from ER; 4 fuses with cis Golgi; 5 Golgi modifies/tags (cis to trans); 6 sorted/packaged at trans face; 7 exocytosis at plasma membrane

Vesicles arrive at which Golgi face? Leave from which?

Arrive at cis; leave from trans

3 destinations of secretory pathway

Plasma membrane, secretion outside the cell, lysosomes

Lysosome pH and what maintains it

About pH 5, kept by proton (H+) pumps in its membrane

Lysosome enzymes are called

Acid hydrolases

Microfilaments: subunit, size, tension or compression

Actin; ~7 nm; resist tension

Intermediate filaments: subunit, size, tension or compression

Keratin (fibrous proteins); ~10 nm; resist tension

Microtubules: subunit, size, tension or compression

Tubulin (alpha/beta dimers); ~25 nm; resist compression

2 functions of microfilaments

Cell shape/movement; muscle contraction, cytokinesis

2 functions of intermediate filaments

Anchor organelles/nucleus; mechanical strength (desmosomes)

2 functions of microtubules

Chromosome movement in mitosis; tracks for vesicle transport; cilia/flagella

Kinesin: walks on what, uses what, head binds, tail binds

Walks on microtubules using ATP; head binds microtubule, tail binds cargo (vesicle)

Cilia and flagella arrangement

9+2 (9 outer microtubule doublets around 2 central)

Flagella vs cilia

Flagella long, few, move the cell; cilia short, numerous

What cements plant cells together?

Middle lamella (pectin)

Primary plant wall contains / secondary wall adds

Cellulose, hemicellulose, pectin / lignin

Plant cells connect through

Plasmodesmata

Intracellular proteins vs ECM proteins shape

Intracellular mostly globular; ECM mostly fibrous

Most abundant ECM protein

Collagen

ECM protein that lets tissue stretch

Elastin

Proteoglycans resist what?

Compression (crushing forces)

Proteins that attach cells to the ECM

Fibronectin and integrins

ECM signaling chain

Matrix molecule binds integrin, reshapes actin filaments, signal reaches nucleus, gene transcription changes, cell activity changes

Why do metastatic cells spread? (ECM)

Lose junctions/integrin attachments and break down ECM, so "stay put" signals fail and gene expression changes

Catabolism vs anabolism

Catabolism breaks down molecules, releases energy; anabolism builds molecules, uses energy

Metabolic pathway

Series of enzyme-catalyzed reactions; product of one is substrate of next

3 purposes of metabolic pathways

Extract energy; store fuels; synthesize building blocks (also eliminate waste)

Energy is the capacity to

Do work or cause change; most comes from the sun

Potential vs kinetic energy

Potential = stored (bonds, gradients); kinetic = motion (heat, movement)

Which bond has MORE potential energy?

Long, weak bond with equally shared electrons (like C-H)

Organisms are ___ systems

Open (exchange matter and energy)

1st law of thermodynamics

Energy can't be created or destroyed, only transformed

2nd law of thermodynamics

Every transformation increases entropy; some energy lost as heat

Base of energy pyramid

Primary producers (autotrophs); upper levels are consumers

Why less energy at higher trophic levels?

Most lost as heat/used in metabolism at each level (2nd law)

Delta G means

Change in free energy = energy available to do work

Exergonic: sign, spontaneous, PE, type

Negative; yes; products lower; catabolic

Endergonic: sign, spontaneous, PE, type

Positive; no; products higher; anabolic

Glucose to CO2 + H2O is exergonic or endergonic?

Exergonic

Amino acids to protein is exergonic or endergonic?

Endergonic

ATP to ADP + Pi is exergonic or endergonic?

Exergonic

Photosynthesis is exergonic or endergonic?

Endergonic

Enzymes: consumed? change direction? lower Ea?

Not consumed; can't change direction or delta G; lower activation energy

3 kinds of cell work

Chemical, transport, mechanical

Energy coupling

Exergonic process drives endergonic one, by transferring a phosphate or electrons

Why does ATP hold so much energy?

3 crowded negatively charged phosphates repel; energy stored in bonds among them

ATP hydrolysis delta G

-7.3 kcal/mol

Coupled: +3.4 with ATP hydrolysis. Overall?

+3.4 + (-7.3) = -3.9 kcal/mol; spontaneous

Oxidation / reduction (mnemonic)

Oxidation = loss of electrons (OIL); reduction = gain (RIG); always together

In respiration which is oxidized / reduced?

Glucose oxidized; O2 reduced

NAD+ : pathway, carries, reduced form

Oxidation (catabolic) pathways; electrons + H+; NADH

NADP+ : pathway, carries, reduced form

Reduction (anabolic) pathways, e.g. photosynthesis; electrons + H+; NADPH

FAD : carries, reduced form

Electrons + H (2 e-, 2 H); FADH2

Coenzyme A carries

Acetyl groups (forms acetyl-CoA); not a redox carrier

3 sources of glucose

Photosynthesis, diet, mobilized storage (glycogen/starch)

Anaerobic pathways: glucose is ___ oxidized, waste is ___

Not completely oxidized; small reduced organic molecules

Overall cellular respiration equation

C6H12O6 + 6 O2 -> 6 CO2 + 6 H2O + energy (ATP + heat); exergonic

Mitochondrion: folds / space between / inner compartment

Inner membrane folds = cristae; intermembrane space; matrix

Glycolysis: location, net ATP, NADH, product

Cytosol; net 2 ATP (substrate-level); 2 NADH; 2 pyruvate

Glycolysis investment phase vs payoff phase

Rxns 1-5 use 2 ATP; rxns 6-10 make 4 ATP (net 2) + NADH

Substrate-level phosphorylation

Direct transfer of a phosphate from a substrate to ADP

Glycolysis regulation points

The irreversible reactions

Primary fuel for the brain

Glucose

Pyruvate oxidation: location, inputs, outputs, ATP

Matrix (cytosol in prokaryotes); 2 pyruvate; 2 acetyl-CoA + 2 NADH + 2 CO2; 0 ATP

Pyruvate carbons to acetyl-CoA carbons

3C to 2C, releasing 1 CO2 and making 1 NADH

Citric acid cycle step 1

Acetyl-CoA + oxaloacetate -> citrate

Citric acid cycle per glucose

2 turns: 6 NADH, 2 FADH2, 2 ATP, 4 CO2

Total NADH / FADH2 / substrate-level ATP / CO2 per glucose

10 NADH, 2 FADH2, 4 ATP, 6 CO2

ETC location and complexes

Inner mitochondrial membrane; 4 complexes + ubiquinone and cytochrome c

ETC: what pumps H+ and where

Energy from electrons pumps H+ from matrix to intermembrane space

Final electron acceptor in aerobic respiration

O2, forming H2O