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28 Cards in this Set
- Front
- Back
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what is a gene |
a length of DNA that codes for one or more polypeptide |
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what is a polypeptide? |
a polymer consisting of a chain of amino acids. bonded with eptide bonds |
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what is a genome? |
the entire DNA sequence of an organism. 3 billion nucleotide base pairs in humans |
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what is a protein? |
a large polypeptide structure made up of amino acids. |
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name some polypeptides in organisms |
-collagen -keratin -haemoglobin enzymes -antibodies -antigens -glycoprotein cell receptors -channel proteins -electron carriers -actin -myosin tubulin in cytoskeleton |
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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 |
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what are the 4 bases |
Adenine Guanine Cytosine Thymine |
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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 |
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describe basic stages of protein synthesis |
-transcription -translation |
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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 |
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where does translation occur? |
ribosome |
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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. |
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what are the 2 main classes of DNA mutation |
-point mutation(substitution) -insertion/deletion mutation |
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what is a mutation? |
a random change in genetic material of a cell |
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what is chromosome mutation |
involves changes in parts of or the whole chromosome |
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what is DNA Mutation? |
change in genes due to the change in nucleotide base sequence |
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what is the main feature of H Bonds |
they are weak |
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what is a DNA nucleotide made up of |
Phosphate group deoxyribose sugar nitrogeous base |
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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. |
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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 |
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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 |
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what is an allele? |
an alternate version of the same gene. same locus on chromosome but different version. |
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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. |
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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. |
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how can mutation be harmful? |
conditions like... -cystic fibrosis -sickle cell anaemia -unregulated cell division (cancel/tumour) -huntington disease-stutter, dementia |
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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 |
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what is the structure of protein? |
primary secondary tertiary quaternary |
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how do prokaryotes synthesise protein? |
they have naked loop of DNA so mRNA is produced there and then. |
