Flashcards in Molecules and Genes - Shearwin Deck (85):
Why is water important?
makes up 2/3 of body
Describe 2 characteristics of water
Polar molecule: has polar covalent bonds as oxygen has stronger attraction for electrons
Hydrogen bonding: form between + and - charges in polar molecule
Properties of molecules that can Hydrogen bond
1. has a higher BPT than other covalent molecules
2. Is more soluble, except for long chains
What is a colloid?
solution containing proteins/other molecules
Dissociation of water (eq.)
h20 -> OH- + H+
What is the key pH range
What happens when the pH goes above/below the key range
below 7.35 = acidosis
below 7 = coma
above 7.45 = alkalosis
above 7.8 = muscle spasms
What are buffers?
stabilise pH by removing/adding H+ ions
(either NaHCO3 or H2CO3)
What is an acid? (include eq.)
solute that dissociates and releases H+ (proton donor)
H2O + CO2 H2CO3 H+ + HCO3-
What does diabetes 1 cause?
acidosis through production of ketones
What does hyperventilation cause?
What macromolecule does each of the following molecules convert to?
Name the 3 type of carbohydrates
What is a monosaccharide?
What is a disaccharide?
2 monomers of monosacch.
hydrolysis of disach. = 2 monomers
dehydration of 2 mono = disach + water
What is a polysaccharide?
starches and glycogen
break down to use energy, join to store energy
Triglyceride hydrolysis (eq.)
Triglyceride + 3h20 -> glycerol + 3 fatty acids
Glycerol dehydration (eq)
glycerol + 3 fatty acids -> Triglyceride + 3h20
What is cis configuration?
h-bonds on the same sign
What is trans configuration?
h-bonds on seperate sides
linked to increased CAD
What is an Adipocyte?
formed from glyolipid and phospholipid forming micelles
How is DNA formed?
dehydration synthesis of nucleotide subunits
What is DNA made off?
sugar phosphate backbone
bases (a, t, c, g)
Draw the structural unit of DNA
What are purines?
A and G
What are pyrimidines?
C and T
Draw the structural unit of RNA
What are major and minor grooves in DNA? How are they formed?
the distances between the double helix
due to angle of glycosidic bonds
Why is A-T weaker than C-G
due to there being 2 N-H bonds in A-T compared to 3
Name the 3 types of RNA
Compare RNA and DNA
RNA contains U instead of T
contains 2 -OH thus more unstable (on the 2nd)
What are proteins?
long chains of AA
What do Amino acids contain?
Draw an amino acid
H, COOH group, NH2 group and variable
How are peptides formed?
AA form peptides through dehydration synthesis
hydrolysis of dipeptide = AA
Name the 4 protein structures
What is a primary protein?
sequence of AA
What is a secondary protein?
results from bonds between atoms along the chain
What is a tertiary protein?
results from interactions between polypeptide chain and water or R group of AA
What is a quaternaty protein?
interaction between various polypeptide chains
How many subunits does keratin and collagen have?
3 - fibrous
How many sub units does Haemoglobin have?
4 - globular
Describe the structure of Haemoglobin
4 subunits - 2 alpha and 2 beta
each subunit made up of many alpha helxes
1 haem molecule in each subunit (Haem carries O2)
Each haem molecule binds to 1 oxygen, via Fe2+
Why does affinity for oxygen increase, as more oxygen are binded?
without oxygen, Fe does not quite fit into the planar structure. when oxygen is binded, Fe fits, and this causes a shape change of the protein, thus 3D structure changes, resulting in more oxygen binding
Name the 4 types of protein dysfunction
1. altered exterior: harmless except sickle cell anemia
2. altered active site: cyanosis
3. altered tertiary structure: misfolding
4. " quaternaty structure
What is sickle cell anemia?
cells become trapped in blood vessels = organ damage
How is SSA caused?
mutation of glutamic to valine in beta chain
as glutamic is philic, whilst valine is phobic,
forms long insoluble chains of Hb, under conditions where deoxy predominates (in tissues, high altitude)
HbS will polymerise and fill cell with haemoglobin = RBC misshapen
What are enzymes?
allow reactions to occur under conditions necessary for life
What are substrates?
Reactants in enzyme reaction
binds to specific site of enzyme
enyzme-substrate complex (where it binds) and reinforced by H-bonds
What happens when enzyme binds to substrate? (include eq.)
enzyme undergoes temporary irreversible change in shape
S + E -> ES -> EP -> E + P
Velocity of reaction (eq.)
(Vmax [s] )/(Km + [s])
What is competitive inhibition?
Where the drug and substrate fight to bind to the same spot on the enzyme
What is non competitive inhibition?
Where the drug binds to a different site on the enzyme, but still removes the function of the enzyme
What are statins?
are competitive inhibitors which lower cholesterol
Name a non competitive inhibitor
Aspirin, preventing prostagladins from forming
What is chromatin?
DNA and histones
What does replication involve? And when does it occur?
It is the first process (occurs during s phase)
DNA Helicase unzips the 2 strands at A/T bonds, as they are weaker
Primase adds RNA primer to begin new strand, whilst DNA polymerase adds nucleotides as well as proof reading.
Draw a section of replication
What is a okuzaki fragment?
RNA primer and associated DNA on lagging strand
Why does replication have to be controlled, and why does it have proof reading abilities?
To prevent the formation of cancer, and so that mistakes are decreased.
What is transcription?
non template (coding) DNA strand is transcripted to RNA
What direction is RNA made in?
5' to 3'
Difference between DNA and RNA?
Uracil instead of T
Name the two types of genes?
Housekeeping = always turned on to allow for normal cell function
tissue specific = turned on/off due to factors; cell type, hormones, etc
Name the 3 stages of RNA synthesis (Transcription)
What is initiation?
RNA Polymerase identifies where to begin transcription of DNA. RNAP binds to promoter region, due to transcription factors
What is Elongation?
Ribonucleotides add to 3' end of RNA
What is Termination?
RNAP terminates when encounters a termination sequence
Explain the mechanism of Transcription?
1. RNA poly. unwinds DNA in nucleus, making a bubble
2. RNA Begins with 5' and has no proofreading mech as RNA does not last long
Explain how mRNA is modified? What is it called? Can you draw the mRNA?
5' cap and 3' poly(A) tail are added to mRNA (Polyadenylation)
This prevents degradation of ends by exonucleases, as well as beginning translation
What are exons?
What are introns? When are they removed? Why are they removed? Draw this proccess
non coding regions
they are removed from mRNA prior to translation
removed to provide range of proteins
Where does replication occur?
Where does transcription occur?
Where does translation occur?
What is translation?
translation of mRNA to AA
how many base codes code for AA?
Name the 3 types of AA
60 combos = general AA
3 combos = STOP codon (UAG, UGA, UAA)
1 combo = START codon (AUG or methionine)
difference between open reading frame (ORF) and untranslated region (UTR)
ORF is the coded region
UTR is the part that signals ribosomes to bind to start codon, ORF and stop codon.
What is frame shift mutation? what does this cause?
Addition and deletion of a base
Destroys the function of the protein
name the 3 mutations in a codon (draw a small diagram)
What is a nonsense mutation?
protein is shorter and non functional
What is a missense mutation?
may change the function
What is silent mutation?
remains the same
What does aminoacyl-tRNA do?
called an adaptor molecule
reads mRNA and supplies AA
A specific AA attaches to tRNA by tRNA sythesase