Biology 1 Flashcards
Who proposed the cell theory?
Matthias Scheiden and Theodor Schwann
What are the postulates of the cell theory?
All living things are made of cells
Cell is the basic functional unit of life
Chemical reactions of life take place inside the cell
Cells come from pre-existing cells
Cells carry genetic info in the form of DNA, which is passed from parent to daughter cell
What are the 6 kingdoms?
Bacteria, Archaea, Protista, Fungi, Plantae, and Animalia
What are the 2 major types of cells?
Prokaryotic and eukaryotic
What do ALL prokaryotes contain?
Cell membrane, cytoplasm, genetic material and ribosomes
What kingdom got split into 2?
Monera split into bacteria and Archaea because they had differing origins
What does the fluid mosaic model propose?
Cell membrane made of phospholipid belayer with proteins embedded throughout
How can the fluidity of the cell membrane be adjusted?
The cell can regulate the fluidity of its membrane by adjusting the amount of unsaturated hydrocarbon tails present in the membrane. The unsaturated hydrocarbon tails are “bent”, and thus do not pack together as closely as saturated hydrocarbon tails. Animal cells can also regulate the fluidity of the cell membrane by adjusting the amount of cholesterol present in the membrane
What are the parts of phospholipid molecules?
Phospholipid molecules have hydrophobic (non polar) fatty chains of carbon and hydrogen and phosphorus containing hydrophilic (polar) heads
What can readily cross the cell membrane and what cannot? And what do the ones that cannot use?
- Small polar molecules like water and small non polar molecules like oxygen are permeable to plasma membrane
- Small charged particles cross membrane via protein channels
- Charged ions or large charged molecules cross membrane via assistance of carrier proteins
What is the nucleolus?
Where rRNA synthesis occurs, not surrounded by a membrane
What is the nucleus and what is the nuclear envelope?
The genetic material of the cell is contained in the nucleus. The nuclear envelope, which separates the nucleus from the rest of the cell, consists of two membranes and is perforated by nuclear pores. The nuclear pores regulate the passage of large macromolecules into and out of the nucleus.
What occurs in the ribosome and what is the functions of the ribosome in prokaryotes and eukaryotes
- Where protein production occurs
- Made of 2 rRNA sequences called ribosomal subunits
- Eukaryotes -> rRNA molecules made in nucleolus function either in cytoplasm as unbound ribosomes or on the outer membrane of the rough ER as bound ribosomes
- Prokaryotes -> lack of membrane bound organelles leads to both rRNA synthesis and ribosome function in cytoplasm
How does a proteins final destination affect it’s production?
Proteins destined for the cytoplasm are synthesized by free ribosomes, while proteins destined for insertion into a membrane or secretion outside of the cell are synthesized by ribosomes bound to the rough endoplasmic reticulum.
What is the endoplasmic reticulum (structure and function)?
- Network of membrane enclosed spaces involved in transport of materials throughout cells, especially materials destined to be secreted by cell
- Two types: Rough and smooth ER
- Rough ER-> studded with ribosomes, plays role in synthesis of proteins
- Smooth ER -> no ribosomes, involved with metabolism and production of lipids
What is the function of the Golgi apparatus?
Receives vesicles from smooth ER and modifies them (like glycosylation), repackages them into vesicles and sends them to cell surface for exocytosis
What is the structure and function of the mitochondria?
- Site of aerobic respiration
- Responsible for converting sugar, fats and other sources of energy into usable energy like ATP
- Has inner and outer phospholipid bilayer
- Inner membrane folded into cristae and has enzymes for ETC
- Within the inner membrane is the mitochondrial matrix
- Mitochondria have their own genome located in matrix (independent of cell genome and looks like bacterial circular chromosomes)
- Divide independently via binary fission
Why do many poisons target the mitochondria?
The mitochondria are very important to the survival of a cell: many poisons target the mitochondria, and render it incapable of producing ATP. Without ATP, the cell cannot carry out its metabolic activities, and the cell dies
How is mitochondrial DNA inherited?
Remember that a zygote receives all of its organelles from its mother; thus any mitochondrial DNA a person has is identical to that of his or her mother.
What is the cytoplasm and what is its function?
- Includes the cytosol (cellular fluid contained within the cell membrane) and organelles
- Where most of the cells metabolic activity occurs
- Transport within the cytoplasm occurs by cyclosis (streaming movement within the cell)
What are vacuoles and vesicles?
- Membrane bound sacs involved in the transport and storage of materials ingested, secreted, processed or digested by cell
- Vacuoles larger than vesicles and more likely to be found in plant than animal cells
What are centrioles and what is their function?
- Made of microtubules
- Involved in spindle organization during cell division
- Not bound by membrane
- Animal cells usually have a pair in a region called centrosome
- Plant cells do not have centrioles
What is the centrosome?
Centrosome organizes microtubules and regulates progression of the cell cycle
What are lysosomes structure and function?
- Membrane bound vesicles with hydrolytic enzymes (intracellular digestion)
- Autolysis: Process when an injured or dying cell self-destructs by rupturing lysosome membrane and release hydrolytic enzymes
- The lysosome maintains a slightly acidic pH of 5 in its interior; this is the pH at which lysosomal activity is greatest
What is autolysis?
Autolysis: Process when an injured or dying cell self-destructs by rupturing lysosome membrane and release hydrolytic enzymes
What are peroxisomes?
Peroxisomes contain oxidative enzymes that catalyze reactions in which hydrogen peroxide is produced and degraded. Peroxisomes break down fats into small molecules; they are also used in the liver to detoxify potentially harmful compounds, such as alcohol
What is the structure and function of each type of cytoskeleton
- Supports the cell, maintains its shape and aids in cell motility
- Made of microtubules, microfilaments, and intermediate filaments
- Microtubules: hollow rods made of tubulin, provide support and framework for organelle movement; centrioles made of microtubules; cilia and flagella are special arrangements of microtubules that involved in cell motility and cytoplasmic movement
- Microfilaments:solid rods made of actin, important for cell movement and support, used in muscle contraction
- Intermediate filaments: Diverse group of filamentous proteins like keratin, structural backbone of cell, can withstand tension, anchor organelles and make cell structure more rigid
- Cilia and flagella are composed of long, stabilized microtubules arranged in a “9+2 structure”: nine pairs of microtubules surrounding two central microtubules for added stability
What are the types of junctions in animal cells and give examples of where they can be found?
- In animal cells, there are three types of intercellular junctions: tight junctions, anchoring junctions, and gap junctions
- In tight junctions, the membranes of neighboring cells are attached, and the cells are bound together so tightly that no material can pass between cells or travel past the junction. Tight junctions, therefore, form a total barrier to transport and diffusion (intestine)
- Another type of cell junction found in animal cells is the anchoring junction. These junctions are found in cells subject to mechanical stress. For example, desmosomes are anchoring junctions that attach epithelial cells in the skin
- A third type of cell junction found in animal cells is the gap junction. These junctions provide a direct connection between the cytoplasm of one cell and the cytoplasm of a neighboring cell via channels. These channels are formed by proteins called connexins. In the heart, the flow of ions through gap junctions allows for rhythmic, coordinated contraction of the heart muscle
What is simple diffusion?
- Passive process (no energy needed)
- Moving dissolved particles down their concentration gradient (from high to low concentration)
What is osmosis?
Simple diffusion of water from region of lower solute concentration to region of higher solute concentration
What is hypo, hyper and isotonic refer to?
- When cytoplasm of cell has lower solute concentration than the extracellular medium, the medium is said to be hypertonic to the cell and water will flow out of the cell into the surrounding medium, process also called plasmolysis and will cause cell to shrivel
- If extracellular environment is less concentrated then the cytoplasm of cell, the extracellular medium is said to be hypotonic and water will flow into the cell, causing it to swell and lyse
- If extracellular environment is same concentration of solutes as the cell cytoplasm, then cell is said to be isotonic to the environment and water will move back and forth in equal amounts across the cell membrane
What is facilitated diffusion?
- Passive transport (requires no energy)
- Net movement of dissolved particles down their concentration gradient through special channels or carrier proteins in the cell membranes
What is active transport?
- Net movement of dissolved particles against their concentration gradients with help of transport proteins
- Requires energy
- Carriers/transporters regulate the cells internal content of ions and large molecules
What are the types of carrier molecules?
- Symporters: move two or more ions or molecules in the same direction across the membrane
- Antiporters: Exchange one or more ions (or molecules) for another ion or molecule across the membrane
- Pumps: Energy dependent carriers that need ATP
What is endocytosis?
- Cell membrane invaginates and forms a vesicle containing extracellular medium (allows cell to bring large volumes of extracellular material into cell)
- Pinocytosis: Ingestion of fluids or small particles
- Phagocytosis: engulfing of large particles
- Receptor binding can trigger endocytosis
What is exocytosis?
Vesicle within the cell fuses with the cell membrane and releases large volume of contents to the outside
What is cell division consist of?
Process in which a cell doubles its organelles and cytoplasm, replicates DNA and then divides into 2
What is Interphase?
- Period of growth and chromosome replication
- Most of cell life (90%) spent in interphase
- After replication the chromosomes have 2 identical sister chromatids held together at central region called centromere
- During interphase the individual chromosomes are not visible and the DNA is uncoiled and called chromatin
What are the parts of interphase?
G1: Initiates interphase, active growth phase, cell increases size and makes proteins, variable length (time)
S: When DNA is synthesized
G2: Cell prepares to divide, grows and makes proteins
What is the M phase?
Last phase of cell cycle is M phase, where mitosis or meiosis occurs, resulting in either 2 identical cells (mitosis) or 4 non-identical cells (meiosis)
What occurs in mitosis?
- Division and distribution of cells DNA to 2 daughter cells and each cell receives complete copy of original genome
- Occurs in somatic cells
- Nuclear division (karyokinesis) is followed by cell division (cytokinesis)
- 4 phases: Prophase, metaphase, anaphase, telophase (I party more at the club)
What are the phases of mitosis and what occurs during each?
Prophase: cell prepares for nuclear division, chromatin is condensed into chromosomes, nuclear membrane dissolves, centriole pairs separate and move towards opposite poles of cell
Metaphase: Centrioles at poles of cell anchor themselves to the cell membrane through formation of spindle fibres, additional spindle fibres radiate from centriole and attach to each chromatid at the kinetochore (protein on centromere of chromosome) and aligns the chromosomes on the metaphase plate
Anaphase: Separation of sister chromatids of each chromosome, centromeres split and chromatids are pulled towards opposite poles by shortening spindle fibres
Telophase:Spindle apparatus disappears, nuclear membrane forms around each set of chromosomes, chromosomes uncoil
What occurs during cytokinesis in plant and animal cells?
Animal cells: Cleavage furrow forms and cell membrane indents along equator of cell pinching through cell
Plant cells: Cell plate forms between two nuclei, splits cell in half allowing cell to divide
What occurs during meiosis?
- Sex cells produced
- Produces haploid cells (upon fertilization resulting cell is diploid)
What is ploidy?
Ploidy: Refers to how many chromosomes an organism has in a homologous set (chromosomes that share structure and gene locations but can have different alleles)
When does crossing over occur and what occurs during it?
Crossing Over: Homologous chromosomes intertwine (process called synapsis), structure is called tetrad (4 sister chromatids involved), interacting parts are called chiasmata, chromatids of homologous chromosomes break and exchange equivalent pieces of DNA
What occurs during each stage in the first meiotic division?
Prophase 1: chromatin condenses into chromosomes, spindle apparatus forms, nucleoli and nuclear membrane disappear, crossing over occurs (genetic exchange between chromatids to increase genetic diversity)
Metaphase 1: Homologous pairs align at equatorial plane and each pair attaches to a separate spindle fiber at the kinetochore
Anaphase 1: Homologous pairs separate and are pulled to opposite poles of the cell (process called disjunction),
Telophase 1: Nuclear membrane forms around new nucleus, 2 haploid cells form in which each chromosome has 2 sister chromatids (intermediate daughter cells)
What occurs during the second meiotic division?
Prophase 2: Nuclear envelope dissolves, nucleoli disappear, centrioles migrate to opposite poles and spindle apparatus begins to form
Metaphase 2: Chromosomes line up on the metaphase plate
Anaphase 2: Sister chromatids of each chromosome are separated and pulled apart (shortening spindle fibres), each separated sister chromatid is considered a chromosome itself
Telophase 2: Nuclear membrane forms, cytokinesis follows, 2 haploid daughter cells are formed per intermediate daughter cell, 4 haploid daughter cells produced
What is a nucleotide made of?
Nucleotide is made of deoxyribose (sugar) bonded to both a phosphate group and a nitrogenous base
What are the types of nitrogenous bases?
Purines: adenine and guanine
Pyrimidines: Cytosine and thymine and (uracil in RNA)
How many hydrogen bonds are formed between bases?
T forms 2 hydrogen bonds with A, and C forms 3 hydrogen bonds with G
What does DNA helicase do?
DNA helicase can break hydrogen bonds between bases and unwind DNA, opening the DNA and creating a replication fork
What does topoisomerase do?
Topoisomerase removes strain of replication fork by cutting, twisting and then rejoining the strands of DNA
What type of replication is DNA replication?
Semiconservative replication where the daughter strands of DNA formed from the parent strands are identical with one parent helix and one newly synthesized strand
Which way does DNA polymerase read and synthesize the DNA strands?
- DNA polymerase reads the parent strand in a 3’ to 5’ direction, creating a new daughter strand in the 5’ to 3’ direction
- DNA polymerase adds nucleotides to the 3’ ends of DNA strands
What is the difference between the leading strand and the lagging strand?
Leading strand has its 3’ end facing towards the replication fork allowing DNA polymerase and the replication fork to travel in same direction
Lagging strand has its 3’ end facing away from the replication fork and go in opposite directions, results in discontinuous synthesis of short fragments of DNA called okazaki fragments
What does DNA ligase do?
DNA ligases joins the fragments of the lagging strand together
What processes occur in the 5’ to 3’ direction?
DNA synthesis, DNA repair, RNA transcription and RNA translation occurs in the 5’ to 3’ direction
In what direction is the mRNA translated and the protein synthesized?
The ribosome translate the mRNA in the 5’ to 3’ direction and the protein is synthesized from the amino terminus (N terminus) to the carboxyl terminus (C terminus)
What are the differences between RNA and DNA?
The sugar is ribose instead of deoxyribose
Uracil is used instead of thymine
Most RNA is single stranded
What are the 3 major types of RNA?
MRNA, tRNA and rRNA
What is mRNA do?
mRNA: carries the complement of a DNA sequence, transport this information from nucleus to ribosome for protein synthesis, mRNA in eukaryotes is monocistronic (1 mRNA codes for one polypeptide)
What does tRNA do?
- Small RNA molecule found in the cytoplasm
- Assists in the translation of mRNAs into a sequence of amino acids by bringing the amino acids coded for in the mRNA to the ribosomes during protein synthesis
- tRNA recognizes both the mRNA codon and its corresponding amino acid
- there is at least 1 tRNA for each amino acid (approx 40 types)
What is the structure of tRNA?
- One end of tRNA has anticodon (3 nt sequence complementary to the mRNA codon) and the other end has an attachment site for corresponding amino acid
- Every amino acid has its own aminoacyl-tRNA synthetase that binds to both the amino acid and its corresponding tRNA, catalyzing their attachment to form a complex
- When a tRNA is complexed with its amino acid, it’s called a charged tRNA
What is the function of rRNA and where is it made in prokaryotes and eukaryotes?
- rRNA is made in nucleolus in eukaryotes
- rRNA is made in cytoplasm in prokaryotes
- rRNA is most abundant type of RNA in cell
- Important part of ribosomal machinery and used during protein assembly in cytoplasm
What is the common promoter for transcription in prokaryotes and eukaryotes?
Eukaryotes Common Promoter: TATA box (30 bp upstream)
Prokaryotes Common Promoter: Pribnow box (10 bp upstream-> TTGACA)
What occurs during transcription?
- RNA polymerase binds to DNA template strand at promoter region
- For RNA polymerase to bind to promoter, transcription factors must assist
- Once RNA polymerase is bound to template strand, it recruits and adds complementary RNA nucleotides (reads in 3’ to 5’ direction and makes RNA in 5’ to 3’ direction like DNA polymerase)
What is hnRNA?
RNA that is not yet processed is called hetero-nuclear RNA (hnRNA) or pre-mRNA
What occurs during post transcription processing?
- Introns are spliced out/removed by the spliceosome
- Exons are the nucleotides necessary to make the protein and kept during post-transcriptional processing
- RNA also has to gain 5’ guanine cap and 3’ poly-A-tail (prevent degradation in cytosol)
- Once down its mRNA and can leave nucleus
What are codons and what direction are they written in?
- Codons are 3 nucleotide sequences on the mRNA that correspond to a specific amino acid
- Codons are written in 5’ to 3’ direction
What are the stop codons?
Stop Codons: UAA, UGA, UAG (you are annoying, you go away, you are gone)
Why is the genetic code considered redundant and degenerate?
Multiple codons code for the same amino acid (redundant and degenerate-> can’t convert back to mRNA)
What does wobble position refer to?
Wobble position-> aminoacyl-tRNA complex’s ability to bind to mRNA despite having non-complementary base pairs for 3rd nucleotide
What is translation and where does it occur?
- mRNA codons are translated into a sequence of amino acids
- Translation occurs in the cytoplasm and involves ribosomes (rRNA), mRNA, tRNA, amino acids, enzymes and proteins
What are the stages of translation?
Initiation: Small ribosomal subunit binds to the mRNA near its 5’ end, scans until start codon (AUG), aminoacyl-tRNA complex is bound with mRNA and small ribosomal subunit -> the large ribosomal subunit binds forming the initiation complex
Elongation: Ribosome moves in the 5’ to 3’ direction along the mRNA synthesizing the protein from its N to C terminus
Translocation: RIbosome advances 3 nucleotides along the mRNA and the charged tRNA is shifted from the A site to the P site and uncharged tRNA is transferred from P site to E site to be expelled; after translocation the A site is empty
Termination: When stop codon is encountered
What are the binding sites on the ribosome?
- A site holds in incoming aminoacyl-tRNA complex which will be the next amino acid added to the growing chain
- P site holds the tRNA that carries the growing polypeptide chain, peptide bond forms when polypeptide is passed from the tRNA in the P site to the tRNA in the A site
- E site is where the uncharged tRNA pauses before its kicked out from ribosome to be recharged
What are some examples of post translational modifications?
- Can be cleavage or addition
- Common addition processes: phosphorylation, glycosylation, carboxylation, or prenylation (adding lipids)
Where does transcription occur in prokaryotes and eukaryotes?
Transcription occurs in nucleus for eukaryotes but in the cytoplasm for prokaryotes
What are the differences in transcription for prokaryotes then eukaryotes?
- After transcription in prokaryotes there is no post transcriptional modifications (have polycistronic mRNA transcripts compared to monocistronic ones of eukaryotes)
- Transcription and translation can occur at same time for prokaryotes because lack of membrane bound organelles
What are the levels of protein structures?
Primary: sequence of amino acids (listed N to C terminus) linked via peptide bonds
Secondary: local 3-D structure of neighbouring amino acids, usually a helix or beta sheets
Tertiary: Folding of polypeptide forming the 3D structure of the entire protein itself, usually assisted by chaperones, relies on hydrophobic/hydrophilic interactions of side groups and disulfide bonds
Quaternary: combining polypeptides to form a complete protein complex, not always present in proteins
What are proteins that are not enzymatic?
Structural proteins (cytoskeleton and motor protein) Binding proteins (transport, attach, or sequester molecules)
What is a catalyst?
Catalyst: Affects the rate of a chemical reaction while remaining unchanged or being regenerated as a product, usually increase reaction rate through reduction of activation energy
What are conjugated proteins?
Conjugated proteins covalently bond to other groups (lipids, sugars, cations etc) that often serve as coenzymes or cofactors
What is a substrate?
The molecule that the enzyme acts on
What is the active site?
The area on enzyme where the substrate binds
TRUE OR FALSE: Enzymes alter the equilibrium constant?
FALSE: Enzymes don’t alter the equilibrium constant, they are not consumed in the reaction, they are pH and temperature sensitive (have optimal values)
What is the Lock and Key Theory?
Lock and Key theory: enzyme active site and substrate fit like lock and key
What is the induced fit theory?
Induced fit theory: More widely accepted, active site has flexibility for shape, when right substrate comes the conformation of active site changes to fit substrate
What happens to enzyme activity when temperature increases?
As temperature increases, the rate of enzyme action increases until optimal temperature (around 37 degrees) anything after bad
What is the optimal pH for human enzymes?
Many human enzymes function best at pH around 7.2 (some in stomach prefer more acidic and some in small intestine prefer basic)
What occurs to the reaction rate and enzymes when you continually increase substrate concentration?
Increasing substrate concentration will increase reaction rate until all active sites are occupied (saturated) and Vmax is reached
What is Vmax?
Vmax is the reaction rate as substrate concentration goes to infinity (more enzyme can be added to change it)
What is Km?
- Km (michaelis constant) is the substrate concentration needed to fill half of the enzymes active sites (½ of Vmax)
- The higher the Km the lower the enzyme’s affinity for that substrate
- The lower the Km the higher the enzyme’s affinity for that substrate
What is competitive inhibition?
Competitive Inhibition: Molecules similar to the substrate bind to the active site and compete with substrate for binding sites on enzyme, interfere with enzyme activity
What is non competitive inhibition?
- Noncompetitive Inhibition: A substance that binds to an enzyme at a site other than the active site (at an allosteric site), changing structure of enzyme and results in nonfunctional active site
- Noncompetitive inhibition is considered to be a type of allosteric inhibition
What do ligases do?
Ligases: catalyze addition or synthesis reactions usually between large similar molecules, usually need ATP
What do isomerases do?
Isomerases: catalyze the rearrangement of bonds within a molecule
What do lyases do?
Lyases: Catalyze the cleavage of a single molecule into 2 products, synthases are ones that reverse the synthesis of two small molecules, dont need water
What do hydrolases do?
Hydrolases: catalyze the breaking of compound into 2 molecules using addition of water, examples are phosphatases, peptidases, nucleases, lipases
What do oxidoreductases do?
Oxidoreductases catalyze oxidation reduction reactions, transfer of electrons, often have a cofactor (electron carrier like NAD+), e.g. dehydrogenase or reductase
What do transferases do?
Transferases: catalyze the movement of functional group from 1 molecule to another, e.g. kinases
What is metabolism?
Metabolism: Sum of all chemical reactions that occur in the body
What are the two types of reactions?
Catabolic Reactions: Break down chemicals and release energy
Anabolic Reactions: Synthesize chemicals and require energy
What are examples of anabolic and catabolic processes?
DNA replication and protein synthesis: anabolic
Cellular respiration is catabolic (convert chemical energy in molecular bonds to usable energy like ATP)
What is external respiration and what is internal respiration?
External: Inhaling and exhaling air into and out of lungs, gas exchange between alveoli and blood
Internal: gas exchange between cells and extracellular fluid
What is the general equation of cellular respiration?
C6H12O6 + O2 -> H2O +CO2
Where does glycolysis occur?
In the cytoplasm in both prokaryotic and eukaryotic cells
What occurs in glycolysis?
Glycolysis: breakdown of glucose into 2 molecules of pyruvate, production of ATP, and reduction of NAD+ into NADH,glucose is oxidized and NAD+ is reduced
What are the stages of glycolysis?
- Energy Investment: step 1-3, 2 ATPS used to add 2 phosphates to glucose (using kinases)
- Cleavage: step 4, Fructose 1,6 bisphosphate goes to PGAL and DHAP and DHAP goes to second PGAL
- Energy Payout: steps 5-9, production of ATP, PGAL converted to pyruvate, reduction of NAD+ to NADH, production of 2 ATP (per PGAL)
How many ATP are made and used in glycolysis?
Glycolysis: 2 ATP used, 4 ATP generated, net 2 ATP per glucose
What is substrate level phosphorylation and what is oxidative phosphorylation?
- Substrate level phosphorylation: ATP synthesis is directly couple with the oxidation of glucose without need of intermediate molecule like NADH
- Oxidative Phosphorylation: needs intermediate electron carrier like NADH or FADH2
What is the net reaction of glycolysis?
Glucose + 2 ADP + 2 Pi + 2 NAD+ -> 2 pyruvate + 2 ATP + 2 NADH + 2 H+ + 2 H2O
How much ATP does anaerobic respiration yield?
Yields 2 ATP per glucose only (from glycolysis)
What is alcohol fermentation?
Alcohol fermentation: occurs in yeast and bacteria, pyruvate produced in glycolysis is converted to ethanol so NAD+ is regenerated and glycolysis can continue
What is lactic acid fermentation?
Lactic Acid Fermentation: Occurs in some fungi and bacteria and human muscle cells during exercise, NAD+ is regenerated once again
How much ATP does aerobic respiration yield?
36-38 ATP
What are the stages of aerobic respiration and where do they occur in the different cell types?
Stages: Pyruvate decarboxylation, citric acid cycle, and electron transport chain (stages occur in mitochondria for eukaryotes and cytoplasm for prokaryotes)
Where does the citric acid cycle and electron transport chain occur in prokaryotes?
Prokaryotes: CAC occurs in cytosol and ETC on bacterial membrane itself
What generally occurs during aerobic respiration?
Pyruvate produced from glycolysis transported into mitochondrial matrix to undergo Pyruvate decarboxylation and produce acetyl-CoA which undergoes reactions in CAC to produce electron carriers (NADH and FADH2) while regenerating oxaloacetate, electron carriers power ETC on inner mitochondrial membrane which moves H+ against concentration gradient to intermembrane space and energy used by ATP synthase on inner membrane to produce ATP
What is pyruvate decarboxylation?
Pyruvate transported from cytoplasm to mitochondria matrix where it loses a CO2 and acetyl group remaining is transferred to coenzyme A to form acetyl-coa and NAD+ reduced to NADH
What occurs during the citric acid cycle and how many ATPs are produced? And what else is produced?
- Acetyl-coa (2C) and oxaloacetate (4C) combine, Two CO2 released, oxaloacetate (4C) is regenerated for next use of cycle
- One ATP produced per cycle via substrate level phosphorylation via GTP intermediate
- One cycle produces 3 NADH and 1 FADH2
- Above is for one acetyl coa since we have 2 everything doubled (for 1 glucose)
What is the net reaction of the citric acid cycle?
Per glucose molecule:
2 acetyl-CoA + 6 NAD+ + 2 FAD + 2 GDP +2 pi + 4 H2O -> 4 CO2 + 6 NADH + 2 FADH2 + 2 GTP + 4 H+ + 2 CoA
What occurs on the electron transport chain and where is it located?
- Located on inside of inner mitochondrial membrane
- Electrons transferred from NADH and FADH2 to oxygen via carrier molecules on inner mitochondrial membrane, as electrons transfer free energy released which is used to form ATP,
What are cytochromes?
Electron carriers that resemble hemoglobin in the structure of their active site, central iron atom capable of reversible redox reaction
How is ATP generated via the proton pump?
- When electrons are passed during ETC-> H+ ions pumped out of matrix into intermembrane space, intermembrane space accumulates H+ becomes acidic and positively charged -> electrochemical gradient creates proton motive force, drives H+ back across inner membrane into matrix, to pass through membrane the H+ flow through channels provided by atp synthases,as they pass through enough energy released to allow phosphorylation of ADP to ATP
- Coupling of the oxidation of NADH and FADH2 with phosphorylation of ADP is called oxidative phosphorylation
How much ATP is produced in respiration from substrate and oxidative phosphorylation?
- 4 ATP produced by substrate phosphorylation (2 from glycolysis and 2 from CAC)
- Oxidative phosphorylation: Eukaryotes: 32 ATP and Prokaryotes: 34 ATP
What happens when glucose is running low in the body?
Glucose is running low-> body uses other energy sources: prefers -> other carbohydrates, then fats, then proteins (these substances are converted to either glucose or glucose intermediates which then can undergo glycolytic pathway and CAC)
How does the body use CHO, proteins and fats for metabolism?
- Carbohydrates: Disaccharides hydrolyzed into monosaccharides which can be converted to glucose or glycolytic intermediates, also can use glycogen in liver as intermediate
- Fats: Fats using lipases are converted to fatty acids and glycerol, glycerol can be converted into PGAL, fatty acid has to be activated in cytoplasm (needs 2 ATP and then in mitochondria can be converted to Acetyl-coa which can enter CAC, fats yield greatest number of ATP per gram (efficient energy storage molecules)
- Proteins: amino acids undergo transamination reaction (lose amino group) to form alpha-keto acid, carbon atoms from amino acids converted to acetyl-coa, pyruvate or intermediate of CAC, oxidative deamination removes ammonia from amino acid
How do photosynthetic bacteria work?
Have membranes that function similar to chloroplasts