Module 4

Cellular Respiration Equation

C₆H₁₂O₆ + 6O₂ + ADP + P_i → 6H₂O + 6CO₂ + ATP + heat

How can metabolic activity be measured?

energy food eaten - wastes excreted; ATP produced; heat produced; amount of H₂O produced; amount of oxygen used up/carbon dioxide produced

What is the easiest way to measure metabolism?

gas exchange; amount of oxygen used up or carbon dioxide produced

Basal Metabolic rate (BMR)

rate at which an animal consumes oxygen while at rest, with an empty stomach, under normal temperature and moisture conditions

Metabolism is required for

a minimal resting lifestyle with no spontaneous activity, no digestion of food, and no physical thermal, or psychological stress

Maximum metabolic rate (MMR)

maximum rate at which oxygen can be transported from the environment to the tissue mitochondria; can be induced by activity/stress

Aerobic energy metabolism parameters

basal metabolic rate is the flood (lower) and maximum metabolic rate is the ceiling (higher)

Aerobic scope

capacity of an organism to increase its aerobic metabolic rate above maintenance level

Aerobic scope equation

MMR - BMR

Glucose

source of energy; produced from digestion of food; stored and oxidized to provide chemical energy

Site of cellular respiration or fermentation

cytoplasm & mitochondria

Mitochondria

organelles that are membrane-bound with two different membranes

Cristae

inner membrane highly folded

Glycolysis occurs in

cytoplasm

Glycolysis

glucose → pyruvate

Glycolysis products

2 pyruvate, 2 ATP, 2 NADH

If oxygen is present, pyruvate…

enters the mitochondria for citric acid cycle

If oxygen is not present, pyruvate …

undergoes fermentation

Fermentation

pyruvate → lactate

Fermentation products

lactic acid, 2 NAD+ (regenerates for glycolysis)

Link Reaction

pyruvate → Acetyl CoA; links the products of glycolysis with the aerobic processes of the mitochondria

Link Reaction Products

acetyl CoA, 2 NADH, 2 CO₂

Krebs Cycle = Citric Acid Cycle = TCA Cycle

Acetyl CoA produces NADH and FADH₂ molecules to feed electrons in Electron transport chain to generate cell’s ATP

Krebs Cycle = Citric Acid Cycle = TCA Cycle products

2 NADH, FADH₂, GTP → ATP, 2 CO₂

Electron Transport Chain (ETC)

final stage of aerobic respiration; releases energy stored within reduced hydrogen carriers to synthesize ATP; drives transport of protons across inner membrane from the matrix to intermembrane space for a proton gradient & electrons reduce O₂ to water; hydrogens pass through ATP synthase to produce ATP into the mitochondrial matrix

Where does link reaction occur?

mitochondria matrix

Where does Krebs cycle/Citric Acid Cycle/TCA Cycle occur?

mitochondrial matrix

Where does Electron Transport Chain occur?

inner mitochondrial membrane

Oxidative Phosphorylation

ETC releases energy stored within the reduced hydrogen carriers to synthesize ATP; derived from oxidation of hydrogen carriers (NADH, FADH₂)

Proton Gradient

higher concentration of protons (H⁺) in intermembrane space than in mitochondrial matrix

Final Electron Acceptor

oxygen

ATP Synthase

proton-driven rotor and ATP-generating enzyme; F₀ unit spins as protons pass through; shaft transmits the rotation to the F₁ unit, causing it to make ATP from ADP and P_i

Summary of Cellular Respiration

electrons carried by NADH & FADH₂; products (~29-34)ATP and water; protons transported outside of inner membrane drive ATP synthase;

Ingestion

the process of bringing food into the digestive tract

What does ingestive provide?

chemical energy for synthesizing ATP, carbon-containing compounds and minerals for building complex macromolecules

Digestion

mechanical and enzymatic breakdown of food

Why is digestion required?

difficult for macromolcules to enter the cell

Alimentary Canal

complete digestive tract that consists fo a tube with a mouth at one end and an anus at the other end

Digestive System

alimentary canal + organs; functionally connected to all body systems & anatomically connected to nervous, cardiovascular, endocrine, and lymphatic systems

Digestive System order

mouth → esophagus → stomach → small intestine → cecum → large intestine → anus

Mouth

buccal cavity; mechanical digestion (teeth, tongue, saliva moistens) & chemical digestion (saliva)

Salivary amylase

digests carbohydrates

lingual lipase

digests lipids (fats)

Esophagus

long, muscular tube that transports food to the stomach; lined with epithelial cells to resist abrasion; no digestion/nutrient absorption; uses peristalsis

peristalsis

smooth muscles contract and relax in coordinated fashion

Stomach

mechanical digestion (muscle contraction), chemical digestion (gastric juice- HCl lowers pH to 1.5-2.0 & mucous to protect stomach lining), enzymatic digestion; no nutrients are absorbed

pepsin

digests proteins

nervous system stimulates gastric cells to produce

gastric juice

chyme

an acidic mixture of food and gastric secretions that passes from the stomach to the small intestine; made by muscles contractions mixing materials

Small Intestine

major site of nutrient absorption; digestion of protein, fats, carbohydrates; undigested food sent to colon; uses peristalsis

How does the small intestine increase surface area?

folding with villi and microvillia

Villi

highly folded surface containing finger-like projections

Epithelial cells

absorb nutrients from digested food; in small intestine

Dense Capillary network

in villi/small intestine; allows nutrients to be released to blood stream; rapidly transports absorbed products

Suspension feeder

any strategy to take food particles out of water column; active and passive; usually can’t move

passive filter feeder

straining suspended matter and food particles from water with a mesh; depends on water flow

passive filter feeder examples

barnacles

Active filter feeder

create own water currents to strain food with mesh; makes own water flow with pump

Active filter feeder examples

mussels, tunicates

Songes

intake through small pores (ostia); expel water out osculum

Deposit feeder

obtaining nutrients from particles that settle on substrate; gain nutrients from microalgae and bacteria

Deposit feeder examples

spaghetti worms; sea cucumbers

Sea Cucumbers

use branched, sticky tentacles to collect organic particles from mud or sand; sediment passes through their alimentary canal where organic matter is digested; inorganic particles are excreted

Herbivores

eat plants or seaweeds

Herbivore examples

muskox, periwinkle snails

Periwinkle snails

use radula to scrape plant material or biofilm off rocks; radula rolls food particles back toward the mouth

Radula

ribbon-like structure covered with hundreds of microscopic chitinous teeth

Consumers

receive energy by consuming other organisms

Carnivore

an animal that feeds on fleshc

carnivore examples

nemertean worm, orcas, sea anemones

Omnivore

food of both plant and animal origin

Nemertean worm

feeds on polychaete worms that burrow in the sand; everts it’s proboscis (elongated appendage from the head of an animal), latches onto its prey and injects with a neurotoxin

Defenses for Prey

chemical, morphological, behavioral

Chemical defense examples

sponges, algae

Morphological defenses

color, spines, shells

Aposemantism

(color) highly noticeable and distinct from harmless organisms; show harmful so don’t eat

Crypsis

(color) avoid detection by other organisms; blends in

Nematocysts

explosive organelles found in all Cnidaria; capsule contains a coiled, hollow, usually barbed thread; projected in self-defense or to capture prey

Behavioral defense example

scallops, urchins, snails

Sea anemone

escape response when touched by sea star; “floats” away; feels touch by chemical cues

Cymothoa exigua

eats tongue of fish; sits in tongue space to eat food that the fish gets

microbiology

study of microscopic organisms such as bacteria, viruses, fungi, protozoa, and algae

Microbiome

collective genomes of all microbes in an environment

microbiota

community of microorganisms themselves

Human body contains roughly as many bacterial cells as

human cells

Herbivores microbial C/N ratio

higher due to plant-based diets (more carbon) and longer intestine

Carnivore microbial C/N ratio

lower with faster turnover and protein-rich diets

What does the microbiome digest?

nutrients not digested or absorbed by teh host

Postbiotics

non-living microbial byproducts that provide a beneficial effect on the host

True/False. There is no gut microbiota variation across animals.

False

Macronutrients

elements required in large amounts for growth and development (P, K, C, H, O, Mg, N)

Micronutrients

elements required in trace amounts for vital biochemical functions (Fe, Cu, Ni, Zn, Mn, Cl)

Limiting Nutrient

nutrients that limit the growth, abundance, or distribution of a population of organisms in an ecosystem due to their scarcity

Common limiting Nutrients in soil and aquatic systems 

phosphorous, nitrogen, iron

Law of the Minimum

productivity dictated not by total resources available, but by the scarcest resource (limiting factor)

Can N₂ be used for growth by living organisms?

no

Nitrogen Cycle

abundance N₂ is fixed by microorganisms to form nitrogen compounds that are used by other organisms to sustain life

Ammonification

process converting organic nitrogen (amino acids, proteins, and nucleic acids in dead plants, animals, or microbes) into inorganic nitrogen like ammonia (NH₃) or ammonium (NH₄⁺)

pH < 7.5, NH₃ is

converted rapidly to NH₄⁺

Decomposers

earthworms, termites, slugs, snails, bacteria, and fungi use enzymes to degrade plant material