Life at Cellular Level Flashcards
Why are cells small?
Small cell keeps a large surface area to volume ratio - needed for easy absorption of substances
Do prokaryotes have mitochondria?
No
What is the difference between pluripotent cells and multipotent cells?
Multipotent - can differentiate into many cell types
Totipotent - can differentiate into every type of cell in the body
What are the key differences between necrosis and apoptosis?
Necrosis - Days, groups of cells, damage to neighbouring cells, inflammation
Apoptosis - Hours, individual cells are induced to die, no damage to neighbouring cells, no inflammation
Describe the shape of mitochondrial DNA
Circular
What does the endoplasmic reticulum do?
Site of protein and glycolipid synthesis
Which proteins does the golgi apparatus add sugars to?
Membrane proteins
Lysosomal proteins
Secretory proteins
What is the word used to describe membrane lipids?
Amphipathic
What function do telomeres have?
They stabilise the ends of the chromosomes
What function do centromeres have?
They ensure distribution of chromosomes to daughter cells when the cell divides
What is splicing?
Removing introns during translation
What is the ribosome composed of?
Ribosomal RNA
What is responsible for autophagy?
The lysosome
What is the function of the cytoskeleton?
Holds organelles in place and moves them
Supports and maintains cell shape
What three structures comprise the cytoskeleton?
Microfilaments
Intermediate filaments
Microtubules
What is the structure of microfilaments?
Made up of actin protein strands - thin and contractile
What are microfilaments responsible for?
Provide structure
Cell cell anchoring
What is the structure of intermediate filaments?
Consists of fibrous proteins, organised in tough rope-like assemblages
What is the function of intermediate filaments?
Stabilise cell structure, prevents collisions within the cell
What is the structure of microtubules?
Thick, Long, hollow cylinders made from tubulin (a dimer composed of alpha and beta tubulin)
What is the function of microtubules?
Transport materials in cytoplasm
What is the peroxisome responsible for?
Oxidation of fatty acids
What type of atoms form the strongest bonds?
Light atoms
What are the two isomers of the c-c double bond?
Cis (meaning same)
Trans (meaning opposite)
What are the names given to the two forms of carbon?
Laevo (left handed)
Dextro (right handed)
What type of amino acids are proteins made from?
Left handed (laevo)
What is defined as comformation?
The precise arrangement of atoms in a molecule
What is the intermediate product between glucose and pyruvic acid, and what products does its formation produce?
Phosphoenolypyruvate
Makes 2 ATP each
Makes 1 NADH each
Is condensation a synthesis or degradation reaction, what does it always produce?
It is a synthesis reaction that produces water
What type of reaction occurs between the pentose sugar of one nucleotide and the phosphate of an adjacent nucleotide?
Dehydration reduction
What is the difference between a nucleoside and a nucleotide?
Nucleoside does not contain a phosphate group
What does the 5’ end of RNA contain?
Contains the phosphate
What enzyme is used to insert viral DNA into the host genome?
Insertase
What is the effect of zidovudine?
It is a reverse transcriptase inhibitor and prevents the virus producing DNA from RNA
What is the structure of triaclyglyceride?
A glycerol backbone connected to three fatty acids
What is the structure of a lipid?
Carboxyl head and a hydrocarbon chain
What is the structure of a phospholipid?
Same structure as triacylglycerol except one of the fatty acids has been replaced with a phosphate group (forming the hydrophilic head)
Are triacylglycerides polar?
No
What is the definition of amphipathic?
A molecule having both hydrophilic and hydrophobic parts.
What is the first law of thermodynamics?
Energy can neither b converted nor destroyed
What is the second law of thermodynamics?
All energy transformations ultimately lead to more disorder, an increase in entropy
What is enthalpy defined as?
The total energy within a system
What is entropy defined as?
The disorder within a system
What is the equation to calculate gibbs free energy?
What is free energy measured in?
Kcal/mol
What does a delta G less than 0 indicate?
The reaction is spontaneous and energy releasing
What does delta G greater than 0 indicate?
That the reaction is spontaeous backwards (endergonic)
What does a delta G equal to 0 mean?
The reaction is at equilibrium
What type of delta G do biological reactions require?
Positive delta G, since they require more order rahter than less
What is meant by energy coupling?
An energetically unfavourable reaction is driven by an energetically favourable reaction.
What are the features of catabolism reactions?
Heat lossComplex oranic molecules are broken down into simpler onesReleases energy that drives chemical reactions
What are the features of anabolic reactions
Simpler substances are combined to form more complex molecules
Require energy
How do exergonic reactions save free energy?
By forming ATP
What is the definition of an apoenzyme?
Require non-protein co-factors
What makes up a holoenzyme?
Cofactor + apoenzyme
What is the function of water?
Bathes our cells
Dissolves and transports compounds
Allows compounds to move between and within cellsParticipates in chemical reactions
Dissipates heat
Which atom are electrons held closer to in an OH bond?
They are held closer to the O atom because the O is more electronegative
Describe the H bonds in water?
They are continually forming and breaking whilst H2O molecules move
Does gaseous H2 contain H bonds?
NO
Where does a hydrogen bond take place?
Between any any eectonegative atom and an H atom that is electropositive
When are H bonds strongest?
When the three atoms involved lie in a straight line
What is the change in H bonding when a hydrophilic molecule like alcohol, aldehyde or ketone is dissolved in water?
H bonds within water and the solute are replaced with more energetically favourable solute-water H bonding
Why is O2 and CO2 poorly soluble in water?
No polarity
Describe the structure of dissolved sodium chloride
Water forms screens around each ion
What effect does does the interaction between a substrate and an enzyme have on the order of water?
Enzyme substrate reaction displaces dsordered water
What is meant by the hydrophobic effect?
They arrange themselves in water to minimise the disruption of hydrogen bonding in the surrounding water molecules
This is energetically favourable
Describe the structural arrangement of water around alyl chains?
H2O molecules form cages around hydrophobic alkyl chains
How do phospholipids minimise disruption of H bonding in solution?
They form bilayers or mxed micells
What kind of structure will proteins adopt when they are in aqeous solution?
They fold up so that the hydrophilic parts of the chain are on the outside and the hydrophobic parts are on the inside, allowing them to be water soluble.
What calculation is used to calculate the dissociation of water?
What does Kw (ionic product of water) always equal in the dossociation of water
1x10-14
How do you calculate pH from the concentration of H+?
pH = -Log [H+]
How do you describe the movement of protons in both acids and bases?
Acids are proton donors and bases are protein acceptors
What equation is given to the equilibrium constant of an acid?
What does the euilibrium constant measure?
It measures the tendancy for any acid to lose a proton and form its conjugate base
What is pKA?
It is the -log of the acid dissociation constant
What is significant about the midpoint of the titration of a weak acid and a base?
Exactly half of tha base is added and half the weak acid is remainingpH = pKa
What is the henderson hasslebalch equation?
What are natural buffers in the body?
Phosphate in the cellsBicarbonate in the blood
