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A level biology > Nucleic acids > Flashcards

Nucleic acids Flashcards

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1
Q

What are the 2 purine bases

A

Adenine and guanine

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2
Q

What are the pyrimidine bases

A

cytosine and thymine/uracil

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3
Q

What is a nucleotide

A

monomer of nucleic acids with a pentose sugar a nitrogenous base and a phosphate group

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4
Q

What are the components of a nucleotide

A

a phosphate group
A nitrogenous base
Pentose sugar

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5
Q

what are chemoautotrophic organisms

A

Organisms that use energy from oxidation of electron donors eg bacteria

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6
Q

What is the structure of ATP

A

three phosphate groups
Base
Ribose sugar

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7
Q

What are the roles of ATP

A

metabolic processes like building proteins from amino acids
Movement - muscle contraction
Active transport -changing shape of carrier proteins

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8
Q

What are the advantages of ATP

A

only 1 enzyme is needed to release the energy in ATP
Releases energy in small amounts
Common source of energy in most chemical reactions

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9
Q

where does ATP transfer energy

A

from energy rich compounds e.g glucose to cellular reactions

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10
Q

what are the issues with energy transfer from glucose

A

energy transfers are inefficient so energy is lost through heat
energy release from glucose is uncontrollable so it would produce enough heat to destroy a cell

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11
Q

what is the structure of DNA

A

2 polynucleotide strands wound round each other to form a double helix
deoxyribose sugar and phosphate groups are on the outside of the molecule and form the backbone
the two strands are antiparalell

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11
Q

how many hydrogen bonds are between cytosine and guanine

A

3

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12
Q

how many hydrogen bonds are between adenine and thymine

A

2

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13
Q

why is DNA suited for its functions

A

it is a large molecule so it carries alot of genetic info
two strands can seperate as they are held together by hydrogen bonds
backbone protects the genetic information inside

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14
Q

what is the structure of RNA

A

a single polynucleotide
contains the sugar ribose
has uracil instead of thymine

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15
Q

what are the 3 types of RNA

A

messenger-mRNA
transport-tRNA
ribosomal-rRNA

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16
Q

What is mRNA

A

synthesised in the nucleus and carries genetic code from DNA to ribosomes in the cytoplasm

17
Q

what is rRNA

A

found in cytoplasm and made up of large complex molecules
made up of proteins and ribosomal rna
site of translation of genetic code onto protein

18
Q

what is tRNA

A

transfer RNA
small single stranded molecule that folds so that base sequences form complementary pairs
carries the anticodon
transports specific amino acids to the ribosomes in protein synthesis

19
Q

what is an anticodon

A

groupf of three bases on a tRNA molecule that corellates with the specfic amino acid being carried

20
Q

what is the functions of DNA

A

replication and protein synthesis

21
Q

when is DNA replicated

A

during interphase in the nucleus

22
Q

what is conservative replication

A

parental double helix remains intact and a whole new double helix is made

23
Q

what is semi conservative replication

A

parental double helix seperates into 2 strands which each act as a template for a new strand

24
Q

What is dispersive replication

A

two new double helicies contain fragments from both strands of the parental double helix

25
Q

What is a gene

A

a section of DNA on s chromosone which codes for a specific polypeptide

26
Q

What are the characteristics of the genetic code

A

three bases encode each amino acid so the code is a triplet code
Stop codons
Code is universal
Non overlapping because each base only occurs in one triplet

27
Q

What is an Extron

A

coding region in the nucleotide sequence of DNA and pre-mRNA that remains present in the final nature mRNA after introns removed

28
Q

What is an intron

A

non coding nucleotide sequence in DNA and pre mRNA that is removed from pre MRNA to produce mature mRNA

29
Q

What happens in translation

A

the sequence of codons on the mRNA is is used to generate a specific sequence of amino acids forming a polypeptide

30
Q

Where does translation occur

A

on a ribosome

30
Q

What is each ribosome made up of

A

two subunits
Larger one has two sites of attachment of tRna molecules
Smaller subunit binds to mRNA

31
Q

What are the three stages of translation

A

initiation
Elongation
Termination

32
Q

what happens in initation

A

a ribosome attaches to start codon at one end of the mRNA molecule

33
Q

what happens in elongation

A

the two amino acids are sufficiently close for a ribosomal enzyme to catalyse the formation of a peptide bonds between them

34
Q

what happens in termination

A

sequence repeats until a stop codon is reached

35
Q

what is amino acid activation

A

once tRNA is released from the ribosome it is free to collect another amino acid from the cytoplasm ,
energy from ATP is needed to attach the amino acid to the tRNA

36
Q

what is post translational modification

A

polypeptides on the ribosome are are transported through the cytoplasm to the golgi and can be folded in to secondary, tertiary or quaternary structure
e.g haemoglobin- 4 polypeptides combined

37
Q

what are the functions of proteins in living organisms

A

hormones, enzymes,antibodies

38
Q
A

A level biology (10 decks)

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