Search

Text Color

Margin Size

Font Type

Enable Dyslexic Font

Unit 4: Cell Metabolism

Last updated

May 14, 2022
Save as PDF
- 3.25: Exocytosis
- 4.1: Enzymes

$\newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} }$

$\newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}}$

$\newcommand{\id}{\mathrm{id}}$ $\newcommand{\Span}{\mathrm{span}}$

( \newcommand{\kernel}{\mathrm{null}\,}\) $\newcommand{\range}{\mathrm{range}\,}$

$\newcommand{\RealPart}{\mathrm{Re}}$ $\newcommand{\ImaginaryPart}{\mathrm{Im}}$

$\newcommand{\Argument}{\mathrm{Arg}}$ $\newcommand{\norm}[1]{\| #1 \|}$

$\newcommand{\inner}[2]{\langle #1, #2 \rangle}$

$\newcommand{\Span}{\mathrm{span}}$

$\newcommand{\id}{\mathrm{id}}$

$\newcommand{\Span}{\mathrm{span}}$

$\newcommand{\kernel}{\mathrm{null}\,}$

$\newcommand{\range}{\mathrm{range}\,}$

$\newcommand{\RealPart}{\mathrm{Re}}$

$\newcommand{\ImaginaryPart}{\mathrm{Im}}$

$\newcommand{\Argument}{\mathrm{Arg}}$

$\newcommand{\norm}[1]{\| #1 \|}$

$\newcommand{\inner}[2]{\langle #1, #2 \rangle}$

$\newcommand{\Span}{\mathrm{span}}$ $\newcommand{\AA}{\unicode[.8,0]{x212B}}$

$\newcommand{\vectorA}[1]{\vec{#1}} % arrow$

$\newcommand{\vectorAt}[1]{\vec{\text{#1}}} % arrow$

$\newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} }$

$\newcommand{\vectorC}[1]{\textbf{#1}}$

$\newcommand{\vectorD}[1]{\overrightarrow{#1}}$

$\newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}}$

$\newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}}$

$\newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} }$

$\newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}}$

$\newcommand{\avec}{\mathbf a}$

$\newcommand{\bvec}{\mathbf b}$

$\newcommand{\cvec}{\mathbf c}$

$\newcommand{\dvec}{\mathbf d}$

$\newcommand{\dtil}{\widetilde{\mathbf d}}$

$\newcommand{\evec}{\mathbf e}$

$\newcommand{\fvec}{\mathbf f}$

$\newcommand{\nvec}{\mathbf n}$

$\newcommand{\pvec}{\mathbf p}$

$\newcommand{\qvec}{\mathbf q}$

$\newcommand{\svec}{\mathbf s}$

$\newcommand{\tvec}{\mathbf t}$

$\newcommand{\uvec}{\mathbf u}$

$\newcommand{\vvec}{\mathbf v}$

$\newcommand{\wvec}{\mathbf w}$

$\newcommand{\xvec}{\mathbf x}$

$\newcommand{\yvec}{\mathbf y}$

$\newcommand{\zvec}{\mathbf z}$

$\newcommand{\rvec}{\mathbf r}$

$\newcommand{\mvec}{\mathbf m}$

$\newcommand{\zerovec}{\mathbf 0}$

$\newcommand{\onevec}{\mathbf 1}$

$\newcommand{\real}{\mathbb R}$

$\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}$

$\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}$

$\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}$

$\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}$

$\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}$

$\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}$

$\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}$

$\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}$

$\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}$

$\newcommand{\laspan}[1]{\text{Span}\{#1\}}$

$\newcommand{\bcal}{\cal B}$

$\newcommand{\ccal}{\cal C}$

$\newcommand{\scal}{\cal S}$

$\newcommand{\wcal}{\cal W}$

$\newcommand{\ecal}{\cal E}$

$\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}$

$\newcommand{\gray}[1]{\color{gray}{#1}}$

$\newcommand{\lgray}[1]{\color{lightgray}{#1}}$

$\newcommand{\rank}{\operatorname{rank}}$

$\newcommand{\row}{\text{Row}}$

$\newcommand{\col}{\text{Col}}$

$\renewcommand{\row}{\text{Row}}$

$\newcommand{\nul}{\text{Nul}}$

$\newcommand{\var}{\text{Var}}$

$\newcommand{\corr}{\text{corr}}$

$\newcommand{\len}[1]{\left|#1\right|}$

$\newcommand{\bbar}{\overline{\bvec}}$

$\newcommand{\bhat}{\widehat{\bvec}}$

$\newcommand{\bperp}{\bvec^\perp}$

$\newcommand{\xhat}{\widehat{\xvec}}$

$\newcommand{\vhat}{\widehat{\vvec}}$

$\newcommand{\uhat}{\widehat{\uvec}}$

$\newcommand{\what}{\widehat{\wvec}}$

$\newcommand{\Sighat}{\widehat{\Sigma}}$

$\newcommand{\lt}{<}$

$\newcommand{\gt}{>}$

$\newcommand{\amp}{&}$

$\definecolor{fillinmathshade}{gray}{0.9}$

Metabolism is the set of life-sustaining chemical transformations within the cells of living organisms. The three main purposes of metabolism are the conversion of food/fuel to energy to run cellular processes, the conversion of food/fuel to building blocks for proteins, lipids, nucleic acids, and some carbohydrates, and the elimination of nitrogenous wastes. These enzyme-catalyzed reactions allow organisms to grow and reproduce, maintain their structures, and respond to their environments.

4.1: Enzymes
This page outlines the role of biological catalysts, primarily proteins known as enzymes, in accelerating chemical reactions by lowering activation energy. Enzyme specificity is highlighted through the "induced fit" mechanism, with activity influenced by pH, temperature, and the need for cofactors. Competitive inhibition occurs when similar substrates vie for binding.
4.2: ATP
This page explains ATP, the primary energy currency in cells, highlighting its role in powering activities like protein synthesis and muscle contraction through energy release from hydrolysis. It details ATP synthesis from ADP and inorganic phosphate and mentions its external roles in signaling tissue responses and regulating physiological functions.
4.3: NAD and NADP
This page discusses the roles of nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) as essential coenzymes in cellular processes. NADP differs from NAD by an extra phosphate and both act as redox agents, gaining electrons and releasing protons. NAD is key in glycolysis and the citric acid cycle, while NADP is produced during photosynthesis and is used in the Calvin cycle and anabolic reactions in plants and animals.
4.4: Glycolysis
This page describes glycolysis as the anaerobic breakdown of glucose in the cytosol, yielding two pyruvic acid molecules and ATP. Pyruvic acid then undergoes fermentation in yeasts (producing ethanol and CO2) or lactic acid in red blood cells and muscles. Both fermentation routes are energy-inefficient. In contrast, pyruvic acid is fully oxidized in mitochondria during cellular respiration, capturing approximately 40% of glucose's energy as ATP.
4.5: Cellular Respiration
This page discusses cellular respiration, detailing its conversion of glucose into ATP through glycolysis and mitochondrial processes, including the citric acid cycle and electron transport chain. It highlights mitochondrial DNA (mtDNA) mutations as a cause of diseases, influenced by heteroplasmy. Mitochondrial Replacement Techniques are being studied to prevent the transmission of defective mtDNA from mothers.
4.6: ATP Synthase
This page discusses ATP synthase, an enzyme complex in mitochondria responsible for ATP synthesis using proton gradients. It has two components: Fo (membrane-embedded) and F1-ATPase (in the matrix), capable of producing over 100 ATP molecules per second. Additionally, it can convert mechanical energy into chemical energy, synthesizing ATP from ADP and Pi at a rate of about 5 ATP molecules per second through rotation, as demonstrated in research using magnetic beads and a rotating magnetic field.
4.7: Photosynthesis - Pathway of Carbon Fixation
This page explains photosynthesis as the conversion of light energy into organic molecules, primarily glucose, using water and carbon dioxide. It highlights the role of light energy in producing ATP and NADPH for CO2 reduction. The Calvin cycle, named after Melvin Calvin, details the reactions where CO2 combines with ribulose bisphosphate to form glucose. Calvin's use of radioactive carbon traced the rapid synthesis of glucose and other molecules in algae during photosynthesis.
4.8: Photosynthesis - The Role of Light
This page explains photosynthesis in autotrophs, highlighting two main processes: the removal of hydrogen from water and the reduction of carbon dioxide through the Calvin Cycle. It details how electrons from water create NADPH and generate ATP via photophosphorylation. Chloroplasts house thylakoid membranes with Photosystems I and II for light absorption and electron transfer, facilitating ATP synthesis through chemiosmosis.
4.9: Photosynthesis - Dicovering the Secrets
This page details the evolution of photosynthesis discoveries, showcasing pivotal figures and their experiments. Early work by Van Helmont, Priestley, Ingen-Housz, and Senebier laid foundational insights, while Blackman's studies distinguished light and dark reactions. Van Niel's emphasis on water's role in oxygen release and Ruben's isotope studies confirmed that the oxygen produced comes from water.
4.10: Chemiosmosis
This page discusses the chemiosmotic theory of ATP synthesis in chloroplasts, supported by observations that light illumination increases the alkalinity of the surrounding medium due to proton pumping. It describes how altering the thylakoid pH by using acidic mediums allows chloroplasts to synthesize ATP in alkaline conditions with ADP and inorganic phosphate, showcasing the role of the proton gradient in ATP production even in the absence of light.
4.11: Metabolism
This page explains that all living organisms rely on energy and matter, processed through metabolism, which includes catabolism (breaking down molecules) and anabolism (building larger molecules). Autotrophs, like plants, create organic molecules via photosynthesis, whereas heterotrophs, such as humans, obtain energy by consuming organic matter.
4.12: Intermediary Metabolism
This page discusses how cells primarily utilize glucose for energy, although other nutrients like fats and proteins can also be metabolized to produce ATP. It highlights the metabolic pathways connecting these different energy sources and emphasizes the necessity of obtaining certain unsaturated fats and essential amino acids from dietary sources.
4.13: G Proteins
This page explains G proteins, which are heterotrimers made of Gα, Gβ, and Gγ subunits, functioning with G protein-coupled receptors (GPCRs). Hormone binding activates the Gα subunit by switching GDP to GTP, influencing effector molecules like adenylyl cyclase to produce cyclic AMP (cAMP). It details different Gα subunits: Gαs (stimulating cAMP), Gαq, Gαi (activating alternative pathways), and Gαt (involved in retinal signal transduction).
4.14: Secondary Messengers
This page explains the role of second messengers in cellular signaling, highlighting their importance in transmitting signals from cell receptors to target sites. It identifies the main classes of second messengers: cyclic nucleotides, inositol trisphosphate, diacylglycerol, and calcium ions.
4.15: Bioluminescence
This page discusses bioluminescence, the natural ability of certain organisms to produce light, including fireflies and fungi. Key components involve luciferin, luciferase, ATP, and oxygen. Fireflies use specific light patterns for mating and can manipulate their light by releasing nitric oxide. Marine species utilize bioluminescence for attracting prey and evading predators.

Support Center

How can we help?