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28 Cards in this Set

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what is a gene

a length of DNA that codes for one or more polypeptide

what is a polypeptide?

a polymer consisting of a chain of amino acids. bonded with eptide bonds

what is a genome?

the entire DNA sequence of an organism. 3 billion nucleotide base pairs in humans

what is a protein?

a large polypeptide structure made up of amino acids.

name some polypeptides in organisms

-collagen


-keratin


-haemoglobin


enzymes


-antibodies


-antigens


-glycoprotein cell receptors


-channel proteins


-electron carriers


-actin


-myosin


tubulin in cytoskeleton

state some characteristics of the genetic code?

-triplet codes.


-4 bases. There are 20 amino acids so the four bases arranged in 3's gives more than enough combinations for amino acids.


-start and stop codes that either code for metionine or no amino acids, indicating stop


-universal throughout all organisms

what are the 4 bases

Adenine


Guanine


Cytosine


Thymine

main differences between RNA and DNA

RNA


single stranded


uracil instead of thymine


ribose sugar




DNA


double stranded helix


anitparallel


thymine instead of uracil


deoxyribose sugar

describe basic stages of protein synthesis

-transcription


-translation

describe transcription

unwind unzip dna helix (helicase enzyme break h bonds)


template strand is used


complementary base pairing (RNA Polymerase form h bonds)


formation of mRNA which is copy of the coding strand (but with uracil)


mRNA leave nuclear pore



where does translation occur?

ribosome

describe translation

-mRNA bind to ribosomes


-start codon AUG


-Transfer RNA (tRNA) with an attached methionine arrives and anticodon (UAC) form H bond which codon. Uses ATP and occurs under polymerase enzyme


-a second tRNA that has anticodon complementary to the codon arrives and binds


-peptide bond form between both amino acids, this is catalysed.


-keeps going until stop codon is translated then polypeptide is produced.



what are the 2 main classes of DNA mutation

-point mutation(substitution)


-insertion/deletion mutation

what is a mutation?

a random change in genetic material of a cell

what is chromosome mutation

involves changes in parts of or the whole chromosome

what is DNA Mutation?

change in genes due to the change in nucleotide base sequence

what is the main feature of H Bonds

they are weak



what is a DNA nucleotide made up of

Phosphate group


deoxyribose sugar


nitrogeous base

what is substitution mutation (point mutation)

when one base is replaced with anouther. e.g


CAN THE BIG RED HEN LAY ONE EGG


CAN THE BIG RED MEN LAY ONE EGG




change meaning of one amino acid. could alter the whole meaning of protein.

what is insertion mutation?

when one or more nucleotide pair is inserted/ADDED to the sequence e.g


CAN THE BIG RED HEN LAY ONE EGG


CAN ATH EBI GRE DHE NLA YON EEG G





what is deletion mutation?

when one or more nucleotide pair is deleted /REMOVED from the sequence


CAN THE BIG RED HEN LAY ONE EGG


CAN HEB IGR EDH ENL AYO NEE GG

what is an allele?

an alternate version of the same gene. same locus on chromosome but different version.

how can mutations be neutral?

amino acids are coded for by more than one combination of triplet codons. Substitution mutation in particular may have NO EFFECT as the code may still code for the same amino acid it was suppose to.




non-coding region mutations have no overall effect to the polypeptide structure.




some effects of mutations ma not be beneficial or harmful. e.g smelling honeysuckle, free lobe, roll tongue etc.

what is frameshift

it is seen in deletion/insertion mutation where all the codes following the mutation are all impacted by the mutation. rendering the code completely different from its original sequence.

how can mutation be harmful?

conditions like...


-cystic fibrosis


-sickle cell anaemia


-unregulated cell division (cancel/tumour)


-huntington disease-stutter, dementia

how can mutations be beneficial

-dark skin protect from UV


-migrate north to absorb the limited sun to produce vit D


-genetic diversity for natural selection

what is the structure of protein?

primary


secondary


tertiary


quaternary

how do prokaryotes synthesise protein?

they have naked loop of DNA so mRNA is produced there and then.