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Biology > DNA > Flashcards

DNA Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Deoxyribonucleic acid

A

Codes for sequence if amino acid in the primary structure of a protein which in turn determine the final 3D structure

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2
Q

Bases bonds

A

AUT has two hydrogen bondin

CG has three hydrogen bonding

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3
Q

Common nuleotide Bases

A

AG - purines - base found in nucleotide has two nitrogen - containing group

CT -pyramidines - base found in nucleotides has one nitrogen - containing group

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4
Q

Mononucleotide contains

A

Phosphate group

Pentose sugar

Nitrogenous containg base

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5
Q

Structure of RNA

A

Phosphate group

Ribose sugar

AUCG

Single stranded

No hydrogen bonds

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6
Q

What is a polynucleotide

A

A polynucleotide is a polymer of mononucleotides

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7
Q

How does mononucleotide join together to form polynucleotide

A

The mononucleotdie are joined through condensation reactions between the phosphate of one mononucleotide and the sugar group of another.

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8
Q

How is DNA formed

A

The two strands of DNA double helix are held togther by hydrogen bond between the complementary base pair

These hydrogen bonds form between the amino and carboxyl groups the purines adn pyramidines bases on the opposite strand

—> 10 bases pairs for each complete twist

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9
Q

Describe the process of DNA replication

A

DNA helicase will cause the two strands of DNA to unwind by breaking the hydrogen bonds between the nitrogen bases

DNA polymerase will stimulate the free mononucleotises to align in front of the template strand according to complementary base pairs

Enzyme ligase will stimulate the formation of phosphodiester bonds between the mononucleotides on the new strand

Two strands automactically coil up through formation of hydrogen bonds forming a new DNA strand identical to the original

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10
Q

Structure of DNA

A

Double stranded

Contains hydrogen bonds

ATCG

Deoxyribose sugar

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11
Q

Structure of mRNA

A

Straight and unbranched shape

Codon

No amino binding site

No hydrogen bonds

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12
Q

Structure of tRNA

A

Clover leaf shape

Anticodon

Amino acid binding site

Has hydrogen bonds

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13
Q

Define semi conservative replication

A

When new DNA is synthesized out of the old DNA but the new DNA will have half of the original strand, and half of the free mononucleotide in the nucleus

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14
Q

Experimental evidence of melsonson and stahls DNA replication theory

A

DNA is in an N15 medium, casuing all of it to be made put of N15.

It is placed in an N14 medium and allow to replicate where half of the strands will be made out of N15 and the otehr half N14

The strand will be allowed to replicate again in teh N14 medium causing 3 quarter of them to be made out of N14 and 1 quarter of them to be made of N14 and N15

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15
Q

Explain why a triplet code is required for syntehsis of a protein

A

Since there are only 4 bases to code for 20 amino acids, if every base coded for one amino acid it wouldnt be enough. Moreover even if the code was a double code it would still only code for 16 amino acids, which is less than 20 . However if it were to use a triplet code, 64 combination would be formed which is more than enough

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16
Q

Explain the nature of a genetic code

A

Triplet code where 3 bases will code for one amino acid

Degenerate meaning each codon can code for more than one amino acid

Non over lapping each codon will be read separately and doesnt interfere with triple codins that are before it or after it

17
Q

Describe the process of ttransciption

A

Part of the DNA unwinds

RNA polymerase will stimulate free mononucleotides to align in frint of the antisense strand according to complementary base pairs to transcribe a copy of the sense strand

Enzyme ligase stimulates formatiob of phosphodiester bonds between the mononucleotides on the mRNA

mRNA detaches from the DNA antisense strand and exits the nucleus

18
Q

Describe the process of translation

A

mRNA carries a copy of genetic code from the nucleus to the ribosome for translation

tRNA attaches to the amino acid to the ribosome, tRNA has anticodon that will be complementary to the codon on mRNA

Peptide bond forms via condensatiob reaction between two amino acid

tRNA detaches from the mRNA

Ribosome moves along the mRNA molecule synthesizing a polypeptide chains until it reaches stop codon

A polypeptide chain from ribosome -> fold into 3D shape -> determine formation of protein

19
Q

Define gene mutation

A

It the change in base sequences in the DNA

20
Q

How can gene mutation be increased by

A

X-rays

Ionising radiation

Certain chemicals

21
Q

Results of mutayion

A

Mutation alter the genes they can result in a differetn amino acid sequence in the encoded polypeptide

If the amino acid sequence changes then when protein is modified into the teritary structure it will form hydorgen and ionic conds in different places and fold differently. This will result in a different 3D shape and therefore non-functioning protein

22
Q

What is insertion

A

When one extra base being added to the sequence

23
Q

Affect of insertion

A

The impact of adding one base is that all subsequent codons are altered. This is known as a frame shift . This type of mutation can be harmful because all the altered codon could potentially code for different amino acids and result in a very different polypeptide chain resulting in a non-functioning protein

24
Q

Define delection

A

Where a base is comepletely lost from the sequence

25
Q

Affect of delection

A

This causes a frame shift to the left. This causes all the codons to be altered which potentially could code for a different sequence of amino acid chain resulting in a different polypeptide chain resulting in a non-functioning protein

26
Q

Define substitution

A

Where one base substitues for another

27
Q

Affect of substitution

A

One base has been changed for a different base but the number of bases remains the same and there is no frame shift . This result in only one codon changing , due to the genetic code being degenerate it may still code for the same amino acid and therefore have no impact

28
Q

Define point mutation

A

Due to the change of ine base in one codon changes a single amino acid which results in a different polypeptide in a different primary strcutude of proteins

29
Q

Cause of sickle cell anaemia

A

Cant carry oxygen efficiently

Prevent blood flowing in the capillaries

Biology (27 decks)

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