Mod002: mantaining life

Question 1

reading frame

Answer 1

how DNA is divided into a set of consecutive, non-overlapping codons.

Question 2

Frameshift mutations

Answer 2

change the reading frame, leading to nonfunctional proteins or terminating protein synthesis altogether

Question 3

Basic of codon

Answer 3

-nearly universal • The genetic code is degenerate( different form code for the same thing) • Stop codons terminate protein synthesis • AUG serves as a start codon as well as coding for methionine

Question 4

Step in RNA transcription

Answer 4

-Initiation: the sigmar factor of RNA polymerase bind to a region before the initiation site of DNA and unwind the double helix -Elongation:RNA polymerase proceeds along the DNA template, unwinding it and synthesizing mRNA by adding nucleotides in the 5’ to 3’ direction, complementary to the DNA template -Termination:When RNA polymerase reaches the termination site, the RNA transcript and polymerase are released from the template

Question 5

tRNA

Answer 5

• Carries a specific amino acid at the 3’ end • Triplet of bases near the middle (drawn at bottom here): anticodon that binds to complementary mRNA codon for the amino acid that the tRNA carries • Aminoacyl-tRNA synthetases charge the tRNAs with amino acids

Question 6

Translation – Ribosome

Answer 6

• Core of ribosomal RNA (rRNA molecules) + associated proteins • Consists of small and large subunits that dissociate when not active and reassociate during translation • Used over and over again, and can use any mRNA and all charged tRNAs to make many different polypeptide products • Three sites to accept tRNAs: E, P, A (exit, peptidyl-tRNA & aminoacyl-tRNA

Question 7

Step of translation

Answer 7

-Initiation: a small subunit bind to mRNA, Methionine-charged tRNA binds to the AUG start codon and a large subunit join in the complex -Elongation: a new tRNA form complimentary bond with the mRNA at at the A site this lead to the formation of peptide bond. the pervious tRNA move to E site and is release. This process repeat -Termination: when the stop codon is reached, a release factor bond to the A site. It disconnect the polypeptide chain and tRNA form the complex and the 2 subunit seperate

Question 8

Splicing out introns

Answer 8

Pre-mRNA splicing involves the precise removal of introns from the primary RNA transcript. The splicing process is catalyzed by protein complexes called spliceosomes that are composed of proteins and RNA molecules called snRNAs. Spliceosomes recognize sequences at the 5’ and 3’ end of the intron.

Question 9

Energy in biological systems

Answer 9

-The energy that sustains most of the earth’s life forms comes from the sun. -Bioenergetics is the study of energy flow through a living system

Question 10

Types of energy in biological systems

Answer 10

Electrical – separation of charges Chemical – stored in chemical bonds Light – electromagnetic radiation stored as photons Mechanical – energy of motion Heat – transfer due to temperature difference

Question 11

What is metabolism

Answer 11

All chemical reaction within the cell

Question 12

Free energy

Answer 12

Gibb’s Free Energy (G) = amount of energy available to do work (i.e. usable energy). All chemical reactions affect G; change in G after a reaction is abbreviated as ∆G. ∆Greaction = Gproducts – Greactants ∆G < 0 — free energy is released in the reaction ∆G > 0 — free energy is required for the reaction

Question 13

Type of metabolism reaction

Answer 13

Catabolic reactions: Complex molecules → free energy + small molecules • Energy is preserved, free energy is created (exergonic) • Entropy increases: from more ordered reactant to more randomly distributed products Anabolic reactions: Free energy + small molecules → complex molecules • Energy is preserved, free energy is required (endergonic) • Entropy decreases: from more randomly distributed reactants to more ordered product

Question 14

What is activational energy

Answer 14

energy require for a reaction to take place

Question 15

Role of Enzyme

Answer 15

-catalyze the reaction by lowering tha activational energy

Question 16

Key concept of respitation

Answer 16

• Cells harvest energy from glucose oxidation
• In the presence of oxygen, glucose is fully oxidized
• Oxidative phosphorylation results in the production of ATP
• In the absence of Oxygen, some energy is still harvested from glucose
• Metabolic pathways are interrelated and regulated
• Energy is transferred as electrons move from one molecule to another
• This happens through Redox reaction

Question 17

What is Glucose oxidation

Answer 17

it is a highly exergonic reaction driving endergonic formation of ATP molecules

Question 18

The process of glucose oxidation

Answer 18

Question 19

Process of Glycolosis

Answer 19

• Glucose is partially oxidized to 2 pyruvatemolecules during glycolysis in the cytosol
• Glycolysis produces 2 ATP and 2 NADH through 10 metabolic reactions
• Pyruvate is further oxidized to acetyl CoA to enable entry into the Citric Acid cycle

Question 20

What is chemiosis

Answer 20

the convertion electricalenergy of a proton concentration gradient to chemicalenergy in ATP

Question 21

Oxidative phosphorylation

Answer 21

ATP is synthesized by re-oxidation of electron carriers in the presence of O2 There are two stages:
Electron transport and Chemiosmosis

Question 22

Electron transport

Answer 22

• Electrons from NADH and FADH2 pass through the respiratory chain of membrane-associated proteins
• Electron flow results in a proton concentration gradient across the Inner mitochondrial membrane

Question 23

Chemiosmosis

Answer 23

Electrons flow back across the membrane through a channel protein ATP synthase, which couples the diffusion with ATP synthesis

Question 24

yield from full glucose oxidation

Answer 24

6 CO2 6 H2O 10 NADH 2 FADH2 32 ATP

Question 25

Oxygenic Photosynthesis

Answer 25

* An endergonic reaction that involve light and gas * Conversion of carbon dioxide and water into carbohydrates and oxygen * 6CO2+6H20=\>C6H12O6+6O2

Question 26

Where does the oxygen from the reaction come from

Answer 26

Water

Question 27

The two pathway in Photosynthesis

Answer 27

* Light dependant reaction (in the thylakoid membrane) * Light independant reaction (in the stroma)

Question 28

What is a light harvesting complex

Answer 28

* It is the site of light reaction * acessory pigment form a funnel shape around the primary pigment so light energry can be absorb better * Know as a photosystem

Question 29

light reaction

Answer 29

* In PS2, water is split into hydrogen proton, electron and oxygen. The electron in place in the reaction center of the PS * The photosynthesis pigment receive energy form sunlight and pass it on until it reach the electron * The excited electron is release from PS2 and place into a ETC * The ETC also use energy from the excited electron to transport hydrogen proton into the thylakoid lumen for ATP synthesis(build up of gradient) by ATP synthase * The electron in then place in PS1 where it it excited once more before accepted by NADP, forming reduced NADP

Question 30

Why is plant normally green

Answer 30

* It is selective in the photon they absorb * Green light aren't absorb by chlorolpyll

Question 31

Light independant reaction

Answer 31

* Involve the fixation of CO2 * CO2 combine with rubisco phosphat by an enzyme called rubisco, forming an unstable 6 carbon compound which breakdown into 2 GP * ATP and reduced NADP is used to convert GP into TP * 80% of TP is used to regenerate RuBP while the rest is used for other fuction( synthesis of starch, cellulose,...)

Question 32

Cyclic pathway

Answer 32

* Occur at PS1 * after the electron is excited, the ETC transport it back to the PS1 * The reaction repeats * only ATP is created, no reduced NADP is form

Question 33

Energy in living being

Answer 33

- Energy is bound as chemical energy - ATP cannot be transported outside of cell but glucose (a major form of bound energy)can - Energy is stored as marco-molecule through anabolism and is release by cathabolism - Energy blance is vital for maintaining life

Question 34

Type of passive transport

Answer 34

* Channel protein: membrane protein that form a tunnel * Carrier protein: protein that bind to the substance and carry them through the bilayer * Ion channel: channel with hydrophillic pores

Question 35

Catabolic interconversion

Answer 35

* Polysaccharides are hydrolysed to glucose, enter glycolysis * fatty acids are broken down to acetyl CoA and fed to the kerb cycle * Glycerol is broken into DHAP for glycolysis * Protein are broken into amino acid and fed into the kerb cycle

Question 36

Glucose balance in human

Answer 36

* marcro molecule that we absorb in food is broken down into smaller molecule such as glucose by the liver * glucose is transported by the bloodstream to where it is needed(muscle, brain,...)

Question 37

Glucose balance in plant

Answer 37

* After it is synthsized, glucose is transported by the phloem vessel to lower part of the tree such as the body or root where it is needed * It is converted and stored as starch so during the night, respiration can take place

Question 38

Key concepts of regulation through signals

Answer 38

* Signals and signaling affect cell functioning (ie rate of metabolic pathways) * Receptors bind signals to initiate a cellular response The response to a signal spreads through the cell – signal cascade * Cells change in response to signals in different ways Adjunct cells can communicate directly

Question 39

How does cell signalling works?

Answer 39

* Chemical signals that target cells can be classified according to signal source and mode of delivery * A signal transduction pathway includes a signal, a receptor, and a range of responses * Not all cells respond to a signal, some may lack the ability to receive the signal * All cells process information from the environment The information can be a chemical (ie glucose or a damaging salt) or a physical stimulus (ie light,temperature) * Signals can come from inside the cell, from neighboring cells or the outside of the organism

Question 40

different chemical signal types

Answer 40

* Autocrine signals affect the cells that made them * Juxtacrine signals affect only adjacent cells * Paracrine signals affect nearby cells * Hormones travel to distant cells, usually via the circular system

Question 41

Requirements to respond to a signal

Answer 41

* To respond to a signal, a cell must have a specific receptorto detect the signal * A signal transduction pathway * Responses may involve enzymesand transcription factors that are either activated or in activated to have the desired response

Question 42

Types of receptors

Answer 42

* Intracellular receptors: located inside the cell, where they interact with physical or chemical signals * Membrane receptors: Large or polar ligands (ie insulin) bind to cell membrane receptors

Question 43

Types of membrane receptors

Answer 43

* Ion channel receptors – allow ions to enter or leave the cell * Protein kinase receptors– catalyse phosphorylation of themselves and/or other proteins * G-Protein linked receptor-Signal binds to a receptor that activates a G protein which then activates an effector protein

Question 44

Glucose transport into the cell

Answer 44

* The isulin bind with the A-site of the isuline receptor * This cause the B-unit of the receptor to be phosphorilise and start to do the same with other protein * cause a cascade * at the end of the cascade is glycogen synthases which conver glucose into glycogen