Nucleic Acids (biological Molecules) Flashcards
What charge does a water molecule obtain
Although the molecule has no overall charge the oxygen atom has a slight negative charge while the hydrogen atoms have a slight positive one
Why is water dipolar
The water molecule has both positive and negative poles
Why is waters specific heat capacity higher than expected
Because water molecules stick together it takes more energy to separate them
How does water act as a buffer and how does this help organisms
Water acts as a buffer against sudden temperature variations as it has such a high specific heat capacity and therefore high boiling point. Making the aquatic environment a temperature - stable one. It also buffers them against sudden temperature changes in terrestrial enviroments
Why is it good for humans that waters latent heat of vaporisation is high
Evaporation of water such as sweat needs a lot of energy and therefore is very effective in cooling mammals as we use our body heat to evaporate the water (losing heat and energy to cool down)
what is an organic ion
ions that contain atleast one carbon to hydrogen bond and contain carbon
what is an inorganic ion
charged molecules that do not contain carbon-hydrogen bonds
how does the concentration of hydrogen ions affect PH
the greater concentration of hydrogen ions , the lower the PH and the lower the concentration of hydrogen ions , the higher the Ph
how does this make the concentration of hydrogen important
this makes the concentration of h+ ions very important for enzyme - controlled reactions(7.4 is average enzyme ph)
how can abnormal levels of hydrogen ions affect enzymes
can interact with the side chains of amino acids and change the secondary and tertiary structures.
where do inorganic ions occur
inorganic ions occur in solution in the cytoplasm and bodily fluids of organisms. the concentration of certain ions can fluctuate and can be used in cell signalling and neuronal transmission
what is the role of sodium(na+) ions
sodium is the major extraceullular cation in animal cells. they are important in the transport of glucose and amino acids across plasma membranes. they are also involved in transmission of nerve impulses and in fluid and electrolyte balance.
what do sodium ions do in plants
in plants na + ions are involved in maintaining cell turgor and in opening and closing stomata
what are the main roles of hydrogen ions
they are important in determining the PH of solutions and therefore the functioning of enzymes. they can also establish trans - membrane electrochemical gradients which can be used to generate ATP
what is the role of calcium (ca2+) ions
component of teeth and bone . and is involved in muscle contraction , blood clotting , activation of some enzymes and cell signalling
in plants what does calcium do
in plants calcium is a component of the cell wall
predict the biological consequences of inadequate levels of calcium in the diet
weak bones and teeth , impaired blood clotting and muscular weakness
what feature of inorganic ions structure enables them to be involved in acid - base regulation
they can accept or donate protons
which inorganic ions are involved in acid - base regulation
HCO3- , CL-, OH-,NH4+,H+
what is the role of nitrate (NO3-) ions
they are an important souce of nitrogen for plants . nitrogen is a component of amino acids and nucleotides.
how do plants obtain nitrate ions
they obtain their nitrogen by eating other organisms. they get their nitrogen from proteins made in plants or in other animals
what is the role of iron ions
found in haemoglobin where they play a role in the transport of oxygen . iron ions are also essential as they are involved in the transfer of electrons during respirtation and photosynthesis.
what is the role of phosphate ions
phosphate ions form a structural role in DNA and a role in storing energy in ATP molecules
What is the monomer of a nucleic acid
Nucleotide
What is a gene
A short sequence of bases which codes for a specific protein
What is a genome
All the genes in an organism
How is dna stored in the nucleus of cells
Chromosomes
What does dna stand for
Deoxyribonucleic acid
What is the shape of DNA
double helix
Who discovered the structure of DNA
James Watson and Francis crick in the 1950s
What is dna
A long chain of repeated units called nucleotides therefore it can be referred to as a polymer
What are the two long strands in dna called
Sugar phosphate backbone
What is the role of the sugar phosphate backbone
Helps hold the bases in the middle of the DNA molecule
What does a DNA nucleotide consist of
Phosphate, base and sugar( deoxyribose pentose sugar)
What does a nucleotide base always contain
Nitrogen
How is a nucleotide formed
Vía a condensation reaction which forms an ester bond between the phosphate and sugar (h20 released) and a glycosidic bond between the sugar and base (h20 released)
How many hydrogen bonds between a and T bases
2
How many hydrogen bonds between c and G bases?
3
How are the nucleotides arranged in a DNA molecule?
They run anti parallel
When the sugar of one nucleotide joins two, the phosphate of another nucleotide, what bond is formed
Phosphodiester bond
Why does DNA from a double helix structure?
Because of the specific hydrogen bonds between the bases and because bases are hydrophobic, where is the phosphate groups are hydrophilic
What is RNA?
RNA is a type of nucleic acid called ribonucleic acid.
How does RNA differ from DNA?
RNA differs from DNA because rna is single stranded, whereas DNA has two strands. Additionally, DNA is much longer than RNA .RNA has a sugar called ribose, whereas DNA has a sugar called deoxy ribose. RNA has the base uracil. Where is DNA. Has the base thymine .
How is DNA stable?
DNA is stable because the phosphodiester backbone protects the more chemically reactive organic bases inside the double helix. Additionally, hydrogen bonds link the organic base pairs forming bridges between the phosphodiester uprights as there are three hydrogen bonds between cytosine and guanine the higher the proportion of c - G pairings, the more stable, the DNA molecule.
How is DNA adapted to carry out its functions
It is a very stable structure which normally passes from generation to generation without significant change. Most mutations are repaired, so persistent mutations are rare.
It’s two separate strands are joined only with hydrogen bonds which allow them to separate during DNA replication and protein synthesis
It is an extremely large molecule and therefore carries an immense amount of genetic information
By having the base pairs within the helical cylinder of the deoxy, ribose, phosphate backbone, the genetic information is to some extent, protected from being corrupted by outside, chemical and physical forces
Base pairing leads to DNA being able to replicate, and to transfer information as mRNA
when does a dna moleule need to replicate
before a cell divides during mitosis and meiosis , this is when a cell divides the two daughter cells will contain the correct amount of genetic material - genetially identical
what is the first step in DNA replication
the origional dna molecule unwinds
what is the 2nd step in dna replication
dna helicase breaks the hydrogen bonds and causes the 2 strands of dna to seperate
what is the 3rd step in dna replication
free nucleotides in the nucleoplasm are attracted to their complemetary base pairs
what is the fourth step in dna replication
the strong sugar phosphate backbone is re joined by dna polymerase which forms a phosphodiester bond between the sugar and phosphate of two nucleotides
what is step 5 in dna replication
this forms 2 identical strands of dna
what is step 6 in dna replication
because the strands each contain half of the origional material it is each called the semi conservative method of replication
where is energy released from
mitocondria
what process releases the most energy
respiration
what is needed in this process
oxgen and glucose
what is energy used for in living things?
muscle contraction , maintaining body temperature , chemical reactions ( condensation for example)
what is the structure of ATP
adenine molecule , ribose molecule , and 3 phosphate groups
what does ATP stand for
adenosine tri phosphate because the adenine and ribose together can be called adenosine
what is ATP
atp is a nucleotide
why is
ATP a phosphorylated macromolecule
it has three phosphate groups
how is atp an immediate energy source
it has unstable bonds between the 2nd and 3rd phosphate which means it has a low activation energy to break. so this bond breaks to release energy
how is ATP recylcable
the bond is constantly breaking and reforming to release energy. it is not used up
what enzyme is needed for the hydrolysis reaction of atp
ATP hydrolase ( this is found in cell membranes and pretty much everywhere)
what is left after the hydrolysis reaction of ATP
adenosine di phosphate and a phosphate ingorganic ion
what reaction joins back the inogranic ion and ADP
condensation reaction
what enzyme is needed for the condensation reaction of ADP
atp synthase (atpase)
and energy and the phosphate
what is the benefit that ATP releases a small but sufficient amount of energy from the complete hydrolysis of ATP
this is enough energy to drive important metabolic reactions while keeping energy wastage low
What is the benefit that ATP can be recycled
The breakdown of ATP is a reversible reaction so can be reformed from ADP and Pi so can be used elsewhere
what is the benefit that ATP exists as a stable molecule
It doesn’t break down unless a catalyst (ATPase) is present so energy won’t be wasted
What is the benefit that the hydrolysis of ATP is quick and easy
It allows cells to respond to a sudden increase in energy demand
What is the benefit that ATP is soluble and moves easily within cells
Can transport energy to different areas of the cell
What is the benefit that ATP forms phosphorylated intermediates
This can make metabolites more reactive and lower the activation energy needed for a reaction
What’s an example of a metabolic process that atp is used for
Cell division and active transport
who proposed the DNA models
watson and crick
who did the DNA experiment
meselson and stahl
what were the methods of dna replication proposed
semi conservative , conservative and fragmented .
what is the semi conservative method of dna replication
each new synthesised strand is paired with half the origional
what is the conservative method of dna replication
two strands , 1 origional and 1 new synthesised strand
what is the fragmented method of dna replication
sections of origional and sections of new synthesised stranf
what was the key thing watson and crick provided that enabled the experiment
the discovery of DNAs structure by watson and crick provided evidence that complementary base pairing was key to dnas ability to replicate
which is the most abundant nitrogen isotope in bases
N14 so we assume all DNA bases will contain N14.
what is a centrifuge
seperates substances out by mass
what is the method meleson and stahl did
first control 1 is made by E coli bacteria grown in a solution of N14 bases. then control 2 , E.coli bacteria is grown in a solution of N15 and left to replicate a few times . the N15 will fully incorporate into the bases.
first experiment - E. coli bacteria with N15 incorporated into the bases are put in N14 medium . it is left to replicate once and the DNA is extracted and put into a centrifuge . a medium band pattern is observed as it is made of half the origional (n!%) and the new (N14) strand
2nd experiment - bacteria from first generation containing half the N15 bases and half N14 bases are put into a solution of N14 and left to replicate a second time . the dna is then extracted and put into a centrifuge . a medium band and light band will be observed . some new strands will contain all light bases and some will contain both
which band shows its semi conservative
the medium band
Describe and explain how the structure of DNA results in accurate replication
Weak hydrogen bonds allows strands to separate , two strands therefore semi - conservative replication is possible,
Why do humans release sm ATP per day
ATP cannot be stored
what base does atp contain
adenine
Use your knowledge of enzyme action and DNA replication to explain why new nucleotides can only be added in a 5’ to 3’ direction.
dna polymerase is only complementary to 5’ side as dna strands are complementary
what do the single DNA strands do
determinr the order of bases / nucleotides
how does the structure of DNA determine its function
-sugar phopshate backbone provides strength and protects bases
-large and long molecule so can store lots of information
-helix so compact
-base sequence codes for amino acids
-double stranded so strands can act as templates
-weak hydrogen bonds allows the strands to seperate
