DNA RNA and protein systensis Flashcards

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1
Q

Describe the structure of DNA

A

a chain of nucleotides composed of dexoribose sugar, phosphate and an organic base (adenine, guanine, cytosine and thymine)

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2
Q

What are purines

A

Adenine and Guanine - double ring structures

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3
Q

What are pyrimidines

A

Thymine and Cytosine - single ring structures

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4
Q

Complementary base pairings

A

bases that will pair together to hold DNA strands together by hydrogen bonds
*cytosine - guanine
*Adenine - thymine

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5
Q

How does the structure of DNA relate to its function

A

*complementary base pairings - allows the DNA to replicate itself and copy the same information to mRNA
*weak hydrogen bonds - allow the strands to separate
*it’s compact and long - large amounts of coded information and can fit inside the nucleus of the cell

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6
Q

Describe the structure of RNA

A

a single stranded chain of nucleotides made of a ribose sugar, phosphate and a base (Adenine, Uracil, Guanine, Cytosine) held together by phosphodiester bonds

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7
Q

what are the 3 types of RNA

A

*mRNA - moves the genetic information from the inside of the nucleus to the cytoplasm
*tRNA - carries the correct amino acid into the sequence of a polynucletide
*rRNA - part of the ribosome

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8
Q

structure of mRNA

A

short single stranded chain of RNA polynucleotide

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9
Q

Structure and function of tRNA

A

structure - single stranded, cloverleaf shape, contains 2 regions : anticodons, amino acid attachmenr site
Function - the anticodons allow the tRNA to bring the correct amino acids

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10
Q

what are genes

A

a sequance of DNA that codes for the production of specifc proteins

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11
Q

What is ment by the DNA code being degenerate

A

There is more than one code for each amino acid. There are 20 amino acids and 64 possible combinations

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12
Q

What is ment by the DNA code being non-overlapping

A

Each base is present in only 1 codon

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13
Q

What is ment by the DNA code being universal

A

Each codon is the code for the same amino acid in all living organism

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14
Q

Where does transcription occur

A

in the nucleus

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15
Q

what does transcription produce

A

pre - mRNA

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16
Q

Describe the process of transcription

A

1) the hydrogen bonds between the 2 strands are broken causing the 2 strands to seperate and the nucleotide bases to be exposed
2) RNA polymers bind to the template strand at the start of the sequance, the template strand is complemetary to the coding strand
3) complementary RNA nucleotides join to the template strand and RNA polymerase moves along the template joining RNA nucleotides together with phosophodiester bonds 4
4) when the RNA polymerase reaches a STOP codon the pre-mRNA strand is released and the DNA recoils

17
Q

Describe the process of splicing

A

The removal of introns from pre-mRNA and binding of the exon ends by a spllicosome in order to make mRNA

18
Q

Where does translation occur

A

at the ribosome in the cytoplasm

19
Q

How many codons can a ribosome hold

A

2

20
Q

What is the start codon

A

AUG

21
Q

Describe the process of translation

A

1) the mRNA binds to the ribosome
2) the tRNA with the complemenatry anticodon to the mRNA codon brings a specific amino acid to the ribosome
3) a second tRNA molecule brings a second amino acid to the ribosome
4) a peptide bond is formed between the 2 amino acids
5) the ribosomes move along 1 codon and the first tRNA molecule is released back into the cytoplasm to bring another amino acid
6) the process contines untill a stop codon is reached and the polypeptide chain is released.