cellbiologi
Endoplasmic reticulum
network of membranous sacs and their tubes, active in membrane sythesis and other synthetic and metabolic processes, has a rough and a smooth region.
Nucleus
Nuclear envelope. Nucleolus. Chromati
Nuclear envelope
double membrane enclosing the nucleus perforated by pores continuous with the ER.
Nucleolus
Nonmembranous structure involved in production of ribosomes.
Transcription
Initiation. RNA polymerase (enzyme) binds to the promoter region of DNA unwinding the double helix and start RNA synthesis. Elongation. RNA rolymerase moves along DNA template strand, adding complementary RNA nucleotides to form the growing mRNA strand. Termination. Trancription stops when RNA polymerase reaches a termination state signal realising new synthesized mRNA
Plasma membrane
A membrane inclosing the cell. Consists of a bilayer of phospholipids.
Phospholipids.
Build up the plasma membrane. It consists of glyserol, two fatty acids and choline. A hydrophilic head and a hydrophobic tail. They form micelles when mixed with water
Ribosomes
Complexes that makes proteins, free in the cytosol or bound in the rough ER or nuclear envelope.
Golgi apparatus
Active in synthesis, modification, sorting and secretion of cell products. Packaging and sorting proteins, transportinf molecules to their destination, modifying lipids and proteins
Lysosome:
Digestive organelle where macromolecules are hydrolyzed. Contains hydrolytic enzymes and assist in phagocytosis
Mitochondria
Cellular respiration occurs here and ATP is generated here
Peroxisome
Various specialized metabolic functions, produced by hydroge peroxide as a by-product and then converted to water
Microvilli
Projections that increase the cells surface area.
Cytoskeleton
Reinforces the cells shape and function in the cell movement. Components are made of protein. Cytoskeleton includes microfilaments, intermediate filaments and microtubules. Maintains cell shape, facilitates intracellular transport, anchord organelles in place and assist in cell division
Centrosome
Regions where the cells microtybules are initiated. Contains a pair of centrioles. Involved in cell divison
Flagellum
motility structure present in some animal cells, composed of a cluster of microtubules within an extension of the plasma membrane
Cell wall
Outer layer that maintains cells shape and protect the cell form mechanical damage. Made of celloluse other polysaccarides and proteins
Central vacuole
Prominent organelle in older plant cells, function include storgare. Breakdown of water products and hydrolysis of macromolecules. Enlargement of the vacuole is a major mechanism of plant growth. Storage of water organic and inorganic waste
Plasmodesmata
Cytoplasmic channels through cells walls that connect the cytoplasm of adjacent cells
Extracellular matrix (ECM)
The functions it has is support, attachemt, movement and regulation. It is primarily composed of glycoproteisn which are proteins and carbohydrates. It is mainly the protein collagen
Animal cells
Endoplasmic reticulum. Nucleus, Plasma membrane, Ribosome, Golgi apparatus, Lysosome, Mitochondria, Peroxisome, Microvilli, Cytoskeleton, Centrosome, Flagellum
Plant cells
Endoplasmic reticulum, nuclus, ribosomes, plasma membrane, ribosome, golgi apparatus, mitochondria, perixisome, cytoskeleton, cell wall, central vacuole, plasmamodesmata.
Protein structure- globular proteins
1. Primary structure- Linear chain of amino acids. 2. Secondary structure- Regions stabilized by hydrogen bonds between atoms of the polypeptide backbone 3. Tertiary structure- three dimensional shape stabilized by interactions between side chains. 4. Quaternary structure- the shape of a protein that consists of multiple polypeptide chains. Each part is called a subunit hemoglobin consists of four subunits and it needs them all to function
Synthesis of cell membrane
Cell membrane originates from the ER or the golgi apparatus. A transmembrane protein must face the right direction. It happens in four stages. 1. Synthesis in ER. 2. Modification in the golgi apparatus. 3. The proteins are transported via vesicles to the plasma membrane 4. Vesicle fuse with the plasma membrane.
The inside of the vesicle becomes the outside of the cell, this is called exocytosis. The opposite of the process of endocytosis.
Transport of substances across the cell membrane
Selective permeability, hydrophobic passes easily and hydrophilic are imbeded. Passive transport, require no energy, diffusion, facilitate diffusion and osmosis. Active transport, require energy
Receptor tyronise kinase
Receptor tyrosine kinase have an extracellular legand binding site, a single transmembrane a-helix and an intracellular tyrosine rich domain.
A signal molecule binds to each reseptor tyrosine kinase monomer and causing the to dimerize, dimerization activates the kinase domains leading to cross-phosphorylation of tyrosine resiudues using ATP. Phosphorylated tyrosine recruit relay protiens and activate multiple intracellular pathways.
This regulated key cellular functions such as growth, surival and differentiation
Pyruvate oxidation
Biochemical reaction that invlolves the oxidation of pyruvate to create acetyl CoA. pyruvate oxidation wil generate: Acetyl- CoA, NADH+ H+, CO2.
Oxidative phsphorylation
Complex 1: NADH donates electrons, H+ is pumped from the matrix to the inter membrane space, electrons are transferred to coenzyme Q. Complex II: FADH2 donates electrons and electrons are transffered to coenzyme Q. Complex III: H+ is pumped from the matrix to the intermembrane spce, electrons are transferred to cytochrome C. Complex IV: H+ is pumped from the matrix to the intermembrane spece, electrons are donated to oxygen which will form water.
Chemiosmosis
H+ flows down to a protein channel that phosphorylates ADP into ATP
Transport mechaism
Active transport, osmosis, tonicity, endocytosis, exocytosis, diffusion, faciliated diffusion
Active transport
A movement across a cell membrane against its concentration or electrochemical gradient mediated by specific transport protein and requiring an expenditure of energy
Osmosis
Diffusion of free water across a selectively permable membrane
Tonicity
The ability pf solutions surrounding a cell to cause that cell to gain or lose water
Endocytosis
Cellular process in which substamces are brought into the cell
Exocytosis
The process when cells dischard waste and other large molecules from the cytoplasm to the cell exterior.
Diffusion
The random thermal motion of particles of liquids, gases and solids. In the precense of a concentration or electrochemical gradient. Diffusion results in the net movement of a substance from a region where its more concentrated to a region where its less concentrated.
Faciliatate diffusion
The passage of molecules or iions down their electrochemical gradient across a biological membrane with the assistant of specific transmembrane transport proteins
Globular proteins
Transport proteins substances. Transcription factors affect the transcription of a gene, when the DNA strand read and a mRNA molecule is formed. Hormones are a signal that is transported with the blood. Receptor proteins receive a signal and transmit the message. Antibodies are defensive proteins secreted from the immune system. Enzymes are proteins that selectively accelerate biochemical reactions.
G protein- coupled receptors
When GDP is bound the G-protein is inactive. A signal molecule binds to G-protein couplet receptor and the g-protein will go from GDP to GTP and become active. The active g-protein will seperate from the receptor and bind to an enzyme which will alter its activity. The Gprotein hydrolyzes GTP to GDP and it will return to the inctive state and detach from the enzyme.
This will regulate cellular respons to external signals
Splicing
Introns are cut out from the primary mRNA transcript and the exons are joined together to make mature mRNA
Denaturation
The weak chemical bonds and interactions get destroyed and the protein will unfold and lose their functional form and loses its function and solubility. Factors that makes this happen are temperature, pH and salt.
Phagocytosis
A type of endocytosis in which large particle substances or small organisms are taken up by a cell. It is carried out by some protists and by a certain immune cells of animals. Cell eating
Pinocytosis
A type of endocytosis in which the cell ingests extra cellular fluid and its dissolved solutes. Cell drinking
Autophagy
A process in which lysosomes use their hydrolytic enzyme to recycle the cells own organic material
Hypotoic solution
Hypo means less and in the cell water will enter the cell faster than it leaves which will make the cell swell and burst
Glycoprotien
A protein with one ore more covalently attached carbohydrates
Amino acids
Are connected through a peptide bons. When a dehydration reaction happens a dipeptide is formed. The ends of the peptide are named and the end of an amino group are called N-terminus and the end of an carboxyl group are called C- terminus. Peptide are multiple linked amino acids.
Side chain
Gives amino acids its properties and our body uses 20 different amino acids to build proteins. Amino acids that are nor glycine show optical isomers where only the L-form builds protein.
Why can oxygen pass freely across the plasma membrane but glucose cant?
The cell membrane consists of phospholipid bilayers with a hydrophilic head and a hydrophobic tail. Oxygen is a nonpolar small sized molecule with hydrophobic compatibilty and this makes it pass the membrane easily by simple diffusion. Glucose is a polar large molecule that has a hydrophilic nauter and it will need a specific transport protein to go through the membrane.
Composition of phospholipids
The fatty acids in the phospholipids affects the membrane, unsaturated fatty acids have a low melting point and a more fluid membrane. Saturated fatty acids have a higher melting point and a more solid membrane. Cholesterol which is in animal cells makes the cell membrane more resistant to temperature changes. It prevents solidification in lower temperature and reduce fluidity of membranes in higher temperature.
Fatty acids
Fatty acids are long carboxylic acid without brancing
Difference between saturated and unsaturated
Unsaturated have double bonds and this will create more space between the phospholipids making the membrane more fluid and saturated have no double bonds and will make the space between the phospholipid tighter making the membrne solid
ATP synthase
Enzymes that produce ATP in the mitochondria. 1. H+ ions flowing down on their gradient enter a channel in a stator Into the rotor. 2. Protons bind to the rotor causing it to spin within the membrane. 3. Each H+ ion makes one complete turn and pass through another channel into the mitochondrial matrix 4. The rotors spinning turns an internal rod which extends into the stationary knob. 5. The rods movement activates the knob, catalyzing the conversion of ADP and PI into ATP
Transmembrane receptors
Located on the plasma membrane. The purpose is to detect hydrophilic signals that cannot pass through the cell membrane. They will detect hydrophilic molecules, for example peptide hormones like insulin. They are polar and cannot cross the hydrophilic bilayer and require a membrane bound reseptor to transmit the signal inside the cell
Intracellular receptors
Is inside the cell mainly in the cytoplasm or nucleus the purpose is to detect hydrophobic signals that can pass through the cell membrane. They will detect hydrophobic molecules like steroid hormones like testosterone. The signlas are nonpolar and can diffuse throught the plasma membrane to bind directly to the receptors
Silent mutation
A nucleotide pair substancec that has no observable effect in the phenotype.
Promoter
A specific nucleotide sequence in the DNA of a gene that binds RNA polymerase, positioning it to start transcribing
Coupled transcription and translation
A hallmark of a prokaryotic gene expression. This occurs when ribosomes associate with and initiate translation of mRNAs whose transcription has not yet concluded.
Poly A tail
Makes the RNA molecule more stable and prevents its degredation
Anticodon
To bring the correct amino acids togther to create a protein from the instructions in the mRNA
Ribozyme
An RNA molecule that functions as an enzyme such as an intron that catalyses its own removal during RNA splicing
Prosthetic group
A non protein component that is tightly bound to proteins. They are essential for the catalytic function of certain enzymes
Hydrolysis
Means water breakage. Dissembles polymers to monomers. A process that is reverse of the dehydration reaction
Dehydration reaction
A chemical reaction in which two molecules become covalently bonded to each other with the removal of a water molecule
Coenzyme A
A coenzyme carrier of non-enzyme bound acyl group and participates in a wide variety of actions
NAD+
An electron acceptor that functions as an oxidizing agent during respiration
Glycolysis
A series of reactions that splits glucose into pyruvate
Catabolism
Metabolic pathways that realeses energy by breaking down complex molecules to simpler molecules
Beta oxidation
Metabolic sequence that breaks fatty acids down to two carbon fragments that enter the citric acid cycle as acetyl CoA
Calvin cycle
The second major state in photosynthesis. Carbon fixation state. A series of enzyme controlled reactions which does not require light
Cell signaling
1. Receptor, a chemical signal is detected by a receptor protein. 2. Transduction, binding of signal molecules cahnges receptor protein, initiatinf the transduction where the signal will be carried on. 3. Response, the transducted signal triggers a specific responce
Ligand gated ion channels
1. Binding by a ligand to the extracellular side cahnegs the proteins shape and the open channel. 2. Allows the flow of specification such as NA+ or CA2+ through a channel of receptors. 3. When a ligand dissociates from the receptor protein the channel closes
Nonsense mutation
Acts as an early stop codon which can result in a nonfunctional protein
Missense mutations
Difference in the sequence which will lead to a different codon. This will alter the function of the protein.
Change the amino acid sequence
Silent mutation
Will change the sequence but lead to the same or similar codon which has no to little effects on the protein
Post translated modifications
Phosphorylation, glycosylation, methylation
Noncompetetive inhibitor
A specific type of enzyme inhibition, the inhibitor binds at an allosteric site seperate the active substrate binding site
Binds to the enzyme away from the active site, altering the shape of the enzyme so that even if the substrate can bind the active site functions less effectively or not at all.
What is the role of phosphate in cell signaling
To dephosphorylate proteins
Ligand
is a molecule that attaches to a receptor, triggering cahnges within the cell
Pacrine signaling
When a cell releases a signal molecule into the environment and a number of cells in the immediate vicinity respond
What happens when the intracellular segment of receptor tyrosine kinase is phosphorylated?
It allows docking of intracelllar proteins involved in signal transduction
Potato chip vs Tortilla chip
The salt dissolves easily in water while the more complex hydrophobic and receptro binding nature of the tortilla chip flavoring makes them more persistent
Why will one NADH + H+ generate more ATP than FADH2?
NADH enters complex I and pumps more protons than FADH2 that enter complex II and because more protin is pumped in Complex I NADH will generate more ATP
Function of light in chloroplast
Te light reaction is crucial for capturing sun energy, producing chemical energy and reduce power necessary for the calvin cycle to synthesize glucose.
How do we produce serum albumin
The first step is transcription of albumin mRNA. This happens in the nucleus 2. In the cytoplasm mRNA binds to a ribosome and translation in the rough endoplasmic reticulum occurs. 3. Protein folding and modification happens in the rough endoplasmic reticulum. The folded albumin is packaged into vesicles and sent to the golgi. 4. The final modification if required occurs in the golgi apparatus and is then packaged into secretory vesicles. 5. The secretary vesicles travel along microtubules toward the plasma membrane and the vesicles fuse with the membrane and the albumin is released into the bloodstream through exocytosis.
Startch vs celloluse
Starch has an 1-4 alpha linkage that the enzyme amylase can break down which we have. Celloluse has a 1-4 betha linkage which we have no enzyme to break down
How does water move in and out of the cell
It moves in via aquaporins that is channel proteins. It makes the water pass through the cell membrane. This proess is called osmosis
Cell membrane hot vs cold
If it is cold the fluid membrane will solidify because the phospholipids will settle in a closed packed arrangement. When it is hot it will become more fluid.
Macromolecules
Carbohydrates. lipids, proteins, nucleic acids
Carbohydrates
Provide the cell with energy and is a part of many cell structures
Lipids
Fats and other non water soluble molecules. Not always macromolecules
Proteins
execute most thing in the cell.
Nucleic acid
RNA single stranded and DNA double stranded
How are macromolecules formed and broken down
Formed via dehydration synthesis and broken down via hydrolysis
Trancription
From DNA to mRNA
Translation
From mRNA to protein
Alternative splicing
Exons from the same gene are joined in diferent combinations leading to a different but related mRNA transcript