Standard answers to learn Flashcards
(19 cards)
Describe the process of transcription
H bonds between nucleotides break
1 strand acts as template
free RNA nucleotides align by complimentary base pairing
U not T
RNA polymerase joins adjacent nucleotides
by phosphodiester bonds
pre-mRNA spliced to form mRNA
Describe the process of translation
mRNA attaches to ribosome at start codon
tRNA molecules carry amino acids to it
tRNA w anticodon complimentary to first codon on mRNA attaches to mRNA by specific base pairing - 2nd trna attaches to next codon in same way
the 2 amino acids attached to trna join by peptide bond using energy from ATP
1st trna molecule moves away
3rd binds to next codon. this amino acid binds to first 2 and second trna moves away
continues until stop codon reached and polypeptide chain moves away from ribosome
Describe the role of antibodies in producing a positive result in ELISA test?
first antibody binds complimentary in shape to antigen
second antibody w enzyme attached is added
second antibody attaches to antigen/ first antibody
substrate added and colour changes
role of haemoglobin in transport of oxygen for resp
Hb associates in lungs
at high pp of oxygen
binding of oxygen makes binding of another easier
hb dissociates xygen in respiring cells
at low partial pressure of oxygen
structure function of glycogen (?)
helix so compact
polymer of glucose easily hydrolysed
branched so more ends for faster hydrolysis
glucose polymer so provides respiratory substrate for energy
insoluble so not easily lost from cell/ does affect water pot
cohesion tension theory
water lost from leaf due to evaporation
lowers water pot of mesophyll cells
water pulled up xylem creating tension
water molecules cohere together by hydrogen bonds
forming continuous water column
adhesion of water molecules to walls of xylem
describe appearance and action of chromosomes in mitosis
prophase
- chromosomes condense and become visible
- appear as 2 sister chromatids joined at centromere
metaphase
- chromosomes line up at equator
- attach to spindle fibres
- by their centromere
anaphase
- centromere divides
- sister chromatids pulled to opposite poles
telophase
- chromatids uncoil and become longer/ thinner
types of transport
simple diffusion- movement of small/ non-polar molecules down conc grad
facilitated diffusion- movement down conc grad via protein carrier/channel
osmosis- movement of water down water pot grad
active transport- movement against conc grad via protein carrier using ATP
cotransport- movement of 2 diff substances using carrier protein
why is DNA the code for proteins
because base sequence
in triplets
determines order of amino acids
DNA in chloroplasts vs nucleus
in chloroplasts: (must be comparative statements)
- DNA shorter
- fewer genes
- DNA circular not linear
- not associated w histones
- no introns
compare and contrast prokaryotic and eukaryotic DNA
nucleotide structure identical
nucleotides joined by phosphodiester bonds
DNA in mitochondria similar to in prokaryotes
eukaryotic is longer
eukaryotic contains introns pro doesn’t
eukaryotic is linear pro circular
eukaryotic is associated w histones pro not
purpose of courtship behaviour
recognise same species
stimulates release of gametes
attract opposite sex
indicate sexual maturity
formation of a pair bond between 2 organisms
sympatric speciation
occurs in same habitat
mutation causes diff flowering times
reproductive separation or no gene flow
diff alleles passed or change in allele frequency
disruptive selection
eventually, diff species cant interbreed to produce fertile offspring
allopatric speciation (something to do with markings?)
no interbreeding/ geographical isolation
mutation linked to diff markings
selection linked to diff marking colours
adapted organisms breed/ diff reproductive success
change in allele frequency
allopatric spetiation
physical barrier causing them to be separated
different selection pressures on either side
evolve diff as diff alleles are more favourable each side
those w more favourable characteristics survive, breed, pass on useful allele so offspring have them too
eventually so diff they can no longer breed to produce fertile offspring
how does methylation lead to cancer?
methyl groups added to both copies of tumour suppressor gene
transcription of tumour suppressor genes is inhibited
leading to uncontrolled cell division
describe processes involved in absorption and transport of digested lipid molecules from ileum into lymph vessels
- micelles contain bile salts and fatty acids/ monoglycerides
- make fatty acids more soluble in water/ carry fatty acids to cell lining/ maintain higher conc of fatty acids in cell lining of ileum
- fatty acids absorbed by diffusion
- triglycerides reformed in cells
vesicles move to cell membrane
structure determined by position of amino acid/ r groups
primary structure is sequence of amino acids
secondary structure formed by H bonds
tertiary structure formed by interactions between r groups
creates active site in enzymes
quaternary structure contains more than 1 polypeptide chain
permeable capillary wall
single cell thick reduces diffusion distance
flattened endothelial cells reduces diffusion distance
fenestrations allows large molecules through
small diameter gives large sa:v
narrow lumen reduces flow rate so more time for diffusion
rbc in contact w wall gives short diffusion distance
