Biology Unit 5 Flashcards - Genetic control of protein structure and fuction

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What is a nucleus?
Part of a cell that contains most of the genetic information
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What is a nucleotide?
Nitrogen containing organic substances that form the bases of the nucleic acids in DNA and RNA
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What do all nucleotides contain?
Pentose sugar, phosphate groups, bases (which join with phosphate groups to form nucleotides)
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What does it mean when the genetic code is described as 'dengenerate'
Most amino acids have have more than one codon
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What are 'stop codons?'
Codons that mark the end of a polypeptide chain
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What is it called when each base sequence of DNA is only read once?
Non-overlapping
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What does it mean when the genetic code is describes as 'universal?'
The same codons code for the same amino acids in all organisms
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What is RNA?
Ribonucleic acid is a polymer made up of repeating mononucleotide sub-units
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What happens once messenger RNA is formed?
It leaves the nucleus via nuclear pores in the nuclear envelope that DNA is too big to fit through and enters the cytoplasm where it associates with ribosomes and acts as a structure for protein building
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What is tRNA?
Transfer RNA is a small molecule which is a single stranded chain folded into a clover-leaf shape so contains hydrogen bonds. Amino acids can easily attach to this area
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What happens during protein synthesis that includes tRNA?
The anticodons found on tRNA pair with 3 complementary organic bases that make up the triplet bases on mRNA
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What is 'Transcription?'
The process of making pre-mRNA using part of the DNA as a template
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What role does DNA helicase have in transcription?
It breaks the hydrogen bonds on DNA between the bases and seperates the 2 strands
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Which enzymes moves alongs the DNA strands creating complementary bases?
RNA Polymerase
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What must be reached to allow the RNA polymerase to detach from the DNA strand?
Stop codon
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Do exons or introns code for proteins?
Exons do code from proteins, introns do not
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What is the term used when introns are removed?
Splicing of pre-mRNA
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What can affect splicing and lead to a genetic disorder?
Mutations
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Explain the process of 'Translations.'
The mRNA is used a template after splicing to which completementary tRNA molecules attach and the amino acids they carry link to form a polypeptide
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What is the role of ribosomes in 'Translation?'
A ribosome becomes attached to the starting codon at one end of the mRNA molecule, it then moves along the mRNA bringing together two tRNA molecules which pair up with the corresponding two codons on the mRNA
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What is the role of DNA ligase?
Reanneals the strands of DNA
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What is a mutation?
Any change to the quantity or the structure of the DNA of an organism
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What is a nonsense mutation?
If the base change results in the formation of a stop codon, therefore the production of the polypeptide chain is stopped and proteins would not be coded for.
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What is a mis-sense mutation?
When the base change results in a different amino acid being coded for. The polypeptide produced with differ in a single amino acid which may become non-fuctional.
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What is a silent mutation?
This is when the substituted base still codes for the same amino acid so the mutation has no effect.
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What is it called when a nucleotide is lost from the normal DNA sequence?
Deletion of bases
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What happens after a base has been deleted?
A 'frame shift' occurs where the reading of the bases shift up one and the gene is now read wrong and the genetic message is altered.
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When can mutations occurs?
They can occur spontaneously during DNA replication
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What are spontaneous mutations?
Permanent changes in DNA that occur without outside influences
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What are the benefits of mutations?
They produce genetic diversity neccessary for natural selection and speciation
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What controls cell division?
Genes, either Proto-oncogenes - which stimulate cell division or Tumour suppressor genes - that slow cell division
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What affect can a mutation have on a Proto-oncogene?
Can cause it to mutate into a oncogene which can either; permanently turn on receptor protein on the cell-surface membrane so cell division in turned on or oncogene may code for a growth factor so cells divide too rapidly.
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What is a tumour suppressor gene?
Opposite roles of proto-oncogenes so inhibit cell division and prevents tumours.
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What affect can a mutation have on a Tumour suppressor gene?
It can become inactivated. Therefore it stops inhibiting cell division so this increases.
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Other cards in this set

Card 2

Front

What is a nucleotide?

Back

Nitrogen containing organic substances that form the bases of the nucleic acids in DNA and RNA

Card 3

Front

What do all nucleotides contain?

Back

Preview of the front of card 3

Card 4

Front

What does it mean when the genetic code is described as 'dengenerate'

Back

Preview of the front of card 4

Card 5

Front

What are 'stop codons?'

Back

Preview of the front of card 5
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